A variety of issues can arise when modeling a multibody mechanism. The finite element modeling of a multibody mechanism depends on the degree of complexity that you require. For example, it is often possible to create a quick, initial approximation of the flexible and rigid parts of a mechanism using standard beam elements and rigid beam/link elements. Alternatively, you can perform detailed modeling of the flexible part using 3D solid elements (or shell or solid-shell elements), and the rigid part using the Mechanical APDL program's extensive contact capabilities.