Abstract:
A structural assembly for use with a structural workpiece includes a bushing and a first member, such as a washer. The bushing is placed in an opening of the structural workpiece and the first member is placed on the bushing. A portion of the bushing within the opening of the structural workpiece is radially expanded (e.g., with a tapered mandrel) into the structural workpiece to achieve an interference fit therewith. An extended portion of the bushing is radially expanded to generate a swaged portion. The swaged portion mechanically captures and retains the first member on the bushing and against the structural workpiece. The combination of a radial flange on the bushing and the retained first member, on opposite surfaces of the structural workpiece, respectively, may operate as bearing surfaces for thrust loading in more than one direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 60/731,322 filed Oct. 28, 2005, which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF DISCLOSURE  
       [0002]     This disclosure generally relates to a structural assembly and methods of installing the same in which a bushing is radially displaced to mechanically retain another member, such as a washer, relative to a workpiece.  
       BACKGROUND DISCUSSION  
       [0003]     Expandable structural assemblies are often installed in workpieces using a tapered mandrel. A variety of structural assemblies and methods of radial expansion using tapered mandrels with or without a split sleeve are described in U.S. Pat. Nos. 3,556,662; 3,892,121; 4,471,643; 4,557,033; 5,083,363; 5,096,349; 5,103,548; 5,127,254; 5,305,627; 5,341,559; 5,433,100; and U.S. patent application Ser. Nos. 10/619,226 (Publication No. 2005/0005669) and 10/633,294 (Publication No. 2005/0025601). These references disclose methods of radially expanding bushings into structural workpieces to improve fatigue performance of the workpieces.  
         [0004]     Bushings often include a single radial flange that serves as a bearing surface. When installed, the radial flange can have a rear face abutting a workpiece and a front face opposing the rear face. The front face can act as a bearing surface and is often machined to achieve the desired overall tolerances. In the event that two bearing surfaces are needed (e.g., bearing surfaces are needed on opposing sides of the workpiece) or in the event that too much material was machined from the front face of the bushing&#39;s flange, one option is to utilize a dual bushing assembly. U.S. patent application Ser. No. 10/726,809 (Publication No. 2004/0111864) describes dual bushing assemblies and methods of installing the same.  
         [0005]     In some applications, however, it may be advantageous to have a washer or plate on the surface of the structural workpiece opposite the radial flange of the bushing. The washer or plate can be bonded or riveted to the structural workpiece. Unfortunately, bonding, riveting, and similar coupling process often increases manufacturing costs due to additional installation time, increased level of skilled labor, and increased material costs. Therefore, it would be desirable to have an improved structural assembly.  
       SUMMARY  
       [0006]     The embodiments described herein are generally related to structural assemblies and methods of installing the same in workpieces. Some embodiments of multi-piece structural assemblies include an expandable member and an engagement member. The expandable member can be installed in a workpiece to couple the engagement member to the workpiece.  
         [0007]     A main portion of the expandable member can be radially expanded (e.g., with a tapered mandrel) in an opening of the workpiece to achieve an interference fit therewith. An end portion of the expandable member can extend away from the workpiece. The engagement member can be mounted on the end portion of the expandable member. The end portion is then radially expanded with a swage mandrel to position the engagement member with respect to the workpiece. In this manner, the multi-piece structural assembly can be easily and rapidly installed using a multi-step expansion process. The installed structural assembly can withstand loads (e.g., thrust loads) in one or more directions. The installed structural assembly, for example, can be somewhat axially and/or rotationally fixed relative to the workpiece, even under dynamic loading, static loading, or both.  
         [0008]     In some embodiments, the expandable member is a bushing having a radial flange. The main portion of the bushing extends between the flange and the end portion. The engagement member can be a washer sized to receive the end portion of the bushing such that the workpiece is interposed between the flange and the washer. After expanding the end portion, the flange and washer can cooperate to apply compressive forces to opposing sides of the workpiece, thereby snuggly holding the workpiece therebetween.  
