Constrained Layer Damper

Abstract

A system includes a first layer of a first polymeric material being visco-elastic when solidified. The first polymeric material covers a first portion of a substrate. A second layer of a second polymeric material (being stiff when solidified) covers at least a portion of the first layer and at least a second portion of the substrate. Additionally, a method includes applying a layer of first polymeric material to a first portion of a substrate. The first polymeric material is visco-elastic when solidified. Additionally, a layer of a second polymeric material (being stiff when solidified) is applied to the first polymeric material and a second portion of the substrate. The first polymeric material is constrained between the second polymeric material and the substrate. Both of the first polymeric material and the second polymeric material are dispensed in fluid form from a bulk source of fluid material.

Description

RELATED APPLICATIONS

[0001] The present application is a continuation in part of U.S. patent application Ser. No. 10/458,889 filed on Jun. 11, 2003, to Robert D. Myers et al., entitled "Constrained Layer Damper," the contents of which are included herein by reference in their entirety.

BACKGROUND

[0002] The present invention generally relates to constrained layer dampers that are used to dissipate vibration energy.

[0003] Undesirable vibration energy occurs in a variety of products and devices. For example, in automotive vehicles, the engine and other automotive systems can cause vibration energy to permeate through the vehicle body and into the vehicle's passenger compartment. Similar undesirable vibration energy results in a variety of other situations, such as in household appliances and other types of transportation vehicles, to name a few.

[0004] To reduce undesirable vibration energy, it is known to adhere single-layer vibration-damping panels and apply single-layer vibration-damping materials to the surfaces of automobile panels, floors, and the like (and to appliances and other devices) to reduce vibration effects inside of the passenger compartment. Single-layer vibration-damping panels and coatings are relatively cost-effective, and they do reduce undesirable vibrations. It is also known to use constrained layer dampers to minimize undesirable vibrations in certain circumstances. Constrained layer dampers generally consist of a layer of polymeric damping material adhered to a surface of a panel of the product (e.g., automobile, appliance, etc.) and a stiff outer top layer that constrains the polymeric damping material, effectively "sandwiching" the polymeric damping material between the stiff outer top layer and the product panel (the "substrate"). It has been determined that constrained layer dampers are generally more effective at reducing undesirable vibration than single layer dampers. However, constrained layer dampers are generally more expensive to manufacture and install.

[0005] The inventors hereof have recognized the need for an improved constrained layer damper and for an improved modular method of installing constrained layer dampers in automated manufacturing settings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 illustrates an exemplary automated manufacturing setting, including a system for applying a constrained layer damper, showing the fluidic application of a first polymeric material.

[0007] FIG. 2 illustrates an exemplary automated manufacturing setting, including a system for applying a constrained layer damper, showing the fluidic application of a second polymeric material.

[0008] FIG. 3 is a cross-sectional view of the constrained layer damper, showing a substrate, a first layer of polymeric material, and a second layer of polymeric material.

[0009] FIG. 4 illustrates an exemplary automated manufacturing setting, including a system for applying a selective constrained layer damper, showing the fluidic application of a first polymeric material.

[0010] FIG. 5 illustrates an exemplary automated manufacturing setting, including a system for applying a selective constrained layer damper, showing the fluidic application of a second polymeric material.

[0011] FIG. 6 is a perspective view of a completed selective constrained layer damper, with the constrained layer areas placed a more than one hot spot location.

[0012] FIG. 7 is a cross-sectional view of the selective constrained layer damper.

DETAILED DESCRIPTION

[0013] An exemplary embodiment of an improved constrained layer damper and a method of applying a constrained layer damper in an automated manufacturing setting is hereinafter disclosed.

[0014] The improved constrained layer damper comprises at least two layers of materials. The "base" layer of material is a visco-elastic polymeric material, which is applied or adhered directly to a panel (substrate) of a product for which the vibration-reducing effect is desired. For example, in the case of an automotive vehicle, the first layer could be applied/adhered to a metal floor panel. The first layer of polymeric material is chosen so as to adhere well to the substrate in question. This material is designed to maximize damping performance defined by the material loss factor in the range of the intended operating temperatures. This loss factor is calculated from the phase angle by which the stress leads the strain in the deformable solid material. This loss factor will be a maximum over the glass transition region of the material, and may achieve values in excess of 1.0 in this region. The corresponding stiffness of the first layer will be low relative to the stiffness of the top or constraining layer, as described hereinafter. Examples of acceptable materials that can be used as the first layer in the improved constrained layer damper include, without limitation, acrylic polymers, synthetic resins, emulsions, and bituminous based materials. Examples of suitable materials would include polyurethanes, styrene block co-polymers, polyureas, silane terminated polyurethanes, modified silane polymers, polyisobutylenes, ethylene propylene diene monomer (EPDM), natural rubber, epoxy resins and other polymer materials that can be modified to achieve the desired physical properties. More specific, commercially-available, materials that can be employed as the base layer in the constrained layer damper include: (1) Sikafloor Pronto 18, a two component peroxide-cured modified PMMA; (2) SikaTransfloor 352 VP, a two component polyurethane; (3) Sikafloor 325, a two component polyurethane; (4) PU Read, a two component polyurethane; and (5) FM 100, a styrene butadiene block copolymer, all of which are commercially available from the assignee hereof.

