Loading rate effect on interlaminar fracture toughness

Loading rate effect on the interlaminar fracture toughness has been extensively investigated. However, a study of the published literature indicates that considerable disagreement still exists and a clear understanding of this highly important issue has yet to be achieved. Various loading configurations and the corresponding experimental methods have been developed to date for measuring dynamic interlaminar fracture toughness of laminated composites and adhesive joints. The main purpose of this paper is to review the interlaminar fracture test, especially the technique to gain the initiation fracture toughness under quasi-static and dynamic loading conditions. Firstly, the experimental technics to measure Mode I, Mode II and Mode I/II interlaminar fracture toughness under quasi-static loading conditions are introduced. Secondly, experimental methods to study the dynamic interlaminar fracture mechanisms are reviewed. These two parts focus on the methods used for determining fracture parameters (load, displacement, initial fracture time, crack length) and fracture toughness, such as theoretical formula, FEM and strain gauges, especially for the dynamic experiments. In the third part of the paper, two main optical measurement techniques used in interlaminar fracture tests are introduced. The last part summaries many of the reported findings of the loading rate effect on the interlaminar fracture toughness.