Modelling of high velocity impact on composite materials for airframe structures application
|Advisor:||Gakwaya, Augustin; Nandlall, Dennis|
|Abstract:||This thesis presents a new lamina material model that addresses shortfalls identified in advanced material models for use in composite impact predictions. The new model combines the ease of use of the Matzenmiller-Lubliner-Taylor model with the robustness of the Ba˘zant crack band method. A material model inter- polation scheme is also presented to allow for the simulation of high strain rate loading events with the new lamina material model. The proposed lamina model is implemented in a commercial Finite Element Method (FEM) code and used in combination with a stack shell approach using cohesive zone elements to predict delamination damage. The proposed material model and chosen discretization enable for the prediction of high velocity through thickness impacts, which lead to the perforation of the targets. To validate the newmaterialmodel, experimental tests are performed on three woven composite materials. These tests consist in perpendicular impacts on Car- bon Fiber Reinforced Polymer (CFRP) panels using an elongated aluminium im- pactor. The elongated projectile is required to record the projectiles’ deceleration histories during the impact event. Postmortem inspections of the panels are also undertaken to quantify the damage sustained by the CFRP targets. Projected delamination areas are quantified through C-Scan inspection of the targets, fol- lowed by visual inspection of the impact sites’ cross sections. Numerical simulations are next carried out using different in-plane and out- of-plane discretization approaches. Three material formulations are also investi- gated: brittle, the proposed model and the proposed model with high strain rate parameters. The results of these simulations are compared to the results obtained experimentally. The new model is found to predict reasonably well the damage encountered in the experimental test and to greatly diminish the mesh size sen- sitivity of the FEM approach. Areas requiring further attention are identified to further move composite material failure prediction from laboratory to industrial applications.|
|Document Type:||Thèse de doctorat|
|Open Access Date:||16 April 2018|
|Collection:||Thèses et mémoires|
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