engleski

Numerical modelling of deformation processes of porous connector housing

The main goal was to investigate porosity influence on mechanical behaviour of the polymer material, the polybutylene terephthalate (PBT) which belongs to the group of (semi-) crystal polymers, or polyester thermoplastics. PBT is often used in electrical industry for connector and plug switches and other components of electrical industry where strict regulations and standards are present. When dealing with automotive industry, PBT can be founded in all sections of the car, from bumpers, handles to electrical connectors, like the one company Yazaki designs and produces. Even thought PBT has envious mechanical properties, very often PBT is additionally glass fibre reinforced. In this thesis, numerical modelling and computer simulations of deformation process are carried out with the glass fibre reinforced and the unreinforced PBT samples. For the microstructure modelling, direct numerical simulation (DNS) is applied on the models based on micro X-ray computed tomography (μ-CT, or CT). Before the analyses, theoretical background of the CT technology is given, along with mechanics of used material and DNS method. The term DNS is usually referred to detail numerical simulations of the heterogeneous materials during which microstructure is directly modelled without multilevel simulations including homogenisation procedures and defining representative volume element (RVE) of a material. During this process, RVE size must be determined and boundary conditions on external surfaces must be investigated for appropriate model deformation. The first part of the thesis is dealing with research on different RVE sizes and their connection with mechanical behaviour. The research is conducted on academic based RVE models and CT gained models. Different sizes of pure PBT samples, along with glass fibre reinforced samples are simulated, respectively. After the research on academic-based models, CT based RVEs are also analysed. Numerical results are validated using appropriate experimental tests. For these purposes, uniaxial experimental tests are conducted on pure and glass-fibre reinforced PBT testing samples. The second part of the thesis deals with investigation of the stress analysis in standard electrical connector for automotive industry. Numerical simulations are conducted on a CT based model of the connector position assurance (CPA) component. Numerical results are then compared with experimental tests. Influence of porosities on CPA mechanical behaviour is investigated. On the CT based models, pores are modelled in different percentages and results are compared afterwards. At the end of the thesis, results are discussed. Potential improvements and future work are given.

Polybutylene terephthalate (PBT) ; finite element method ; direct numerical simulation (DNS) ; micro X-ray computed tomography ; representative volume element (RVE) ; electrical connector

nije evidentirano