SUMMARY

Sheet forming of carbon-fiber thermoset prepreg is of interest in aerospace industry because of the following reasons: 1) sheet forming has can be highly automated and requires relatively cheap equipment. 2) carbon-fiber thermoset prepreg is currently the most superior material in terms of strength to weight ratio. The current limitation of this process is the risk of developing wrinkling defects. This thesis proposes two tasks to model and predict wrinkling in forming.
The first task is to model wrinkling empirically. This empirical model seeks to quantify the risk of wrinkling based on the component design geometry. This model can serve as a quicker and simpler alternative to the complex computational models. It can also provide a guideline for engineers to facilitate designing for manufacturing.
The second task is to construct a computational material model that can be used for process simulations. An inverse finite element framework is proposed as a new approach to obtain the material property parameters for the computational model. In the process of developing this model, the constitutive equation, element types, integration methods will be evaluated regarding their applicability to the forming process.