FIELD OF THE INVENTION
The present invention relates to transition-joints for joining structural and mechanical parts made from dissimilar materials.
BACKGROUND OF THE INVENTION
Two issues with joining dissimilar materials are material compatibility and applicability of the joining process. More particularly, there are issues involved with joining aluminum to magnesium, to steel or to composites with known joining processes, such as fusion welding (e.g., gas metal arc welding) and solid-state welding (e.g., friction stir welding). These include metallurgical incompatibility, which results in uncontrolled cracking in welds and/or formation of brittle intermetallics; drastic differences in electromotive potential, which may lead to galvanic corrosion in the presence of salts and/or moisture; and incompatibility in the coefficient of thermal expansion, which could cause formation of intense residual stresses at joints and lead to failure under certain loading conditions, such as stress corrosion.
SUMMARY OF THE INVENTION
The invention covers a transition-joint that can be used to join different materials by conventional processes that are commonly used to join the individual materials to themselves, but which cannot always be joined to other materials. The new transition-joint affords more flexibility in the design of the transitions, so the individual materials (e.g., steel and aluminum) can be joined welded and/or bolted through slip-type joints that more readily accommodate variations in the dimensional tolerances of parts, are easier to control and can result in joints with superior mechanical properties (e.g., fatigue and strength). The new transition-joints also allow the option of fabrication of the joint away from the structures in which they will be used and the option of fabrication of the joint as party of subassemblies later to be incorporated, through welding or bolting, into a larger structure.
In one embodiment, the present invention provides an assembly comprising a first structural member made from a first material, said first structural member having a flange, a second structural member made from a second material, said second structural member having a flange, a third structural member made from the first material, said third structural member having at a first flange and a second flange, wherein the flange of the first structural member contacts the first flange of the third structural member and the flange of the second structural member contacts the second flange of the third structural member, so as to lock the first member and second member together; and wherein the first structural member and the third structural member are joined directly to one another.
In another embodiment, the present invention provides an assembly, comprising a first structural member made from a first material, said first structural member having a first flange and a second flange, a second structural member made from a second material, said second structural member having a first flange and a second flange, a third structural member made from the first material, said third structural member having at a first flange and a second flange, a fourth structural member made from the first material, said fourth structural member having at a first flange and a second flange; wherein the first flange of the first structural member contacts the first flange of the third structural member, the second flange of the first structural member contacts the first flange of the fourth structural member, the first flange of the second structural member contacts the second flange of the third structural member, and the second flange of the second structural member contacts the second flange of the fourth structural member, so as to lock the first member and second member together; and wherein the first structural member and the third structural member are joined directly to one another and the first structural member and the fourth structural member are joined directly to one another.
The structural members of these assemblies that are made of the same or similar materials may be joined directly to one another by any welding process known in the art, including fusion, buried arc, laser beam or gas metal buried welding. In a further embodiment, the assemblies can further comprise one or more adhesives joining at least two structural members to one another. The assemblies can also further comprise one or more fasteners, including bolts or rivets, joining at least two structural members to one another.
The invention further provides methods for assembling the transition-joints disclosed herein.
Further features and advantages of the invention will appear more clearly on a reading of the detailed description of the embodiments of the invention, which is given below by way of example only with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention, reference is made to the following detailed description of the embodiments considered in conjunction with the accompanying drawings, in which:
FIG. 1A is one embodiment of cross-sectional view of a transition-joint assembly;
FIG. 1B is top-perspective cross-sectional view of the transition-joint assembly in FIG. 1A;
FIG. 2A is another embodiment of a cross-sectional view of a transition-joint assembly comprising a fastener;
FIG. 2B is top-perspective cross-sectional view of the transition-joint assembly in FIG. 2A;
FIG. 3 is another embodiment of a cross-sectional view of a transition-joint assembly utilizing partial-swivel type joints;
FIG. 4A is another embodiment of a cross-sectional view of a transition-joint assembly that is welded to a beam's web through a slip-fit double lap-fillet joint.
FIG. 4B is top-perspective cross-sectional view of the transition-joint assembly in FIG. 4A.
FIG. 5A is another embodiment of a cross-sectional view of a transition-joint to be intersected with a second transition-joint assembly.
FIG. 5B a lateral view of the transition-joint assembly in FIG. 5A.
FIG. 5C is top-perspective cross-sectional view of the transition-joint assembly in FIG. 5A and a second transition-joint assembly with which it is to be intersected.
FIG. 6A is another embodiment of a lateral view of intersected transition-joint assemblies.