         [0009]     The washer, in some embodiments, can have an inner surface defining a throughhole with an inner diameter sized to receive the end portion of the bushing. The end portion of the bushing can be radially expanded to move it into physical contact with the inner surface of the washer. For example, the washer can be urged against the structural workpiece during a swage expansion process in which the end portion is expanded from an initial configuration to an expanded and swaged configuration. The swage expansion process can form an angled or flared swaged end portion.  
         [0010]     In some embodiments, an assembly is configured for use with a structural workpiece having a first surface, a second surface, and an opening extending from the first surface to the second surface. The assembly comprises a bushing having a hollow body comprising a first portion, a second portion, and a third portion. The second portion extends between the first portion and the third portion. The first portion has a radial flange extending therefrom. The third portion is radially expandable beyond an outer circumference of the second portion, wherein the radial flange is configured to abut against the first surface of the structural workpiece and the third portion is configured to extend longitudinally beyond the second surface of the structural workpiece when the second portion is received in the opening of the structural workpiece. The assembly also includes a first member having a first face, a second face, and an inner surface defining a passageway extending between the first face and the second face. The first face is configured to be adjacent to the structural workpiece. The inner surface is positionable on the third portion of the bushing and comprises a first section and a second section angled with respect to the first section. The third portion is movable between an initial position and a swaged position. The third portion contacts the angled second section to retain and at least longitudinally fix the first member to the structural workpiece when the third portion is in the swaged position.  
         [0011]     In yet other embodiments, an installed structural assembly comprises a workpiece having a first surface, a second surface opposing the first surface, and an opening extending from the first surface to the second surface. A bushing having a hollow body is positioned in the opening of the workpiece. The hollow body comprises a first portion, a second portion, and a third portion, the first portion having an outwardly extending member extending along the first surface of the workpiece. The second portion is positioned between the first portion and the third portion. The third portion has flared swaged section that extends outwardly from the second surface of the workpiece. An engagement member has an inner surface, a first face, and a second face opposing the first face, the first face of the engagement member facing the second surface of the workpiece. The swaged section of the bushing is configured to contact the inner surface so as to at least longitudinally fix the member against the workpiece.  
         [0012]     In one aspect, a structural workpiece has a first surface, a second surface, and an opening extending from the first surface to the second surface. The workpiece receives a multi-piece assembly that includes a bushing and a first member. In some embodiments, the bushing has a hollow body comprising a first portion, a second portion, and a third portion. The first portion is coupled to the second portion and has a radial flange extending therefrom. The radial flange can be abutted against or adjacent to the first surface of the structural workpiece. The second portion can be received in the opening of the structural workpiece. The third portion is coupled to the second portion and extends longitudinally beyond the second surface of the structural workpiece. At least a portion of the third portion is radially expandable beyond an outer circumference of the second portion. In some embodiments, the first member has an inner surface and a first surface. The inner surface engages the third portion of the bushing. The first surface of the first member is contiguous with the structural workpiece. The inner surface of the first member comprises a generally straight section coupled to an angled section. When installed, the end portion of the bushing is swaged to contact the angled section to at least longitudinally fix the first member to the structural workpiece.  
         [0013]     In another aspect, a method of retaining a first member relative to a structural workpiece includes inserting a bushing into an opening in the structural workpiece. The bushing has a hollow body including a first portion, a second portion, and a third portion. The first portion is coupled to the second portion and has a radial flange extending therefrom. The radial flange is near or abutted against one surface of the structural workpiece. The second portion is received in the opening of the structural workpiece. The third portion is coupled to the second portion and extends longitudinally beyond an opposite surface of the structural workpiece. A first member is placed onto the third portion of the bushing such that the member is generally contiguous with the structural workpiece. At least the second portion of the bushing is radially expanded into the structural workpiece. At least a section of the third portion of the bushing is radially swaged to form a swaged portion that contacts an angled section of an inner surface of the first member to longitudinally retain the member on the bushing and to urge the member against the structural workpiece.  
