U.S. patent application number 14/575539 was filed with the patent office on 2015-07-16 for rope pre-failure warning indicator system and method.
This patent application is currently assigned to SlingMax, Inc.. The applicant listed for this patent is SlingMax, Inc.. Invention is credited to Gregory D'ELIA, Scott ST. GERMAIN.
Application Number | 20150197408 14/575539 |
Document ID | / |
Family ID | 53520737 |
Filed Date | 2015-07-16 |
United States Patent
Application |
20150197408 |
Kind Code |
A1 |
ST. GERMAIN; Scott ; et
al. |
July 16, 2015 |
ROPE PRE-FAILURE WARNING INDICATOR SYSTEM AND METHOD
Abstract
A pre-failure indicator system for determining a degradation or
failure condition includes a rope having an elongated structural
strand and a pre-failure indicator strand. The pre-failure
indicator strand has a tensile strength less than a tensile
strength of the structural strand. The pre-failure indicator strand
constructed of a conductive wire. The pre-failure indicator strand
is configured to fail when the rope is subject to tension that
exceeds the tensile strength of the structural strand. An indicator
generates a detectable signal when the pre-failure indicator strand
fails. A transceiver detects the detectable signal. The transceiver
is configured to transmit a warning upon receipt of the detectable
signal.
Inventors: |
ST. GERMAIN; Scott; (Aston,
PA) ; D'ELIA; Gregory; (Aston, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SlingMax, Inc. |
Aston |
PA |
US |
|
|
Assignee: |
SlingMax, Inc.
Aston
PA
|
Family ID: |
53520737 |
Appl. No.: |
14/575539 |
Filed: |
December 18, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61927744 |
Jan 15, 2014 |
|
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|
Current U.S.
Class: |
340/668 |
Current CPC
Class: |
G01M 5/0033 20130101;
D07B 1/148 20130101; B65H 63/02 20130101; G01N 2203/0664 20130101;
G01M 5/0025 20130101; D07B 1/145 20130101; G01M 11/086
20130101 |
International
Class: |
B65H 26/02 20060101
B65H026/02; B65H 63/02 20060101 B65H063/02 |
Claims
1. A pre-failure indicator system for determining a degradation or
failure condition, the pre-failure indicator system comprising: a
rope having an elongated structural strand and a pre-failure
indicator strand, the pre-failure indicator strand comprised of a
conductive wire and configured to fail when the rope is subject to
tension that is less than the tensile strength of the structural
strand; an indicator that generates a detectable signal when the
pre-failure indicator strand fails; and a transceiver that detects
the detectable signal, the transceiver configured to transmit a
warning upon receipt of the detectable signal.
2. The pre-failure indicator system of claim 1, wherein the
structural strand is comprised of a plurality of structural
strands.
3. The pre-failure indicator system of claim 1, wherein the
conductive wire is comprised of a multiple conductive wires.
4. The pre-failure indicator system of claim 1, wherein the
conductive wire is constructed of a metal.
5. The pre-failure indicator system of claim 4, wherein the metal
is comprised of one of copper and silver.
6. The pre-failure indicator system of claim 1, wherein the
indicator includes an electrical signal generator and the
detectable signal comprises an electrical signal.
7. The pre-failure indicator system of claim 1, wherein the
conductive wire is constructed one of carbon fibers and a
conductive polymeric material.
8. The pre-failure indicator system of claim 1, wherein the
conductive wire includes a first end and a second end, a first
terminal connected to the first end and a second terminal connected
to the second end.
9. The pre-failure indicator system of claim 8, wherein the first
terminal includes a first electronic signal transmitter, a first
electronic signal receiver and a first electronic signal
transceiver.
10. The pre-failure indicator system of claim 1, wherein the
conductive wire is constructed of a material designed and
configured to degrade at a faster rate than the structural strand
based on exposure an environmental factor, the environmental factor
selected from the group consisting of ultraviolet radiation,
abrasion and dry rot.
11. The pre-failure indicator system of claim 1, further
comprising: a time-domain reflectometry ("TDR") device associated
with a first terminal of the rope, the TDR device configured to
send a pulse signal into the pre-failure indicator strand and sense
a time until a return pulse is received at the TDR device, the time
being recorded.
12. A pre-failure indicator system for determining a degradation or
failure condition, the pre-failure indicator system comprising: a
multiple rope unit including a plurality of ropes, a first rope of
the plurality of ropes including a pre-failure indicator strand
having a tensile strength less than a tensile strength of the
multiple rope unit such that the pre-failure indicator strand fails
when the multiple rope unit is subject to tension that exceeds the
tensile strength of the pre-failure indicator strand before the
multiple rope unit fails, the pre-failure indicator strand
comprised of a conductive wire; an indicator that generates a
detectable signal associated with the pre-failure indicator strand;
and a transceiver that detects the detectable signal and transmits
a warning upon receipt of the detectable signal.
13. The pre-failure indicator system of claim 12, wherein the
plurality of ropes also includes a second rope and a third
rope.
14. The pre-failure indicator system of claim 12, wherein each of
the plurality of ropes is constructed of a material selected from
the group consisting of synthetic fibers, natural fibers and a
combination of synthetic and natural fibers, each of the plurality
of ropes including a plurality of structural strands.
15. The pre-failure indicator system of claim 12, wherein the
conductive wire is constructed of a metallic material.
16. A pre-failure indicator system for determining a degradation or
failure condition, the pre-failure indicator system comprising: a
rope including a plurality of structural strands and a pre-failure
indicator strand, the pre-failure indicator strand having a tensile
strength less than a tensile strength of the structural strands
such that the pre-failure indicator strand fails when the rope is
subject to tension that exceeds the tensile strength of the
pre-failure indicator strand, the pre-failure indicator strand
comprised of a conductive wire having a first end and a second end;
a first signal source connected to the first end and configured to
impart a signal into the conductive wire; a signal detector
connected to the conductive wire and configured to detect the
signal and convert the signal; and a signal transmitter in
communication with the signal detector, the signal transmitter
configured to transmit the converted signal.
17. The pre-failure indicator system of claim 16, wherein the
structural strands are constructed from a material selected from
the group consisting of natural fibers, synthetic fibers and a
combination of natural and synthetic fibers.
18. The pre-failure indicator system of claim 16, wherein the
conductive wire is constructed of a metallic material.
19. The pre-failure indicator system of claim 16, wherein the
signal is comprised of an electric current.
20. The pre-failure indicator system of claim 16, wherein the
signal source is selected from the group consisting of signal
generator, an analog signal generator, a function generator, a
microwave signal generator, a pitch generator, an arbitrary
waveform generator and a frequency generator.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 61/927,744, filed on Jan. 15, 2014, entitled
"Rope Pre-Failure Warning Indicator Systems," the entire contents
of which are incorporated herein by reference in their
entirety.
FIELD OF THE INVENTION
[0002] The preferred invention relates generally to a system for
warning when a rope is about to fail and, more particularly,
relates to wired-, RFID-, and fiber optic-based warning indicators
that notify users or bystanders of the rope of a condition that, if
not mitigated, may lead to failure of the rope or notify of
imminent failure of the rope.
BACKGROUND OF THE INVENTION
[0003] Rope has many purposes, including recreational and
industrial usages. Ropes come in many varieties and lengths and may
be made of natural or synthetic fibers. The length, material, and
strength of a given rope may be tailored to the particular
applications for which the rope may be used. Heavy duty
applications of rope include ship mooring and towing, industrial
rigging and hoisting, and winching.
