U.S. patent application number 13/652308 was filed with the patent office on 2013-09-19 for expandable fastener assembly with deformed collar.
This patent application is currently assigned to FATIGUE TECHNOLOGY, INC.. The applicant listed for this patent is FATIGUE TECHNOLOGY, INC.. Invention is credited to Timothy Howard Johnson, Leonard Frederick Reid, James Ryunoshin Ross.
Application Number | 20130239399 13/652308 |
Document ID | / |
Family ID | 40242677 |
Filed Date | 2013-09-19 |
United States Patent
Application |
20130239399 |
Kind Code |
A1 |
Reid; Leonard Frederick ; et
al. |
September 19, 2013 |
EXPANDABLE FASTENER ASSEMBLY WITH DEFORMED COLLAR
Abstract
At least one embodiment generally relates to an installation
assembly for an opening in a workpiece that includes a swaged
collar, an inner member, and an outer member. The swaged collar has
a first end, a second end, and a main body extending between the
first end and the second end. The main body includes an inner
surface defining a passageway through the collar. The inner member
has a mandrel section for expanding the outer member. The inner
member is used to expand the outer member and to keep the outer
member in an expanded state.
Inventors: |
Reid; Leonard Frederick;
(Issaquah, WA) ; Johnson; Timothy Howard;
(Seattle, WA) ; Ross; James Ryunoshin; (Seattle,
WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FATIGUE TECHNOLOGY, INC. |
Seattle |
WA |
US |
|
|
Assignee: |
FATIGUE TECHNOLOGY, INC.
Seattle
WA
|
Family ID: |
40242677 |
Appl. No.: |
13/652308 |
Filed: |
October 15, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12253141 |
Oct 16, 2008 |
8312606 |
|
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13652308 |
|
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60999517 |
Oct 16, 2007 |
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Current U.S.
Class: |
29/525.03 ;
29/283.5; 411/43 |
Current CPC
Class: |
F16B 5/02 20130101; F16B
19/05 20130101; Y10T 29/4995 20150115; B21J 15/147 20130101; Y10T
29/53996 20150115; B21J 15/022 20130101; B23P 19/06 20130101; Y10T
29/53878 20150115; F16B 19/1036 20130101; B23P 11/00 20130101; F16B
39/026 20130101; B21J 15/105 20130101 |
Class at
Publication: |
29/525.03 ;
29/283.5; 411/43 |
International
Class: |
F16B 19/10 20060101
F16B019/10; B21J 15/14 20060101 B21J015/14; B23P 11/00 20060101
B23P011/00 |
Claims
1. A fastener assembly installable in an opening of a workpiece,
comprising: a collar; an outer member configured to be positioned
in the opening, the outer member including a
longitudinally-extending passageway, a coupling section, a head,
and an expandable section between the coupling section and the
head, the coupling section adapted to protrude from the workpiece
and to be coupled to the collar; and an inner member including a
narrow section, a propping stem, and a mandrel section between the
narrow section and the propping stem, the propping stem dimensioned
and configured to prop the expandable section of the outer member
after the mandrel section radially expands the expandable section
in the opening of the workpiece to produce an interference fit
between the outer member and the workpiece.
2. The fastener assembly of claim 1, wherein the expandable section
has an inner surface defining at least a portion of the
longitudinally-extending passageway and an inner circumference, the
inner circumference is less than an outer circumference of the
propping stem.
3. The fastener assembly of claim 1, wherein the inner member
further includes a detachable shank and a decoupling feature
between the detachable shank and the narrow section, the detachable
shank separable from the narrow section at least proximate the
decoupling feature when an axial load is applied to the detachable
shank.
4. The fastener assembly of claim 1, wherein the outer member is
radially expandable from an initial configuration for placement in
the opening of the workpiece to an expanded configuration to cold
work the workpiece and to produce an interference fit with the
workpiece.
5. A method for fastening together a multi-component workpiece
having an opening, the opening extending between a first side and a
second side of the workpiece, the method comprising: positioning a
hollow outer member in the opening; moving a portion of an inner
member on the second side of the workpiece within the hollow outer
member, the inner member including a mandrel section; radially
expanding at least a portion of the outer member using the mandrel
section of the inner member; positioning a collar on the first side
of the workpiece such that the collar surrounds the outer member;
and swaging the collar to deform the collar against the outer
member.
6. The method of claim 5, wherein radially expanding the portion of
the outer member produces an interference fit with the
workpiece.
7. The method of claim 5, further comprising radially expanding the
portion of the outer member while swaging the collar to deform the
collar against the outer member.
8. The method of claim 5, wherein the hollow outer member shields
the opening of the workpiece from shear loads as the portion of the
outer member is radially expanded to produce an interference fit
between the outer member and the workpiece and/or induce fatigue
enhancing compressive stresses in the workpiece.
9. The method of claim 5, further comprising providing a clearance
fit between the hollow outer member and the opening of the
workpiece prior to radially expanding the portion of the outer
member and the workpiece.
10. The method of claim 5, wherein swaging the collar includes
forming grooves lengthwise along an exterior of the collar.
11. The method of claim 5, further comprising: coupling an
installation apparatus on the first side of the workpiece to a
detachable shank of the inner member protruding outwardly from the
collar; and moving a swaging assembly of the installation apparatus
along the collar to form a plurality of elongate swage grooves
along an exterior of the collar.
12. The method of claim 11, further comprising separating the
detachable shank from a propping stem of the inner member after
moving the swaging assembly along the collar, wherein an
interference fit is formed by the propping stem and the outer
member.
13. The method of claim 5, wherein swaging the collar includes
deforming the collar using a plurality of ball bearings.
14. The method of claim 5, wherein radially expanding the portion
of the outer member includes radially expanding substantially all
of an axial length of the outer member within the opening.
15. The method of claim 5, further comprising: developing
compressive stresses in the workpiece sufficient to alter fatigue
performance of the workpiece by radially expanding the outer member
in the opening.
16. The method of claim 5, further comprising moving a propping
section of the inner member into the radially expanded portion of
the outer member.
17. A swaging assembly for an installation apparatus, comprising: a
housing having a first end, a second end, and a bore extending
between the first end and the second end; and an actuating device
including a passageway and a plurality of spaced apart bearing
elements surrounding the passageway, the actuating device movable
through the bore towards the second end such that the bearing
elements swage a collar of a fastener assembly protruding from a
workpiece against which the swaging assembly is placed.
18. The swaging assembly of claim 17, wherein the bearing elements
are spherical bearings held by corresponding sockets in a sidewall
of the actuating device.
19. The swaging assembly of claim 17, wherein the bearing elements
are adapted to produce corresponding grooves along an exterior of
the collar.
20. The swaging assembly of claim 17, wherein the actuating device
includes a tubular member having an inner surface defining the
passageway, the bearing elements protrude inwardly from the tubular
member into the passageway.
21. The swaging assembly of claim 17, wherein the plurality of
bearing elements are circumferentially spaced from one another
about the passageway.
