Abstract:
A bushing with wave relieving geometric features includes a unique geometric end feature such as a countersink or arcuate surface, which creates a pocket, volume, and/or reservoir, to receive an amount of material that is extruded in a longitudinal direction during radial expansion of the bushing. At the mandrel exit side of the bushing, the extruded material may be accumulated from a propagating wave of material preceding a radial-expansion mandrel. At the mandrel entry side of the bushing, the extruded material may be caused by the radial force of the expansion mandrel near the unrestrained end surface at the entry side of the bushing. The unique geometric end features of the bushing may also include a high portion on the end surface of the bushing to direct the fastener clamp-up loads through the radial flange of the bushing and into the workpiece.

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. 60/795,888 filed Apr. 27, 2006, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND  
       [0002]     1. Field of Disclosure  
         [0003]     This disclosure generally relates to a structural member, such as a bushing, having geometrical features that may reduce surface upset at the ends of the member when the member is radially expanded into a workpiece.  
         [0004]     2. Description of the Related Art  
         [0005]     Conventional structural members, which may be hollow members such as bushings, with or without a radial flange, liners, sleeves, tubes, pipes, etc. are commonly installed into openings of workpieces for a variety of reasons. Bushings, for example, may be installed in the workpiece to reinforce and/or structurally support the region around the opening. In addition, the radial flange of the bushing may function as a washer to transmit the fastener clamp-up loads into the workpiece and/or structural joint.  
         [0006]     One method of installing structural members, which shall be referred to in this section as bushings, is the FORCEMATE® installation method developed by Fatigue Technology, Inc. The FORCEMATE® installation method is especially suitable for components that will undergo repetitive load cycles and/or may be susceptible to accumulating fatigue damage. The FORCEMATE® installation method utilizes an installation tool to pass a tapered mandrel (i.e., expansion mandrel) through a passage in the bushing after the bushing has been placed in the opening of the workpiece. The tapered mandrel radially expands the bushing into the opening to obtain a controlled, but consistently higher, interference fit than would be achievable by other installation methods, such as shrink or press fitting methods. In addition, the FORCEMATE® installation method may induce beneficial residual compressive stresses into the structural material surrounding the opening, which may advantageously extend the fatigue and damage tolerance (e.g., crack growth) life of the component, assembly, and/or installation. The FORCEMATE® installation method, as well as other cold-working methods, tooling, and the like, such as the BUSHLOC®, FORCETEC®, and FLEXMATE® methods are described in 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; 5,405,228; 5,245,743; 5,103,548; 5,127,254; 5,305,627; 5,341,559; 5,380,136; 5,433,100; and in U.S. patent application Nos. U.S. patent application Ser. Nos. 09/603,857; 10/726,809 (U.S. Pat. No. 7,100,264); 10/619,226 (U.S. Pat. No. 7,024,908); and 10/633,294 (US/2005/0025601).  
         [0007]     Installation of conventional bushings has been known to produce a certain amount of extruded material, upset material, and/or distorted material, near at least one end of the bushing. In some cases, the amount of upset material is typically minimal and may be removed with a subsequent machining process to make the upset material substantially flush with the corresponding end surface of the bushing (e.g., the end surface may be the exposed end surface of the radial flange or may be the exposed end surface of the non-flange end of the bushing).  
         [0008]     Conventional bushings are typically configured to have the non-flanged end surface be a bit under-flush to flush, but not over-flush, relative to the surface of the workpiece. To achieve such an under-flush condition, a number of variables should be accounted for, such as the workpiece thickness tolerance, the bushing manufacturing length tolerance, and/or the extrusion or growth of the bushing during the radial expansion installation process.  
         [0009]     In wing assemblies, for example, the installed bushings must meet specific flushness requirements. One such requirement in the aerospace industry is that the non-flanged end of the bushing must be flush to under flush within a range of 0 to 0.008 inches from the workpiece surface to maximize the bearing area of the bushing in the workpiece. If a bushing were to be installed in an over-flush or protruding condition relative to the workpiece surface, such a condition may cause the protruding bushing end to contact and/or damage a mating part. In addition, such an over-flush bushing condition may adversely alter the fastener clamp-up load distribution through the assembled members. Such an altered load path is typically undesirable, and may lead to structural joint problems after the airplane is in service.  