[0004] Heavy duty applications require large, often long ropes with
high working load limits and high tensile strength. The working
load limit of a rope relates to the maximum load capacity under
which the rope should be used. The tensile strength of a rope
relates to the amount of force required to break the rope. The
working load limit and tensile strength are generally highest
immediately after manufacture, before the rope is used.
[0005] As a rope ages as a result of exposure to environmental
factors, the fibers that make up the rope may become dry, may rot
or may otherwise have their strength, elasticity or other
structural features degraded, thereby weakening both the working
load limit and the tensile strength of the rope. In addition, as
the rope is used, it may become subject to abrasion, cuts or other
environmental factors to its fibers, which also weaken the working
load limit and tensile strength of the rope. Other environmental
factors that may weaken the working load limit and tensile strength
of the rope include poor maintenance, ultraviolet radiation
exposure, bending, kinks, knots, wear, fatigue, retention of water,
and other related environmental factors. Individually or
cumulatively, such conditions may lead to unexpected failure of the
rope when the rope is in use. The likelihood of failure may be
enhanced during initial acceleration and inertia, for example, at
the initiation of a lifting operation.
[0006] Often, damage to rope fibers and yarns may not be detected,
noticed, or raise significant concern because, for example, the
length of the rope, the damage is internal, the localized damage
appears to be minimal, and/or the environment where the rope is
located (e.g., the rope is used under water as a mooring line).
Yet, even minimal damage, in the aggregate, can set the stage for
unexpected and catastrophic rope failure when the rope is exposed
to excessive tension. If the damage is significant enough, on the
whole, the load carrying capacity of the rope is likely less than
the tensile strength of the rope before it was damaged. Rope
failure may result in snap back, which can have numerous
significant negative consequences for operators, users, technicians
and third parties associated with the rope.
[0007] Rope snap back is a dangerous condition, and, for example,
may lead to serious injury and even death to individuals located
proximate the rope during a failure and snap back condition. Heavy
duty uses of ropes are generally accompanied by high tension on the
rope. If the rope, breaks while the rope is under high tension,
each parted portion of the rope may rapidly and violently whips
away from the break point. A large, heavy rope moving at snap back
velocity can produce severe blunt force trauma to any individual in
its path. Indeed, snap back is recognized as one of the biggest
hazards to deckhands on ships. Particularly as concerns ship
mooring and tugging, excessive tension applied to a rope caused by
sudden changes in wind, tide, waves/wake, and water currents,
coupled with an aging or damaged rope can set the stage for a
hazardous condition.
[0008] There is a need in the art for ways to identify an imminent
or potential rope failure or over-stress condition on a rope. An
advanced warning that a rope is near its breaking point should
provide operators of the rope with an opportunity to take
corrective action. An advanced warning may allow individuals in the
snap back zone of the rope to clear out of the way before the rope
breaks. An advanced warning system will enhance safety of high
tension rope operation. An advanced warning system will also
provide a technician with an opportunity to repair and/or replace
an over-stressed or damaged rope before failure occurs such that
damage to personnel and equipment associated with the rope can be
avoided.
BRIEF SUMMARY OF THE INVENTION
[0009] The disclosure features systems that indicate whether a rope
is damaged, stressed, subject to excessive tension or is otherwise
potentially damaged, and provides an advanced warning of a
potential failure or breakage of the rope. In general, the rope
systems comprise one or more ropes, including multiple rope units
in which more than one of the ropes are used together to enhance
the overall working load limit and tensile strength, with at least
one rope comprising one or more pre-failure indicator strands that
have a tensile strength that is less than the tensile strength of
the rope or multiple rope unit system on the whole. Because one or
more or pre-failure indicator strands have a lower tensile
strength, relative to the tensile strength of the rope or rope
units, one or more of these strands become compromised or otherwise
break when the rope or the multiple rope unit is subject to tension
that exceeds the tensile strength of the one or more pre-failure
strands. The one or more pre-failure indicator strands comprise an
indicator that provides information about the state of the strands,
and by proxy, the state of the rope.
[0010] The rope may comprise natural materials, synthetic
materials, or a hybrid of natural and synthetic materials. The
fibers or strands of the rope, including structural strands and
pre-failure warning indicator strands, generally comprise such
materials. The one or more pre-failure indicator strands may
comprise materials that are capable of being degraded by
environmental factors, such as exposure to ultraviolet radiation
(e.g., from the sun) at a faster rate than the natural or synthetic
materials from which the structural strands or units of the rope
are fabricated. The one or more pre-failure indicator strands may
also comprise materials that are capable of being degraded by
abrasion (e.g., by dirt or grit or by use of the rope or the rope
coming into contact with various surfaces that may abrade the rope)
at a faster rate than the natural or synthetic materials from which
the structural strands of the rope are fabricated. The one or more
pre-failure indicator strands may further comprise materials that
are capable of being degraded by environmental factors, such as
exposure to ultraviolet radiation or other environmental conditions
(e.g., from exposure to the elements, and advanced age) at a faster
rate than the natural or synthetic materials of which the
structural strands of the rope are fabricated. The one or more
pre-failure indicator strands may also comprise materials that are
capable of being fatigued (e.g., from mechanical movement of the
rope over time) at a faster rate than the natural or synthetic
materials out of which the structural strands of the rope are
fabricated.
[0011] The preferred indicator may generate a detectable signal.
The indicator may comprise a dye that is released when one or more
of the strands become compromised or otherwise break. Thus, a dye
may comprise a detectable signal. The detectable signal may
comprise a radio frequency signal, an electrical signal, or a light
signal. The systems also may comprise a detector that detects the
detectable signal and the detector may comprise a transceiver that
detects the detectable signal, determines whether the one or more
pre-failure indicator strands has broken based on the presence or
the absence of the detectable signal, and transmits a warning or
alarm if the one or more pre-failure indicator strands has broken.
The warning may comprise a warning signal. The alarm may comprise
an audible alarm, a visible alarm, and/or a tactile alarm upon the
overstressing of the rope or breakage of the indicator strand. The
transceiver may emit the alarm, or may signal an alarm generator to
emit the alarm.
[0012] In some aspects, the indicator comprises a radio frequency
identification ("RFID") tag. The RFID tag may be an active RFID tag
that includes a power source that allows the tag to generate a
detectable signal. The RFID tag may be a passive or semi-passive
RFID tag that generates a detectable signal upon coming into
contact with a signal generated from an RFID detector that powers
the RFID tag components in order to generate the detectable signal.
The detector and/or transceiver may thus comprise an RFID signal
detector. In aspects in which an active RFID tag is used, the one
or more pre-failure indicator strands preferably comprise a shield
that blocks the detectable signal generated from the active RFID
tag. Thus, although the RFID signal is substantially continuously
generated, the signal is not detected when it is blocked by the
shield. The absence of the RFID signal indicates that the one or
more pre-failure indicator strands have maintained their integrity.
But when the one or more pre-failure indicator strands become
compromised or break, the shield also breaks such that the RFID
signal is no longer blocked, and may be freely detected. The
presence of an unshielded, detectable RFID signal indicates that
the one or more pre-failure indicator strands have lost their
integrity.
[0013] In some aspects, the one or more pre-failure indicator
strands comprises a conductive wire and the indicator comprises an
electrical signal generator. The electrical signal may comprise an
electrical current, an analog signal, a digital signal, any
combination of an electrical current, an analog signal or a digital
signal and nearly any variety of signal that may be transmitted and
detected upon over-stress or breakage of strands and/or fibers of
the rope. The detector and/or transceiver may thus comprise an
electrical signal detector. The electrical signal is preferably
generated by the electrical signal generator, traverses the
conductive wire, and is detected by the electrical signal detector.