22. The swaging assembly of claim 17, wherein the actuating device
extends from the first end of the housing and includes a biasing
member, the biasing member is between the first end of the housing
and an outwardly extending retainer of the actuating device to bias
the actuating device away from the first end of the housing.
Description
BACKGROUND
[0001] 1. Field of Technology
[0002] This disclosure generally relates to expandable fastener
assemblies and methods of using the same.
[0003] 2. Description of the Related Art
[0004] Fastener assemblies are often used to interconnect a
plurality of workpieces, such as a stack of plates or other
structural members. Conventional fastener assemblies have a bolt
and a collar that cooperate to apply a clamp-up force to the
workpieces. For example, two workpieces can be joined together by
overlapping the workpieces to create a joint. A fastener assembly
can be installed at the joint by drilling a hole through the
overlapping portions of the workpieces and positioning a rod in the
hole. The workpieces are clamped between a head of the rod and the
collar. Unfortunately, these types of joints are susceptible to
fatigue damage and have undesired electrical properties.
[0005] Contaminates (e.g., moisture, chemicals, debris, and other
foreign substances) can become lodged between faying surfaces of
joints resulting in increased wear and corrosion. Cyclic loading
can lead to fatigue problems. The fastener assembly may allow the
workpieces to move relative to one another, which may result in
fretting, excessive stresses at the interface of the hole and
fastener assembly, vibrations, and the like. In aerospace
applications, conventional joints may thus have a relatively short
in-service life.
[0006] Aircraft are often made of lightweight composite structures
that are unable to withstand high electrical currents as well as
their metallic counterparts. Composite structures may be damaged by
high electrical currents caused by lightning strikes because
composite structures do not readily conduct away the electrical
currents and electromagnetic forces generated by lightning strikes.
Electrical currents tend to not pass through the composites
structures (e.g., carbon fiber structures) with poor electrical
conductivity and instead pass through highly conductive materials,
such as metals. Metal fastener assemblies can conduct electrical
currents between layers of composite structures. Unfortunately,
loosening of the components of the fastener assembly may result in
movement between these components of the fastener assembly,
movement of the workpiece, and the accumulation of contaminates at
the faying surfaces. These problems may result in arcing or other
electrical related problems that may cause fires or explosions.
Conventional fastener assemblies may thus be unsuitable for many
aerospace applications. Additionally, conventional sleeve/bolt
systems have a tendency to cause damage in composite laminates when
tolerances stack up to make interferences relatively high. Leading
edges of conventional bolts are too abrupt for use with thin-walled
sleeves. Shear loading along the holes of composite workpieces may
be damaged (e.g., delamination), during installation.
BRIEF SUMMARY
[0007] Some embodiments disclosed herein include fastener
assemblies adapted to apply desired clamp-up forces to workpieces.
The fastener assemblies can be installed in openings in the
workpieces in order to hold together the components of the
workpieces. In some embodiments, the fastener assemblies can be
installed in a joint of an aircraft. The installation can have
desirable mechanical characteristics, electrical characteristics,
and the like for enhancing performance, even after extended use
under cyclic loading, static loading, or both.
[0008] In some embodiments, an installation includes a workpiece
and a fastener assembly. The fastener assembly includes a swaged
collar, an inner member, and an expanded outer member. The outer
member is between the inner member and the workpiece. The swaged
collar is coupled to the outer member or the inner member, or both.
The inner member, in some embodiments, has a relatively narrow
section, a relatively wide section, and a mandrel section between
the narrow section and the wide section. A portion of the outer
member is in an expanded state and is between the wide section and
the workpiece. The workpiece is captured between the collar on one
side of the workpiece and a head of the outer member on another
side of the workpiece. In some embodiments, the workpiece comprises
multiple components that are held together by the fastener
assembly.
[0009] In some embodiments, a method of fastening together a
multi-piece workpiece having an opening is provided. The opening
extends between a first side and a second side of the workpiece.
The method includes positioning a hollow expandable fastener
through the opening. An inner member is positioned within the
hollow expandable fastener. The inner member includes a mandrel
section and is on the second side of the workpiece. The inner
member is moved through the expandable fastener to radially expand
at least a portion of the fastener. A collar is positioned on the
first side of the workpiece. The collar, in some embodiments, is
radially compressed onto coupling features of the expanded fastener
to capture the workpiece between a head of the fastener and the
collar.
[0010] In some embodiments, an installation comprises a workpiece,
a swaged collar, an inner member, and a radially expanded outer
member. The workpiece has an opening. The swaged collar has a first
end, a second end, and a main body extending between the first end
and the second end. The main body includes an inner surface
defining the passageway. The inner member has a narrow section, a
propping section, and a mandrel section between the narrow section
and the propping section. The radially-expanded outer member is in
the opening of the workpiece. The inner surface of the collar has
been compressed against at least one locking feature of the
expanded outer member to fix the collar and the outer member
together. The outer member has been expanded from an unexpanded
state to an expanded state by the mandrel section. The propping
section keeps the outer member in the expanded state to maintain an
interference fit and/or induced fatigue enhancing compressive
stresses in the workpiece produced when the outer member is
expanded from the unexpanded state to the expanded state. In some
embodiments, the unexpanded outer member can fit in the opening
with a clearance fit.
[0011] In some embodiments, a fastener assembly is installed in an
opening of a workpiece and comprises a collar, an outer member, and
an inner member. The outer member is configured to be positioned in
the opening of the workpiece. The outer member includes a
longitudinally-extending passageway, a coupling section, a head,
and an expandable section between the coupling section and the
head. The coupling section is adapted to protrude from the
workpiece and to be coupled to the collar. The inner member
includes a narrow section, a propping stem, and a mandrel section
between the narrow section and the propping stem. The propping stem
is dimensioned and configured to prop the expandable section of the
outer member after the mandrel section radially expands the
expandable section in the opening of the workpiece. In some
embodiments, the outer member is radially expanded from an initial
configuration for placement in the opening of the workpiece to an
expanded configuration to cold work the workpiece and/or to produce
an interference fit with the workpiece. The outer member in the
initial configuration can provide a clearance fit with the opening
of the workpiece.
[0012] In some embodiments, a method for fastening together a
multi-component workpiece having an opening extending between a
first side and a second side is provided. The method includes
positioning a hollow outer member in the opening of the workpiece.
A portion of an inner member on the second side of the workpiece is
moved within the hollow outer member. The inner member includes a
mandrel section. At least a portion of the outer member and the
workpiece is expanded using the mandrel section of the inner
member. The collar is positioned on the first side of the workpiece
such that the collar surrounds the outer member. The collar is
swaged. In some embodiments, swaging the collar includes forming
longitudinally-extending grooves along an exterior of the
collar.
[0013] In some other embodiments, a swaging assembly for an
installation apparatus includes a housing and an actuating device.
The housing has a first end, a second end, and a bore extending
between the first end and the second end. The actuating device
includes a passageway and a plurality of spaced apart bearing
elements surrounding the passageway. The actuating device is
movable through the bore towards the second end such that the
bearing elements swage a collar of a fastener assembly protruding
from a workpiece against which the swaging assembly is placed.