FIG. 6B is top-down view of the intersected transition-joint assemblies in FIG. 6A.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Referring to FIGS. 1A and 1B, a transition-joint assembly of one embodiment the invention 10 includes a first structural member, in this embodiment a top locking plate or “T” extrusion, comprising a first material (e.g., steel, magnesium, composite, etc.) 12 having flanges 18, a second structural member comprising a second material 14 having flanges 24, and a third and a fourth structural member, in this embodiment side locking extrusions, comprising the first material 16 having flanges 20 and 22. The second structural member, in this embodiment, has a “T” shape when viewed in cross-section. The structural members 12, 14, and 16 may be made from any material suitable for a transition-joint, including aluminum, T6 temper 6061 aluminum alloy, aluminum alloy composites, steel, magnesium, organic based composites (e.g., carbon fibers bonded together) and inorganic based composites (e.g., metallic fibers braded and adhesively bonded) or similar composites. The flanges of the side locking extrusions 20 and 22 should contact the flanges of the locking plate or “T” extrusion 18 and the flanges of the second structural member 24 sufficiently so as to mechanically interlock the structural members and prevent the first structural member 12 and second structural member 14 from separating once the side locking extrusions 16 are welded to the top locking plate or “T” extrusion 12. In this embodiment, when viewed in cross-section, the third and fourth structural members 16 are adapted to conform to the outer contour of the first structural member 12 and the second structural member 14 when joined. The flange of the side locking extrusions 20 forms a butt-joint with the top locking plate or “T” extrusion 28 that may be welded along its length. In a further embodiment, sealant or adhesive 26 can be placed between the structural members 12, 14 or 16 to bond structural members to one another and/or reduce wear and corrosion of the structural members.
Referring to FIGS. 2A and 2B, the welds of a transition-joint assembly of another embodiment of the invention 30 may be made from any welding process known in the art, such as fusion-based (e.g., GMAW, GTAW, LBW, LSBW, etc.) or solid-state based (e.g., FSW, FW Plunge, etc.). Alternatively, the welds 30 need not be included, and the welding process described above could be substituted with any other joining and fixation processes known in the art that ensures the mechanical interlocks between structural members do not separate. The transition-joint may include an additional component made of the first material 33 that can be welded to the first structural component 12 and an additional component made of the second material 36 welded to the second structural element 14. FIGS. 2A and 2B also show the use of an optional fastener 40 in the transition-joint that can be used to prevent flanges 22 of the side locking extrusions 16 from separating from the second structural member 14.
Another embodiment of the present invention is illustrated in FIG. 3, which shows a transition-joint utilizing a partial-swivel joint 44 between the top locking plate or “T” extrusion 14 and the flanges 20 of the side locking extrusions 18. In this embodiment, use of partial-swivel type joints 44 having a radius of curvature allows the loading of the side locking extrusions 18 against the edges of the top locking plate or “T” extrusion 46 so that they can be welded to one another, while allowing a firm point of contact 48 between the tapered surface of the flanges of the second structural member and the flanges of the side locking extrusions when using a backup anvil (as during FSW). The side locking extrusions 18 can also optionally comprise a thickened lower surface 50 for improved contact with a backup anvil.
FIGS. 4A and 4B show a transition-joint assembly of the invention 10 that is welded to a beam's web 60 through slip-fit double lap-fillet joints 62.
FIGS. 5A and 5B show a first transition-joint assembly of the invention 80 that is to be intersected and joined with a second transition-joint assembly. FIG. 5B is a lateral view of the transition-joint assembly 80 shown in FIG. 5A. A notch 82 is present in the side locking extrusions 16 of assembly 80.
FIG. 5C shows the first transition-joint assembly of FIGS. 5A and 5B and a second transition-joint assembly 90 with which it is to be intersected and joined. A notch 92 is present in the side locking extrusions 16 of the second transition-joint assembly 90. The notch 92 mechanically mates with the notch 82 so that the side locking extrusions 16 of the first transition-joint assembly 80 contact the side locking extrusions 16 of the second transition joint assembly 92, the flange 18 of the first structural member 12 of the second transition joint assembly 92 and the flange 24 of the second structural member 14 of the second transition joint assembly 92.
FIG. 6A shows the first and second transition-joints 80 and 90 respectively of FIG. 5C fully mated with one another. The transition-joints 80 and 90 can be welded to each other at any contact points between them. The welds may be made from any welding process known in the art, such as fusion-based (e.g., GMAW, GTAW, LBW, LSBW, etc.) or solid-state based (e.g., FSW, FW Plunge, etc.). Alternatively, the welds need not be included, and the welding process described above could be substituted with any other joining and fixation processes known in the art that ensures that the intersected first and second transition joint assemblies 80 and 90 respectively do not separate.
FIG. 6B shows a top-down view of the first and second transition-joints 80 and 90 respectively of FIG. 5C fully mated with one another. It should be understood that the first and second transition joints 80 and 90 respectively do not need to intersect each other at a right angle as shown in FIGS. 6A and 6B.
It should be understood that the embodiments described herein are merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the invention. Accordingly, all such variations and modifications are intended to be included within the scope of the embodiments described herein as defined in the appended claims.
Patent Application
20110219719