The presence of the electrical signal indicates that the one or
more pre-failure indicator strands have maintained their integrity,
however, when the one or more pre-failure indicator strands become
compromised or break, the electrical signal can no longer traverse
the conductive wire and can no longer be detected. The absence of
the electrical signal indicates that the one or more pre-failure
indicator strands have lost their integrity.
[0014] In some aspects, the one or more pre-failure indicator
strands comprise one or more fiber optic cables and the indicator
comprises a light source. The one or more fiber optic cables may
comprise a simplex or a duplex arrangement. The detector and/or
transceiver may thus comprise a light detector. The light is
generated by the light source, traverses the one or more fiber
optic cables, and is detected by the light detector. The presence
of the light signal indicates that the one or more pre-failure
indicator strands have maintained their integrity, but when the one
or more pre-failure indicator strands become compromised or break,
the light signal can no longer traverse the one or more fiber optic
cables and can no longer be detected. The absence of the light
signal indicates that the one or more pre-failure indicator strands
have lost their integrity. In addition, if the fiber optic cable
becomes partially damaged or compromised at a particular location,
the light signal changes, the light detector may detect the change
in the light signal and provide an indication that the fiber optic
cable is damaged or partially damaged.
[0015] In some aspects, the one or more pre-failure indicator
strands comprises one or more tubes or a plurality of pouches and
the indicator comprises a dye. The dye may comprise a colored dye
and may comprise an ultraviolet dye. The dye is enclosed within the
one or more tubes or the pouches. Upon release from the enclosure,
the dye permeates the rope fibers and reaches the external surface
of the rope, where it can be detected. The absence of the dye on
the rope surface indicates that the one or more pre-failure
indicator strands have maintained their integrity, but when the one
or more pre-failure indicator strands become compromised or break,
the dye may be detected. The presence of the dye on the rope
surface indicates that the one or more pre-failure indicator
strands have lost their integrity.
[0016] The invention also features methods for detecting whether a
rope is damaged, stressed, or subject to excessive tension. In
general, the methods comprise determining whether one or more
pre-failure indicator strands of a rope have broken by detecting
the presence or the absence of a detectable signal generated by an
indicator operably connected to the one or more pre-failure
indicator strands. The methods may further comprise taking remedial
action to avoid failure of the rope. The methods may further
comprise producing an audible alarm, a visible alarm, and/or a
tactile alarm if it is determined that one or more pre-failure
indicator strands of the rope have broken.
[0017] The methods may be used in accordance with any of the ropes,
multiple rope units, or pre-failure indicator systems described or
exemplified herein. For example, the method steps may be carried
out through the structural components of the ropes and the systems.
These structural components include any of the structures described
or exemplified herein. In accordance with the methods, the
detectable signal may comprise the release of an indicator dye, or
may comprise an electrical signal, or may comprise a light
signal.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0018] The foregoing summary, as well as the following detailed
description of the invention, will be better understood when read
in conjunction with the appended drawings. For the purpose of
illustrating the invention, there are shown in the drawings
embodiments which are presently preferred. It should be understood,
however, that the invention is not limited to the precise
arrangements and instrumentalities shown. In the drawings:
[0019] FIG. 1 is a front elevational view of a rope pre-failure
indicator system in accordance with a first preferred embodiment of
the present invention, wherein a portion of a rope is shown with
cross-sections taken along a longitudinal plane of the rope and at
one end at a plane substantially perpendicular to the longitudinal
axis of the rope;
[0020] FIG. 2A is front elevational view of the rope pre-failure
indicator system of FIG. 1 with a different arrangement of RFID
tags and wherein cross-sections are taken along a longitudinal
plane of the rope and at one end at a plane substantially
perpendicular to the longitudinal axis of the rope;
[0021] FIG. 2B is a front elevational view of a rope pre-failure
indicator system in accordance with a second preferred embodiment
of the present invention, wherein a portion of a rope is shown with
cross-sections taken along a longitudinal plane of the rope and at
one end at a plane substantially perpendicular to the longitudinal
axis of the rope;
[0022] FIG. 2C is a front elevational view of a rope pre-failure
indicator system in accordance with a third preferred embodiment of
the present invention, wherein a portion of a rope is shown with
cross-sections taken along a longitudinal plane of the rope and at
one end at a plane substantially perpendicular to the longitudinal
axis of the rope;
[0023] FIG. 2D is a front elevational view of a rope pre-failure
indicator system in accordance with a fourth preferred embodiment
of the present invention, wherein a portion of a rope is shown with
cross-sections taken along a longitudinal plane of the rope and at
one end at a plane substantially perpendicular to the longitudinal
axis of the rope;
[0024] FIG. 3 is a front elevational view of a portion of a
multiple-rope unit in accordance with a fifth preferred embodiment
of the present application, including RFID tags in accordance with
the first preferred embodiment of the present invention;
[0025] FIG. 4 is a front elevational view of the portion of the
multiple-rope unit of FIG. 3, including RFID tags in accordance
with the first preferred embodiment of the present invention;
[0026] FIG. 5 is a front elevational view of the portion of the
multiple-rope unit of FIG. 3, including a fiber optic cable in
accordance with the second preferred embodiment of the present
invention;
[0027] FIG. 6 is a front elevational view of the portion of the
multiple-rope unit of FIG. 3, including a conducting wire in
accordance with the third preferred embodiment of the present
invention; and
[0028] FIG. 7 is a front elevational view of the portion of the
multiple-rope unit of FIG. 3, including indicator dye in accordance
with the fourth preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0029] Various terms relating to aspects of the disclosure are used
throughout the specification and claims. Such terms are to be given
their ordinary meaning in the art, unless otherwise indicated.
Other specifically defined terms are to be construed in a manner
consistent with the definition provided herein.
[0030] Certain terminology is used in the following description for
convenience only and is not limiting. Unless specifically set forth
herein, the terms "a", "an" and "the" are not limited to one
element but instead should be read as meaning "at least one". The
words "right," "left," "lower," and "upper" designate directions in
the drawings to which reference is made. The words "inwardly" or
"distally" and "outwardly" or "proximally" refer to directions
toward and away from, respectively, the geometric center or
orientation of the device and related parts thereof. The
terminology includes the above-listed words, derivatives thereof
and words of similar import.
[0031] The disclosure relates to systems and methods for
determining whether rope failure is imminent, for example, because
the rope is overloaded or is under excessive tension. Foundational
features include radio frequency identification tags, fiber optics,
conductive wires, and sensors that convey information about the
condition of the rope to a user.
[0032] Referring to FIG. 1, a rope pre-failure indicator system 10a
for a single rope in accordance with a first preferred embodiment
of the present invention is illustrated. The first preferred
pre-failure indicator system 10a includes a rope 20 having
structural strands 22 of nearly any type. The rope 20 may be
comprised of a plurality of structural strands 22 that may be
constructed of any suitable number of yarns and fibers fabricated
from any suitable natural or synthetic material or a combination of
natural and synthetic materials. The rope 20 is not limited to
including the plurality of structural strands 22 and may include a
single elongated structural strand 22 that is designed and
configured to carry a tensile load of a predetermined capacity. The
structural strand 22 has a longitudinal axis that extends through
the strand 22 from a first end to a second end. The longitudinal
axis of the structural strand 22 generally follows a centerline of
the structural strand 22 and/or rope 20 and may bend or arc if the
strand 22 and/or rope 20 is positioned in a bent or arced position,
such as the positions and/or orientations of the strands 22 in
FIGS. 3-7. The rope 20 and structural strands 22 may have any
working load limit and any tensile strength. In preferred
configurations, the strands 22 may have a working load limit in the
approximate range of one thousand (1,000) to one million pounds
(1,000,000) and a tensile strength in the approximate range of five
thousand (5,000) to five million (5,000,000) pounds, but are not so
limited. The strands 22 may have nearly any working load limit
and/or tensile desired by the designer and/or user, for example,
the strands 22 may have a maximum breaking load greater than five
million (5,000,000) pounds for certain offshore mooring
applications. The system 10a and methods are useful, among other
things, for mooring, lifting, winching, and hoisting applications,
or any other applications in which snap back is a concern. Each of
the systems 10a, 10b, 10c, 10d, 10f of the preferred embodiments
are also useful, among other things, for mooring, lifting,
winching, and hoisting applications, or any other applications in
which snap back or nearly any variety of failure of the rope 20 is
a concern.
