Abstract:
A method of forming a stress isolating joint on a dump body of on an off-highway rubber-tired haulage vehicle includes providing a first plate having an elongated edge, a top side, and a face, and providing a second plate including an elongated edge. Overlapping the first and second plates to define a widened seam bounded at least in part by the elongated edges of the respective plates, and welding along the elongated edge of the first plate to join the elongated edge of the first plate to an adjacent surface of the second plate. The weld and at least a portion of the second plate disposed along the widened seam cooperate to permit the second plate to apply a resisting load to the face of the first plate in response to the application of a load against an opposing face of the first plate.

Description:
RELATED APPLICATIONS 
     This application is a division of U.S. application Ser. No. 10/151,801 filed May 21, 2002 now U.S. Pat. No. 6,568,744, which claims priority from U.S. Provisional Application Serial No. 60/294,143, filed May 29, 2001. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to dump bodies for off-highway rubber tired haulage vehicles, such as dump trucks. More specifically, the present invention relates to a joint isolation system for reducing stress in joints between adjacent plates or other components in a dump body. 
     BACKGROUND OF THE INVENTION 
     Dump bodies for off-highway rubber tired haulage vehicles are typically constructed from a plurality of plates that have been welded together. According to common practice, dump bodies include a floor, sidewalls, and a front wall. Many times a cab protector is attached to the top edge of the front wall in order to protect the truck cab during loading operations. 
     According to common practice, the plates which form the bulk of the load carrying surfaces are joined, such as by welding, to adjacent plates and/or supporting frame members to form the finished dump body. In order to keep the overall weight of the dump body below a desired level, manufacturers often try to use the thinnest plates possible. However, it is known that thin, flat plates are generally not well suited for carrying loads perpendicular to their surface. 
     Although flat plates can be stiffened somewhat by increasing the thickness of the plates, in dump body applications merely thickening all of the plates is not a desirable option, as such an approach increases the weight of the dump body, thus lowering the hauling capacity of the haulage vehicle. Consequently, thin plates are often welded to other reinforcing supporting plates disposed at intervals, or are otherwise connected to and supported by a network of supporting frame members. The thin plates serve the goal of keeping the overall weight down, while the other reinforcing members provide the necessary strength. Two examples of typical prior art construction techniques are shown in FIGS. 8 and 9, both of which experience significant stress along the weld lines indicated as W 1  and W 2  in FIG. 8, and W 3  in FIG.  9 . 
     Unfortunately, according to conventional construction techniques, such joints often experience problems, such as, by way of example rather than limitation, problems with metal fatigue. This metal fatigue is often most prevalent precisely at the weld lines in the dump body. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view taken from below of a dump body assembled in accordance with the teachings of the present invention; 
     FIG. 2 is an enlarged fragmentary view in perspective taken from above at the circumscribed portion of FIG.  1  and illustrating a joint between a thin plate and another plate assembled in accordance with the teachings of a first disclosed embodiment of the present invention; 
     FIG. 2A is an enlarged fragmentary view in perspective taken from below and from the opposite side of the joint shown in FIG. 2; 
     FIG. 3 is a cross-sectional view thereof; 
     FIG. 4 is an enlarged fragmentary view in perspective taken similar to FIG.  2  and illustrating a joint between a thin plate and another plate in accordance with the teachings of a second disclosed embodiment of the present invention; 
     FIG. 4 a  is an enlarged fragmentary view in perspective illustrating a joint between a thin plate and another plate in accordance with the teachings of an alternative disclosed embodiment of FIG. 4; 
     FIG. 5 is a cross-sectional view taken along line  5 — 5  of FIG. 4; 
     FIG. 6 is an enlarged fragmentary view in perspective taken at the circumscribed portion of FIG. 1 of a joint assembly in accordance with the teachings of a third disclosed embodiment of the present invention; 
     FIG. 6 a  is an enlarged fragmentary view in perspective taken at the circumscribed portion of FIG. 1 of a joint assembly in accordance with the teachings of a fourth disclosed embodiment of the present invention; 
     FIG. 6 b  is an enlarged fragmentary view in perspective taken at the circumscribed portion of FIG. 1 of a joint assembly in accordance with the teachings of a fifth disclosed embodiment of the present invention; 
     FIG. 6 c  is an enlarged fragmentary view in perspective taken at the circumscribed portion of FIG. 1 of a joint assembly in accordance with the teachings of a sixth disclosed embodiment of the present invention; 
     FIG. 7 is an a cross-sectional view of FIG. 6; and 
     FIGS. 8 and 9 illustrate joints between plates assembled in accordance with the prior art. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following description of the disclosed embodiments are not intended to limit the scope of the invention to the precise form or forms detailed herein. Instead, the following description is intended to be illustrative of the principles of the invention so that others may follow its teachings. 
