PSI - Issue 68

A.H. Jabbari et al. / Procedia Structural Integrity 68 (2025) 874–879 Jabbari et al. / Structural Integrity Procedia 00 (2025) 000–000

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As visualized in Fig. 6, plastic deformation around the inserted wedge occurs in both specimen types with elastoplastic behavior, resulting in a non-linear relationship between the contact force and the applied displacement. According to Figs. 4 (b) and 5 (a), similar applied displacement or similar expected SIF induce greater contact force in CT specimens than in DCB specimens. Consequently, the resulting plastic deformation in the CT specimens is more remarkable and causes a non-monotonic relationship between the offset of the equivalent contact force and the applied displacement. In fact, local plastic deformation can promote the pile-up of specimen material in front of the wedge, which shifts the effective position of the equivalent contact force.

Fig. 6. Equivalent plastic strain (PEEQ) at the contact zone between specimen and wedge after inserting the wedge into the notch: displacement of 0.4 mm applied to CT specimen with (a) elastic behavior and (b) elastoplastic behavior; displacement of 2.0 mm applied to DCB specimen with (c) elastic behavior and (d) elastoplastic behavior. 4. Conclusions The present study uses finite element (FE) simulations to investigate the feasibility of employing CT specimens loaded by wedges for evaluating environment-assisted cracking of materials. Based on the results of this study, the conclusions can be summarized as follows: • Wedge-loaded CT specimens can basically be used for evaluating environment-assisted cracking. The advantages of these specimen type are compact dimensions, easy manufacturing and simple loading. However, determining the actual force applied is challenging. • Linear relationships between the stress intensity factor (SIF) and the applied displacement and the contact force, respectively, were observed for CT specimens consisting of elastic materials. This also applies to DCB specimens consisting of elastic materials. • After inserting the wedge, plastic deformation around the wedge was identified for both CT and DCB specimens consisting of elastoplastic materials. This deformation explains the non-linear relationship between the equivalent contact force and the applied displacement. • For CT specimens, the offset of the equivalent contact force from the nominal loading line is considerable, but it is negligible for DCB specimens, especially for those with elastic behavior. For the CT specimens with elastoplastic behaviour, a notable pile-up of the material may occur in front of the wedge, which suddenly changes the position of the equivalent contact force. • Although the use of wedge-loaded CT specimens is feasible for evaluating environment-assisted cracking, FE simulations are required for calculating the actual stress intensity factor, the correct equivalent contact force as well as its effective position. Acknowledgement The authors would like to thank HyCentA Research GmbH and the project team of the HyDestiny and ReMET projects for supporting this work. HyCentA is funded within the Competence Centers for Excellent Technologies (COMET) programme by the federal ministries BMK and BMAW, and co-funded by the provinces of Styria, Upper Austria, Tyrol and Vienna as well as by industrial partners. The COMET programme is managed by FFG (www.ffg.at/comet).