         [0014]     In yet other aspects, a method of mounting an engagement member to a workpiece is provided. The engagement member has an inner surface that defines an opening. The method includes placing a bushing in a hole in the workpiece such that an expandable end portion of the bushing extends outwardly from the workpiece. The expandable end portion of the bushing is placed in the opening of the engagement member. At least a portion of the inner surface of the engagement member defines a circumference greater than an outer circumference of the bushing. The end portion is radially expanded with a tapered swaging mandrel to bring the end portion into contact with the at least a portion of the inner surface to axially fix the engagement member relative to the workpiece. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     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. For example, the shapes of various elements and angles are not drawn to scale, and some of these elements are arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn, are not intended to convey any information regarding the actual shape of the particular elements, and have been solely selected for ease of recognition in the drawings.  
         [0016]      FIG. 1A  is a cross-sectional view of a structural assembly positioned in a structural workpiece, where a bushing of the structural assembly is in an initial unexpanded position, according to one illustrated embodiment.  
         [0017]      FIG. 1B  is an enlarged cross-sectional view of the structural assembly and workpiece of  FIG. 1A .  
         [0018]      FIG. 1C  is an enlarged cross-sectional view of an engagement member and a portion of the bushing of the structural assembly of  FIG. 1A .  
         [0019]      FIG. 2  is an isometric, partial cross-sectional view of the structural assembly of  FIG. 1A , where a swaging mandrel is being moved towards the radially expanded bushing, according to one illustrated embodiment.  
         [0020]      FIG. 3A  is an isometric, partial cross-sectional view of the structural assembly of  FIG. 2 , where a swaged portion of the bushing retains the engagement member relative to the structural workpiece.  
         [0021]      FIG. 3B  is an enlarged, partial cross-sectional view of the swaged portion and engagement member of the structural assembly of  FIG. 3A . 
     
    
     DETAILED DESCRIPTION  
       [0022]     In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments. However, one skilled in the art will understand that the embodiments may be practiced without these details. In some instances, well-known structures associated with cold expansion tooling, expansion mandrels, and various assemblies and/or methods regarding structural retention have not necessarily been shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments. In addition, well-known cold expansion and/or cold working methods and/or processes, which may include installing structural assemblies into the opening of a structural workpiece have also not necessarily been shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments of the invention. It is appreciated and understood that the process of installing structural assemblies into the opening of the structural workpiece may or may not result in the creation of an annular zone of residual compressive stresses in the structural workpiece and/or other associated structure.  
         [0023]     In the following description and for purposes of brevity, reference may be made to cold expansion or radial expansion of various components. This reference is not intended to limit or otherwise narrow the scope of the disclosure. The process of radial expansion is to be broadly interpreted as any process that radially expands at least some of the material of a component either directly or indirectly (e.g., radially expanding a washer into another member). The radial expansion may be done for a number of purposes or combination of purposes, such as retarding the initiation and growth of a fatigue crack, achieving a fatigue benefit in the structural workpiece, mechanically capturing a component, retaining a component against the structural workpiece, or some combination thereof. It is further understood that radially expanding one component in the structural workpiece may or may not induce beneficial compressive residual stresses and may or may not produce fatigue-enhancing benefits in other outlying or nested components.  
         [0024]     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.” 
         [0025]     It should be noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a structural assembly including “a washer” includes a washer, or two or more washers. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.  
         [0026]     The headings provided herein are for convenience only and do not interpret the scope or meaning of the claimed invention.  
         [0027]     The following description relates to a structural assembly that includes an expandable member and an engagement member configured to engage the expandable member. The expandable member can be installed in an opening of a structural workpiece and includes a radially outwardly extending flange that cooperates with the engagement member to react loads (e.g., axial loads such as thrust loads). When installed, the outwardly extending flange and engagement member can securely couple the expandable member to the workpiece while enhancing performance (e.g., fatigue performance) of the workpiece. The structural workpiece can be compressed or otherwise tightly held between the flange and the engagement member.  
