This report discusses the effects of omitting constraint modes corresponding to applied loads in systems modeled with component mode synthesis. A method of correcting for the omitted constraint modes is also developed. A free component mode synthesis method is applied to a continuous model of an axial rod-spring system, and the effect of omitted constraint modes on the static, steady-state harmonic, and transient response is studied. The effect of omitted constraint modes on the transient response of an asymmetric beam is presented using the free and fixed component mode synthesis methods implemented in MSC/NASTRAN. A simple pinned truss finite element model is also studied.
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