An experimental study for identifying crack initiation forces in single-lap bonded joints

• Published in: Engineering fracture mechanics Vol. 241; p. 107372
• Main Authors: Sawada, Takahiko, Kawamori, Takashi, Matsunaga, Masahiro, Fujiyasu, Yosuke, Ueki, Yosuke
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 01.01.2021; Elsevier BV
• Subjects: Adhesive joints; Bonded joints; Crack initiation; Digital image correlation; Digital imaging; Failure analysis; Failure detection; Finite element method; Lap joints; Single-lap bonded joints; Strain distribution; Strain gauges; Substrates; Finite element method; Single-lap bonded joints; Failure detection; Digital image correlation
• ISSN: 0013-7944; 1873-7315
• DOI: 10.1016/j.engfracmech.2020.107372

•This study focuses on determining the crack-initiation force of adhesives.•Failure progression of adhesive is analyzed by integrating multiple methods.•The extended finite element is combined with the virtual crack closure technique.•Digital image correlation is incorporated in the relative displacement method (RD).•The RD is experimentally validated to accurately detect crack-initiation force. This paper highlights a method for determining crack initiation force in adhesives used for single-lap joints (SLJs). Crack onset behavior was investigated by combining multiple techniques of failure progressive analysis. The proposed relative displacement method (RD) incorporated digital image correlation (DIC), focusing on bending strain behavior responses to the RD of substrates. Deformation acceleration calculated from the strain distribution drastically increased with increasing crack initiation force and lied within 3% accuracy range, as compared with the behavior of bending compliance measured by a strain gage. The RD was confirmed practical for detecting crack initiation force in SLJs.