         [0028]     As used herein, the term “expandable member” is a broad term and includes, but is not limited to, a bushing, sleeve (including a split sleeve), fitting, fastener, and other structures that are suitable for coupling to a workpiece. In some embodiments, the expandable member can be expanded from a first configuration (pre-installed configuration) to a second configuration (installed configuration). For example, the expandable member may be a bushing that is radially expanded an amount sufficient to form an interference fit with a hole in a workpiece. The expandable member can be further expanded to hold the engagement member against the workpiece. The term expandable member refers to a member in a pre-expanded state and a post-expanded state, unless the context dictates otherwise.  
         [0029]     The expandable member can be a bushing for cold working. A bushing can be, without limitation, a generally cylindrical liner or fitting used to contain, reduce frictional interaction, and/or define a passageway in which one or more components (e.g., hoses, wires, conduits, and the like) can pass through. The type and configuration of the bushing can be selected based on, for example, the desired compressive residual stresses in the workpiece, function of the bushing, and other criteria known in the art. The bushing can include a radially outwardly extending member, an end portion, and a hollow body extending therebetween. The end portion of the expandable member can extend generally along a longitudinal axis of the expandable member. For example, the end portion can extend in a direction substantially parallel to a long axis of the expandable member.  
         [0030]     The bushing and engagement member may be used to control clearances. The installed structural assembly, for example, can have a relatively small profile as compared to traditional bushing assemblies, thereby providing flexibility when choosing an appropriate installation location. The bushing, engagement member, or both can be machined or otherwise processed to achieve the desired clearance. For example, any portion of the bushing protruding from the engagement member can be made, for example, flush with the engagement member.  
         [0031]     The engagement member can be a thrust-bearing member (e.g., a washer), a back-up or reinforcement plate (e.g., hard-point structure) around an opening, and/or a coupling mechanism. Coupling mechanisms can be used for electrical connections, fluid connections, conduit assembly, and/or other types of assemblies coupled to the workpiece. As used herein, the term “washer” is a broad term and includes, but is not limited to, a ring or ring-like member used to provide tightness to a joint, to relieve friction, to prevent leakage, and/or to distribute pressure. In some embodiments, a washer can be a somewhat flat disk with a throughhole. For example, the washer can be continuous or discontinuous (e.g., a split ring washer) disk shaped member. The washer can be made of plastic, metal, composite, ceramic, combinations thereof, and other materials suitable for contacting a workpiece.  
         [0032]      FIG. 1A  shows a structural assembly  100  having a structural workpiece  102 , an unexpanded bushing  104 , and a washer  106 . The unexpanded bushing  104  extends through the workpiece  102  and washer  106 , where the washer  106  is near or adjacent to the workpiece  102 . Generally, the bushing  104  can be expanded to form an interference fit with the workpiece  102  (as shown in  FIG. 2 ). The bushing  104  can then be expanded again to hold the washer  106  near or against the workpiece  102 , as shown in  FIG. 3A .  
         [0033]     As used herein, the term “workpiece” is broadly construed to include, without limitation, a parent structure having at least one hole or opening suitable for processing (e.g., receiving an expandable member, undergoing cold expansion, etc.). The hole can be, for example, a through hole, counter bore, or other type of hole. The workpiece  102 , for example, can be a lug, panel, web, spar, rib, conduit, fitting, outer bushing, grommet, outer sleeve, and/or some other type of structure. In some embodiments, the workpiece is a bulkhead, fuselage, engine, or other structural member of an aircraft. The exemplary workpieces provided above are for illustrative purposes and are not meant to limit or narrow the scope of the claims. The illustrated structural workpiece  102  is representative of any structural member and may be made from a variety of materials, such as metal, composite (e.g., fiber-reinforced composite), plastic, combinations thereof, or other materials suitable for engaging the structural assembly  100 .  
