Invariant-Based Method for Improving Efficiency of Mechanical Testing in Aerospace Certification of Carbon Fiber-Epoxy Composites

The current challenge with qualification of carbon fiber composites in the aerospace industry would be the low efficiency of testing hundreds of samples. The Trace Theory strives to streamline the qualification process by utilizing a material’s Trace to predict properties of composites using Excel programs and basis data. To test this theory, predicted properties from the program, QuickLam, were compared to experimental data. Unidirectional 0° (T1), unidirectional 90° (T2), quasi-isotropic (T3), and hard quasi-isotropic (T4) laminates were made using HexTowR carbon fiber and TC250 resin provided by TenCate Advanced Composites. Tensile and compression tests were done according to ASTM D3039 and ASTM D695. Five samples were tensile tested for each orientation, with tensile strengths ranging from 39 MPa to 1806 MPa across T1-T4. Six samples were compression tested for each composite orientation with strengths varying from 236 MPa to 1198 MPa across all the laminates. The experimentally measured tensile and compressive strengths were then compared to the values predicted using T1 laminate results as a basis in QuickLam. The most accurate prediction from the program was for the hard quasi-isotropic layup, T4, which yielded a percent difference of 3.6% for tensile strength and 6.7% for compressive strength. It was concluded that although more testing would need to be done, the Trace Theory can be accurate in predicting properties for certain laminates