     Referring now to FIG. 1 of the drawings, a dump body assembled in accordance with the teachings of the present invention is generally referred to by the reference numeral  10 . It will be understood that the dump body  10 , in a preferred environment of use, is for attachment to an off-highway rubber-tired haulage vehicle (not shown) or other suitable vehicles in which the dump body  10  may prove beneficial. However, the teachings of the invention are not limited to off-highway rubber-tired haulage vehicles, to dump bodies, or to any other particular environment of use. 
     The dump body  10  includes a floor  12 , a pair of sidewalls  14  (only a single sidewall is visible in FIG.  1 ). The other sidewall may be a mirror image of the one shown. The dump body  10  also includes a front wall  16 . The floor  12 , the sidewalls  14 , and the front wall  16  cooperate to generally define a payload space  18 . The dump body  10  includes a rearward portion  20  defining a spillway  22 . A pair of brackets  24  are provided on a bottom surface  26  of the floor  12 , which brackets  24  enable the dump body  10  to pivot relative to the frame of a dump truck (not shown) about an axis  28  using one or more conventional actuators (not shown) of the type commonly employed in the art. 
     The dump body  10  also includes a pair of plates  30 ,  32  which meet in overlapping relationship to define an elongated seam  34 . As shown in FIG. 2, the plate  30  forms a lower portion  36  of the sidewall  14 , while the plate  32  forms an upper portion  38  of the floor  12 . The lower portion  36  of the plate  30  and the upper portion  38  of the plate  32  are joined together to form a joint  40  disposed generally along the elongated seam  34 . Although the joint  40  is shown at an intersection between the sidewall  14  and an upturned portion of the floor  12 , it will understood that the teachings disclosed herein are equally applicable to other seams formed at the intersection of other plates used in the construction of the dump body  10 . 
     Referring to FIGS. 2,  2 A and  3 , the plate  30  includes a pair of opposed faces  42 ,  44  and an elongated edge  46 , while the plate  32  includes a pair of opposed faces  48 ,  50  and an elongated edge  52 . A weld  54 , which may be, for example and not limitation, a fillet weld, extends along the elongated edge  46  of the plate  30 , and interconnects the elongated edge  46  of the plate  30  to the face  50  of the plate  32 . It will be noted that there is no weld securing the elongated edge  52  of the plate  32  to the face  42  of the plate  30 . The weld  54  may be continuous along a length of the plates  30 ,  32 . Alternatively, the weld  54  may consist of a plurality of discrete weld sections (not shown). 
     It will be noted from each of FIGS. 2,  2 A and  3  that the plate  30  includes a thickness T 1  while the plate  32  includes a thickness T 2 . It will also be understood that the plates  30 ,  32  will experience a load generally indicated by the reference arrow L due to the payload carried in the payload space  18  of the dump body. As shown, the load L is applied to the face  44  of the plate  30  above the seam  34 , and to the face  50  of the plate  32  below the seam  34 . Other loads may be applied simultaneously along one or more different directions as would be known to those of skill in the art. 
     In operation, the plates  30 ,  32  may be assembled as shown using conventional welding techniques and conventional materials. As shown in FIG. 3, stress at the line of intersection (indicated as “A” in FIG. 3) between the edge  52  of the plate  32  and the face  42  of the plate  30  will be lessened and or minimized, if not eliminated entirely. This may be compared to the prior art construction illustrated in FIG. 8, in which two welds are employed along the seam as indicated by W 1  and W 2 . As would be evident to those of skill in the art, in the conventional construction, in response to application of the load L stresses would be present along both of the welds W 1  and W 2 . 
     Referring again to FIGS. 2,  2 A and  3 , in response to the application of the load L as shown, the upper portion  38  of the plate  32  may bend slightly about the line B (or about a line extending generally parallel to the line B), due at least in part to the face  42  of the plate  30  pressing against the face  50  of the upper portion  38  of the plate  32 . Consequently, the upper portion  38  of the plate  32  applies a resistive, spring-like force as the plate  32  (e.g., the upper portion  38  of the plate  32 ) resists bending about the line B or about a line extending generally parallel to the line B. Again, this occurs without causing a stress riser at the line A, thus reducing metal fatigue related problems along the line A. 