         [0034]     The illustrated structural workpiece  102  of  FIG. 1A  includes a first surface  108 , a second surface  110  opposing the first surface  108 , and at least one opening  112  extending from the first surface  108  to the second surface  110 . The bushing  104  is closely received by the opening  112  of the workpiece  102 .  
         [0035]     The illustrated bushing  104  of  FIG. 1A  includes a tubular body  114  and a radial flange  116  connected to the tubular body  114 . The tubular body  114  includes a first portion  118 , a second portion  120 , and a third portion  122 . The radial flange  116  is coupled to the first portion  118 . The second portion  120  extends generally between the first surface  108  and the second surface  110  of the structural workpiece  102 . The third portion  122  can extend outwardly from the first surface  110  of the structural workpiece  102 . The third portion  122  can also extend at least partially through a passageway  123  (see  FIG. 1B ) of the washer  106 . The illustrated bushing  104  extends in the direction of its longitudinal axis  127  beyond the first member  106 .  
         [0036]      FIGS. 1B and 1C  show close-up views of the washer  106  positioned on the bushing  104  and at least proximate the second surface  110  of the structural workpiece  102 . As shown in  FIG. 1B , the washer  106  includes an inner surface  124  defining the passageway  123 , an outer surface  126  opposing the inner surface  124 , an abutment surface  128 , and a bearing surface  130 , according to the illustrated embodiment. The abutment surface  128  contacts or is adjacent to the second surface  110  of the structural workpiece  102 . If the washer  106  is spaced from the workpiece  102 , the swaging expansion process (described in connection with  FIG. 2 ) can move the washer  106  against the second surface  110  of the workpiece  102 , if needed or desired.  
         [0037]      FIG. 1C  shows the inner surface  124  of the washer  106  including a generally straight section  132  and an angled section  134 . A gap  136  can be formed between the angled section  134  and an outer surface  137  of the bushing  104 . In some embodiments, including the illustrated embodiment of  FIG. 1C , an angle  138  is defined by the angled section  134  and the outer surface  137 . Although the illustrated angle  138  is fairly large, it is understood that the angle  138  may be quite shallow. For example, the angle  138  can be equal to or smaller than about 10 degrees. In some embodiments, the angle  138  is equal to or larger than about 2 degrees, 4 degrees, 5 degrees, 10 degrees, or ranges encompassing such angles. In one embodiment, the angle  138  is in the range of about 10 degrees to about 30 degrees. The angle  138  can also be larger than 30 degrees. One or more ductile materials can be used to reduce, limit, or substantially eliminate cracking of the bushing  104 . Such a large angle may result in significant displacement of the third portion  122  of the bushing  104  during the swaging process. Thus, swaging or similar processes may cause cracking or unacceptable strain energy levels in the structural assembly  100 , especially if brittle materials are used to form the structural assembly  100 .  
         [0038]     The illustrated angled section  134  has a first perimeter  139  proximate the section  132  and a second perimeter  141  proximate the bearing surface  130 . The perimeter of the angled section  134  can increase (e.g., gradually increase, incrementally increase, uniformly increase, etc.) from the first perimeter  139  to the second perimeter  141 . In the illustrated embodiment, the angled section  134  defines a generally frusto-conical surface  145  extending between the straight section  132  and the bearing surface  130 . In other embodiment, the surface  145  can have regular or irregular configurations or any other configuration suitable for engaging the swaged bushing  104 . In some embodiments, the surface  145  can be concave, convex, flat, or combinations thereof.  