[0033] The rope 20 may be comprised of natural fibers (e.g., hemp,
jute, or other suitable natural material) or synthetic fibers
(e.g., polyester, polyethylene, nylon, K-Spec.RTM. (Slingmax,
Inc.), high-modulus polyethylene ("HMPE"), liquid crystal polymer
("LCP"), aramid, para-aramid, or other suitable synthetic material)
or a combination of any suitable proportion of natural fibers and
synthetic fibers. The rope 20 may be comprised of any suitable
number of such structural strands 22. The fibers of the structural
strands 22 may be comprised in a yarn. A plurality of yarns may be
assembled to comprise a strand 22. A plurality of strands 22 may be
assembled to comprise the rope 20. The rope 20 may comprise any
structure (e.g., laid, wound, braided, plaited). The rope 20 may
comprise a core of a plurality of structural strands 22 and an
outer sheath comprising a plurality of structural strands 22. The
rope 20 may have any length.
[0034] The rope preferably includes one or more pre-failure
indicator strands 30. The one or more pre-failure indicator strands
30 preferably are integral of interwoven with the structural
strands 22 that together comprise the rope 20, but in some aspects,
the one or more pre-failure indicator strands 30 are external to
the main body of the rope 20 or a bundle of structural strands 22.
In some aspects, the one or more pre-failure indicator strands 30
comprise a core of the rope 20 around which the plurality of
structural strands 22 are wrapped. The one or more pre-failure
indicator strands 30 may comprise a plurality of interwoven fibers
that together constitute a yarn, with a plurality of yarns
interwoven together to constitute the strand 30. The one or more
pre-failure indicator strands 30 need not be the same size or have
the same make-up as the structural strands 22 that make up the rope
20, such that the one or more pre-failure indicator strands 30 may
be a substructure of the rope 20, or may be made of a different
material, or a different number of fibers, or a different number of
yarns, or have different properties relative to the structural
strands 22 that make up the rope 20. In some aspects, the one or
more pre-failure indicator strands 30 may be substantially
identical to the structural strands 22, except the one or more
pre-failure indicator strands 30 may be pre-damaged in order that
they may fail at a tension that is less than the tensile strength
rating of the rope 20. For example, in a preferred configuration,
the structural strands 22 may be designed and configured to fail at
a load of approximately two hundred thousand pounds (200,000 lbs)
and the indicator strand 30 may be designed and configured to fail
at a load of one hundred sixty thousand pounds (160,000 lbs) or
approximately eighty percent (80%) of the failure load of the
structural strands 22. The structural strands 22 and indicator
strand 30 are not limited to such a ratio or to such failure loads,
but the described ratio and failure loads comprise a non-limiting
preferred configuration that a designer or user may desire.
[0035] In some aspects, the one or more pre-failure indicator
strands 30 comprise a material that degrades under exposure to
environmental factors, such as ultraviolet light/radiation at a
rate that is faster than the structural strands 22 of the rope 20
degrade under ultraviolet light/radiation. In some aspects, the one
or more pre-failure indicator strands 30 comprise a material that
degrades under abrasive forces at a rate that is faster than the
structural strands 22 degrade under abrasive forces. In some
aspects, the one or more pre-failure indicator strands 30 comprise
a material that dries or dry rots at a rate that is faster than the
structural strands 22 dry or dry rot. In other preferred aspects,
the one or more pre-failure indicator strands 30 comprise a
material that fatigues at a rate that is faster than the structural
strands 22 fatigue.
[0036] The one or more pre-failure indicator strands 30 may be
positioned at any suitable location among the structural strands
22, including substantially near the center of the rope 20,
substantially near the edge of the rope 20 or at any other position
between the center and edge of the rope 20. The one or more
pre-failure indicator strands 30 may also be located at a position
to best identify interior fatigue or damage to the rope 20. The one
or more pre-failure indicator strands 30 may span substantially the
entire length of the rope 20 or may be positioning in the rope 20
at predetermined lengths or portions, for example, where failure of
the rope 20 is expected or frequent or where the rope 20 is
typically fatigues, degraded, damaged, abraded or otherwise has a
tendency or history of failure. In addition, the pre-failure
indicator strands 30 may be positioned at locations on the rope 20
where visual inspection is difficult or impossible and the
pre-failure indicator strands 30 may be monitored via non-visual
mechanisms and methods, as described herein.
[0037] In the preferred embodiments, the one or more pre-failure
indicator strands 30 have a tensile strength that is less than the
tensile strength of the structural strands 22, such that the one or
more pre-failure indicator strands 30 breaks at a rope tension that
is less than the tension under which the rope 20 itself will break.
The tensile strength of the one or more pre-failure indicator
strands 30 may be at or slightly above the working load limit of
the structural strands 22 and substantially below the tensile
strength of the structural strands 22. The tensile strength of the
one or more pre-failure indicator strands 30 preferably lies
between the working load limit and the tensile strength of the
structural strands 22 on the whole, such that the one or more
pre-failure indicator strands 30 will break before the rope 20
itself breaks. For example, in a preferred configuration, the rope
20 may comprise a three-strand rope 20 having a maximum load of two
hundred thousand pounds (200,000 lbs), wherein the two structural
strands 22 have a tensile strength of seventy-one thousand pounds
(71,000 lbs) and the single indicator strand 30 has a tensile
strength of fifty-eight thousand pounds (58,000 lbs), wherein the
rope 20 may be constructed of a high-modulus polyethylene ("HMPE")
material. The one or more pre-failure indicator strands 30 may
indicate upon failure or damage that the rope 20 is stressed such
that corrective action or clearance of the snap back zone or other
zone in the vicinity of the rope 20 may be undertaken in advance of
failure of the rope 20. In addition, failure or damage to the
pre-failure indicator strands 30 may indicate that replacement or
repair of the rope 20 is necessary or that inspection of the rope
20 is necessary before additional significant loads are applied to
the rope 20.
[0038] The one or more pre-failure indicator strands 30 are
preferably operably connected to an indicator that generates a
detectable signal or is otherwise capable of generating a
detectable signal. The one or more pre-failure indicator strands 30
may comprise a conduit for this detectable signal such that the
detectable signal may traverse the one or more pre-failure
indicator strands 30.
[0039] In the first preferred embodiment, as shown in FIG. 1, the
one or more pre-failure indicator strands 30 includes a plurality
of RFID tags 40 attached thereto or integrated therein. Each RFID
tag 40 is capable of generating a detectable signal, for example,
an RFID signal such as a radio wave. The first preferred embodiment
is not limited to including RFID tags 40, as the RFID tags 40 may
be comprised of nearly any type or variety of wireless radio
technology that transmits or is configured to transmit a signal
when desired by the designer. The one or more pre-failure indicator
strands 30 may include a plurality of passive RFID tags 40 attached
to the pre-failure indicator strands 30. The passive RFID tag 40
typically does not include its own power source, but may include
components that generate a current to power the RFID tag 40 when
such components are brought into proximity of emissions from an
RFID transceiver 42. The one or more pre-failure indicator strands
30 may include a plurality of semi-passive RFID tags 40, which
preferably include their own power source, but the power source
does not drive signal transmission from the RFID tag 40. The one or
more pre-failure indicator strands 30 may include a plurality of
active RFID tags 40. An active RFID tag 40 includes a power source,
preferably a battery, to power the RFID tag 40 and transmit the
signal. The active RFID tag 40 preferably transmits a continuous
signal. As shown in FIG. 2A, the one or more pre-failure indicator
strands 30 may include one or more elongate RFID tags 40, which
extend over significant lengths of the pre-failure indicator
strands 30.
