Simulation of micromechanical stresses in fiber-reinforced thermoplastics

Bachelor’s thesis or Master’s thesis

Topic of the work:

Short-fiber-reinforced thermoplastics (SFT) are predominantly processed using the injection moulding process, as this method enables the economical, high-quality and automatic production of components. Due to the flow conditions within the melt, the short fibers align themselves within the molten polymer matrix, resulting in an anisotropy of the mechanical properties. Only macroscopic parameters such as the direction-dependent stiffness can be determined experimentally. However, in order to investigate the microscopic damage processes during fatigue, it is necessary to determine the micromechanical stress between fiber and matrix as a function of the local fiber orientation. For this purpose, the material is modeled using the finite element method with a unit cell model. With a thesis at IKV you have the opportunity to acquire comprehensive knowledge in the field of simulation of anisotropic materials and thus learn industry-relevant skills.

© IKV

The work is related to this research project:

The fatigue mechanisms in short-fiber-reinforced plastics are not yet fully understood. This is mainly due to the anisotropic layer structure, which induces a complex stress state in the component due to layer interactions. A macroscopic characterisation of the meso level thus becomes impossible. For this reason, an injection moulding tool was developed at IKV that generates sheet geometries with unidirectional short-fiber reinforcement. This makes it possible for the first time to characterize the degradation of mechanical properties during fatigue in the meso plane as a function of fiber orientation. As part of the working group, you will contribute to research into material fatigue and thus support IKV in increasing the sustainability and operational safety of technical thermoplastics.

Objective:

The aim of your work will be to use unit cell models to simulate and evaluate the development of the stress and damage state at the micro level. For this purpose, the components of the stress state of the matrix phase are analysed at the micro level. The aim is to improve the understanding of materials during dynamic cyclic fatigue. Sensitivity analyses are also used to determine the influences of the model parameters and characteristics. You will document your methodology and the knowledge you have gained in a Bachelor’s or Master’s thesis.

Your profile:

• Enrolled student of a STEM subject
• Independent and quality-conscious way of working
• Interest in programming and simulation
• Ideally initial experience with the finite element method

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