         [0010]     To correct an over-flush condition and/or to remove the upset material, the excess material may be machined off (i.e., ground). If the workpiece is a titanium lug or a hardened, surface-treated steel, for example, extreme care must be taken to not damage the workpiece when using a grinding wheel to remove the excess or over-flush portion of the bushing. This type of a machining operation to bring the bushing flush with the workpiece may be done hundreds of times in a single component, such as a wing skin or fuselage skin. In turn, this may add significant time and cost to the overall assembly, as well as increase the risk of damaging the overall assembly, which may be nearly complete.  
         [0011]     The amount of bushing extrusion may vary significantly based upon a particular application. For example, some assemblies may call for the installation of a bushing that has a thick wall. Radially expanding a thick-walled bushing into a workpiece typically requires a larger mandrel pull or draw force. The large force often results in a greater amount of bushing material being upset and may also result in the formation of a substantially large extrusion or growth from at least one end of the bushing. Additionally, or alternatively, the extrusion or growth may not be uniform across the non-flanged end of the bushing where, for example, the majority of the growth occurs in an area adjacent to the inner surface of the bushing.  
         [0012]     It has been determined that the overall grip length of one type of thick-walled bushing may vary by as much as ±0.020 inches from a pre-installed state with no upset material present at one end of the bushing to a post-installed state with upset material present. This type of bushing growth makes it difficult to keep the entire bushing end surface flush or under-flush relative to the workpiece surface during installation of the bushing.  
         [0013]     The upset material is extruded and/or displaced axially from at least one end of the bushing as the tapered mandrel is passed through the bushing. In one instance, a wave of material adjacent to the inner-surface region of the bushing is longitudinally pulled or pushed in the direction of the mandrel travel. In another instance, the radial force of the tapered mandrel causes at least a small amount of material to be pushed axially out and away from the mandrel entry side of the bushing. Thus, the upset material may occur on the flange side or the opposite side of the bushing. The amount of upset material on a particular side of the bushing corresponds, at least in part, to the direction of the mandrel travel.  
         [0014]     Consequently, conventional bushings may not adequately and repeatedly meet certain quality and/or aerodynamic requirements or specifications. Based on the foregoing, it would be desirable to have a bushing or like component configured to overcome at least some of the aforementioned drawbacks of conventional bushings when radially expanded into a workpiece.  
       SUMMARY OF THE INVENTION  
       [0015]     At least one embodiment generally relates to a bushing having a unique geometric end feature such as a countersink detail, a counterbore, or a combination of the two features, for the purpose of receiving an amount of material that is extruded in a longitudinal direction during radial expansion of the bushing. At the mandrel exit side of the bushing, the extruded material may be accumulated from a propagating wave of material preceding a radial expansion mandrel. At the mandrel entry side of the bushing, the extruded material may be caused by the radial force of the expansion mandrel near the unrestrained end surface at the entry side of the bushing. The unique geometric end features of the bushing may also include a high portion on the end surface of the bushing to direct the fastener clamp-up loads through the radial flange of the bushing and into the workpiece.  
         [0016]     In one aspect, a structural member installable in an opening of a workpiece by radial expansion via an expansion mandrel includes a tubular body having a first end, a second end opposite the first end, a peripheral outer surface disposed between the first and the second ends, the tubular body having a first face at the first end, a second face at the second end, and an inner surface that extends between the first and the second ends to form a longitudinally-extending passage therebetween, wherein in a pre-installed state the tubular body has a first recess formed on the first face about the longitudinally-extending passage and adjacent thereto, the first recess having a volume sized to accommodate a first amount of upset material that will be formed by passage of the expansion mandrel through the longitudinally-extending passage to install the structural member in the opening of the workpiece.  
         [0017]     In another aspect, a structural member installation includes a workpiece having an opening formed therein; and a tubular body having a first end, a second end opposite the first end, a peripheral outer surface disposed between the first and the second ends, the tubular body having a first face at the first end, a second face at the second end, and an inner surface that extends between the first and the second ends to form a longitudinally-extending passage therebetween, wherein in an installed state the peripheral outer surface deformingly engages the workpiece to form an interference fit therewith and a first amount of upset material formed by passage of an expansion mandrel through the longitudinally-extending passage to install the structural member in the opening of the workpiece is accommodated by a first recess adjacent to and surrounding the longitudinally-extending passage such that the first amount of upset material does not extend outwardly from the first face of the tubular body or inwardly from the inner surface into the longitudinally-extending passage.  
