Physically based constitutive models for crash of composites
Doctoral thesis, 2019
The matrix behaviour is modelled by combining damage and friction on the microcrack surfaces. The transverse mechanisms are modelled efficiently using a criterion for final failure, interaction of damage modes and a continuous response between compression and tension. The model is validated against 45- and 90-degree specimens. The fibre compression mode is fibre kinking growth, a very complex mechanism, responsible for high energy absorption. A homogenized 3D model based on Fibre Kinking Theory (FKT) is developed. It includes initial fibre misalignments and further rotations are governed by equilibrium with shear nonlinearity. The model is implemented in a commercial Finite Element (FE) software together with a mesh objective methodology. Furthermore, another formulation with similar physical principles but more suitable, efficient and robust for crash simulations is developed, implemented in an FE software and validated against experiments. The results show good qualitative and quantitative agreement. The proposed models allow for a reduction of physical testing required to develop crashworthy structures.
Chalmers, Industrial and Materials Science, Material and Computational Mechanics
Development and numerical validation of a 3D fibre kinking model for crushing of composite; Sérgio Costa; Martin Fagerström; Robin Olsson.
Improvement and validation of a physically based model for the shear and transverse crushing of orthotropic composites
Journal of Composite Materials,; Vol. 53(2019)p. 1681-1696
Mesh objective implementation of a fibre kinking model for damage growth with friction
Composite Structures,; Vol. 168(2017)p. 384-391
A physically based model for kink-band growth and longitudinal crushing of composites under 3D stress states accounting for friction
Composites Science and Technology,; Vol. 135(2016)p. 39-45
This work is focused on modelling the complex physical mechanisms involved in crash of composites. The results show good qualitative and quantitative agreement. Thus, the proposed models allow the reduction of physical testing required to develop crashworthy structures.
Areas of Advance
Composite Science and Engineering
Learning and teaching
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4621
Chalmers University of Technology
Opponent: Pedro Camanho, University of Porto