Fracture mechanics testing of fiber-reinforced polymer composites: The effects of the “human factor” on repeatability and reproducibility of test data

Fracture mechanics data from fiber-reinforced polymer-matrix (FRP) composites are required for damage-tolerant design. Quantifying scatter is essential for determining design limits. Scatter is affected by the “human factor”, i.e., process and test operator actions. Intrinsic scatter from manufacture, processing and environment shall be preserved; extrinsic scatter from specimen preparation, test set-up, measurement resolution, and analysis minimized. Automated processes yield fairly consistent scatter, but additive manufacturing of FRP composites has not reached the same maturity level yielding more defects or weak interfaces. The potential of digital technology for reducing scatter and quantifying single and multiple delamination propagation are also discussed.