         [0039]     With reference to  FIGS. 1A  to  1 C, the illustrated unexpanded bushing  104  can be radially expanded into the structural workpiece  102  by at least one of the methods described in the above-referenced patents, patent applications, combinations thereof, or by an equivalent method. One type of radial expansion method that may be used is moving a tapered mandrel through the passageway  123  of the bushing  104  to radially expand the bushing  104  into the structural workpiece  102 . The flange  116  can seat against the first surface  108  during the process. The bushing  104  can be radially expanded a sufficient amount to cold work or otherwise process an adjacent region of the structural workpiece  102 . This expansion process may provide some retention of the washer  106  with respect to the post-expanded bushing  104 , workpiece  102 , or both. In some embodiments, the washer  106  is fixed (e.g., axially fixed, rotationally fixed, or otherwise fixed) with respect to the workpiece  102 , bushing  106 , or both. The washer  106  can be at least longitudinally fixed relative to the bushing  104  and positioned next to or against the structural workpiece  102 .  
         [0040]     It is understood that the washer  106  may be loosely retained on the bushing  104 . For example, the washer  106  can be rotationally free relative to the outer surface  137  of the expanded bushing  104  and/or relative to the structural workpiece  102 .  
         [0041]     It has been found that the materials of the various components of the structural assembly  100 , the amount of pull force on the tapered mandrel, and possibly other parameters may limit or prevent the washer  106  from being adequately retained relative to the bushing  104  and/or structural workpiece  102 . For example, when the material of the structural workpiece  102  has a higher elastic energy than both the bushing  104  and washer  106 , testing (e.g., testing using Finite Element Analysis (FEA)) has shown that the interference necessary to retain and fix the washer  106106  relative to the bushing  106  and the structural workpiece  102  was not readily achievable. In order to achieve a high degree of retention/fixation of the washer  106  relative to the bushing  104  and the structural workpiece  102 , testing has shown that the amount of expansion would have to exceed a threshold amount of expansion that would likely induce an unwanted amount of cracking (e.g., stress cracking, micro-cracking, and other types of cracking) in the bushing  104  and/or structural workpiece  102 . The bushing  104  can be subjected to another expansion process to achieve the desired performance.  
         [0042]      FIG. 2  shows the bushing  104  after it has been radially expanded by, for example, one of the tapered mandrels discussed above and in accordance with known radial expansion methods and/or processes, which may be those that are described in the above-referenced patents and/or patent applications. In  FIG. 2  also shows mandrel  140  about to engage the third portion  122  of the bushing  104  to perform another expansion process. In the illustrated embodiment, the mandrel  140  is in the form of a swaging mandrel spaced from the installed bushing  104 .  
         [0043]     A tapered section  141  of the swaging mandrel  140  is forced into the bushing  104  with a force “F” to a desired penetration depth  142  such that the end  143  of the tapered section  141  is positioned at  144  (indicated in phantom line in  FIG. 2 ). The force F applied to the swaging mandrel  140 , the insertion depth  142  of the swaging mandrel  140 , and the configuration of the mandrel  140  (e.g., the rate of taper of the tapered section  141 ) may be selected so that the washer  106  is held between the swaged bushing  104  and the workpiece  102 , as shown in  FIG. 3A .  
         [0044]     The washer  106  can be retained relative to the structural workpiece  102  and the amount of strain energy or preload in the bushing  104  can remain below an identified threshold. The force F is applied to the swaging mandrel  140  to swage (e.g., radially displace) the third portion  122  and possibly some of the second portion  120  of the bushing  104 . In some embodiments, the amount of force F applied to the swaging mandrel  140  can be varied during insertion to help urge the mandrel  140  into the bushing  104  to the desired penetration depth  142 . That is, varying the force F can help work the tapered section  141  into the bushing  104 . In other embodiments, the force F can be a generally a constant force.  
         [0045]      FIGS. 3A and 3B  show the structural assembly  100  after the swaging mandrel  140  has been inserted into and then retracted from the bushing  104 . In  FIG. 3A , the end portion  122  of the bushing  104  is swaged.  FIG. 3B  shows a close-up view of a swaged portion  146  of the bushing  104 . To close the gap  136  ( FIG. 1C ) that previously existed between the inner surface  124  of the washer  106  and the bushing  104 , the end portion  123  can be swaged to form the swaged portion  146 .  