         [0018]     In yet another aspect, a method of radially expanding a structural member into a workpiece includes positioning an expansion mandrel at an entrance of a longitudinally-extending passage extending through the structural member, the structural member having a first end, a second end opposite the first end, a peripheral outer surface disposed between the first and the second ends, the structural member further having a first face at the first end, a second face at the second end, and an inner surface that extends between the first and the second ends to form the longitudinally-extending passage therebetween; passing the expansion mandrel through the longitudinally-extending passage from the first face to a second face of the structural member to radially expand at least a portion of the structural member into the workpiece; and longitudinally displacing some of the material of the structural member into at least one recess having a volume sized to accommodated a first amount of upset material, wherein the volume of the recess is sufficient to receive the displaced material without permitting any of the displaced material to extend beyond a desired distance relative to the respective face.  
         [0019]     In still yet another aspect, a method of manufacturing a structural member to be secured into an opening of a workpiece, the method includes forming an outer surface and an inner surface, the outer surface radially offset from the inner surface to form a wall of the structural member; forming first end and a second end opposite the first end; forming a first face at the first end and a second face at the second end, the inner surface extending between the first and the second ends to form a longitudinally-extending passage therebetween; and forming a recess into at least one of either the first face or the second face, wherein the recess defines a volume sized to accommodated a first amount of upset material expected when an expansion mandrel is passed through the longitudinally-extending passage during a radial expansion process to secure the structural member into the opening of the workpiece. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     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.  
         [0021]      FIG. 1  is a cross-sectional view of a prior art structural member in an opening of a workpiece, wherein the structural member is about to be radially expanded by an expansion mandrel, according to one illustrated embodiment.  
         [0022]      FIG. 2  is a cross-sectional view of the prior art structural member of  FIG. 1  after being radially expanded in the opening of the workpiece, wherein the structural member includes first and second displaced-material portions formed during a radial expansion process, according to one illustrated embodiment.  
         [0023]      FIG. 3  is a detailed cross-sectional view of the first displaced material portion of  FIG. 2 , wherein the first displaced-material portion is located at a mandrel entrance side of the structural member, according to one illustrated embodiment.  
         [0024]      FIG. 4  is a detailed cross-sectional view of the second displaced-material portion of  FIG. 2 , wherein the second displaced-material portion is located at a mandrel exit side of the structural member, according to one illustrated embodiment.  
         [0025]      FIG. 5  is a cross-sectional view of a prior art installation of two workpieces that are adversely influenced by displaced-material portions of a radially-expanded structural member located in one of the workpieces, according to one illustrated embodiment.  
         [0026]      FIG. 6A  shows the prior art installation of  FIG. 5  having a fastener to clamp the two workpieces together, according to one illustrated embodiment.  
         [0027]      FIG. 6B  shows another prior art installation having a fastener to clamp the two workpieces together, according to one illustrated embodiment.  
         [0028]      FIG. 7  is a cross-sectional view of a first structural member in a pre-radially expanded state having geometric features capable of accommodating an amount of displaced material expected when the first structural member is radially expanded with a cold-expansion mandrel, according to one illustrated embodiment.  
         [0029]      FIG. 8  is a cross-sectional view of the first structural member of  FIG. 7  in a post-radially-expanded state showing the displaced material received in the geometric features, according to one illustrated embodiment.  
         [0030]      FIG. 9  is a cross-sectional view of a second structural member in a pre-radially expanded state having geometric features capable of accommodating an amount of displaced material expected when the second structural member is radially expanded with a cold-expansion mandrel, according to one illustrated embodiment.  
         [0031]      FIG. 10  is a cross-sectional view of the second structural member of  FIG. 9  in a post-radially-expanded state showing the displaced material received in the geometric features, according to one illustrated embodiment. 