[0014] In some embodiments, a fastener assembly can include an
inner member, an outer member, and a collar. The wall thickness of
the outer member can be sufficiently large to ensure that the outer
member induces compressive stresses in the workpiece and/or an
interference fit with a workpiece when the outer member is radially
expanded. In some embodiments, the wall thickness of the outer
member can be generally equal to a wall thickness of the
collar.
[0015] In some embodiments, a fastener assembly includes an inner
member, an outer member, and a collar. The inner member can
radially expand the outer member to form an interference fit with
the workpiece. The workpiece can comprise a composite material. For
example, the workpiece can comprise one or more composite panels
and one or more metal panels. The workpiece can be a stack of
different types of panels, and the outer member can form
interference fits with each of these panels. Advantageously, the
outer member can be inserted through the stack with a clearance fit
to minimize, limit, or substantially prevent damage of any of the
panels, including composite panels, if any. In some embodiments,
the outer member can be radially expanded a sufficient amount to
produce compressive stresses in the workpiece. For example, the
workpiece can be comprised mostly or entirely of metal in which
compressive stresses can be induced without cracking the workpiece.
If the workpiece comprises composite materials, the compressive
stresses can be kept below a level that causes damage to the
workpiece. In some embodiments, compressive stresses that improve
fatigue performance may not be produced in the workpiece.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0016] In the drawings, identical reference numbers identify
similar elements or acts. The sizes and relative positions of
elements in the drawings are not necessarily drawn to scale.
[0017] FIG. 1 is a side elevational view of an installation
including a multi-component workpiece and an expandable fastener
assembly that has a deformed collar, according to one illustrated
embodiment.
[0018] FIG. 2 is a partial cross-sectional view of an installation
of FIG. 1.
[0019] FIG. 3 is a cross-sectional view of the installation of FIG.
2.
[0020] FIG. 4 is a detailed view of the fastener assembly of FIG.
3.
[0021] FIG. 5 is an isometric view of an expandable fastener
assembly installed in a multi-component workpiece. The workpiece
and a collar of the fastener assembly are shown cut-away.
[0022] FIG. 6 is an isometric view of the fastener assembly and the
workpiece of FIG. 5. The workpiece, the collar, and an expandable
outer member are shown cut-away.
[0023] FIG. 7 is a pictorial view of an inner member of an
expandable fastener assembly, according to one embodiment.
[0024] FIG. 8 is a side elevational view of the inner member of
FIG. 7.
[0025] FIG. 9 is a side elevational view of the inner member of
FIG. 7 after the inner member has been broken apart.
[0026] FIG. 10 is a detailed view of the inner member of FIG.
8.
[0027] FIG. 11 is a detailed view of a mandrel section of an inner
member, in accordance with one embodiment.
[0028] FIG. 12 is a side elevational view of an installation
apparatus for installing an expandable fastener assembly, in
accordance with one embodiment.
[0029] FIG. 13 is an elevational view of the installation apparatus
installing an expandable faster assembly in a workpiece. A puller
unit of the installation apparatus is shown partially cut-away.
[0030] FIG. 14 is a cross-sectional view of a swaging assembly, in
accordance with one embodiment.
[0031] FIG. 15 is a pictorial view of an expandable outer member
ready for installation in an opening of a workpiece, in accordance
with one illustrated embodiment. The workpiece is shown
cut-away.
[0032] FIG. 16 is a pictorial view of an inner member spaced from
an expandable outer member in a hole of a workpiece. The workpiece
is shown cut away.
[0033] FIG. 17 is a pictorial view of a deformable collar ready for
placement over an expandable outer member assembled with an inner
member. The workpiece is shown cut away.
[0034] FIG. 18 is a pictorial view of a swaging assembly ready for
installing an assembled fastener assembly. The workpiece is shown
cut away.
[0035] FIG. 19 is a cut-away view of a swaging assembly ready to
deform a collar of an expandable fastener assembly, according to
one illustrated embodiment.
[0036] FIG. 20 is a cut-away view of the swaging assembly of FIG.
19 after deforming the collar, according to one illustrated
embodiment.
[0037] FIG. 21 is a cut-away view of the swaging assembly after
breaking apart the inner member, according to one illustrated
embodiment.
[0038] FIG. 22 shows the swaging assembly separated from the
installed fastener assembly, according to one illustrated
embodiment.
[0039] FIG. 23 is a pictorial view of a swaging assembly, according
to one illustrated embodiment.
[0040] FIG. 24 is a bottom view of the swaging assembly of FIG.
23.
[0041] FIG. 25 is a cross-sectional view taken along a line 25-25
of FIG. 24. A jaw assembly is shown removed.
[0042] FIG. 26 is a cross-sectional view of the swaging assembly
taken along a line 25-25 of FIG. 24, wherein the swaging assembly
includes a jaw assembly.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0043] In the following description, certain specific details are
set forth in order to provide a thorough understanding of various
aspects of the representative embodiments. One skilled in the art,
however, will understand that the embodiments may be practiced
without these details. The fastener assemblies, installation
apparatuses, and processes disclosed herein can be used to couple
together workpieces and, in some embodiments, may improve
in-service performance of these workpieces, such as electrical
performance, mechanical performance, fatigue performance, or the
like. The fastener assemblies can be expandable fastener assemblies
installed in different types of workpieces and at a wide range of
locations. The term "expandable fastener assembly" refers to a
fastener assembly both in a pre-expanded state and an expanded
state, unless the context dictates otherwise.
[0044] Unless the context requires otherwise, throughout the
specification and claims which follow, the word "comprise" and
variations thereof, such as, "comprises" and "comprising" are to be
construed in an open, inclusive sense, that is as "including, but
not limited to."
[0045] The terms "proximal" and "distal" are used to describe the
illustrated embodiments and are used consistently with a
description of non-limiting exemplary applications. The terms
"proximal" and "distal" are used in reference to the user's body
when the user operates an installation apparatus to install
fasteners assemblies, unless the context clearly indicates
otherwise. It will be appreciated, however, that the illustrated
embodiments can be located or oriented in a variety of desired
positions.
[0046] As used in this specification and the claims, the singular
forms "a," "an," and "the" include plural referents unless the
content clearly dictates otherwise. It should also be noted that
the term "or" is generally employed in its sense including "and/or"
unless the context clearly dictates otherwise.
[0047] FIGS. 1-3 show an expandable fastener assembly 100 installed
in a multi-component workpiece 108. The workpiece 108 includes a
first structural member 110 and a second structural member 120 that
overlaps the first structural member 110 to form a lap joint 124.
The fastener assembly 100 includes a deformable collar 130, an
expandable outer member 140 extending through the workpiece 108 and
the collar 130, and an inner member 145 extending through the outer
member 140. The workpeice 108 is captured between a flange 150 of
the collar 130 and a head 160 of the outer member 140 to reduce,
limit, or substantially prevent relative movement between the
members 110, 120. The illustrated collar 130 and head 160 are
positioned on first and second sides 143, 144 of the workpiece 108,
respectively. A user on the first side 143 of the workpiece 108 can
install the fastener assembly 100.