[0015] The improved constrained layer damper further includes an "outer" or "top" layer of material that is applied to the base visco-elastic polymeric material. The outer layer of material is also a polymeric material, but the outer polymeric material layer has a high degree of stiffness when in its solid state. The stiffness of the outer layer will generally be a factor of ten times higher in stiffness than the base layer, and will have Young's Modulus (E') in excess of 1.0.times.(10).sup.9 MPa over the glassy region of the material. The outer layer of material is formulated to ensure that the glass transition region of the material and corresponding roll-off in modulus are above the operating temperature range in the application. This material may be homogeneous in nature or may incorporate reinforcing fibers or fillers to enhance stiffness. The outer layer of material may be applied as a single or multiple component system. Examples of acceptable materials that can be used as the second layer in the improved constrained layer damper include, without limitation, epoxy resins, polyureas, acrylic polymers, polyurethanes, epoxy polyurethane hybrids, polyesters, modified polyesters, and other polymers that can be modified to achieve the desired physical properties. More specific, commercially-available, materials that can be employed as the top layer in the constrained layer damper include: (1) Sikadur 32, a two component toughened epoxy; (2) Sikafloor 381, a two component chemically-resistant epoxy; and SikaGard 62, a two component epoxy.

[0016] The respective polymeric materials are chosen so that they adhere well to each other. Preferably, the respective polymeric materials are chosen such that they solidify without the application of heat. Specifically, it is preferable that the polymeric materials are chosen such that they solidify by cooling to room temperature, by drying, by chemical reaction at room temperature, or by other known means of solidifying or curing that do not require the application of heat above room temperature. In this way, the inventive constrained layer damper can be installed onto vehicles (and other manufactured products) in a more flexible way. That is, the two layers of the constrained layer damper can be applied after the vehicle (or other manufactured product) passes through the paint shop, which is normally the location on the assembly line where high temperatures are applied to the vehicle. If the constrained layer damper were to employ materials that required high temperatures to solidify, then the constrained layer damper would have to be applied to the vehicle (or other product) before it reached the paint shop. If the preferred polymeric materials are used--which do not require heat to solidify--then the constrained layer damper may be applied after the vehicle passes through the paint shop, which is sometimes desirable to maintain the integrity of the paint shop process. Furthermore, if the polymeric materials used for the constrained layer damper do not require heat to solidify, the different layers can be applied at different locations on the assembly line without regard to where the location(s) of application are relative to the paint shop.

[0017] In other embodiments of the invention, the improved constrained layer damper may include more than two layers of material, where the layers of material alternate between the visco-elastic polymeric material of the first layer and the stiff polymeric material of the second outer layer.

[0018] The improved constrained layer damper is adapted to be applied dynamically during the manufacture of a product, such as an automotive vehicle, in an automated manufacturing setting. Referring to FIGS. 1 and 2, an exemplary automated manufacturing setting is illustrated, which, in this particular example, is a setting for automated manufacturing of automotive vehicles. FIGS. 1 and 2 illustrate a partially-manufactured automotive vehicle on an assembly line. At the illustrated point in the manufacturing process, the automotive vehicle still has an exposed floor panel 10 (substrate). It is desirable to include a vibration damper on floor panel 10 of the automotive vehicle. FIG. 1 illustrates a first articulated robot arm 12a, having an applicator head 14a with a nozzle for dispensing fluid materials. The exemplary automated manufacturing setting also includes a second articulated robot arm 12b, having an applicator head 14b with a nozzle for dispensing fluid material. The articulated robot arms 12a and 12b are electronically controlled by a control device (not shown), such as, for example, a computer workstation. The articulated robot arms 12a and 12b are controlled so that the robot arms are selectively positioned relative to the floor 10 of the automotive vehicle to dispense fluid material thereon.

[0019] The first applicator head 14a disposed on the articulated arm robot 12a is fluidly-connected to at least one source of fluid material (not shown). The second applicator head 14b disposed on the articulated arm robot 14b is also fluidly-connected to at least one source of fluid material (not shown), which is different from the fluid source connected to applicator head 14a. In some embodiments, the respective sources of fluid materials are drums or bulk containers of fluid materials. Various known metering and fluid delivery components and systems can be used to deliver desired amounts of the fluid materials from the respective sources to the corresponding applicator heads on the articulated robot arms.

[0020] The above-described system can be used to implement the improved constrained layer damper on the floor (or other substrate) of an automotive vehicle (or other manufactured product). For example, in one embodiment, a first layer of visco-elastic polymeric material 16a is dispensed, in fluid form, from the applicator head 14a of the robot arm 12a onto the substrate 10. The first layer of material is allowed to solidify and adhere to the substrate 10. Then, as shown in FIG. 2, the second layer of material 16b is dispensed, in fluid form, from the applicator head 14b of the robot arm 12b onto the first layer of visco-elastic polymeric material 16a. The second layer of material 16b is allowed to solidify into a stiff layer, which "sandwiches" the middle visco-elastic polymeric material 16a against the substrate 10, thereby creating the constrained layer damper. FIG. 3 illustrates a cross-section of the constrained layer damper, wherein a visco-elastic polymeric material 16a is "sandwiched" between the substrate 10 of the vehicle and a stiff polymeric material 16b.