     
    
     DETAILED DESCRIPTION  
       [0032]     In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one skilled in the art will understand that the embodiments may be practiced without these details. In other instances, well-known structures and methods associated with cold working and/or installing a structural member into an opening in a workpiece may not be shown or described in detail to avoid unnecessarily obscuring descriptions of the disclosed embodiments. The structural member can be a bushing, sleeve (including a split sleeve), liner, shank, rivet, or other similar component. It is appreciated and understood that the process of installing the component into the opening of the workpiece may or may not result in the creation of a zone of residual compressive stress (e.g., an annular zone of compressive stresses) in the workpiece or workpieces.  
         [0033]     In the following description and for purposes of brevity, reference shall be made to cold working and/or radial expanding of the workpiece. This reference is not intended to limit or otherwise narrow the scope of the disclosure. In the context of this description, the process of cold expansion is to be broadly interpreted as any process that radially expands at least some of the material surrounding the opening in the workpiece, even if the expansion is for the purpose of impeding the growth of a fatigue crack. It is further understood that cold expanding the opening of the workpiece may or may not induce beneficial compressive residual stresses and may or may not produce fatigue-enhancing benefits in the workpiece.  
         [0034]     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.” 
         [0035]     The headings provided herein are for convenience only and do not interpret the scope or meaning of the claimed invention.  
         [0036]     The following description generally relates to a structural member with geometric features that permit the member to be radially expanded into an opening of a workpiece while reducing, limiting, or substantially eliminating unwanted deformed, upset, or distorted regions of the member that may adversely affect the structural joint and/or create an undesirable installation condition. In some embodiments, the structural member may even be the workpiece itself. By way of example, the process of passing an expansion mandrel through a thick-walled bushing and radially expanding the thick-walled bushing into the workpiece may result in at least some amount of deformation (e.g., upset, displaced, and/or distorted material) near both the mandrel entry and exit sides of the bushing.  
         [0037]     In some bushing installations in which the mandrel is pulled from the non-flanged end toward the flanged end of the bushing, the radial flange of the bushing may move away or separate from the workpiece, thus creating an undesirable gap between the radial flange of the bushing and the workpiece. Gaps between the bushing and the workpiece can significantly reduce the performance of the installation.  
         [0038]     Large stresses can develop in the bushing. As the mandrel is passed through the busing, the stresses can result in a plastic flow of bushing material with a large amount of residual strain energy. The residual strain energy can be relieved as the mandrel exits through the upset material and displacement of the radial flange. The bushing flange may be re-seated against the workpiece in a subsequent seating operation. However, this seating operation may have to be performed hundreds of times for a single component, which may increase the time and the cost to manufacture the component.  
         [0039]      FIG. 1  shows a pre-radially-expanded installation  100  comprising a workpiece  102  and a conventional, pre-radially-expanded structural member  104 . An expansion mandrel  106  is passed through the structural member  104  to radially expand the structural member  104  into the workpiece  102 . For example, the mandrel  106  may be pulled in a mandrel direction  108 , which in the illustrated embodiment is directed from the flange side  110  to the non-flange side  112  of the structural member  104 .  
         [0040]      FIG. 2  shows a radially-expanded installation  200  comprising a workpiece  202  and a radially-expanded structural member  204 . A mandrel (e.g., the mandrel  106  of  FIG. 1 ) passing through the structural member  204  in the mandrel direction  208  radially expands the structural member  204  such that an outer surface  214  of the radially-expanded member forms a tight interference fit with the workpiece  202 . The inner perimeter of a passage  218  formed by the inner surface  216  is enlarged by the passage of the mandrel. A wall thickness between the outer and the inner surfaces  214 ,  216  may be reduced by the passage of the mandrel. In addition, the radially-expanded structural member  204  includes a first surface  220  and an opposing second surface  222 . In one embodiment, the radially-expanded structural member  204  may include a radial flange  224 . Other embodiments may omit the radial flange  224 .  
         [0041]     The inner surface  216  may be allowed to displace axially during the expansion process. The lack of axial constraint permits at least some of the material along and adjacent to the inner surface  216  of the structural member  204  to be axially deformed (e.g., permanently upset or distorted). In the illustrated embodiment, a first upset region  226  is observable at the mandrel entry side  228  of the structural member  204 , while a second upset region  230  is observable at the mandrel exit side  232 .  
