Comparison of supported and partially supported configurations for the machining of thin composites laminates for the aerospace industry

This project was in partnership with CRIAQ. In the aerospace industry, the actual practice to support thin parts during machining is to use dedicated fixtures with curved surfaces that match the ones of the work pieces. This requires a large inventory of fixtures which is costly in terms of design and manufacturing as well as in terms of shop floor space. This project will focus on the study of part fixtures in order to propose flexible (and affordable) fixture configurations for the machining of thin composite laminates. The project will initially focus on a simple geometry (flat plates of specified dimensions) made of a quasi-isotropic [0/90/45/-45]s laminate stacking sequence. Comparison of unsupported and supported machining operations will be performed by considering variations in the laminate thickness and plate size. Finite element analysis will be used to evaluate the laminate deformations and stresses, under the action of the cutting forces, required to prevent delaminating and cracks based on the support configurations under study (fully supported VS flexible fixture). In this analysis, the fully supported configuration will be taken as reference considering it is actually used and accepted by the aerospace industry. From the numerical analysis, a model based on the laminate thickness and dimension will be proposed to support the aerospace industry in the design of efficient flexible support configurations. The model and the results of the numerical analysis will be validated through machining experiments realized on specific thin and thick laminates. The optimal machining conditions known for the supported case will be utilized for comparison with best conditions required for the partially supported case. CTA has different machine-tools and a manufacturing facility of composites that will help in the experimental part of this project.

Kaml Hasni
Faculty Supervisor: 
Drs. J-F Chatelain & G. Lebrun