[0021] As described above, if polymeric materials that do not require heat to solidify are chosen for the base and outer layers of the constrained layer damper, then the application of the base and outer layers may occur anywhere in the assembly/manufacturing process without regard to where in the process heat may be applied. For example, in the situation of an automotive vehicle, the layers of the constrained layer damper may be applied subsequent to the paint shop, which, in certain situations, is preferable to maintain the integrity of the paint process.

[0022] In another embodiment of the invention, each of the applicator heads 14a and 14b are configured to dispense a plurality of different versions of the two different layers of materials that comprise the constrained layer damper. For example, a variety of visco-elastic polymeric materials may be acceptable for use in the disclosed improved constrained layer damper, though certain visco-elastic polymeric materials may have better qualities than others. Many times, those materials that have superior qualities are more costly. Therefore, this embodiment includes a first applicator head 14a that can dispense, for example, a plurality of visco-elastic polymeric materials to be used as the first material layer in the constrained layer damper, applied to the substrate 10. Further, applicator head 14b may be configured to dispense one or more different stiff polymeric materials to be used as the outer layer in the constrained layer damper. In this way, the particular configuration of the constrained layer damper can be customized from one automotive vehicle to the next. For example, for Vehicle A, a first visco-elastic polymeric material can be dispensed from the applicator head onto the substrate and a first stiff polymeric material can then be dispensed onto the visco-elastic polymeric material to form the constrained layer damper. Then, for Vehicle B, which can be the next vehicle on the same assembly line, second visco-elastic polymeric material can be dispensed from the applicator head onto the substrate of vehicle B. Then, a second stiff polymeric material can be dispensed onto the second visco-elastic polymeric material to form the constrained layer damper. In this way, it is possible to customize the particular materials used to form the constrained layer damper from one vehicle to the next. For example, where a relatively inexpensive vehicle and a relatively expensive vehicle are assembled on the same automated assembly line, higher quality/cost materials can be used to form the constrained layer damper for the relatively expensive vehicle, and lower quality/cost materials can be used to form the constrained layer damper for the relatively inexpensive vehicle. A control device, such as a computer workstation could be used to control the application of the different materials for different vehicles.

[0023] In another embodiment of the invention, the functions of the two articulated robot arms 12a and 12b could be combined into a single articulated robot arm having one or more nozzles configured to dispense a first layer of visco-elastic polymeric material to a substrate 10, as well as one or more nozzles configured to dispense a second layer of stiff polymeric material onto the visco-elastic polymeric material. As in previous embodiments, the articulated robot arm, including the various dispensing nozzles thereon, would be electronically controlled by a controller device, such as a computer workstation.

[0024] In yet another embodiment, either the visco-elastic polymeric material or the stiff polymeric material can be applied in a solid piece form, and the other material can be dispensed from an articulated robot arm in fluid form. For example, a solid piece of visco-elastic polymeric material can be applied directly to the substrate of the automotive vehicle. The solid piece of visco-elastic polymeric material can be adhered to the substrate in a variety of known ways, such as by using heat, ultraviolet radiation, etc. Then, after the solid piece of visco-elastic polymeric material is adhered to the substrate, the outer layer of stiff polymeric material can be dispensed, in fluid form, from an applicator head on a robot arm over the visco-elastic polymeric material. The outer polymeric material is solidified, at which time it becomes stiff and, in combination with the substrate, "sandwiches" the middle visco-elastic polymeric material. As indicated above, additional alternating layers of the two polymeric materials can be added to the constrained layer damper. Alternatively, the first visco-elastic polymeric material can be dispensed onto the substrate of the automotive vehicle from the applicator head on the articulated robot arm, and the second stiff polymeric material can be applied over the visco-elastic polymeric material in a solid piece. More specifically, the first layer of visco-elastic polymeric material can be dispensed, in fluid form, from the applicator head of the robot arm to the substrate. The fluid material is solidified and adhered to the substrate. Then, a solid piece of stiff polymeric material can be adhered to the first layer of visco-elastic polymeric material. This solid piece of stiff polymeric material may be a dedicated constraining layer for the damping system, or this functionality may be incorporated into carpet backing, headliners, or other interior trim components added at a later stage in the assembly process. Similarly to above, additional alternating layers of the respective materials can be applied to create a multi-layer constrained layer damper.

[0025] In addition to the benefits described above, the application of the improved constrained layer damper in the manner described allows the constrained layer damper to be customized even further, depending on the particular vehicle (or product) upon which it is applied. For instance, the number of alternating layers can be customized, and the thickness of the visco-elastic polymeric material and the stiff polymeric material can be customized. Moreover, it is possible to apply single-layer dampers to some vehicles on the assembly line and to apply constrained layer dampers on other vehicles on the same assembly line.