[0048] As used herein, the term "expandable outer member" is a
broad term and includes, but is not limited to, a fastener,
bushing, sleeve (including a split sleeve), fitting, structural
expandable member (e.g., expandable members that are incorporated
into structural workpieces), or other one-piece or multi-piece
structures suitable for installation in a workpiece. An expandable
outer member can be expanded from a first configuration to a second
configuration. In some embodiments, for example, the expandable
outer member 140 is a hollow fastener that is radially expanded
from an initial pre-expanded state to a post-expanded state in
order to create a desired fit, such as an interference fit, with an
inner surface 154 forming an opening 155, illustrated as a
through-hole in the workpiece 108. The term "expandable outer
member" refers to an outer member both in a pre-expanded state and
post-expanded state, unless the context clearly dictates otherwise.
The illustrated outer member 140 is in a post-expanded state.
[0049] Various types of expansion processes may be employed to
install the fastener assembly 100. In a cold expansion process, for
example, the expandable outer member 140 is radially expanded
without appreciably raising the temperature of the outer member 140
to produce residual stresses in the workpiece 108. The residual
stresses can significantly increase fatigue life by reducing the
applied stresses at the opening 155 to reduce the stress intensity
factor and to increase the crack growth life. In some embodiments,
the magnitude of the peak residual compressive circumferential
stress at the opening is less than or about equal to the
compressive yield stress of the workpiece 108. The compressive
stress zone may span one radius to one diameter from the edge of
the opening 155. A balancing zone of tensile stresses can be
located beyond the circumferential compressive stress zone. The
compressive stresses in the workpiece can be sufficient to alter
fatigue performance of the workpiece to increase the service life
of the workpiece by, for example, at least about 10.times.,
30.times., or 50.times.. The illustrated expanded fastener assembly
of FIGS. 1-3 may induce compressive stresses in the workpiece 108
for enhanced fatigue performance.
[0050] As used herein, the term "workpiece" is broadly construed to
include, without limitation, a structure suitable for receiving the
fastener assembly 100. Workpieces can have at least one opening in
which the fastener assembly 100 is installed and can be made, in
whole or in part, of one or more metals (e.g., steel, aluminum,
titanium, or the like), polymers, plastics, composites, resins,
combinations thereof, or the like. Multi-component workpieces can
include any number of panels, sheets, or other components capable
of being coupled together using the fastener assembly 100. The
illustrated workpiece 108 includes two flat panels 110, 120 mated
together; however, any number of panels (e.g., three or more
panels) can be held together using the fastener assembly 100. In
other embodiments, the workpiece 108 can be a single panel. Such
workpieces can be made, in whole or in part, of a composite
material, such as a multi-laminate panel. The fastener assembly 100
can help inhibit, limit, or substantially prevent damage, such as
delamination. Hybrid workpieces can be made of a wide range of
different materials, including composite materials and metals. In
some embodiments, the workpiece is a hybrid workpiece includes one
or metal panels and one or more composite panels.
[0051] In some embodiments, the workpiece includes a plurality of
panels. At least one of the panels can comprises a composite
material (e.g., a fiber-reinforced composite material) and at least
one of the panels comprises another material, such as a metal. A
clearance fit can be produced with each of the panels to insert the
outer member 140 into the workpiece. An interference fit is
produced with each of the panels when the outer member 140 is
expanded. In some embodiments, a hybrid workpiece includes one or
metal panels and one or more composite panels. In some embodiments,
the workpiece includes only metal panels or only composite panels.
Any number of panels can be connected together using the fastener
assembly 100.
[0052] With continued reference to FIGS. 1-3, the collar 130 has
been deformed to couple the collar 130 to the expanded outer member
140. The outer member 140 can be tensioned to inhibit or prevent
loosening of the collar 130. The head 160 of the outer member 140
and the collar 130 can compress the workpiece 108 to limit,
minimize, or substantially prevent fretting of the panels 110,
120.
[0053] The collar 130 provides generally uniformly distributed
stresses (e.g., contact stresses) in a region of an outer surface
123 of the panel 120 proximate the opening 155 to avoid unwanted
stress concentrations. For example, if the workpiece 108 is made of
a composite material that is susceptible to cracking or
delaminating, the flange 150 and/or head 160 can have a radial
thickness sufficiently large to keep compressive stresses in the
workpiece 108 at or below an acceptable level to limit, reduce, or
eliminate cracking or delamination. The fastener assembly 100 can
also enhance the desired electrical conductivity of the workpiece
108 and, in some embodiments, maintains the integrity of coatings,
including platings, or any other treatments on the workpiece 108,
even coating on faying surfaces. The outer member 140 can insulate
the workpiece 108 from the inner member 145 such that an electrical
current can pass through the inner member 145.
[0054] Referring to FIG. 4, the collar 130 includes a main body 180
extending generally longitudinally from the flange 150 and a
passageway 190 extending between opposing ends 200, 210 of the
collar 130. The illustrated collar 130 is a swagable collar. The
term "swagable collar" refers to a collar both in a pre-swaged
state and a post-swaged state, unless the context clearly dictates
otherwise. A swaging process has been performed to axially and
rotationally fix the swaged collar 130 shown in FIG. 4 to the outer
member 140.
[0055] The expandable outer member 140 of FIG. 4 includes a tubular
main body 250 extending generally longitudinally from the head 160
and a longitudinally-extending passageway 260 extending between
opposing ends 270, 280. The tubular main body 250 includes a
radially expandable portion 213 and a coupling section 235. The
expandable portion 213 extends from the head 160 through the panels
110, 120. At least a substantial portion of the opening 155 can be
radially expanded to produce a desired fit with the expandable
portion 213. The axial length of the expandable portion 213 can be
selected based on the thickness T of the workpiece 108. For
example, the axial length of the expandable portion 213 can be
slightly less than, equal to, or slightly greater than the
thickness T of the workpiece. Substantially all of the longitudinal
length of the expandable portion 213 is in an expanded state. For
example, at least 90% of the length of the expandable portion 213
can be expanded. Thus, most of the opening 155 between the head 160
and collar 130 is also expanded.
[0056] The expandable portion 213 can protrude from the first side
143 of the workpiece 108 such that the entire opening 155 is
expanded. The coupling section 235 includes a plurality of locking
features 220 proximate the end 270. The locking features 220 are
illustrated as external grooves that can bear against an inner
surface 217 of the collar 130. The external grooves 220 can be
helical external threads, an array of spaced apart grooves, or the
like. The locking features 220 can also be bumps, ridges,
projections, recessed regions, combinations thereof, or the like.
The locking features 220 and the inner surface 217 can lock
together to axially fix and/or rotationally fix the collar 130 to
the outer member 140.