         [0042]      FIG. 3  shows a detailed view of the upset region  226  located along and adjacent to the inner surface  216  and further located at the mandrel entry side  228 . The first upset region  226  may be formed because the first surface  220  is a free surface and a Poisson&#39;s affect occurs due to the radial-expansion force of the mandrel  106  ( FIG. 1 ) near the entry side  228 . The Poisson&#39;s affect is generally understood to mean that the lateral or transverse strain normal to the direction of the applied stress in an elastic member is not equal to zero. “Mechanics of Materials,” by Ferdinand P. Beer and E. Russell Johnston, Jr., 1991, by McGraw-Hill, Inc. In the illustrated embodiment, the applied stress is the radial stress from the mandrel  106  while the transverse strain comprises the first upset region  226 .  
         [0043]      FIG. 4  shows a detailed view of the upset region  230  located along and adjacent to the inner surface  216  and further located at the mandrel exit side  232  of the member  204 . Generally, the upset region  230  at the mandrel exit side  232  will be larger than the upset region  226  at the mandrel entry side  228  because the upset region  230  is typically caused by a wave of material that is drawn or pushed by the mandrel  106 . The wave of material propagates ahead of the expansion mandrel  106  during radial expansion. It has generally been found that thick-walled bushings, for example, are more susceptible to forming a larger, more extended, and/or more protruded second upset region  230  than thin-walled bushings. The mandrel forces during expansion of thick-walled bushings tend to be relatively large to ensure an adequate interference fit between the thick-walled structural member  204  and the workpiece  202 .  
         [0044]     In conjunction with the formation of the upset region  230 , a pocket  234  may be formed by an end surface  235  of the structural member  204 . The structural member  204  can be configured with an under-flush grip length before the member is installed into the workpiece  202 , which results in the illustrated under-flush end surface  235 .  
         [0045]      FIG. 5  shows an installation  300  comprising a first workpiece  302 , a structural member  304 , and a second workpiece  336 , according to one illustrated embodiment. The second workpiece  336  should be in flush contact with the first workpiece  302 , but the second upset region  330  causes the second workpiece  336  to be separated from the first workpiece  302  by a gap or space  338 . In the illustrated embodiment, the direction of mandrel travel is indicated by the arrow  339 . It is appreciated that the grip length of the structural member  304  could be shortened to keep the upset region  330  from becoming over-flush with respect to the abutting surface  341  of the workpiece  302 . However, shortening the grip length of the structural member  304  may adversely reduce the bearing area between the structural member  304  and the workpiece  302 , thus leading to yet another undesirable condition.  
         [0046]      FIG. 6A  shows the installation  300  of  FIG. 5  further comprising a fastener  340  inserted through the structural member  304 , the first workpiece  302 , and the second workpiece  336 , respectively. A threaded end  341  of the fastener  340  receives a threaded nut  342 . Optionally, a washer  344  may be placed between the nut  342  and the second workpiece  336  to protect the surface of the second workpiece. As the fastener  340  and nut  342  combination is torqued down, the first upset region  326  causes the clamp-up forces in the installation  300  to proceed approximately along a load path line  348  (shown in phantom line). It is typically highly advantageous in a structural joint to have the fastener clamp-up forces be distributed along the radial flange  224  ( FIG. 2 ), the first workpiece  302 , and the second workpiece  336 . The illustrated upset regions  326 ,  330  generate an undesirable load path during fastener clamp-up.  
         [0047]      FIG. 6B  shows a structural joint  400  comprising a fastener  440  inserted through a first structural member  404  and a second structural member  405 , which are located in a first workpiece  402  and a second workpiece  436 , respectively. A threaded end  441  of the fastener  440  receives a nut  442 . Optionally, a washer  444  may be positioned between the nut  442  and the second workpiece  436 . As the first and second structural members  404 ,  405  are radially expanded by an expansion mandrel being pulled in a direction  407 , at least one upset region  426  is formed on the flanged-side of the first structural member  404 . In addition and as shown in the illustrated embodiment, the strain energy from the radial-expansion process can cause a flange  451  to move away from the workpiece  402 .  