[0040] The one or more pre-failure indicator strands 30 may include
a shield 44 that blocks the RFID tag 40 signal, such that the
signal may only be detected when the shield 44 is compromised,
thereby indicating that the one or more pre-failure indicator
strands 30 are also compromised, with a compromised pre-failure
indicator strand 30 indicating that the rope 20 is stressed,
including that the rope 20 is under excessive tension, including
tension that exceeds the tensile strength of the one or more
pre-failure indicator strands 30 or that failure of the rope is
approaching or is imminent. The shield 44 may comprise aluminum,
shielding polymeric materials or other suitable materials that are
known in the art as capable of blocking an RFID signal. When the
shield 44 is compromised and at least one of the RFID tags 40 is
not compromised, the RFID signal is no longer blocked such that the
RFID tag 40 may still transmit the signal, which may freely pass
through the compromised shield 44 and thereafter be detected by the
RFID signal transceiver 42. Compromised, as used herein, includes,
but is not limited to cracking, breaking, rupturing, fragmenting,
damaging, severing, and other forms of damage. The rope pre-failure
indicator system 10a of the first preferred embodiment also
includes an RFID signal transceiver 42.
[0041] The RFID signal transceiver 42 may transmit a signal that
activates a passive RFID tag 40 in order that the passive RFID tag
40 may transmit its signal. The RFID signal transceiver 42 may
receive the signal from a passive or active RFID tag 40. In some
aspects, when the RFID signal, formerly blocked by the shield 44,
is freed by a compromised shield 44, the RFID signal transceiver 42
receives the signal from the RFID tag 40. Receipt of the RFID
signal indicates that the one or more pre-failure indicator strands
30 at least is compromised and may have broken. The RFID signal
transceiver 42 may then warn a user and/or individuals in the
vicinity of the rope 20 or its snap back zone, through an audible
alarm, a visible warning, and/or a tactile alarm such as vibration.
The RFID signal transceiver 42 may itself issue the warning or
alarm or may cause a separate device to issue the warning or alarm
or the recipient of a warning message from the RFID signal
transceiver 42 may issue the warning or alarm. Having received the
warning signal, alarm or warning message, the user may take
corrective action and/or any individual in a danger area may
extricate themselves from the area.
[0042] Referring to FIG. 2B, in an alternative or second preferred
embodiment of a rope pre-failure indicator system 10b, the one or
more pre-failure indicator strands 30 may be comprised of, in
addition to or in lieu of RFID tags 40, one or more fiber optic
cables 50 (FIG. 2B). The one or more pre-failure indicator strands
30 may be one or more fiber optic cables 50. The one or more fiber
optic cables 50 transmit light between a first terminal 54a, which
is preferably positioned at a first end of the rope 20, and a
second terminal 54b, which is preferably positioned at a second end
of the rope 20. The first and second terminals 54a, 54b are
operably connected to the ends of each fiber optic cable 50 that
may be included in the rope 20. The first and second terminals 54a,
54b are not limited to being connected to or positioned at the ends
of the rope 20 and may be positioned at any location between ends
of the rope 20, for example, at opposite sides of a location on the
rope 20 wherein failure, damage and/or fatigue are expected to
occur or likely to occur on the rope 20. In addition, the first and
second terminals 54a, 54b may be positioned at opposite sides of a
portion of the rope 20 that is located where visual inspection of
the rope 20 is difficult or impossible to monitor the integrity of
the rope 20 in such locations.
[0043] A detectable signal transmitted through the fiber optic
cable 50 may comprise light. The terminals 54a, 54b may transmit
and/or receive a light signal, which passes through the fiber optic
cable 50. Each terminal 54a, 54b may comprise a transmitter on one
end of each fiber optic cable 50 and a receiver on the other end of
each fiber optic cable 50. Thus, each terminal 54a, 54b may
comprise a fiber optic transmitter, a fiber optic receiver, or a
fiber optic transceiver. In some aspects, at least one fiber optic
cable 50 transmits light in one direction and at least one fiber
optic cable 50 transmits light in a reverse direction, for example,
as part of a duplex transmission. In some aspects, one or more
fiber optic cables 50 alternate the direction of the light
transmission in the same cable 50.
[0044] Each terminal 54a, 54b may include a signal generation
source 56a, 56b, preferably a light source 56a, 56b that is
operably connected to each fiber optic cable 50. The light source
56a, 56b may be any suitable light source 56a, 56b, including a
light emitting diode or a laser such as a fabry-perot ("FP") laser,
distributed feedback ("DFB") laser or a vertical cavity
surface-emitting laser ("VCSEL") that is operably connected to each
fiber optic cable 50. The signal generation source 56a, 56b may
also be comprised of an electric generation source, a vibration
generation source or nearly any other source that is configurable
to send a signal into the cable 50. Each terminal 54a, 54b may also
include a detector 58a, 58b, which is operably connected to each
fiber optic cable 50, detects the light and converts the light into
a signal that is transmitted to a receiver 52.
[0045] Under non-stressed or non-load conditions, the integrity of
the one or more fiber optic cables 50 is maintained such that the
light emitted by the light source 56 may freely traverse the fiber
optic cable 50 between each terminal 54a, 54b. In the non-load
condition, the transmitted light may be detected by the detector
58. In overloaded conditions, the one or more pre-failure indicator
strands 30 may be compromised or break, for example, because the
tension on the rope 20 exceeds the tensile strength of the one or
more pre-failure indicator strands 30 or the elongation of the rope
20 exceeds the maximum elongation of the pre-failure indicator
strands 30. The one or more fiber optic cables 50 are compromised
such that the integrity of the one or more fiber optic cables 50 is
not maintained or the fiber optic cables 50 break in the overload
condition and the light only partially traverses or does not
traverse the fiber optic cable 50 between each terminal 54a, 54b
and cannot be detected by the detector 58. Interruption of the
light transmission between each terminal 54a, 54b indicates that
the rope 20 is stressed, is under excessive tension or that failure
of the rope 20 is approaching or imminent. As a non-limiting
example, the fiber optic cable 50 may have a maximum elongation of
approximately four percent (4%) and the structural strands may have
a maximum elongation of approximately five percent (5%), such that
the fiber optic cable 50 breaks before the structural strands 22
break during use. The fiber optic cable 50 may be constructed of
glass, plastic, polymeric materials or nearly any material that is
able to take on the size and shape of the fiber optic cable 50,
perform the described functions of the fiber optic cable 50 and
withstand the normal operating conditions of the rope 20 and fiber
optic cable 50.