[0057] The inner surface 217 can be a generally smooth tubular
surface and can be made, in whole or in part, of a material with a
yield strength that is less than the yield strength of the material
of the locking features 220. When the inner surface 217 is
compressed against the locking features 220, the locking features
220 can cause appreciable deformation (e.g., plastic deformation,
elastic deformation, or both) of the inner surface 217. In this
manner, the collar 130 can be locked to the expandable outer member
140. In some embodiments, the coupling section 235 has one or more
coupling features (e.g., internal threads, a bonding layer, an
adhesive, etc.) that facilitate coupling with the locking features
220.
[0058] The head 160 is in the form of a chamfered flange for
seating in a countersink 237 of the workpiece 108. The head 160 has
a countersink 239 to receive a complementary shaped head 310 of the
inner member 145. An outer surface 315 of the head 160 is generally
flush with an outer surface 311 of the panel 120 and an outer
surface 313 of the head 310. The configurations of the countersinks
237, 239 can be selected such that the head 160 and/or head 310 sit
slightly above, at, or below the surface 311 of the panel 120. The
outer surfaces 311, 313, 315 can be made flush using various
processes, such as a machining process, to be within a desired
tolerance, for example, a manufacturing tolerance associated with
the installation. The illustrated heads 160, 310 can reduce the
occurrence of lightning strikes.
[0059] In other embodiments, the heads 160, 310 may protrude from
the second side 144 of the workpiece 108. For example, the head 160
can lie along and protrudes from the surface 311 of the panel
120.
[0060] Referring to FIGS. 4-6, the inner member 145 is shown
installed (i.e., after it has expanded the outer member 140 and has
been broken apart). The inner member 145 includes a narrow section
300, the head 310, and a stem 320 between the narrow section 300
and head 310. A mandrel section 330 is positioned between the
narrow section 300 and the stem 320.
[0061] The mandrel section 330 can expand the outer member 140, and
in some embodiments, the stem 320 can limit or substantially
prevent constriction of the outer member 140. The stem 320 can prop
the expanded portion 213 to maintain desired compressive stresses
in the workpiece 108. The inner member 145 can be, without
limitation, a fastener, a rod (e.g., a threaded rod), a bolt, a
stud, a shank, a mandrel, or the like. The illustrated inner member
145 has a solid cross-section.
[0062] With continued reference to FIG. 4, a selected amount of
residual compressive stress is induced in the workpiece 108 because
of the radial expansion of the outer member 140. The compressive
stresses may enhance the fatigue life of the installation. The
amount of radial expansion of the outer member 140 may be selected
to achieve corresponding amounts of residual compressive stresses
in the workpieces 110, 120. The fastener assembly 100 is suitable
for performing a cold expansion process. The process of cold
expansion is broadly interpreted as any process that radially
expands at least some of the material surrounding the opening 155
with appreciably raising the temperature of the workpiece 108. It
is further understood that cold working the opening 155 may or may
not induce beneficial compressive residual stresses and may or may
not produce fatigue-enhancing benefits in the structural workpiece
108. Determining the desired amounts of stresses in the workpieces
110, 120, the amount of interference between the outer member 140
and the inner member 145, and the amount of interference fit
between the outer member 140 and the collar 130 may be an iterative
process to achieve specific design goals, for example, installing
the assembly 100 into the workpiece 108 without damaging the
workpiece 108. In some embodiments, the interference fits are
sufficient to keep the outer member 140 and/or inner member 145,
even without installing the collar 130, from migrating under
operation, vibration, and/or other types of loads.
[0063] If the workpiece 108 is made of a low strain material, over
expansion may cause strains that may cause crack initiation, crack
propagation, fracture, or the like. In addition, if the workpiece
108 is made of fiber-reinforced composites, excessive strains may
cause delamination between layers, fiber de-bonding, or the like.
The outer member 140 can be inserted into the workpiece 108 with a
clearance fit to reduce, limit, or substantially prevent damage to
the composite workpiece 108. A high interference can be achieved
without over-expanding the member 140 to limit, reduce, or
substantially prevent damage associated with over expansion. The
high interference fit can also increase the fatigue life of the
workpiece 108 because the workpieces 110, 120 are held tightly
together. The inner member 145 can prevent an appreciable amount of
contraction of the expanded member 140 to achieve a wide range of
high interference fits.
[0064] FIGS. 7-8 show the inner member 145 prior to installation.
The inner member 145 includes a detachable section 340 coupled to
the narrow section 300. The detachable section 340 includes an
engagement region 342 and a shank 346. The detachable section 340
is a break away component and can be integrally formed with the
narrow section 300. In other embodiments, the detachable section
340 is a separate component that is detachably coupled to the
narrow section 300 by an adhesive, weld, or the like.
[0065] The engagement region 342 can be releasably coupled to an
installation apparatus and includes a plurality of engagement
features 344a, 344b, 344c, 344d (collectively 344). In some
embodiments, including the illustrated embodiment of FIGS. 7 and 8,
the engagement features 344 are circumferential grooves spaced
apart from each other with respect to a longitudinal axis 360 of
the inner member 145. The engagement features 344 can be other
types of coupling features for temporarily or permanently coupling
to installation apparatuses.
[0066] When a sufficient force is applied to the engagement region
342, the inner member 145 breaks at the decoupling feature 350 to
allow separation of the shank 346 and the narrow section 300, as
shown in FIG. 9. A cross-sectional area taken at 362 of the
decoupling feature 350 is less than the cross-sectional areas of
the other sections of the inner member 145. The cross-sectional
area at 362 can thus be the minimum cross-sectional area of the
member 145. The decoupling feature 350 may serve as a crack
initiation site. Cracks can propagate generally along a plane that
is substantially perpendicular to the longitudinal axis 360. FIG. 9
shows the detachable section 340 separated from the narrow section
300 after the decoupling feature 350 has fractured.
[0067] The decoupling feature 350 can be an edge notch. Exemplary
edge notches can include, without limitation, a circumferential
groove having a generally U-shaped cross-section, V-shaped
cross-section, or the like. Other types of edge notches or parting
features can be used to control stress concentrations, crack
initiation, and/or crack propagation such that the detachable
section 340 is separable from the narrow section 300 without
appreciably damaging to any significant extent other components of
the fastener assembly 100.
[0068] FIG. 10 shows the mandrel section 330 includes a first
expansion portion 331 and a second expansion portion 333. The first
expansion portion 331 is connected to the narrow section 300. The
second expansion portion 333 is connected to the stem 320. Angles
of taper .alpha., .beta. of the expansion portions 331, 333,
respectively, can be selected based on the desired amount of
expansion of the outer member 140, rate of expansion of the outer
member 140, desired stresses/strains of the outer member 140 and/or
the workpiece 108. In some embodiments, the angle of taper .alpha.
is equal to or greater than the angle of taper .beta.. For example,
the angle .alpha. can be at least 30 degrees greater than the angle
.beta.. Such embodiments are especially well suited for controlled
expansion without producing significant amounts of longitudinally
displaced material of the components, e.g., longitudinally
displaced material of a sidewall of the outer member 140. Surfaces
371, 373 of the mandrel section 330 can thus slide smoothly along
the inner surface of the outer member 140.
