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Effect of strain-rate and moisture content on the mechanical properties of adhesively bonded joints
M. Johar,K. J. Wong,S. A. Rashidi,M. N. Tamin 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.5
Mechanical performance of polymer-based adhesive joints is susceptible to moisture absorption. In this respect, this study establishes a validated methodology for predicting the mechanical responses of adhesively bonded joints under strain rate-dependent and moisture conditions. For this purpose, adhesively bonded lap-joint specimens were tested under the opening (Mode I) and in-plane shear (Mode II) loadings at machine crosshead displacement rates up to 500 mm/min. The mechanics response of the adhesively bonded joint is predicted using the extended cohesive zone model to capture the strain rate- and absorbed moisture-dependent effects. Good correlation of the predicted and measured flexural responses are demonstrated for the independent case of the mixed-mode flexure (MMF) test configuration. The corresponding failure processes of the adhesively bonded joint are described in terms of the characteristic interface damage and stress evolution.
W. A. Siswanto,M. Nagentrau,A. L. Mohd Tobi,M. N. Tamin 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.11
We compared the quasi-static and dynamic simulation responses on elastic-plastic deformation of advanced alloys using Finite element (FE) method with an explicit numerical algorithm. A geometrical model consisting of a cylinder-on-flat surface contact under a normal load and sliding motion was examined. Two aeroengine materials, Ti-6Al-4V and Super CMV (Cr-Mo-V) alloy, were employed in the FE analysis. The FE model was validated by comparative magnitudes of the FE-predicted maximum contact pressure variation along the contact half-width length with the theoretical Hertzian contact solution. Results show that the (compressive) displacement of the initial contact surface steadily increases for the quasi-static load case, but accumulates at an increasing rate to the maximum level for the dynamic loading. However, the relatively higher stiffness and yield strength of the Super CMV alloy resulted in limited deformation and low plastic strain when compared to the Ti-6Al-4V alloy. The accumulated equivalent plastic strain of the material point at the initial contact position was nearly a thousand times higher for the dynamic load case (for example, 6.592 for Ti-6Al-4V, 1.0 kN) when compared to the quasi-static loading (only 0.0072). During the loading step, the von Mises stress increased with a decreasing and increasing rate for the quasi-static and dynamic load case, respectively. A sudden increase in the stress magnitude to the respective peak value was registered due to the additional constraint to overcome the static friction of the mating surfaces during the sliding step.