[0026] In another embodiment, an improved damping system having a selective constrained layer damper includes an outer layer over the substrate and a constrained layer placed between the outer layer and the substrate at selected predetermined locations. With a thin additional layer at selective locations the damping system achieves superior damping properties at the selective locations. Stated another way, the improved damping system includes a single layer damper and a two layer constrained damper at certain locations considered "hot spots." By using a single layer system for the overall damper and a constrained damper system at areas identified as hot spots, the cost of manufacture, time of manufacture, weight, overall thickness of the damping system, as well as other factors, are improved.

[0027] A hot spot is an area where it is desirable to have additional damping. That is to say, it is desirable to have more damping than the single layer can provide. The hot spot is generally an arbitrary location identified on the substrate by a customer, supplier, etc. The additional damping at the hot spot reduces vibration or noise when the substrate (or the associated article of manufacture using the substrate) is in use.

[0028] As described below, a constrained layer damper is selectively placed at locations where additional damping is desired as a treatment to reduce structure-borne sound and/or vibration. Generally, the selective constrained layer damper converts Kinetic energy of a vibrating surface into thermal energy in a polymeric layer, thereby dissipating the vibrational energy. At locations other than the hot spots, an extensional single layer of material is applied to the substrate. In this way, the outer layer of the constrained layer damper behaves as a single dissipative layer for the areas not considered hot spots. The single layer damper converts vibrational energy to heat through extension and compression of the dissipative layer.

[0029] The constrained layer, placed at the identified hot spots, is a visco-elastic polymeric material which is applied or adhered directly to a panel (substrate) of a product for which the vibration-reducing effect is desired. This is similar to the base layer described above. The constrained layer portions are not placed as a full layer on the substrate, but rather are concentrated at the hot spots. For example, in the case of an automotive vehicle, the selective constrained layer damper could be applied/adhered to a metal floor panel. The constrained layer of polymeric material is chosen so as to adhere well to the substrate in question. This material is designed to maximize damping performance defined by the material loss factor in the range of the intended operating temperatures. This loss factor is calculated from the phase angle by which the stress leads the strain in the deformable solid material. This loss factor will be a maximum over the glass transition region of the material.

[0030] The corresponding stiffness of the constrained layer will be low relative to the stiffness of the outer or constraining layer, as described hereinafter. Examples of acceptable materials that can be used as the constrained layer in the selective constrained layer damper include, without limitation, synthetic resin, natural resins, water based or solvent type, bituminous or cement based materials, and other polymer materials that can be modified to achieve the desired physical properties. Other examples include, but are not limited to, polyurethanes, styrene block co-polymers, acrylic polymers, polyureas, silane terminated polyurethanes, modified silane polymers, polyisobutylenes, EPDM, natural rubber, Poly vinyl chloride, epoxy resins, waterbased resins, and bituminous based materials, and other materials having visco-elastic properties. Other examples of resins include, but are not limited to, Acrylics, Acrylonitrile-Butadiene-Styrene (ABS), Epoxies, Fluoropolymers, Polyamide-Imides, Polyethylene, Polyimides, Polypropylene, Polystyrene, Polyvinyl Acetate, and Polyesters.

[0031] Specific commercially-available materials that can be employed as the base layer in the selective constrained layer damper include, but are not limited to: (1) Sikafloor Pronto 18, a two component peroxide-cured modified PMMA; (2) SikaTransfloor 352 VP, a two component polyurethane; (3) Sikafloor 325, a two component polyurethane; (4) PU Read, a two component polyurethane; and (5) FM 100, a styrene butadiene block copolymer, (6) Sikamelt 9283, a thermal plastic rubber based hotmelt adhesive. All of which are commercially available from the assignee hereof.

[0032] The selective constrained layer damper further includes an "outer" or "top" layer of material that is applied to the base visco-elastic polymeric material. The outer layer of material is also a polymeric material, but the outer polymeric material layer has a high degree of stiffness when in its solid state. The stiffness of the outer layer will generally be a factor of ten times higher in stiffness than the constrained layer, and will have Young's Modulus (E') in excess of 1.0.times.(10).sup.9 MPa over the glassy region of the material. The outer layer of material is formulated to ensure that the glass transition region of the material and corresponding roll-off in modulus are above the operating temperature range in the application. This material may be homogeneous in nature or may incorporate reinforcing fibers or fillers to enhance stiffness.

[0033] The outer layer of material may be applied as a single or multiple component system. Examples of acceptable materials that can be used as the outer layer in the selective constrained layer damper include, without limitation, synthetic or natural resins, water based or solvent type, bituminous or cement based materials, and other polymer materials modified to achieve the desired physical properties. Examples of suitable materials would include, but are not limited to, epoxy resins, polyureas, acrylic polymers, polyurethanes, epoxy polyurethane hybrids, polyesters, modified polyesters, waterbased resins, and other polymers that can be modified to achieve the desired physical properties. Specific commercially-available materials that can be employed as the outer layer in the selective constrained layer damper include, but are not limited to: (1) Sikadur 32, a two component toughened epoxy; (2) Sikafloor 381, a two component chemically-resistant epoxy; (3) SikaGard 62, a two component epoxy; and (4) Sika Damp 1202, a waterbased spray-on damper material.

