This dissertation presents an innovative analysis methodology to enhance the design of composite structures by extending their work range into the postbuckling regime. This objective is accomplished by using the numerical simulation capabilities of nonlinear finite element analysis combined with continuum damage mechanics models to simulate the onset of failure and the subsequent material properties degradation. A complete analysis methodology is presented with increasing levels of complexity. The methodology is validated by correlation of analytical results with experimental data from a set of hybrid carbon/epoxy glass/epoxy composite panels tested under shear loading using a picture frame fixture.