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. |