[0034] The respective polymeric materials that comprise the outer layer and constrained layer are chosen so that they adhere well to each other. Moreover, because the selective constrained layer damper also includes outer layer 30 as adhering to substrate 10, the material for outer layer 30 is chosen for adherence to the constrained layer (e.g., at hot spots 20, 22, 24) as well as adherence to the material substrate 10. Additionally, the material chosen for outer layer 30 also takes into account the constraining function, at hot spots 20, 22, 24, as well as the single layer damping elsewhere.

[0035] The respective polymeric materials, in an embodiment, are chosen such that they solidify without the application of heat. In this case, the polymeric materials are chosen such that they solidify by cooling to room temperature, by drying, by chemical reaction at room temperature, or by other known means of solidifying or curing that do not require the application of heat above room temperature. In this way, the selective constrained layer damper can be installed onto vehicles (and other manufactured products) in a more flexible way. That is, the two layers of the selective constrained layer damper can be applied after the vehicle (or other manufactured product) passes through the paint shop, which is normally the location on the assembly line where high temperatures are applied to the vehicle. Where polymeric materials are used which do not require heat to solidify, the selective constrained layer damper may be applied after the vehicle passes through the paint shop, which is sometimes desirable to maintain the integrity of the paint shop process. Furthermore, where polymeric materials used for the selective constrained layer damper do not require heat to solidify, the different layers can be applied at different locations on the assembly line without regard to where the location(s) of application are relative to the paint shop.

[0036] In an alternative embodiment, one or more of the layers (e.g., outer layer 30 and/or the constrained layer(s) at hot spots 20, 22, 24) may be dried by the application of heat (e.g., in an oven or by direct forced hot air). That is to say, the outer layer 30 may be air-dried while the constrained layers may be heat dried. Alternatively, the constrained layers may be air-dried while the outer layer is heat dried. Also, the constrained layers and the outer layer may both be heat dried. By adding the flexibility to the drying process, outer layer 30 or the constrained layer at hot spots 20, 22, 24 may be applied before or after the vehicle passes through the paint shop.

[0037] In other embodiments, the selective constrained layer damper may include more than two layers of material, where the layers of material alternate between the visco-elastic polymeric material of the constrained layer and the stiff polymeric material of the outer layer.

[0038] The selective constrained layer damper is adapted to be applied dynamically during the manufacture of a product, such as an automotive vehicle, in an automated manufacturing setting. Referring to FIGS. 4 and 5, an exemplary automated manufacturing setting is illustrated, which in this particular example is a setting for automated manufacturing of automotive vehicles. FIGS. 4 and 5 (similar to FIGS. 1 and 2) illustrate a partially-manufactured automotive vehicle on an assembly line. At the illustrated point in the manufacturing process, the automotive vehicle still has an exposed floor panel 10 (substrate). It is desirable to include a vibration damper on floor panel 10 of the automotive vehicle. FIG. 4 illustrates first articulated robot arm 12a, having applicator head 14a with a nozzle for dispensing fluid materials. The exemplary automated manufacturing setting also includes second articulated robot arm 12b, having applicator head 14b with a nozzle for dispensing fluid material. The articulated robot arms 12a and 12b are electronically controlled by a control device (not shown), such as, for example, a computer workstation. The articulated robot arms 12a and 12b are controlled so that the robot arms are selectively positioned relative to the floor 10 of the automotive vehicle to dispense fluid material thereon.

[0039] The first applicator head 14a disposed on the articulated arm robot 12a is fluidly-connected to at least one source of fluid material (not shown). The second applicator head 14b disposed on the articulated arm robot 14b is also fluidly-connected to at least one source of fluid material (not shown), which is different from the fluid source connected to applicator head 14a. In some embodiments, the respective sources of fluid materials are drums or bulk containers of fluid materials. Various known metering and fluid delivery components and systems can be used to deliver desired amounts of the fluid materials from the respective sources to the corresponding applicator heads on the articulated robot arms.

[0040] The above-described system can be used to implement the selective constrained layer damper on the floor (or other substrate) of an automotive vehicle (or other manufactured product). For example, in one embodiment, areas of visco-elastic polymeric material 16a are dispensed, in fluid form, from the applicator head 14a of the robot arm 12a onto the substrate 10 in selective areas. In the embodiment shown, for example, visco-elastic polymeric material 16a is dispensed at a first hot spot 20, a second hot spot 22, and a third hot spot 24. The hot spots 20, 22, 24 are areas that are desired to have the constrained layer damper. The other areas of substrate 10 are not desired to have a constrained layer damper and thus, will be coated with a single layer damper as described in FIG. 5.

