Identification of mode I and III fracture toughness of a structural silicone sealant

The present study focusses on the experimental determination of mode I and I I I fracture toughness for structural silicone sealants. Large deflections are explicitly considered in the theoretical framework employed for evaluating the experiments. Tests are performed with a structural silicone sealant manufactured in thin layers. Double cantilever beam specimen are loaded with out-of-plane shear to measure the mode I I I fracture toughness of the adhesive. The methodology of the evaluation is validated numerically. The assumptions made in the development of the theoretical framework result in a maximum deviation between numerical results and the approximation formula of less than 10%. Additionally, double cantilever beam specimen are submitted to cleavage loading in order to determine the mode I fracture toughness. We measure a mode I fracture toughness of DOWSIL™ TSSA of G I c = ( 3 . 64 ± 0 . 91 ) N/mm . In case of out-of-plane shear loading, the fracture toughness is found to be G I I I c = ( 7 . 03 ± 0 . 94 ) N/mm . The outlined experiments are suitable for arbitrary nonlinear elastic materials undergoing large deflections during fracture toughness testing. • Revised derivation for the evaluation of out-of-plane double cantilever beam tests. • Identification of fracture toughness for thin and hyper-elastic adhesives. • Influence of initial crack length on measured energy release rates is investigated.