     Referring now to FIGS. 4 and 5, a joint  140  shown therein is assembled in accordance with the teachings of a second disclosed embodiment of the present invention. Again, the joint  140  is disposed along a seam  134  defined by overlapping portions of adjacent plates  130 ,  132 , similar to that described above with respect to the first embodiment, with a lower portion  136  of the plate  130  and an upper portion  138  of the plate  132  overlapping at the seam  134 . 
     The plate  130  includes a pair of opposed faces  142 ,  144  and an elongated edge  146 , while the plate  132  includes a pair of opposed faces  148 ,  150  and an elongated edge  152 . A weld  154 , which may be, for example and not limitation, a fillet weld, extends along the elongated edge  146  of the plate  130 , and interconnects the elongated edge  146  of the plate  130  to the face  150  of the plate  132 . It will be noted that there is no weld securing the elongated edge  152  of the plate  132  to the face  142  of the plate  130 . In a preferred form, the weld  154  may be continuous along a length of the plates  130 ,  132 . Alternatively, the weld  154  may consist of a plurality of discrete weld sections (not shown). 
     It will be noted from each of FIGS. 4 and 5 that the plate  130  includes a thickness T 1  while the plate  32  includes a thickness T 2 . It will further be noted that in the disclosed embodiment, the thickness T 1  is less than the thickness T 2 . 
     In the embodiment of FIGS. 4 and 5 the elongated edge  152  of the plate  132  includes a chamfered portion  155 . A plurality of apertures  157  are spaced at intervals along the upper portion  138  of the plate  132 , with the apertures  157  being spaced away from the elongated edge  152 . As shown in FIG. 5, each aperture  157  will reveal an exposed portion  156  of the face  142  of the plate  130 . Each aperture  157  includes a perimeter  158 , and a weld  160 , for example a fillet or other suitable weld may be provided, such that at least part of the exposed portion  156  of the face  142  is secured to the perimeter  158  of the aperture  157 , thus further securing the plates  130 ,  132  together. 
     In a preferred form, the weld  160  may extend substantially around the perimeter  158  of the aperture  157 . Alternatively, the weld  160  may take the form of a single weld section within the perimeter  158  or a plurality of discrete weld sections within the perimeter  158 . 
     In operation, the plates  130 ,  132  also may be assembled using conventional welding techniques and conventional materials. As shown in FIG. 5, stress at the line of intersection (indicated as “A” in FIG. 5) between the edge  152  of the plate  132  and the face  142  of the plate  130  will be lessened and/or minimized, if not eliminated entirely. Further, in response to the application of the load L as shown, the upper portion  138  of the plate  132  may bend slightly about the line B (or about a line extending generally parallel to the line B), such that the upper portion  138  applies a resistive, spring-like force as the plate resists bending about the line B. Again, this occurs without causing a stress riser at the line A, thus reducing metal fatigue related problems along the line A. This load is further resisted by the weld  160  in the apertures  157 . 
     As an alternative, the apertures  157  and the weld  160  may be replaced with a line of mechanical fasteners  162  disposed at intervals along the seam  140  as shown in FIG. 4 a . In the illustrated embodiment, three mechanical fasteners  162  which may be, for example and not limitation a set of nut and bolt fasteners, are inserted through apertures  157  which are extended through both the plates  130  and  132  to hold the two plates  130  and  132  together. The size, location, and spacing of such mechanical fasteners may be readily calculated using known engineering principles. 
     Referring now to FIGS. 6 and 7, a joint  240  is formed by overlapping portions of a long plate  230  and a short plate  232 . Both of the plates  230  and  232  carry a load L, and both plates are supported by a frame member  233  (the plates  230 ,  232  and the frame member  233  are also shown in FIG.  1 ). It will be understood that the joint  240 , in a preferred environment of use, forms a part of the dump body  10  (FIG. 1) of an off-highway rubber-tired haulage vehicle, as well as in other applications in which the details (to be discussed below) of the joint  240  may prove beneficial. However, the application of the joint  240  is not limited to any particular environment of use. 
     In the disclosed example, and referring to FIG. 1, the frame member  233  forms part of a generally box-shaped stiffener  211 , which extends generally transverse relative to the pivot axis  28 . In the disclosed example, a pair of such box-shaped stiffeners  211  are provided, with additional or fewer such stiffeners  211  being provided as needed. Another such box-shaped stiffener  213  may also be provided extending generally parallel to the axis of rotation  28 . Again, additional or fewer stiffeners may be used. In the disclosed example, the stiffener  211  typically includes the frame member  233  consisting of a generally vertically oriented plate, another vertically oriented plate (mostly obscured in FIG. 1) spaced away from the frame member  233 , and an interconnecting bottom plate  235 . 