[0041] The first layer of material deposited at hot spots 20, 22, 24 is allowed to solidify and adhere to the hot spots identified on substrate 10. Then, as shown in FIG. 5, an outer layer 30 of material 16b is dispensed, in fluid form, from the applicator head 14b of the robot arm 12b onto the constrained layer of visco-elastic polymeric material 16a. Outer layer 30 of material 16b is allowed to solidify into a stiff layer, which "sandwiches" the middle visco-elastic polymeric material 16a against the substrate 10, thereby creating the selective constrained layer damper at each hot spot. Moreover, outer layer 30 is applied directly to substrate 10 at locations other than hot spots 20, 22, 24 and becomes a single layer damper.

[0042] FIG. 6 is a perspective view of a completed selective constrained layer damper, with the constrained layer placed at more than one location. Shown in phantom lines, hot spots 20, 22, 24 are constrained layer dampers at the hot spots and outer layer 30 is a single layer damper elsewhere. As shown, outer layer 30 substantially covers the entirety of substrate 10. However, it is also foreseen that outer layer 30 will cover only portions of substrate 10. Such a selective application allows for attachment points for other assemblies to have direct contact with substrate 10. Alternatively, outer layer 30 may only be desired to be applied to portions of substrate 10 that realize vibration. Other portions of substrate 10 may not require damping and thus, would not be covered by outer layer 30.

[0043] FIG. 7 illustrates a cross-section of the selective constrained layer damper at hot spot 22, wherein a visco-elastic polymeric material 16a is "sandwiched" between the substrate 10 of the vehicle and a stiff polymeric material 16b. The single layer portion of the selective constrained layer damper comprises outer layer 30 that adheres to substrate 10 at interface 40. A portion of hot spot 22 is shown that forms a constrained layer damper comprising the constrained layer 22 that adheres to outer layer 30 at interface 42 and also adheres to substrate 10 at interface 44. In the embodiment shown, the constrained layer (e.g., hot spot layers 20, 22, 24) comprises a layer of visco-elastic material that is approximately zero point four millimeters (0.4 mm) thick. Outer layer 30 is approximately three millimeters (3 mm) thick, and the substrate (as a metal) is zero point eight millimeters (0.8 mm) thick.

[0044] If polymeric materials that do not require heat to solidify are chosen for the constrained layer and outer layer of the selective constrained layer damper, then the application of the constrained layer and outer layer may occur anywhere in the assembly/manufacturing process without regard to where in the process heat may be applied. For example, in the situation of an automotive vehicle, the layers of the selective constrained layer damper may be applied subsequent to the paint shop, which, in certain situations, is preferable to maintain the integrity of the paint process.

[0045] As discussed above, alternative embodiments provide that outer layer 30 and/or the constrained layer at hot spots 20, 22, 24 are dried by the application of heat (e.g., in an oven or by direct forced hot air). In this way outer layer 30 may be air-dried while the constrained layers may be heat dried. Alternatively, the constrained layers may be air-dried while the outer layer is heat dried. Also, the constrained layers and the outer layer may both be heat dried. Therefore, outer layer 30 or the constrained layer at hot spots 20, 22, 24 may be applied before or after the vehicle passes through the paint shop.

[0046] In another embodiment, each of the applicator heads 14a and 14b are configured to dispense a plurality of different versions of the two different layers of materials that comprise the selective constrained layer damper. For example, a variety of visco-elastic polymeric materials may be acceptable for use in the disclosed selective constrained layer damper, though certain visco-elastic polymeric materials may have better qualities than others. Many times, those materials that have superior qualities are more costly. Therefore, this embodiment includes a first applicator head 14a that can dispense, for example, a plurality of visco-elastic polymeric materials to be used as the first material layer in the selective constrained layer damper, applied to the substrate 10. Further, applicator head 14b may be configured to dispense one or more different stiff polymeric materials to be used as the outer layer in the selective constrained layer damper. In this way, the particular configuration of the selective constrained layer damper can be customized from one automotive vehicle to the next.

[0047] For example, for Vehicle A, a first visco-elastic polymeric material can be dispensed from the applicator head onto the substrate and a first stiff polymeric material can then be dispensed onto the visco-elastic polymeric material to form the selective constrained layer damper. Then, for Vehicle B, which can be the next vehicle on the same assembly line, second visco-elastic polymeric material can be dispensed from the applicator head onto the substrate of vehicle B. Then, a second stiff polymeric material can be dispensed onto the second visco-elastic polymeric material to form the selective constrained layer damper. In this way, it is possible to customize the particular materials used to form the selective constrained layer damper from one vehicle to the next. For example, where a relatively inexpensive vehicle and a relatively expensive vehicle are assembled on the same automated assembly line, higher quality/cost materials can be used to form the selective constrained layer damper for the relatively expensive vehicle, and lower quality/cost materials can be used to form the selective constrained layer damper for the relatively inexpensive vehicle. A control device, such as a computer workstation could be used to control the application of the different materials for different vehicles.

[0048] In another embodiment, the functions of the two articulated robot arms 12a and 12b could be combined into a single articulated robot arm having one or more nozzles configured to dispense a first layer of visco-elastic polymeric material to a substrate 10, as well as one or more nozzles configured to dispense a second layer of stiff polymeric material onto the visco-elastic polymeric material. As in previous embodiments, the articulated robot arm, including the various dispensing nozzles thereon, would be electronically controlled by a controller device, such as a computer workstation.

