On the application of fracture mechanics to the size scaling of bonded composite lap joints

The use of large composite materials in large aircraft structures has been widely adopted within the aerospace industry. In the airframe design process, large scale tests (including large components and full scale tests) are required to capture accurately all possible locations of failure. However, large scale tests are expensive and time consuming, which makes it impractical and inefficient to include every possible failure scenario. Current practice is using a test pyramid so that the number of large scale tests can be reduced with the support of testing small scale coupons and components. However, a crucial question still remains: how to relate the small coupon tests to large scale tests.