     Referring to FIGS. 6 and 7, the plate  230  is long relative to the plate  232  (e.g., the plate  230  extends further to the right and further to the left when viewing FIGS. 6 and 7, much further than the plate  232  which is visible in outline in FIG.  1  and which, in the disclosed example, generally surrounds the stiffeners  211  and  213 ). 
     The plate  230  includes faces  242 ,  244 . In the preferred environment of use, the face  242  may be referred to as a bottom face, while the face  244  may be referred to as a top face. The plate  232  includes faces  248 ,  250 , and includes an elongated edge  252 . Again, in the preferred environment of use and when oriented in the in use position shown, the face  248  may be referred to as a bottom face, while the face  250  may be referred to as a top face  250 . Thus, the top face  250  of the plate  232  abuts the bottom face  242  of the plate  230 . The plate that forms a portion of the frame member  233  abuts the bottom face  248  of the plate  232 , and is joined thereto by a weld  253 . 
     The elongated edge  252  of the plate  232  includes a chamfered portion  255 , and a plurality of apertures  257  are spaced at intervals along the seam  234 , with the apertures  257  being spaced away from the elongated edge  252 . The size, location, and spacing of such apertures may be readily calculated using known engineering principles. 
     As shown in FIG. 7, each aperture  257  will expose a portion  256  of the bottom face  242  of the plate  230 . Each aperture  257  includes a perimeter  258 , and a weld  260 , for instance a fillet weld, may be provided, such that part of the exposed portion  256  of the face  242  is secured to the perimeter  258  of the aperture  257 , thus further securing the plates  230 ,  232  together. In a preferred form, the weld  260  may extend substantially around the perimeter  258  of the aperture  257 . Alternatively, the weld  260  may take the form of a single weld section within the perimeter  258  or a plurality of discrete weld sections within the perimeter  258 . As a further alternative, the apertures  257  and the weld  260  may be replaced with a line of mechanical fasteners (not shown) disposed along the seam  234 . 
     In operation, the plates  230 ,  232  also may be assembled using conventional welding techniques and conventional materials. As shown in FIG. 6 and 7, stress at the line of intersection A between the edge  252  of the plate  232  and the face  242  of the plate  230  will be lessened and/or minimized, if not eliminated entirely. Further, in response to the application of the load L as shown, a portion  238  of the plate  232  may bend slightly roughly about a line B extending into the plane of FIG. 7, such that the portion  238  applies a resistive, spring-like force as the plate  232  resists bending about the line B. Again, this occurs without causing a stress riser at the line A, thus reducing metal fatigue related problems along the line A. The load L may further be resisted by including the weld  260  in the apertures  257 . 
     Referring now to FIGS. 6 a ,  6   b  and  6   c , there is illustrated three alternative embodiments of the joint  240 , illustrated as joint  240   a , joint  240   b , and joint  240   c.    
     Turning to FIG. 6 a , there is illustrated a plate  230   a  which is long relative to a plate  232   a . The plate  230   a  includes faces  242   a ,  244   a . In the illustrated embodiment, the face  242   a  may be referred to as a bottom face, while the face  244   a  may be referred to as a top face. The plate  232   a  includes faces  248   a ,  250   a ,  251   a  and includes an elongated edge  252   a . Again, in the illustrated environment of use and when oriented in the in use position shown, the face  248   a  may be referred to as a bottom face, the face  250   a  may be referred to as a top face, and the face  251   a  may be referred to as a side face. Thus, the top face  250   a  of the plate  232   a  abuts the bottom face  242   a  of the plate  230   a . The plate that forms a portion of the frame member  233   a  abuts the bottom face  242   a  of the plate  230   a , and the plate that forms a portion of the frame member  233   a  also abuts the side face  251   a  of the plate  232   a  and is joined thereto by a weld  253   a . A weld  254   a  may also be provided to join the frame member  233   a  to the plate  230   a ,  232   a.    
