Stability of a simple elastic structure, namely a Chilver structure, is to be investigated. The study will concentrate on the effect of structural imperfections on the critical load of the structure. A computer program will be developed to search for the critical direction of the imperfection,i.e., the direction in which the load carrying capacity of the structure is a minimum for any given amplitude of the imperfection. This study will help structural engineers understand the behavior of imperfect structures.Ball State UniversityMuncie, IN 47306

This study intends to develop a useful tool for the investigation of the behavior of three-dimensional elastic frame structures undergoing large deformations and large rotations, using a mini-computer with an attached array processor. An updated Lagrangian finite element formulation is established by employing conventional two node-twelve degree of freedom beam elements. In order to trace the pre- and post-buckling equilibrium path, an improved nonlinear solution procedure is proposed. The software is designed to make it possible to solve large-scale problems on a mini-computer by adopting a hypermatrix scheme and the segmentation into a number of processors which are independent programs. The software is simulated to estimate the performance of the software on a combined mini-computer/array processor system. By using the simulator time measurements are performed for three different cases of large-scale three-dimensional frame structure models, which verify the usefulness of the array processor in the solution of non-linear finite element structural problems. With the use of the hypermatrix scheme, an alternative solution algorithm for system of linear equations is proposed. The accuracy of the finite element formulation and the effectiveness of the solution algorithms implemented are demonstrated by carefully selected two- and three-dimensional frame examples. Finally, directions for further research are discussed.