[0069] FIG. 11 shows a mandrel section 377 that has a
longitudinally curved surface 379 for sliding smoothly along the
outer member 140. The mandrel section 377 can expand the outer
member 140 without producing as much longitudinally material as the
mandrel section 330 of FIG. 10.
[0070] FIG. 12 shows an installation apparatus 384 that includes an
installation tool 386 for installing the fastener assembly 100.
Generally, the installation tool 386 includes an actuator unit 388
(illustrated as a puller unit) and a swaging assembly 396 (shown in
dashed line) carried by the puller unit 388. The puller unit 388
includes a grip 390. A user can manually grasp the grip 390 for
comfortably holding and accurately positioning the installation
tool 386. The illustrated grip 390 is a pistol grip. However, other
types of grips can also be utilized.
[0071] The installation tool 386 can be driven electrically,
hydraulically, pneumatically, or by any other suitable drive
system. In some embodiments, the puller unit 388 houses a drive
system capable of driving a component of the fastener assembly 100,
preferably along a predetermined path (e.g., a line of action), in
a proximal direction and/or distal direction. A pair of fluid lines
392, 394 of the installation apparatus 384 provides pressurized
fluid (e.g., pressurized gas, liquid, or a combination thereof) to
a piston drive system that operates the swaging assembly 396.
[0072] Referring to FIG. 13, the swaging assembly 396 includes an
outer housing 398, an actuating device 400, and a biasing member
402 between the outer housing 398 and the actuating device 400. The
actuating device 400 is moved through the outer housing 398 towards
the workpiece 108 to cause a swaging mechanism 404 to swage the
collar 130. The outer housing 398 is held against the workpiece 108
as the puller unit 386 pulls on the inner member 145 to remove the
detachable section 340.
[0073] FIG. 14 shows the outer housing 398 having a generally
tubular main body 412, a first end 413, a second end 415, and a
bore 416 extending between the first end 413 and the second end
415. The bore 416 is a longitudinally-extending passageway sized
and dimensioned to closely surround the actuating device 400.
[0074] The biasing member 402 pushes on the housing 398 and a
retainer 420, illustrated as a flange of the actuating device 400,
to move the actuating device 400 in a proximal direction to move a
shoulder 422 of the actuating device 400 against a shoulder 414 of
the outer housing 398. The illustrated biasing member 402 is
captured between a face 430 of the retainer 420 and an opposing
face 432 of the outer housing 398. The biasing member 402 can
include, without limitation, one or more springs (e.g., helical
springs, conical springs, and the like). In some embodiments, the
biasing member 402 is a round wire helical compression spring
surrounding a sleeve 406 of the device 400. Although the
embodiments illustrated herein show the biasing member 402 as a
spring, it is understood that other mechanical devices known in the
art that are capable of exerting a force can be used in place of
the mechanical spring.
[0075] The sleeve 406 is closely received by the outer housing 398
and includes the shoulder 422. An inner surface 487 of the sleeve
406 defines a passageway 489. In the illustrated embodiment, the
sleeve 406 is movable between a proximal position (e.g., when the
shoulder 422 bears against the shoulder 414) and a distal position
(illustrated in FIG. 14). A distance of travel D of the actuating
device 400 can be selected based on the dimensions of the outer
housing 398 and the sleeve 406.
[0076] The retainer 420 is coupled to an exterior surface 442 of
the sleeve 406. A stop 448 can limit, minimize, or substantially
prevent relative movement between the retainer 420 and the sleeve
406. The stop 448 of FIG. 14 is a ring that is at least partially
disposed within an annular recess 444 at a proximal end 450 of the
sleeve 406.
[0077] The swaging mechanism 404 includes a plurality of swaging
elements 462a, 462b, 462c, 462d (collectively 462). The swaging
elements 462 can be generally similar to each other, and
accordingly, the following description of one of the swaging
elements applies equally to the others, unless indicated otherwise.
The swaging elements 462 can be circumferentially spaced about the
sleeve 406 and can protrude inwardly from the inner surface 487
into the passageway 489. In the illustrated embodiment, the swaging
elements 462 are ball bearings, each positioned in a corresponding
socket 464a, 464b, 464c, 464c (collectively 464) in a sidewall 469
of the sleeve 406. For example, the swaging element 462a can rotate
freely within the complementary socket 464. The ball bearings 462
can be generally spherical bearings made, in whole or in part, of a
hard material suitable for deforming collars.
[0078] The swaging mechanism 404 can include six swaging elements
462 spaced generally equally apart by about 30 degrees with respect
to a longitudinal axis 491 of the actuating device 400. The number
of the swaging elements 462 may be greater or less than the
illustrated exemplary number depending on various design
objectives. For example, the swaging mechanism 404 can have more
than six swaging elements 462 to increase the number of contact
points created during the swaging process.
[0079] FIGS. 15-22 illustrate one method of installing the fastener
assembly 100. Generally, the expandable outer member 140 is
positioned in the opening 155. The inner member 145 is inserted
into the expandable outer member 140. The collar 130 is moved over
the outer member 140 such that the workpiece 108 is between the
collar 130 and the head 160 of the outer member 140. The outer
member 140 is expanded into the workpiece 108 using the mandrel
section 330 of the inner member 145. The collar 130 is fixed to the
expanded outer member 140.
[0080] Referring to FIG. 15, the outer member 140, in a
pre-expanded state, is inserted into the opening 155 of the
workpiece 108. A clearance fit, or other type of suitable fit, can
be provided for convenient assembly. If the workpiece 108 is made
of a composite material, a clearance fit can be provided to reduce,
minimize, or substantially prevent damage to the workpiece 108 as
the outer member 140 is placed within the opening 155. The opening
155 can closely receive the outer member 140 to reduce the amount
of expansion required to install the outer member 140.
[0081] In the illustrated embodiment, the outer member 140 on the
second side 144 of the workpiece 108 is moved sequentially through
the first and second panels 120, 110. When the head 160 is seated
in the countersink 237, the coupling section 235 protrudes from the
first side 143 of the workpiece 108. In some embodiments, a
substantial portion of the coupling section 235 extends outwardly
from the opening 155. The illustrated coupling section 235 is
spaced apart from the opening 155.
[0082] FIG. 16 shows the outer member 140 positioned in the opening
155 and ready to receive the inner member 145. The detachable
section 340 of the inner member 145 is inserted into and advanced
through the passageway 260 of the outer member 140 until at least a
portion of the detachable section 340 projects outwardly from the
inner member 140.
[0083] As shown in FIG. 17, the collar 130 can be positioned on the
first side 143 of the workpiece 108. The collar 130 can be moved
over the detachable section 340 and the outer member 140 such that
the collar 130 rests against the workpiece 108. The collar 130
surrounds at least a portion of the coupling section 235.
