Thermoforming Finite Element Analysis of Continuum Fiber Reinforced Plastics using ABAQUS

Abstract

Thermoforming simulations are an essential part in engineering design of components made of Continuous Fiber Reinforced Plastics (CFRP) with thermoplastic matrix known as Organic Sheets (OS). Through the simulations, the post-deformed fiber orientation can be calculated, which is essential for the determination of the mechanical properties of the component. Furthermore, draping problems can be detected, which may be corrected by adjusting the geometry of the tools or reinforcing some sections of the component. This thermoforming simulation would help to avoid unexpected failure of thermoformed components. The challenge of the thesis is the implementation of a suitable material model using Finite Element Software (FES). ABAQUS is one of the leading software programs in non-linear simulations, which has an open architecture that allows a scientific study of complex material models. Finished material models for OS are not stored in the program. However, these material models can be incorporated through the ABAQUS fabric material behavior, using either the test data based fabric or a VFABRIC subroutine. The aim of this thesis is modeling the thermoforming Finite Element Analysis (FEA) of OS using ABAQUS. Therefore, the following objectives are outlined. The first objective is the definition of the boundary condition and the deformation mechanisms that are displayed in the thermoforming simulation. The second objective is to implement a preliminary thermoforming process in ABAQUS, modeling the die, the stamp, the holder as analytical rigid components, and modeling the blank as a flat surface made of a “Dummy Material” such as Aluminum. The third objective is to do a deep research of the different possibilities of defining a material model in ABAQUS, and the necessary software requirements to run the thermoforming simulation with user defined material models. The fourth objective is to implement a macro-scale material model for OS in ABAQUS. Probably, shear force dependence against shear angle of the material angle can be mapped. Further post-processing operations unknown for now are done, such as the possibility of evaluating the shear angle, the fiber orientations and any component folds. The fifth and last objective is to document all the research done and create a tutorial guide that would help future researchers to refine de model by mapping more deformation mechanisms or more adjusted material models. A sensibility analysis to capture the influence of the geometry tools (holder dimensions, blank dimensions), fabric material test data (uniaxial tensile tests and picture frame tests) and boundary conditions (punch speed, holder load, friction coefficient) with shear angles is performed.