     As shown in FIG. 6 a , each aperture  257   a  will expose a portion of the bottom face  242   a  of the plate  230   a . Each aperture  257   a  includes a perimeter  258   a , and a weld  260   a , for instance a fillet weld, may be provided, such that part of the exposed portion of the face  242   a  is secured to the perimeter  258   a  of the aperture  257   a , thus further securing the plates  230   a ,  232   a  together. In a preferred form, the weld  260   a  may extend substantially around the perimeter  258   a  of the aperture  257   a . Alternatively, the weld  260   a  may take the form of a single weld section within the perimeter  258   a  or a plurality of discrete weld sections within the perimeter  258   a . As a further alternative, the apertures  257   a  and the weld  260   a  may be replaced with a line of mechanical fasteners (not shown). 
     Turning to FIG. 6 b , there is illustrated a plate  230   b  which is long relative to a plate  232   b . The plate  230   b  includes faces  242   b ,  244   b . In the illustrated embodiment, the face  242   b  may be referred to as a bottom face, while the face  244   b  may be referred to as a top face. The plate  232   b  includes faces  248   b ,  250   b ,  251   b  and includes an elongated edge  252   b . Again, in the illustrated environment of use and when oriented in the in use position shown, the face  248   b  may be referred to as a bottom face, the face  250   b  may be referred to as a top face, and the face  251   b  may be referred to as a side face. Additionally, a portion of the frame member  233   b  includes faces  234   b ,  235   b . The face  234   b  may be referred to as the top face, while the face  235   b  may be referred to as the bottom face. Thus, the top face  250   b  of the plate  232   b  abuts the bottom face  235   b  of the frame member  233   b . The frame member  233   b  abuts the bottom face  242   b  of the plate  230   b  and is joined thereto by a weld  254   b . The side face  251   b  of the plate  232   b  abuts the bottom face  242   b  of the plate  230   b  and is joined thereto by a weld  253   b.    
     As shown in FIG. 6 b , each aperture  257   b  will expose a portion of the bottom face  235   b  of the supporting member  233   b . Each aperture  257   b  includes a perimeter  258   b , and a weld  260   b , for instance a fillet weld, may be provided, such that part of the exposed portion of the face  235   b  is secured to the perimeter  258   b  of the aperture  257   b , thus further securing the supporting member  233   b  and the plate  232   b  together. In a preferred form, the weld  260   b  may extend substantially around the perimeter  258   b  of the aperture  257   b . Alternatively, the weld  260   b  may take the form of a single weld section within the perimeter  258   b  or a plurality of discrete weld sections within the perimeter  258   b . As a further alternative, the apertures  257   b  and the weld  260   b  may be replaced with a line of mechanical fasteners (not shown). 
     Finally, turning to FIG. 6 c , there is illustrated a joint  240   c  which is constructed in a similar manner as joint  240   b . In the illustrated embodiment, a plate  230   c  is long relative to a plate  232   c . The plate  230   c  includes faces  242   c ,  244   c . In the illustrated embodiment, the face  242   c  may be referred to as a bottom face, while the face  244   c  may be referred to as a top face. The plate  232   c  includes faces  248   c ,  250   c ,  251   c  and includes an elongated edge  252   c . Again, in the illustrated environment of use and when oriented in the in use position shown, the face  248   c  may be referred to as a bottom face, the face  250   c  may be referred to as a top face, and the face  251   c  may be referred to as a side face. Additionally, a portion of the frame member  233   c  includes faces  234   c ,  235   c . The face  234   c  may be referred to as the top face, while the face  235   c  may be referred to as the bottom face. Additionally, a plate  261   c  includes faces  262   c ,  264   c . The face  262   c  may be referred to as the top face, while the face  264   c  may be referred to as the bottom face. Thus, the top face  250   c  of the plate  232   c  abuts the bottom face  235   c  of the frame member  233   c . The frame member  233   c  abuts the bottom face  242   c  of the plate  230   c  and is joined thereto by a weld  254   c . The side face  251   c  of the plate  232   c  abuts the bottom face  242   c  of the plate  230   c  and is joined thereto by a weld  253   c . The bottom face  264   c  of the plate  261   c  abuts the top face  244   c  of the plate  230   c  and is joined thereto by a weld  270   c.    
     Similar to the joint  240   b , as shown in FIG. 6 c , each aperture  257   c  will expose a portion of the bottom face  235   c  of the supporting member  233   c . Each aperture  257   c  includes a perimeter  258   c , and a weld  260   c , for instance a fillet weld, may be provided, such that part of the exposed portion of the face  235   c  is secured to the perimeter  258   c  of the aperture  257   c , thus further securing the supporting member  233   c  and the plate  232   c  together. Furthermore, an aperture (hidden and thus not shown) in the plate  261   c  will expose a portion of the top face  244   c  of the plate  230   c . Each aperture (hidden) includes a perimeter (hidden and thus not shown), and a weld (hidden and thus not shown) such that the part of the exposed portion of the face  244   c  is secured to the perimeter (not shown) of the aperture (not shown), thus further securing the plates  261   c ,  230   c  together. 