[0084] FIG. 18 shows the swaging assembly 396 ready to receive the
assembled fastener assembly 100 in an unexpanded state. A puller
unit (e.g., the puller unit 388 illustrated in FIG. 12) can be
coupled to the detachable section 340 protruding outwardly from the
collar 130. The puller unit is activated to pull the inner member
145 proximally through the outer member 140 (indicated by the arrow
357 of FIG. 18). The mandrel section 330 expands the outer member
140 as it passes through the outer member 140 and the stem 320
props the expanded portion 213 of the outer member 140 to limit,
minimize, or substantially prevent contraction of the outer member
140. During this process, the workpiece 108 is pulled against the
swaging assembly 396. As the head 310 seats in the head 160, the
puller unit compresses the workpiece 108 between the collar 130 and
the head 160.
[0085] When the mandrel section 330 moves through the outer member
140, the mandrel section 330 radially expands the outer member 140
from an initial configuration to an expanded configuration to cold
work, the workpiece 108 to produce an interference fit with the
workpiece 108, or the like. The outer member 140 can shield the
inner surface 154 of the opening 155 to prevent, limit, or
substantially eliminate damage to the workpiece 108. The wall
thickness of the outer member 140 can be increased to increase
shielding. The outer member 140 remains stationary with respect to
the workpiece 108 as the tubular main body 250 is expanded. The
outer member 140 can control stresses induced in the workpiece 108
throughout a portion or the entire thickness of the workpiece
108.
[0086] The outer surface 359 of the inner member 145 includes an
outer perimeter 361 that is sized to be equal to (e.g., maximum
tolerance conditions) or at least slightly smaller than the inner
perimeter of the "radially expanded" outer member 140. This
relative sizing allows the stem 320 to follow the mandrel section
330 into the expanded outer member 140 and to prop open the outer
member 140. In some embodiments, the inner member 145 can be
inserted into the outer member 140 without damaging an inner
surface 263 of the outer member 140.
[0087] The relative sizing of the mandrel section 330 and the stem
320 can also permit the stem 320 to be passed into the radially
expanded outer member 140 so that the outer member 140 can produce
an interference fit with the inner member 145, which both supports
and limits the radial contraction of the outer member 140. In some
embodiments, elastically, radially spring back of radially-expanded
outer member 140 produces a secure interference fit therewith to
achieve desired clamp-up forces, even relatively large clamp-up
forces.
[0088] The opening 155 can be expanded without compromising the
structural integrity of the workpiece 108, even the free edges 483,
485 of the opening 155. Because the workpiece 108 is not exposed to
any appreciable frictional forces during the expansion process,
damage (e.g., delamination) of the one or both of the panels 110,
120 can be kept at or below a desired level, even in material
proximate to the free edges 483, 485 shown in FIG. 15. The
composition, dimensions, and configuration of the outer member 140
can be selected to minimize, limit, or substantially prevent
undesired stresses (e.g., shear stresses) in the workpiece 108
while producing desired stresses (e.g., compressive stresses) in
the workpeice 108.
[0089] Referring to FIG. 19, an outer surface 493 of the collar 130
is a generally cylindrical surface. The actuating device 400
contacts and bears against the outer surface 493. The actuating
device 400 is moved distally towards the flange 150 of the collar
130. A gripping mechanism of the puller unit pulls on the inner
member 145 to keep the puller unit against the workpiece 108 while
the swaging elements 462 roll along the outer surfaced 493.
[0090] As the swaging elements 462 roll along the outer surface
493, the swaging elements 462 compress the collar 130 against the
expanded outer member 140. The swaging elements 462 cooperate to
radially displace the collar 130 inwardly so as to press the inner
surface 217 of the collar 130 against the locking features 220.
Each swaging element 462 can produce a longitudinally-extending
swage groove. The grooves can have an arcuate cross-section,
including a generally U-shaped cross-section, or other suitable
cross-sections. As used herein, the term "groove" includes, but is
not limited to, a generally long narrow furrow or channel. In some
embodiments, the swaging elements 462 can push material of the
collar 130 towards the workpiece 108 to increase the clamp-up
forces. Each of the swaging elements 462 can cause a flow of
material ahead of the interface between the swaging elements 262
and the collar 130. This flow of material can be pushed towards the
flange 150 and results in significantly increased clamp-up
forces.
[0091] FIG. 20 shows a plurality of grooves 495 circumferentially
spaced from one another about the collar 130. The depths and widths
of the grooves 495 can be increased by increasing the compressive
forces applied by the swaging elements 462. The illustrated grooves
495 extend generally longitudinally along the collar 130. The
grooves 495 can extend along most of the longitudinal length of the
main body 180 to lock a substantially portion of the longitudinal
length of the collar 130 to the outer member 140.
[0092] At full stroke, the swaging elements 462 are proximate the
flange 150. After completing the swaging process, the puller unit
can break off the exposed detachable section 430. A sufficient
axial load can be applied to the inner member 145 to fracture the
inner member 145 at or near the decoupling feature 350. FIG. 21
shows the inner member 145 after it is broken. A fracture surface
512 of the inner member 145 can be flush or adjacent to the end 270
of the member 140.
[0093] FIG. 22 shows the installed fastener assembly 100 and the
swaging assembly 396 separated from the assembly 100. The swaging
assembly 396 can be separated from the installed fastener assembly
100 after the detachable section 340 is removed.
[0094] The outer member 140 can contribute to the clamp-up of the
workpiece 108, along with the swaged collar 130, to enhance
performance (e.g., improve conductivity) and may result in some
compliance that inhibits or precludes failure of the fastener head
160 in single shear loading conditions. The illustrated fastener
assembly 100 can also be conveniently dissembled. When the inner
member 145 is removed, the outer member 140 can spring back (e.g.,
contract inwardly) and, in some embodiments, can allow for the
joint to be disassembled without damage to the workpieces 110, 120.
The wall thickness of the outer member 140 can be sufficiently
large to allow the inner member 145 to be slide out of the outer
member 140 that remains generally stationary. In contrast,
conventional thin-walled sleeve/bolt assemblies may come out
together resulting in unwanted damage to workpiece, especially when
the workpiece is made of a composite material.
[0095] The outer member 140 can have an outer diameter that is
slightly less than 0.25 inches and a wall thickness that is equal
to or greater than about 0.03 inches. Such an outer member 140 can
be installed in a 0.25 inch diameter hole. The outer member 140 can
be radially-expanded into the workpiece 108 to form an integral
part of the fastener assembly 100. In some embodiments, the outer
member 140 has a wall thickness of about 0.04 inches and is made,
in whole or in part, of steel (e.g., stainless steel), titanium, or
the like. The inner member 145 can be made of a relatively hard
material, such as stainless steel, suitable for radially-expanding
the outer member 140. The dimensions and configurations of the
inner member 145 and outer member 140 can be selected based on the
installation configuration.
[0096] The fastener assembly 100 can provide enhanced electrical
conductivity through the workpiece, especially at joints of
workpieces made of composite materials. The outer member 140 can
insulate the workpiece 108 from the inner member 145. High clamp-up
forces ensure that multi-component workpieces are held together
during the service life of the workpiece. Various types of
substances (e.g., lubricants) can be applied to the fastener
assembly 100 to facilitate installation and/or enhance performance.