[0049] In yet another embodiment, either the visco-elastic polymeric material (e.g., the constrained layer for the hot spots) or the stiff polymeric material (the outer layer) can be applied in a solid piece form, and the other material can be dispensed from an articulated robot arm in fluid form. For example, a solid piece or pieces of visco-elastic polymeric material can be applied directly to the substrate of the automotive vehicle at locations identified as hot spots. The solid piece(s) of visco-elastic polymeric material can be adhered to the substrate in a variety of known ways, such as by using heat, ultraviolet radiation, etc. Then, after the solid piece of visco-elastic polymeric material is adhered to the substrate, the outer layer of stiff polymeric material can be dispensed, in fluid form, from an applicator head on a robot arm over the visco-elastic polymeric material. The outer polymeric material is solidified, at which time it becomes stiff and, in combination with the substrate, "sandwiches" the middle visco-elastic polymeric material to form a constrained layer damping system at the hot spots, as well as providing a single layer damper where the outer layer directly adheres to substrate 10.

[0050] As indicated above, additional alternating layers of the two polymeric materials can be added to the selective constrained layer damper. Alternatively, the first visco-elastic polymeric material can be dispensed onto the substrate of the automotive vehicle from the applicator head on the articulated robot arm, and the second stiff polymeric material can be applied over the visco-elastic polymeric material in a solid piece. More specifically, the first layer of visco-elastic polymeric material can be dispensed, in fluid form, from the applicator head of the robot arm to the substrate. The fluid material is solidified and adhered to the substrate. Then, a solid piece of stiff polymeric material can be adhered to the first layer of visco-elastic polymeric material. This solid piece of stiff polymeric material may be a dedicated constraining layer for the damping system, or this functionality may be incorporated into carpet backing, headliners, or other interior trim components added at a later stage in the assembly process. Similarly to the examples above, additional alternating layers of the respective materials can be applied to create a multi-layer selective constrained layer damper.

[0051] In addition to the benefits described above, the application of the selective constrained layer damper in the manner described allows the selective constrained layer damper to be customized even further, depending on the particular vehicle (or product) upon which it is applied. For instance, the number of alternating layers can be customized and the thickness of the visco-elastic polymeric material and the stiff polymeric material can be customized. Moreover, it is possible to apply single-layer dampers to some vehicles on the assembly line and to apply selective constrained layer dampers on other vehicles on the same assembly line. Additionally, the placement of the constrained layer dampers at hot spots 20, 22, 24 may change with each vehicle, or may not be desired for some vehicles. In this way, the customized application methods may apply full constrained layer dampers, selective constrained layer dampers, or single layer dampers, and may switch therebetween, depending upon the vehicle under assembly.

[0052] Preferred embodiments have been disclosed. A person of ordinary skill in the art would realize, however, that certain modifications would come within the teachings of this Invention, and the following claims should be studied to determine the true scope and content of the invention. In addition, the methods and structures of representative embodiments can be incorporated in the form of a variety of embodiments, only a few of which are described herein. It will be apparent to the artisan that other embodiments exist that does not depart from the spirit of the invention. Thus, the described embodiments are illustrative and should not be construed as restrictive.

Claims

1. A system comprising: a first layer of a first polymeric material being visco-elastic when solidified, said first polymeric material covering a first portion of a substrate; and a second layer of a second polymeric material covering at least a portion of said first layer and covering at least a second portion of said substrate, said second polymeric material being stiff when solidified.

2. The system of claim 1, wherein at least one of said first and said second polymeric materials dispensed in fluid form solidifies at room temperature without the addition of an external, non-chemical catalyst.

3. The system of claim 1, wherein at least one of said first and said second polymeric materials dispensed in fluid form solidifies when heated above room temperature.

4. The system of claim 1, wherein at least one of said first polymeric material and said second polymeric material is dispensed from an applicator head disposed on an articulated robot arm.

5. The system of claim 1, wherein said first polymeric material and said second polymeric material are dispensed from separate sources of fluid material.

6. The system of claim 5, wherein said first polymeric material and said second polymeric material are both dispensed from a common applicator head disposed on an articulated robot arm.

7. The system of claim 5, wherein a first version of said first polymeric material is applied to a first product and a second version of said first polymeric material is applied to a second product, and said first version and said second version have relatively different vibration damping characteristics.

8. The system of claim 5, wherein said substrate is a panel of an automotive vehicle.

9. The system of claim 1, wherein a first version of said first polymeric material is applied to a first product and a second version of said first polymeric material is applied to a second product, and said first version and said second version have relatively different vibration damping characteristics.

10. The system of claim 1, wherein said first polymeric material is a first thickness and said second polymeric material is a second thickness when said substrate forms part of a first product of manufacture; and said first polymeric material is a third thickness and said second polymeric material is a fourth thickness when said substrate forms part of a second product of manufacture.

