Nonlinear Identification Problems Under Large Deflections

This paper presents a method of identifying unknown parameter and force histories for nonlinear structures. The nonlinearities treated are those that arise from large deflections and rotations and/or from material behavior in the form of elastic-plastic and hyperelastic responses. The method is based on a sensitivity response approach in conjunction with a general finite element program; it can determine multiple isolated force histories as well as multiple forces in the form of traction distributions. Because it successfully allies a general finite element program with the inverse methods, there is (potentially, at least) little restriction on the geometric and material complexity of the problems that can be handled. Experimental data from a very flexible beam-like structure is used to demonstrate the attributes of the developed method. Both quasi-static and dynamic tests are performed and evaluated.