         [0048]     As the fastener  440  and nut  442  combination is torqued down, the first upset region  426  causes the clamp-up forces in the structure to proceed approximately along a load path line  448 , which may generate a substantial amount of shear stress between the radial flange  451  and a body  453  of the first structural member  404 , where the shear region is shown by dashed line  449 . It is typically advantageous in a structural joint to have the load path line  448  from the fastener clamp-up forces be carried directly through the radial flange  411  and into the first workpiece  402  to reduce or limit the shear stresses in the region  415 . Consequently, the upset region  426 , with or without the additional flange gapping, may cause an undesirable load path through the structural joint  400 .  
         [0049]      FIG. 7  shows a structural member  500  in a pre-radially-expanded state. The structural member  500  can be configured to reduce, limit, or substantially eliminate unwanted protruding of deformed material formed during installation.  
         [0050]     The illustrated structural member  500  includes an outer circumferential surface  502  and an inner surface  504  that forms a passage  506  through the structural member  500 , according to one illustrated embodiment. In addition, the structural member  500  includes a first surface  508  and a second surface  510  opposed to the first surface  508 . In the illustrated embodiment, the first surface  508  is substantially perpendicular to a longitudinal axis  511  of the structural member  500 . In some embodiments, a radial flange contact surface  509  is substantially perpendicular to the longitudinal axis  511  and the surface  508  may be non-perpendicular to the axis  511 . The arrow  513  represents the direction the mandrel  106  ( FIG. 1 ) can travel through the passage  506  of the structural member  500  during radial expansion of the structural member  500 .  
         [0051]     The second surface  510  includes a first region  512  and a second region  514 . A portion  512   a  of the first region  512 , which is radially adjacent to and/or includes a portion of the inner surface  504 , is longitudinally located from the first surface  508  by a first member length  516 .  
         [0052]     The second region  514  extends radially outward from the first region  512 . A portion  514   a  of the second region  514 , which is radially located farthest from the inner surface  504 , is longitudinally located from the first surface  508  by a second member length  518 . In one embodiment, the first member length  516  is less than the second member length  518  such that the first region  512  and the second region  514  form a recess  520 .  
         [0053]     The recess  520  may generally be referred to as, but not limited to, a pocket, countersink, counterbore, chamfer, taper, or the like. The recess  520  is dimensioned to receive at least some material that may be deformed when the structural member  500  is installed (e.g., radially expanded into the opening of a workpiece). The recess  520  can define a volume sized to receive a desired amount of mandrel exit upset material  530  ( FIG. 8 ) expected to form on the expansion mandrel exit side  528  of the structural member  500 . In some embodiments, a substantial portion of the upset material  530  is received in the recess  520 . The recess  520  can become smaller as the amount of upset material  530  is increased. In some embodiments, the upset material  530  does not extend beyond a surface  524 , as shown in  FIG. 8 . The depth  522 , cross-sectional area, and configuration of the recess  520  can be selected based on the amount and location of upset material  530 . The surface  524  is the surface located farthest from the first surface  508 . The outer diameter of the recess  520  is less than the outer perimeter that corresponds to the outer surface  502 . The surface  524  may be an approximately flat surface surrounding the recess  520 . The size of the surface  524  can be a function of the wall thickness of the structural member  400 , as well as other design parameters, according to one embodiment.  
         [0054]      FIG. 8  shows the structural member  500  in a radially-expanded state after the expansion mandrel  106  has passed through the passage  506  of the structural member  500  to radially expand the structural member  500  into the workpiece  102 . The recess  520  accommodates the mandrel exit upset material  530 . The mandrel exit upset material  530  is the same material as the material of the structural member  500 , but is shown with different cross-hatching for the sake of clarity.  
         [0055]     The structural member  500  can further include an entry recess  526  defined by a surface  527  (illustrated as an arcuate surface). The surface  527  extends between the inner surface  504  and the first surface  508 . The entry recess  526  can receive a selected amount of mandrel entrance upset material  532  ( FIG. 8 ) that forms when the expansion mandrel  106  ( FIG. 1 ) enters the opening  506  and begins to radially expand the structural member  500 .  
         [0056]      FIG. 9  shows a structural member  600  in a pre-radially-expanded state. The structural member  600  can include an outer surface  602  and an inner surface  604  that forms a passage  606  through the structural member  600 . In addition, the structural member  600  includes a radial flange  608 , a first surface  610 , and a second surface  612 . The first surface  610  is substantially perpendicular to a longitudinal axis  611  of the structural member  600 . The arrow  613  represents the direction the mandrel  106  ( FIG. 1 ) passes through the passage  606  when the structural member  600  is radially expanded.  
