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

• Published in: International journal of adhesion and adhesives 2025-01, Vol.136, p.103881, Article 103881
• Main Authors: Rheinschmidt, F., Schneider, J., Rosendahl, P.L.
• Format: Article
• Language: English
• Subjects: Experimental test design; Fracture toughness; Material properties of adhesives; Silicones
• ISSN: 0143-7496
• DOI: 10.1016/j.ijadhadh.2024.103881

The present study focusses on the experimental determination of mode I and III 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 III 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 GIc=(3.64±0.91)N/mm. In case of out-of-plane shear loading, the fracture toughness is found to be GIIIc=(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.