         [0046]     The swaged portion  146  can be flared or otherwise expanded radially outward and may advantageously longitudinally fix the washer  106  on the bushing  104 , may maintain tight contact between the washer  106  and the second surface  110  of the structural workpiece  102 , and may fix (e.g., rotationally fix, axially fix, or combinations thereof) the washer  106  relative to the structural workpiece  102 . An outer surface  149  of the swaged portion  146  can have a similar configuration as the surface  145  of the bushing  106 . Exemplary surfaces  149  can have regular or irregular configurations or any other configuration suitable for engaging the washer  106 . Similar to the surface  145 , the surface  149  can be concave, convex, flat, or combinations thereof.  
         [0047]     The structural assembly  100  of  FIGS. 3A and 3B  may advantageously achieve sufficient fixation (e.g., longitudinal fixation, axial fixation, rotational fixation, and combinations thereof) between the bushing  104  and the workpiece  102 , between the washer  106  and the bushing  104 , or between the washer  106  and the structural workpiece  102 . Fixation can be achieved without exceeding the threshold amount of expansion that induces an unwanted amount of cracking. Thus, cracking can be kept at or below an acceptable level.  
         [0048]     In some embodiments, fixation of the washer  106  may prevent the washer  106  from being dislodged or loosened from the structural assembly  100  under a variety of dynamic and/or static loading conditions. Accordingly, the washer  106  is well suited for cyclic loading. Moreover, the fixation may be sufficient to reduce, limit, or substantial prevent galling, wear, and other part-to-part contact problems that can arise when relative motion is permitted between parts in contact with one another.  
         [0049]     After completion of the swaging process, a section  148  of the bushing  104  may optionally be removed, trimmed, worn down, sanded, or otherwise machined. For example, the section  148  of  FIG. 3B  extending outwardly from the washer  106  can be removed. The bushing  104  and the washer  106 , in some embodiments, can be faced, sanded, worn down, or otherwise processed to be within a desired tolerance (e.g., a tolerance associated with the washer  106 ).  
         [0050]     The swaging process described herein may advantageously provide a higher degree of interference between the bushing  104  and the washer  106  than can be achieved by merely radially expanding the body of the bushing  104  with the tapered mandrel alone. In addition, the swaging process may prevent removal of the washer  106  and may sufficiently fix the washer  106  relative to the structural workpiece  102 . The swaged portion  146  of the bushing  104  can sufficiently capture, retain, and/or fix (e.g., lock) the washer  106  relative to the structural workpiece  102  so that no additional or alternative mechanical attachment technique is necessary, such as applying adhesive between the washer  106  and structural workpiece  102  or installing rivets. Thus, the washer  106  can be rapidly and conveniently secured against the workpiece  102 . In some embodiments, however, adhesives, bonding agents, fasteners (e.g., rivets), or other coupling means can also be used to further reduce or limit undesirable relative movement of the structural assembly  100 .  
         [0051]     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 as U.S. Pat. Nos. 3,556,662; 3,892,121; 4,471,643; 4,557,033; 5,083,363; 5,096,349; 5,103,548; 5,127,254; 5,305,627; 5,341,559; 5,433,100; and U.S. patent application Ser. Nos. 09/603,857; 10/619,226 (Publication No. 2005/0005669); 10/633,294 (Publication No. 2005/0025601); and 10/726,809 (Publication No. 2004/0111864) are incorporated herein by reference. Aspects can be modified, if necessary, to employ devices, features, and concepts of the various patents, applications, and publications to provide yet further embodiments.  
         [0052]     These and other changes can be made in light of the above detailed description. In general, in the following claims, the terms used should not be construed to limit the invention to the specific embodiments disclosed in the specification and the claims, but should be construed to include all types of retainer assemblies and/or kits that operate in accordance with the claims. Accordingly, the invention is not limited by the disclosure, but instead its scope is to be determined entirely by the following claims.