[0046] The receiver 52 may comprise a processor, and may comprise a
computer or a handheld device. The receiver 52 indicates to a user
that a failure or reduction in light transmission has been
detected, meaning that the rope 20 has been subject to high or
excess tension and that if the situation is not mitigated or
remedied, the rope 20 may fail. In addition, if the overload
situation cannot be mitigated or remedied in sufficient time,
failure of the rope 20 is possible or imminent. The receiver 52
may, for example, warn a user or individuals in the vicinity of the
rope 20, including a snap back zone or other danger zone, through
an audible alarm, a visible warning, and/or a tactile alarm such as
vibration that a potential failure or overload condition is
detected and the rope 20 may require repair or the snap back zone
may require evacuation for unloading of the rope 20. Having
received the warning signal from the receiver 52, the user may take
corrective action and/or bystanders may move to a safe location
away from the snap back or danger zone of the rope 20. In addition,
the receiver 52 may be able to detect reduced transmission of light
through the fiber optic cable 50 and may be able to detect a
distance from the first and/or second terminal 54a, 54b where the
reduction in light occurs. Such detection may permit the operator
to determine where damage occurred to the fiber optic cable 50 and
an estimate of the damage such that the rope 20 can be repaired,
reinforced, replaced or otherwise corrected to ensure proper
operation of the system associated with the rope 20. In addition,
this technique may be able to detect location of abrasion, fatigue
and/or environmental breakdown of the rope 20, which the operator
or a technician can remedy prior to the occurrence of any
catastrophic failure of the rope 20.
[0047] Referring to FIG. 2C, in an alternative or third preferred
embodiment of a rope pre-failure indicator system 10c, the one or
more pre-failure indicator strands 30 may comprise, in addition to
or in lieu of RFID tags 40 and in addition to or in lieu of one or
more fiber optic cables 50, one or more conductive wires 60. The
one or more pre-failure indicator strands 30 may be comprised of
one or more of the conductive wires 60. The one or more conductive
wires 60 transmit electrical signals between first and second
terminals 64a, 64b, preferably connected to opposite ends of the
rope 20 and operably connected to each end of each conductive wire
60. The first and second terminals 64a, 64b are not limited to
being connected to opposite ends of the rope 20 and may be
connected at locations between the ends of the rope 20. The
terminals 64a, 64b may transmit and/or receive an electronic
signal, which passes through the conductive wire 60. Thus, a
detectable signal may comprise an electronic signal. Each terminal
64a, 64b may comprise a transmitter on one end of conductive wire
60 and a receiver on the other end of the conductive wire 60. Thus,
each terminal 64a, 64b may comprise an electronic signal
transmitter, an electronic signal receiver, or an electronic signal
transceiver. In its simplest form, the electronic signal may
comprise an electric current. The signal may comprise an analog or
digital signal. The one or more conductive wires 60 is preferably
constructed of a metal that is capable of conducting electricity or
electrical signals, including copper or silver, or other suitable
conductive metal. The conductive wires 60 may alternatively be
constructed of other conductive materials, such as carbon fibers,
conductive polymeric materials or other materials that are designed
and configured to conduct signals, such as an electrical current,
between the first and second terminals 64a, 64b. The conductive
wire 60 may alternatively or, in addition, be constructed of a
material designed and configured to degrade at a faster rate than
the structural strands 22 based on exposure an environmental
factor. The environmental factor may include ultraviolet radiation,
abrasion, dry rot or other related environmental factors that may
impact the strength, elasticity, toughness or other structural
features of the structural strands 22 during normal operating
conditions and, generally, over a period of time in the operating
conditions.
[0048] Each terminal 64a, 64b may comprise a signal source 66a,
66b, which may comprise a current source and/or a voltage source.
The signal source 66a, 66b may comprise a processor. The signal
source 66a, 66b may comprise a signal generator, including an
analog signal generator, a function generator, a microwave signal
generator, a pitch generator, an arbitrary waveform generator, a
frequency generator, or other suitable signal generator known in
the art. The signal source 66a, 66b is operably connected to each
end of the conductive wire 60. Each terminal 64a, 64b may also
include a detector 68a, 68b, which is operably connected to each
conductive wire 60, detects the electronic signal and converts it
into a warning or conveys the signal to an electronic signal
receiver 62.
[0049] Under non-stressed conditions, the integrity of the one or
more conductive wires 60 is maintained such that the electrical
signal generated by the signal source 66a, 66b may freely traverse
the conductive wires 60 between each terminal 64a, 64b and may be
detected by the electronic signal receiver 62. When the one or more
pre-failure indicator strands 30 are compromised, for example,
because the tension on the rope exceeds the tensile strength of the
one or more pre-failure indicator strands 30, the one or more
conductive wires 60 may become compromised such that the integrity
of the one or more conductive wires 60 is not maintained and fails.
As a non-limiting preferred example, the conductive wire 60 may be
comprised of an eighteen (18) gauge copper wire 60 that is
preferably sized such that it is not destroyed by crushing forces
of the structural strands 22 during use. The conductive wire 60
could be inserted into a rope 20 having a working load limit of two
hundred thousand pounds (200,000 lbs) for providing a pre-warning
indication of potential damage to the rope 20 or degradation of the
properties of the rope 20. When the conductive wire 60 fails, the
electrical signal does not traverse the conductive wires 60 between
the first and second terminals 64a, 64b or may travel through the
conductive wire 60 at a lower volume, level or rate. The change in
flow of signal through the conducting wire 60 is communicated from
the first and/or second terminals 64a, 64b to the receiver 62.
Interruption and/or change of the electrical signal transmission
between the terminals 64a, 64b may indicate that the rope 20 is
stressed or damaged, including that the rope 20 is under excessive
tension or that failure of the rope 20 is likely or imminent. For
example, interruption of the electrical signal transmission between
the terminals 64a, 64b may indicate that the load has exceeded the
recommended working load limits of the structural strands 22 and
has exceeded the tensile strength of the indicator strand 30,
thereby indicating that the rope 20 has been subjected to a load
exceeding its recommended working load, capacity or rated load. The
receiver 62 preferably provides a warning signal to the user as a
result of the change in the flow of signal through the conducting
wire 60, such as a visual or audible signal to the user. The
receiver 62 may also send a warning or maintenance message to
predetermined individuals via nearly any form of messaging, such as
telephone, text, email or other related messaging means and
mechanisms.
[0050] Referring to FIG. 2D, in an alternative or fourth preferred
embodiment of a rope pre-failure indicator system 10d, the one or
more pre-failure indicator strands 30 may comprise, in addition to
or in lieu of RFID tags 40, fiber optic cables 50, or conductive
wires 60, a visual overload indicator such as an indicator dye 70.
The one or more pre-failure indicator strands 30 may include one or
more tubes or one or more pouches that contain the indicator dye
70. The tubes or pouches are preferably frangible, and thus are
compromised when the rope 20 is subject to tension that exceeds the
tensile strength of the one or more pre-failure indicator strands
30, thereby releasing the indicator dye 70. The tubes or pouches
may comprise any suitable material, including a plastic, polymeric,
composite, glass, or other material that may flex yet break at
desired tension levels. Once released, the indicator dye 70
preferably diffuses or flows through the structural strands 22 or
flows onto an external surface of the rope 20 where the indicator
dye 70 can be visually detected and inspected by a user. The
indicator dye 70 may be any suitable dye that can be detected, and
may comprise a color, and/or may comprise a fluorescent color,
and/or may comprise an ultraviolet dye that may be detected via
ultraviolet light. In addition, the visual overload indicator 70
may be comprised of nearly any material that provides a visual
indication on the surface of the rope 20 to provide a visual
indication or warning to the user that the rope 20 has been damaged
or subjected to an overload condition.
[0051] Under non-stressed conditions, the integrity of the one or
more pre-failure indicator strands 30 and the visual overload
indicator 70 is maintained such that the tube or pouch retains the
preferred dye 70. When the one or more pre-failure indicator
strands 30 are compromised, for example, because the tension on the
rope 20 exceeds the tensile strength of the one or more pre-failure
indicator strands 30, the tubes or pouches are compromised such
that the indicator dye 70 is released from its enclosure and can be
detected. Release of the indicator dye 70 may also occur when the
rope 20 is not under tension or being used and in such cases may
signal internal damage to the rope 20, including abrasive or dry
rot damage that has occurred in at least some locations throughout
the rope 20 or damage to portions of the structural strands 22. In
such cases, the rope 20 may be removed from service or used at
lower working load limits or at lower tension to avoid failure.