For example, the outer member 140 and inner member 145 can be
passivated and dry film lubed. The passivated surfaces can provide
electrical insulation between the components of the fastener
assembly 100. The dry film lube can reduce the forces required to
install the fastener assembly 100.
[0097] Workpieces may comprise a wide range of different materials,
including materials (e.g., composite materials), that are
susceptible to damage due to high strains. Composite materials may
include two or more materials with significantly different
properties, such as physical properties (e.g., mechanical
properties, electrical properties, etc.), chemical properties, or
the like. For example, composite materials may include, without
limitation, reinforcing elements (e.g., fibers, particles, and the
like), fillers, binders, matrix, and the like. Wood, fiberglass,
polymers, plastics, metals, ceramics, glass, or the like can be
combined to produce one or both of the illustrated composite panels
110, 120 with properties that are different from the properties of
its constituents individually. In some embodiments, the workpiece
108 can comprise a fiber-reinforced composite, particle-reinforced
composite, laminate (e.g., a stack of laminas), or combinations
thereof. The matrix of the reinforced composites can be made of
metal, polymers, ceramics, and other suitable materials for
encapsulating other reinforcement features. The laminates can be
unidirectional laminates, cross-ply laminates, angle-ply laminates,
symmetric laminates, and the like.
[0098] The fastener assembly 100 can be installed in the composite
workpiece 108 while maintaining the integrity of the workpiece 108.
The outer member 140, for example, can be easily inserted into the
opening 155. The inner member 145 can expand the outer member 140
such that the expanded outer member 140 produces an interference
fit with the workpiece 108. To minimize, limit, or substantially
prevent damage to the material surrounding the opening 155, the
amount of radial expansion can be below a threshold amount of
expansion that would cause unwanted damage, such as micro-cracking,
buckling of fibers, and the like, of the workpiece 108.
[0099] Composites may have relatively low strain capabilities as
compared to metals. The fastener assembly 100 can produce
compressive loading in the composite material surrounding the
opening 155. If the compressive loading is too high, fibers in a
fiber-reinforced composite material can buckle, which in turn
affects the material's properties. Micro-buckling of fibers may
significantly reduce the water resistance of the composite material
because buckled fibers may cause micro-cracking of the matrix
surrounding the fibers. Splitting due to Poisson's ratio effect,
matrix yielding, fiber splitting, de-bonding (e.g., fiber
de-bonding, interlaminate de-bonding, and the like), and other
failure modes are often caused by compressive loading or high
strains. Advantageously, the fastener assembly 100 can be installed
using sufficiently low levels of strain to control the amount of
damage, if any, to the workpiece 108. For example, the outer member
140 in an un-expanded state can be installed with a clearance fit
or a slight interference fit, as well as other types of fits, until
the inner member 145 expands the outer member 140. Advantageously,
the fastener assembly 100 can be installed using sufficiently low
levels of strain to control the amount of damage, if any, to the
workpiece 108. The fastener assembly 100, for example, can be
installed with a slight interference fit or other type of fit that
keeps the fastener assembly 100 fixed to the workpiece 108.
Outwardly directed compressive forces can be applied to the
workpiece 108 without compromising the structural integrity of the
workpiece 108.
[0100] By knowing the final dimensions of the installed fastener
assembly, a desired amount of radial interference between the
expanded outer member 140 and the inner member 145 may be selected.
It is understood that the inner member 145, the outer member 140,
and/or the opening 155 in the workpiece 108 may have generally
circular cross-sections or non-circular cross-sections such that
the amount of interference may need to be expressed with alternate
language. It is generally understood that when components are
assembled with an "interference fit," a contact pressure is present
between the components after assembly.
[0101] Further, the installation can be accomplished with both the
inner and outer members 140, 145 at substantially the same
temperature. In some embodiments, the average temperature of the
inner member 140 can be less than about 10 degrees Celsius of the
average temperature of outer member 145. In some embodiments, for
example, the average temperature of the inner member 140 can be
less than 5 degrees Celsius of the average temperature of outer
member 145. This eliminates the need to freeze or heat one of the
respective members, which reduces manufacturing time and costs.
Thermal processes can often lead to the formation of a condensate,
which in turn leads to corrosion of the workpiece 108.
[0102] Other types of swaging assemblies can be used to install
expandable fastener assemblies. FIG. 23-25 show a swaging assembly
510 that includes a multi-piece outer housing 512, a restraint 514,
and a biasing member 576 between the outer housing 512 and the
restraint 514. A gripping mechanism 520 has a jaw 522 for gripping
an inner member. The inner member can be inserted into a bore 524
of the gripping mechanism 522. An actuation assembly 530 includes
coupling features 540, illustrated as internal threads, for
coupling to a puller unit.
[0103] FIG. 26 shows the swaging assembly 510 with a jaw assembly
545. The jaw assembly 545 includes interior engagement region 546
configured to engage the engagement region of an inner member, such
as the engagement region 342 discussed in connection with FIGS.
7-9. The illustrated engagement region 546 has a complementary
shape to the engagement region 342 of the inner member 145. The jaw
assembly 545 is moveable between an open configuration for
receiving the inner member 145 and an open configuration for
releasing the detachable section 340 after breaking if off.
[0104] The various embodiments described above can be combined to
provide further embodiments. All of the above U.S. patents, patent
applications and publications referred to in this specification, as
well U.S. Provisional Patent Application No. 60/999,517, filed Oct.
16, 2007, U.S. application Ser. No. 12/253,141; U.S. Pat. Nos.
3,566,662; 3,892,121; 4,187,708; 4,423,619; 4,425,780; 4,471,643;
4,524,600; 4,557,033; 4,809,420; 4,885,829; 4,934,170; 5,083,363;
5,096,349; 5,103,548; 5,127,254; 5,245,743; 5,305,627; 5,341,559;
5,380,136; 5,405,228; 5,433,100; 7,024,908; 7,100,264; and
7,375,277; U.S. Patent Publication Nos. 2005/0025601; 2007/0110541;
2007/0289351; 2007/0295050; 2008/0005887; 2008/0034831; and
2008/0066518; and International Application No. WO 2007/082077 are
incorporated herein by reference. Aspects can be modified, if
necessary or desired, to employ devices, features, elements (e.g.,
fasteners, bushings, nut plates, and other types of expandable
members), and concepts of the various patents, applications, and
publications to provide yet further embodiments. The fastener
assemblies disclosed herein can be made, in whole or in part, of
the materials (e.g., materials, coatings, liners, etc.) disclosed
in the concepts of the various patents, applications, and
publications to provide yet further embodiments
[0105] From the foregoing it will be appreciated that, although
specific embodiments of the invention have been described herein
for purposes of illustration, various modifications may be made
without deviating from the spirit and scope of the invention.
Accordingly, the invention is not limited except as by the
disclosed embodiments and the appended claims.
* * * * *