     In a preferred form, the weld  260   b  and the weld (hidden, securing the plate  261   c ) may extend substantially around the perimeter  258   b  of the aperture  257   b  as well as the perimeter of the aperture in the plate  261   c . Alternatively, the welds may take the form of a single weld section within the perimeters or a plurality of discrete weld sections within the perimeters. As a further alternative, the apertures and the welds may be replaced with a line of mechanical fasteners (not shown). 
     In order to further improve the performance of the dump body  10 , the dump body  10  may also be provided with a perimeter reinforcing beam as outlined in copending and commonly assigned U.S. patent application Ser. No. 10/152,595, the entire disclosure of which is hereby incorporated herein by reference. 
     Further, in order to still further improve the performance of the dump body  10 , the dump body  10  may also be provided with one or more of a curved floor, curved sidewalls, a curved front wall, and/or a curved cab protector, as outlined in copending and commonly assigned U.S. patent application Ser. No. 10/152,889, the entire disclosure of which is hereby incorporated herein by reference. 
     A joint isolation system according to the teachings of the present invention may be used on a variety of fabricated structures such as, by way of example rather than limitation, a dump body for off-highway trucks. In accordance with the disclosed example, the joint isolation system may provide a more fatigue resistant joint by isolating the highest stresses from the fatigue prone features of the joint, such as welds or fasteners. Joint isolation in accordance with the disclosed example may be enabled at least in part by providing a spring-like supporting member that distributes the highest stresses to a location without fatigue prone features. 
     When the dump body is loaded, the payload pushes on the floor, the sidewalls, and the front wall, and these forces are distributed within the structure in a manner dependent on the stiffness of the members as would be known applying known engineering principles. As the main plates (upon which the material is bearing) are made thinner in order to save weight or for other considerations, the stresses in these thinner plates become higher, and the fatigue life may be dramatically reduced when using conventional fabrication techniques. 
     It is known that the fatigue resistance of welded structures is typically much less than that of the parent metal. The lower fatigue life is usually seen at the toe of the welds and, according to conventional wisdom, is caused by microscopic defects created during the welding process, stress riser caused by the geometry of the weld, and by very high residual tensile stresses inherent with the melting and re-solidification during the welding process. 
     A joint assembled according to the disclosed example of the present invention may allow higher working stresses to be tolerated by isolating the welds from the high stress areas of the structure. This isolates the microscopic defects, stress risers, and the residual stresses from the high stress zone, allowing the parent material to provide the increased fatigue performance. 
     The joint isolation system may be implemented in several ways. One embodiment is a splice joint between two thicknesses of plates. According to the first disclosed example, the critical toe of the fillet weld is on the thicker member. The material bearing on the inside of the dump body causes the interface between the two plates to bear against one another with the thick plate acting as a spring supporting the thinner plate. The highest stress location on the thin plate is where it is supported by the thicker plate and there is no weld, therefore the fatigue life is improved. 
     According to the second disclosed example (FIGS.  6  and  7 ), a joint in the area of a stiffener or reinforcement is provided. In this example, the critical toe of the fillet weld is on the plate  232 , and this location is strengthened by both of plates  232  and  230 . The material bearing on the inside of the body causes the interface between the two plates to bear against one another with the short plate ( 232 ) acting as a spring supporting the long plate ( 230 ). The highest stress location on the long plate is where it is supported by the short plate (at or near line A) where there is no weld, and therefore the fatigue life is improved. 
     Optional features such as chamfers, holes, holes with perimeter welds, fasteners, or other means can be used to optimize the behavior the joint. The joint could even be made free of all welds by using fasteners instead. 
     A dump body assembled in accordance with the exemplary features disclosed herein will experience a significant weight reduction for the dump body by allowing the main plates to be made thinner. The resulting lighter weight dump body allows the dump truck to operate more efficiently, use less fuel, or allow more payload to be hauled, while still providing an acceptable service life. 
     Those skilled in the art will appreciate that, although the teachings of the invention have been illustrated in connection with certain embodiments, there is no intent to limit the invention to such embodiments. On the contrary, the intention of this application is to cover all modifications and embodiments fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.