[0052] Detection of the presence of the indicator dye 70 on the
rope 20 surface indicates that the rope 20 is stressed, including
that the rope 20 is under excessive tension or that failure of the
rope 20 is imminent or may occur if the load is not removed from
the rope 20. Detection may be according to any suitable
methodology, including visual inspection, or by use of a light
source 72 which may aid visual inspection where there is
insufficient ambient light or by use of an ultraviolet light source
72, which would allow visualization of the presence of the
ultraviolet dye 70. In some aspects, a detector 74 for detecting
the indicator dye 70 may be used.
[0053] Detection of an indicator dye 70 may be automated, for
example, with the use of equipment 76 that continually monitors the
rope 20 for the presence of the indicator dye 70 on the surface of
the rope 20. The monitoring equipment 76 may include a processor
and an alarm generator 78 that emits an audible alarm, a visible
alarm, and/or a tactile alarm upon the detection of the indicator
dye 70, thereby warning a user or individuals in the vicinity of
the rope 20, including a snap back zone or other danger zone of a
pre-failure condition in the rope 20. Having received an alarm from
the monitoring equipment 76, the user may take corrective action,
and/or bystanders may move to a safe location away from the snap
back or danger zone of the rope 20.
[0054] For manual monitoring, for example, by visual detection,
including through the use of a light source 72, the individual
carrying out inspection of the rope 20 may utilize an alarm
generator 78, which the user may activate to emit an audible alarm,
a visible alarm, and/or a tactile alarm, when a pre-failure
condition in the rope 20 is detected.
[0055] Ropes 20 having the features described herein are also
provided in accordance with the disclosure. For example, in some
aspects, the rope 20 may include one or more pre-failure indicator
strands 30 having a tensile strength greater than the working load
limit of the rope 20 and less than the tensile strength of the rope
20 or the structural strands 22, such that the one or more
pre-failure indicator strands 30 break when the rope 20 is subject
to tension that exceeds the tensile strength of the one or more
pre-failure strands 30. In some preferred aspects, the one or more
pre-failure indicator strands 30 comprise a plurality of active
RFID tags 40, which may comprise a shield 44 that blocks
transmission of the RFID signal generated by the RFID tags 40 until
the shield 44 is compromised. In some preferred aspects, the one or
more pre-failure indicator strands 30 comprise a conductive wire
60. In some preferred aspects, the one or more pre-failure
indicator strands 30 comprise one or more fiber optic cables 50. In
some preferred aspects, the one or more pre-failure indicator
strands 30 comprise one or more tubes or one or more pouches that
contain an indicator dye 70. The ropes 20 may include other
features described or exemplified herein, including an indicator
that generates a detectable signal such as a light source 56, 72,
an electrical signal generator 66, a light detector 58, 72 or an
electrical signal detector 68.
[0056] Referring to FIGS. 3-7, in an alternative or fifth preferred
embodiment of a rope pre-failure indicator system 10f, the rope
pre-failure indicator system 10f may be used in a multiple rope
unit. For example, in some applications, multiple ropes 20a, 20b,
20c are used together to enhance the overall working load limit and
tensile strength of a system. Two or more ropes 20a, 20b, 20c, each
including at least one structural strand 22, may be combined into a
multiple rope unit, for example, three ropes 20a, 20b, 20c may be
combined into a multiple rope unit, but the system 10f is not so
limited and the system may include more or less than three ropes
20a, 20b, 20c. In some aspects, four, five, six, seven, eight,
nine, ten, eleven, twelve, or more than twelve ropes 20a, 20b, 20c
may be combined into a multiple rope unit. Each rope 20a, 20b, 20c
in the multiple rope unit does not need to be physically joined to
an adjacent rope 20a, 20b, 20c and it is sufficient that a
plurality of ropes 20a, 20b, 20c are in proximity to each other to
make up the multiple rope unit or system 20f. In some aspects, the
plurality of ropes 20a, 20b, 20c are braided or twisted together to
keep the ropes 20a, 20b, 20c from separating and to maximize the
overall working load limit and tensile strength of the multiple
rope unit.
[0057] The ropes 20a, 20b, 20c may each include a plurality of
structural strands 22 that may be comprised of any suitable number
of yarns and fibers fabricated from any suitable natural or
synthetic material, or combination of natural and synthetic
materials. The ropes 20a, 20b, 20c may have any working load limit
and any tensile strength. The systems and methods are useful, among
other things, for mooring, lifting, winching, and hoisting
applications, or any other applications in which snap back is a
concern.
[0058] Any of the ropes 20a, 20b, 20c in the multiple rope unit may
be comprised of natural fibers, synthetic fibers, or a combination
of any suitable proportion of natural fibers and synthetic fibers.
In a given multiple rope unit, different ropes 20a, 20b, 20c made
of different fibers may be used such that not all of the ropes 20a,
20b, 20c are natural ropes 20a, 20b, 20c or not all of the ropes
20a, 20b, 20c are synthetic ropes 20a, 20b, 20c. In some aspects,
all of the ropes 20a, 20b, 20c are made of the same material.
[0059] At least one of the ropes 20a, 20b, 20c, among the plurality
of ropes 20a, 20b, 20c in the multiple rope unit of the fifth
preferred embodiment includes one or more pre-failure indicator
strands 30. Accordingly, certain of the ropes 20a, 20b, 20c
preferably do not include the pre-failure indicator strands 30 and
are constructed of one or more structural strands 22 without the
pre-failure indicator strand 30 therein. The one or more
pre-failure indicator strands 30 preferably has the same properties
as described above, in terms of make-up, size, location within the
rope 20, and ultraviolet, fatigue, abrasion, or dry rot degradation
potential. The one or more pre-failure indicator strands 30
preferably has a tensile strength that is less than the tensile
strength of the multiple rope unit or the tensile strength of the
structural strands 22, such that the one or more pre-failure
indicator strands 30 break at a tension that is less than the
tension under which the multiple rope unit will fail, including a
tension that is less than the tension under which the ropes 20 that
make up the multiple rope unit will break. The tensile strength of
the one or more pre-failure indicator strands 30 may be at or
slightly above the working load limit of the multiple rope unit,
which itself is higher than the working load limit of the
individual ropes 20a, 20b, 20c that make up the unit, and
substantially below the tensile strength of the multiple rope unit,
which itself is higher than the tensile strength of the individual
ropes 20a, 20b, 20c that make up the unit. The tensile strength of
the one or more pre-failure indicator strands 30 preferably lies
between the working load limit and the tensile strength of the
multiple rope unit or the structural strands 22 such that the one
or more pre-failure indicator strands 30 will break before the
multiple rope unit fails by having one or more of the ropes 20a,
20b, 20c break. The one or more pre-failure indicator strands 30
serve to convey that the multiple rope unit is stressed such that
corrective action or clearance of the snap back zone or other zone
in the vicinity of the multiple rope unit may be undertaken well in
advance of the failure of the multiple rope unit.
