A straight section built with one-dimensional truss elements is used in a dynamic analysis. The model has boundary conditions prescribed at nodes 2, 3, and 4 (nodes TRUSS.3, TRUSS.5, and TRUSS.7 in the model defined in terms of an assembly of part instances) using user subroutine DISP, while at nodes 5, 6, and 7 (TRUSS.9, TRUSS.11, and TRUSS.13) the boundary conditions are prescribed using an amplitude definition. A displacement variation is specified at nodes 2 and 5 (TRUSS.3 and TRUSS.9), a velocity variation is specified at nodes 3 and 6 (TRUSS.5 and TRUSS.11), and an acceleration variation is specified at nodes 4 and 7 (TRUSS.7 and TRUSS.13). The variation prescribed is

For the variations specified using DISP, the appropriate derivatives and integrals have to be incorporated into the subroutine. For the amplitude specification ABAQUS automatically performs the necessary differentiation and integration. Identical variations are specified in both methods such that the results should be identical.