PSI - Issue 42

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Procedia Structural Integrity 42 (2022) 647–654

23 European Conference on Fracture - ECF23 Fracture testing of adhesive joints in mixed-mode I+III 23 European Conference on Fracture - ECF23 Fracture testing of adhesive joints in mixed-mode I+III

Niklas Ladwig * , Dennis Domladovac * , Stephan Marzi * * Technische Hochschule Mittelhessen, Wiesenstraße 14, 35390 Gießen, Germany Niklas Ladwig * , Dennis Domladovac * , Stephan Marzi * * Technische Hochschule Mittelhessen, Wiesenstraße 14, 35390 Gießen, Germany

© 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the 23 European Conference on Fracture – ECF23 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of 23 European Conference on Fracture - ECF23 Keywords: Epoxides, Adhesive Joints, Mixed-Mode I+III 1. Introduction The experimental characterization of the fracture behavior of adhesive joints to obtain data necessary for a proper joint design has been subject to a lot of research activities in recent years. While most research in this area focused on fracture single in single modes I and II as well as in a combination of those, relevant literature on mode III or on mixed-mode I+III is scarce. In the 1990’s, Chai [3] loaded an adhesively bonded DCB specimen in out of plane direction to apply mode III loading and applied further mode I by using a screw [4]. The fracture envelopes of the adhesive joints were found in an established manner based on the Irwin-Kies equation and beam theory, which required an identification of the current crack tip position during the experiments. The pioneer work of Chai has been picked up recently by Safei et al. [13] and by Akhavan-Safar et al. [1], who investigated bulk polymers and brittle adhesive joints. As they observed Abstract The Mixed-M de Controlled Double Cantilever Beam (MC-DCB) test ha b e developed to tes samples under mixed-mode loading in a c mbination of mod I nd mode III. The mix d-mode ratio defined bas d on J -integral and the principle of superimposition olds even in the case of nonlinear fracture behavior. This mixe -mode r io is externally controlled to be constant during h en ire test dura ion by realizing the MC-DCB test setup as a dual-actuator test in a biaxial testing m c ine. In this work, test results at constant mode-mixi y on two different kinds f adhesive joints are presented: elastic-plastic adhesi joints made of SikaPower®-498 and rather brittl adhesive joints made of Henkel Teroson® EP4510GB. These recently achieved test r sults give mor detailed information on th frac ure of particular adhesive joints. With regard t coh sive zone modell ng of possible joint failure, the tr ction-separation ehavior at the initial crack t p has been evaluated by considering the crack-tip opening displacement, which has been measured by digital image correlation in the experiments. © 2020 The Authors. Published by Elsevier B.V. This is an ope acces article under the CC BY-N -ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) P er-review un r responsibility of 23 Europ an Conference on Fracture - ECF23 Keywords: Epoxides, Adhesive Joints, Mixed-Mode I+III 1. Introduction The experimental chara terization of th fracture behavior of adh sive joints to obtain data necess ry for a proper joint d sig has bee subject to a lot of research activities in recent years. While most research in this area focused fracture single in single modes I and II as well as in a combination of those, relevant literature on mode III or on mixed-mode I+III is scarce. In the 1990’s, Chai [3] loaded an adhesively bonded DCB specim in out of plane direction to apply mode III loading and applied further m de I by usi g a screw [4]. The fracture envelopes of the adhesive joi ts were found in an established manner based on t e Irwin-Kies equation and beam theory, which required an identification of the current crack tip position during the experime ts. The pioneer work of Chai has been pick d up recently by Safei et al. [13] and by Akhavan-Safar et al. [1], who investigated bulk polymers and brittle adhesive joints. As they observed Abstract The Mixed-Mode Controlled Double Cantilever Beam (MC-DCB) test has been developed to test samples under mixed-mode loading in a combination of mode I and mode III. The mixed-mode ratio is defined based on J -integral and the principle of superimposition holds even in the case of nonlinear fracture behavior. This mixed-mode ratio is externally controlled to be constant during the entire test duration by realizing the MC-DCB test setup as a dual-actuator test in a biaxial testing machine. In this work, test results at constant mode-mixity on two different kinds of adhesive joints are presented: elastic-plastic adhesive joints made of SikaPower®-498 and rather brittle adhesive joints made of Henkel Teroson® EP4510GB. These recently achieved test results give more detailed information on the fracture behavior of the particular adhesive joints. With regard to cohesive zone modelling of possible joint failure, the traction-separation behavior at the initial crack tip has been evaluated by considering the crack-tip opening displacement, which has been measured by digital image correlation in the experiments.

2452-3216 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of 23 European Conference on Fracture - ECF23 2452-3216 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of 23 European Conference on Fracture - ECF23

2452-3216 © 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the 23 European Conference on Fracture – ECF23 10.1016/j.prostr.2022.12.082