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Dhaneshwar Mishra,Y. Eugene Pak(박유근),Seung-Hyun Yoo(유승현) (사)한국CDE학회 2011 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2011 No.1
Materials used for various applications are inherently inhomogeneous though we consider it homogeneous and isotropic for simplicity of analysis. Composite materials which are very common now a days for various applications in both large and small structures are designed in such a way that it has different layers and these layers have different material properties gives rise to the material inhomogeneity at the interfaces of these layers. Material inhomogeneity can cause stress concentration. Energy can be released or absorbed depending upon the elastic modulus mismatch between interfacing layers. The stress concentration along with energy release rate (GC) when reaches at its critical value can contribute to material failure. We have presented analytical solution for M-integral, the measure of energy release rate for self similar expansion in fiber, coating and matrix and studied the effect of material inhomogeneity by choosing different shear modulus ratio of fiber - matrix and coating ? matrix. The effect of coating thickness on energy release rate is also studied. It has been found that combination of stiffer fiber and softer coating in comparison to matrix absorbs energy while when fiber becomes softer and coating becomes stiffer with respect to matrix, it releases energy. Thickness of coating also have significant effect on energy release or absorb rate as in case of thicker coating, the energy release/absorb rate is smaller in both coating and matrix region while it increases significantly when we choose thinner coating. This study will be very helpful for understanding the energy release/absorb due to material inhomogeneity and coating thickness and thus help to understand the critical region of failures in such structures which can contribute for design improvements for composite structures with inclusions.
임의로 기울어진 2차원 격자 결함에 대한 물질 배치 힘
서유정(Youjung Seo),박유근(Y. Eugene Pak) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
The configurational forces on arbitrary-oriented line singularities that are subjected to far-field loads in an infinite isotropic solid are evaluated by the path-independent J<SUB>k</SUB> , M , and L-integrals. The translational forces, J<SUB>k</SUB>, acting on these singularities are obtained in closed-form expressions which are shown to be equivalent to the generalized Peach-Koehler force¹. The self-similar expansion forces, M, for the nuclei of strain are obtained when the normal stresses exists. Likewise, the rotational forces, L, for the concentrated couple moment exists only when the normal stresses are present.