         [0057]     The second surface  612  includes a first region  614  and a second region  616 . A portion  614   a  of the first region  614 , which is radially adjacent to and/or includes a portion of the inner surface  604 , is longitudinally located from the first surface  610  by a first member length  618 . The second region  616  extends radially outward from the first region  614 . A portion  616   a  of the second region  616  is radially spaced from the inner surface  604  and is radially farther from the longitudinal axis  611  than the outer surface  602 . In addition, the portion  616   a  of the second region  616  is longitudinally located from the first surface  610  by a second member length  620 . In one embodiment, the first member length  618  is less than the second member length  620  such that the first region  614  and the second region  616  form a recess.  
         [0058]     The recess  622  may generally be referred to as, but not limited to, a countersink, gradual taper, and/or an arcuate surface. The recess  622  is dimensioned to receive a selected amount of a mandrel exit upset material  630  ( FIG. 10 ) that may be deformed as the expansion mandrel  106  exits the structural member  600  during the radial-expansion process. The recess  622  includes a depth  624  which, in combination with the area of at least the first region  614 , provides a volume sized to receive the mandrel exit upset material  630  ( FIG. 10 ) expected to form on the expansion mandrel exit side of the structural member  600  without permitting the material  630  to extend beyond a portion  634  ( FIG. 10 ) adjacent to a surface  626 . In one embodiment, the surface  626  is a flat surface located longitudinally farthest from the first surface  610  and is also substantially parallel to the first surface  610 . Optionally, the structural member  600  may include an entry recess  628  proximate a countersink surface or an arcuate surface  529 .  
         [0059]      FIG. 10  shows the structural member  600  in a radially-expanded state after the expansion mandrel  106  has passed through the opening  606  of the structural member  600  to radially expand the structural member  600  into the workpiece  102 . The recess  622  accommodates the mandrel exit upset material  630 . The mandrel exit upset material  630  is the same as the material of the structural member  600 , but is shown with different cross-hatching for the sake of clarity.  
         [0060]     In some embodiments, the volume of the recess  622  is sufficient to receive the mandrel exit upset material  630  without permitting the mandrel exit upset material  630  to extend beyond a portion  634  of the structural member  600 . In another embodiment, the volume of the recess  622  is sufficient to receive the mandrel exit upset material  630  without permitting the material  630  to extend up to and/or become flush with the portion  634  of the structural member  600 . In the illustrated embodiment, the surface  626  is angled by an angle, θ, towards the first surface  610 , such that the portion  634  is located farthest from the first surface  610  relative to the surfaces  612  and  626 .  
         [0061]     One purpose for having the surface  626  angled towards the first surface  610  and not allowing the mandrel exit upset material  630  to extend beyond the portion  634  is to ensure that a load path  638  (e.g., the load path for the fastener clamp-up loads or other applied loads) goes through the radial flange  608  and directly into the workpiece  102 .  
         [0062]     The portion  634  can be located radially outwardly from a cutout  640  so that the load path  638  does not travel through the thinnest or narrowed portion of the radial flange  608 . Accordingly and as illustrated, the portion  634  is located radially outward on the flange  608  to allow the fastener clamp-up loads to be reacted through the radial flange  608 , which may operate as a washer to spread the load into the workpiece  102 . If the mandrel exit upset material  630  were permitted to extend beyond the portion  634 , the fastener clamp-up loads would react through the bushing wall  642  and generate a non-desirable shear load  644  through the radial flange  608 . Further, another countersink surface  628  may accommodate the mandrel entrance upset material  632 .  
         [0063]     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. 3,566,662; 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; 5,405,228; 5,245,743; 5,103,548; 5,127,254; 5,305,627; 5,341,559; 5,380,136; 5,433,100; and U.S. patent application Ser. Nos. 09/603,857; 10/726,809 (U.S. Pat. No. 7,100,264); 10/619,226 (U.S. Pat. No. 7,024,908); and 10/633,294 (US/2005/0025601) 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.  
         [0064]     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 bushings, sleeves, liners, and other similar components that are installable in an opening of a workpiece and 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.