Concurrent Design and Material Selection for Trusses

The choice of the best material (meaning the least mass of material carries the given loads safely) is different for axially loaded tension and compression members. Using two materials in trusses, one for tension members and the other for compression members, is not a good solution because of manufacturing restrictions, potential for galvanic corrosion, and other incompatibility problems. In this paper, we develop a criterion for choosing a single material for a truss with given loads in all its members. These loads change when the geometry of the truss changes, which in turn changes the choice of the best single material. Then a question arises: what is the best choice of a single material, truss geometry, and shapes and sizes of cross-sections of the members that maximizes the stiffness, minimizes the material weight or cost, and carries the loads safely? Here, we present criteria and a method for concurrent design and material selection using simple triangulated trusses as examples. 1