Mechanics issues in the manufacture of thermoplastic composites.

摘要

The objective of this research is to enhance the science base of thermoplastic composite processing through the development of models relating processing conditions to the residual stress states and mechanical properties of the final products.;The first part of the research is devoted to the modeling of thermoplastic sheet forming. This refers to a process in which flat pre-consolidated sheets are formed into curved shapes. One of the problems encountered as a result of this process is the appearance of misaligned and wavy fibers which can degrade the quality and mechanical properties of the part. A mechanical model is developed to simulate the growth of fiber waviness under the stress states likely to be present during the process. The model consists of discreet fiber and matrix phases coupled into a large, planar system. Numerical results are presented for a composite system with 1000 fibers to demonstrate the viability of the model for large systems.;The second part of the research addresses the in-situ consolidation process. This process, which is used in filament winding and tape laying, involves continuous localized melting and consolidation of the material. The stresses induced by this process are considerably smaller than those produced by bulk consolidation processes. A model is developed to predict the thermoelastic stresses induced by the process at any instant of time. A superposition of the instantaneous solutions is then used to predict the build up of elastic stresses during a simulated filament winding process.