11. The system of claim 1, wherein said substrate is a panel of an automotive vehicle.

12. The system of claim 1, wherein said first polymeric material is selected from the group consisting of synthetic water based resins, synthetic solvent based resins, natural water based resins, natural solvent based resins, bituminous based materials, cement based materials, polyurethanes, styrene block co-polymers, acrylic polymers, polyureas, silane terminated polyurethanes, modified silane polymers, polyisobutylenes, EPDM, natural rubber, Poly vinyl chloride, epoxy resins, and waterbased resins.

13. The system of claim 1, wherein said second polymeric material is selected from the group consisting of epoxy resins, polyureas, acrylic polymers, polyurethanes, epoxy polyurethane hybrids, polyesters, modified polyesters, and waterbased resins.

14. A method comprising: Applying a layer of first polymeric material to a first portion of a substrate, said first polymeric material being visco-elastic when solidified; applying a layer of second polymeric material to said first polymeric material and a second portion of said substrate such that said first polymeric material is constrained between said second polymeric material and said substrate, said second polymeric material being stiff when solidified; and wherein both said first polymeric material and said second polymeric material are dispensed in fluid form from a bulk source of fluid material.

15. The method of claim 14, wherein at least one of said first and said second polymeric materials dispensed in fluid form solidifies at room temperature without the addition of an external, non-chemical catalyst.

16. The method of claim 14, wherein at least one of said first and said second polymeric materials dispensed in fluid form solidifies when heated above room temperature.

17. The method of claim 14, wherein at least one of said first polymeric material and said second polymeric material is dispensed from an applicator head disposed on an articulated robot arm.

18. The method of claim 14, wherein said first polymeric material and said second polymeric material are dispensed from separate sources of fluid material.

19. The method of claim 18, wherein said first polymeric material is dispensed from a first applicator head disposed on a first articulated robot arm; and said second polymeric material is dispensed from a second applicator head disposed on a second articulated robot arm.

20. The method of claim 18, wherein said first polymeric material and said second polymeric material are both dispensed from a common applicator head disposed on an articulated robot arm.

21. The method of claim 18, wherein said applying a layer of first polymeric material to said substrate comprises applying a first version of said first polymeric material to a first product and applying a second version of said first polymeric material to a second product, and said first version and said second version of said first polymeric material have relatively different vibration damping characteristics.

22. The method of claim 18, wherein said substrate is a panel member of an automotive vehicle.

23. The method of claim 14, wherein said applying a layer of first polymeric material to said substrate comprises applying a first version of said first polymeric material to a first product and applying a second version of said first polymeric material to a second product, and said first version and said second version of said first polymeric material have relatively different vibration damping characteristics.

24. The method of claim 14, further comprising: applying a first thickness of at least one selected from said fluidic first polymeric material and said fluidic second polymeric material when said substrate forms part of a first product of manufacture; and applying a second thickness of the at least one selected from said fluidic first polymeric material and said fluidic second polymeric material when said substrate forms part of a second product of manufacture.

25. The method of claim 14, wherein said substrate is a panel member of an automotive vehicle.

26. The method of claim 14, wherein said first layer material is selected from the group consisting of synthetic water based resins, synthetic solvent based resins, natural water based resins, natural solvent based resins, bituminous based materials, cement based materials, polyurethanes, styrene block co-polymers, acrylic polymers, polyureas, silane terminated polyurethanes, modified silane polymers, polyisobutylenes, EPDM, natural rubber, Poly vinyl chloride, epoxy resins, and waterbased resins.

27. The method of claim 14, wherein said second layer material is selected from the group consisting of epoxy resins, polyureas, acrylic polymers, polyurethanes, epoxy polyurethane hybrids, polyesters, modified polyesters, and waterbased resins.

28. A method for installing a constrained layer damper on a product of manufacture, comprising: applying a first layer of a first polymeric material to a first portion of a substrate of the product, said first polymeric material being visco-elastic; applying a second layer of a second polymeric material to at least a portion of said first polymeric material and a second portion of said substrate, such that said first polymeric material is constrained between said second polymeric material and the substrate of the product, said second polymeric material being stiff when solidified; and wherein at least one of said first polymeric material and said second polymeric material is dispensed in fluid form during the manufacture of the product from a bulk source of fluid material.

29. The method of claim 28, wherein at least one of said first and second polymeric materials solidify without the application of heat above room temperature, and the first polymeric material is selected from the group consisting of a bituminous based material, a silane terminated polyurethane, a polyurea, and an epoxy polyurethane hybrid.

30. The method of claim 28, wherein at least one of said first and second polymeric materials solidify when heated above room temperature.

31. The method of claim 28, wherein the first polymeric material is selected from the group consisting of synthetic water based resins, synthetic solvent based resins, natural water based resins, natural solvent based resins, bituminous based materials, cement based materials, polyurethanes, styrene block co-polymers, acrylic polymers, polyureas, silane terminated polyurethanes, modified silane polymers, polyisobutylenes, EPDM, natural rubber, Poly vinyl chloride, epoxy resins, and waterbased resins.

32. The method of claim 28, wherein said second polymeric material is selected from the group consisting of epoxy resins, polyureas, acrylic polymers, polyurethanes, epoxy polyurethane hybrids, polyesters, modified polyesters, and waterbased resins.