[0060] The one or more pre-failure indicator strands 30 are
preferably operably connected to an indicator, such as the RFID
tags 40, the fiber optic cable 50, the conductive wire 60 or the
indicator dye 70, that generates a detectable signal or is
otherwise capable of generating a detectable signal. The one or
more pre-failure indicator strands 30 may comprise a conduit for
this detectable signal such that the detectable signal may traverse
the one or more pre-failure indicator strands 30. In some aspects,
the one or more pre-failure indicator strands 30 include the
plurality of active RFID tags 40 of the first preferred embodiment,
as described above for the one or more pre-failure indicator
strands 30 used in accordance with the rope 20c (FIG. 3 and FIG. 4)
in the multiple-rope unit. In some aspects, the one or more
pre-failure indicator strands 30 include the one or more fiber
optic cables 50 of the second preferred embodiment, as described
above for the one or more pre-failure indicator strands 30 used in
accordance with a single rope 20b (FIG. 5) in the multiple-rope
unit. In some aspects, the one or more pre-failure indicator
strands 30 comprise a conductive wire 60 as described above for the
one or more pre-failure indicator strands 30 used in accordance
with a single rope 20b (FIG. 6) in the multiple-rope unit. In some
aspects, the one or more pre-failure indicator strands 30 comprise
the indicator dye 70 as described above for the one or more
pre-failure indicator strands 30 used in accordance with a single
rope 20b (FIG. 7) in the multiple-rope unit.
[0061] The disclosure also features methods for detecting a
pre-failure condition in the rope 20 or in ropes 20a, 20b, 20c in
the multiple rope unit. In general, the methods comprise
determining whether one or more pre-failure indicator strands 30 of
one or more ropes 20, 20a, 20b, 20c have broken by detecting the
presence or the absence of a detectable signal generated by an
indicator operably connected to the one or more pre-failure
indicator strands 30 and, optionally, taking remedial action to
avoid failure of the one or more ropes 20, 20a, 20b, 20c and/or
emitting an audible alarm, a visible alarm, and/or a tactile alarm
if it is determined that one or more pre-failure indicator strands
30 of the one or more ropes 20, 20a, 20b, 20c have broken. The
methods may be used in accordance with any rope pre-failure
indicator system 10a, 10b, 10c, 10d, 10f described or exemplified
herein. The rope 20, 20a, 20b, 20c may be a mooring rope 20, 20a,
20b, 20c, which may be under water.
[0062] Referring to FIGS. 1-2D, in operation, the rope pre-failure
indicator systems 10a, 10b, 10c, 10d, 10f are used to determining
whether the pre-failure indicator strands 30 of the rope 20 have
broken. The systems 10a, 10b, 10c, 10d, 10f are able to monitor the
ropes 20 by detecting the presence or the absence of the detectable
signal generated by an indicator, such as the RFID tags 40, the
detectors 58a, 58b, 68a, 68b or the indicator dye 70. The RFID tags
40, the detectors 58a, 58b, 68a, 68b or the indicator dye 70 are
operably connected to the pre-failure indicator strands 30 such
that the signal or indication is provided when the indicator strand
30 fails or is stressed to a degree that prompts the indication.
The user, upon receipt of the indication or warning is able to take
remedial action to avoid failure of the rope 20. The indication
that the indicator strand 30 fails or is stressed preferably
comprises an audible alarm, a visible alarm, and/or a tactile
alarm. The indicator strands 30 may include a fiber optic cable 50
with a light signal passing therethrough. The fiber optic cable 50
may be comprised of a duplex fiber optic cable 50.
[0063] Referring to FIGS. 2B and 2C, in the second and third
preferred embodiments, the first and/or second terminals 54a, 54b,
64a, 64b may include a time-domain reflectometry ("TDR") device
60a, 60b, 70a, 70b. The TDR device 60a, 60b, 70a, 70b is preferably
able to send a pulse signal into the fiber optic cable 50 or the
conductive wire 60 and the time until a return pulse is sensed by
the first and/or second terminals 54a, 54b, 64a, 64b is recorded.
The recorded time is preferably transmitted to the receiver 52, 62,
which calculates the length of the cable 50 or wire 60 until there
is a discontinuity. The discontinuity may be indicated as an
opposite end of the cable 50 or wire 60 or may be an intermediate
position along the cable 50 or wire 60. If the discontinuity is the
opposite end of the cable 50 or wire 60, the receiver 52, 62
determines that the rope 20 is operating properly or is
structurally functional, the receiver 52, 62 indicates a potential
failure of the rope 20. In addition, based on the calculation, the
receiver 52, 62 may be able to determine where along the length of
the rope 20, the discontinuity occurs and preferably communicates
this information to the user, operator or technician, such that the
rope 20 can be inspected at the indicated portion. The TDR device
60a, 60b, 70a, 70b may be incorporated into the first and second
terminals 54a, 54b, 64a, 64b, may be incorporated into only one of
the first and second terminals 54a, 54b, 64a, 64b or may be
comprised of a separate device that is selectively operable with
the rope 20 for inspection purposes.
[0064] The rope pre-failure indicator systems 10b, 10c of the
second and third preferred embodiments are not limited to inclusion
or incorporation of the TDR device 60a, 60b, 70a, 70b and may
operate without the TDR device 60a, 60b, 70a, 70b. The inclusion of
the TDR device 60a, 60b, 70a, 70b is preferred as the TDR device
60a, 60b, 70a, 70b provides the ability to determine a location of
a discontinuity and to determine where damage may have occurred to
the rope 20 along its length. Such location of damage can be
advantageous in relatively long ropes 20, ropes 20 where access to
portions of the rope 20 is difficult or ropes 20 where gaining
access to one of the ends of the ropes 20 is difficult. The TDR
device 60a, 60b, 70a, 70b is also advantageous in that only one end
of the rope 20 is required for access as the TDR device 60a, 60b,
70a, 70b sends a signal from the same end of the rope 20 that the
return signal is received. Accordingly, the TDR device 60a, 60b,
70a, 70b may be selectively applied to one end of the rope 20, such
as a rope 20 used to support a floating structure in a body of
water where one end of the rope 20 is submerged in fluid and is
generally not accessible. In these situations, the TDR device 60a,
60b, 70a, 70b can be transported for interaction with the end of
the rope 20 extending out of the fluid for sending the signal,
receiving the return signal and transmission of the results for
calculation. Such portable TDR devices 60a, 60b, 70a, 70b can be
used to conduct periodic tests on the rope 20 for sample testing or
for testing during service downtime of the rope 20 or the structure
associated with the rope 20. The TDR device 60a, 60b, 70a, 70b is
not limited to being portable or to being operated from only one
end of the rope 20 and the TDR device 60a, 60b, 70a, 70b may be
integrated with the first and second terminals 54a, 54b, 64a, 64b
or may be otherwise arranged for inspection of the rope 20.
Integration of the TDR device 60a, 60b, 70a, 70b with the first and
second terminals 54a, 54b, 64a, 64b may be advantageous for
applications where constant checking or testing of the rope 20 is
desired, such as static applications or for ropes 20 having a
relatively consistent load during a relatively long service
time.
[0065] The TDR device 60a, 60b, 70a, 70b is preferably able to
sound an alarm or provide a warning to the user, operator or other
predetermined personnel when the return signal indicates a
discontinuity in the fiber optic cable 50 or the conductive wire 60
at a location other than the opposite end of the fiber optic cable
50 or the conductive wire 60. Such warnings or notifications are
particularly useful in applications such as winching, where the
rope 20 could be attached to a drum end or in static applications,
such as a structure where a permanent connection would be made. The
warning would provide an indication to the user, operator or other
predetermined personnel that the rope 20 requires further
inspection, removal, replacement, repair or other remediation.
[0066] It will be appreciated by those skilled in the art that
changes could be made to the embodiments described above without
departing from the broad inventive concept thereof. It is
understood, therefore, that this invention is not limited to the
particular embodiments disclosed, but it is intended to cover
modifications within the spirit and scope of the present invention
as defined by the appended claims.
* * * * *