Journal of Science and Technology of Composites

Journal of Science and Technology of Composites

Simulated nano-indentation method for estimation of micro-residual stresses of a unidirectional composite ply

Document Type : Research Paper

Authors
Mahmood Mehrdad Shokrieh
Mohammad Hasan Shaali
Composites Research Laboratory, Center of Excellence in Experimental Solid Mechanics and Dynamics, School of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran
Abstract
Indentation test is a method in which the behavior of a material, in response to the indentation can provide a variety of information. Residual stresses within the body and modulus of elasticity are of the most important information that can be obtained from this response. A composite material is a combination of two or more different materials and due to this difference and heterogeneity a residual stress occurs in them. Considering the destructive effects of this kind of stresses on performance of composite structures, it is necessary to determine the magnitudes and distribution of them. Currently there are some mechanical experimental methods for determining macro residual stresses in laminated composites. However, there is no mechanical experimental method for determination of micro residual stresses in a unidirectional ply. In this research, a finite element simulation of the indentation test for determining the modulus of elasticity and micro-residual stresses of a unidirectional composite ply is presented. For this purpose, an appropriate representative volume element of the unidirectional composite ply has been considered and a virtual indentation has been applied on it. The results show that the estimated modulus of elasticity for the fiber in this way depends on the penetration depth, while the estimated residual stresses are independent of the penetration depth. To evaluate the effect of matrix on the results of the indentation in fibers, an isotropic material with similar properties to the glass fiber, has been modeled and the results were compared with the results of indentation on composites.  

Graphical Abstract

Simulated nano-indentation method for estimation of micro-residual stresses of a unidirectional composite ply
Keywords
Determination of residual stresses
Micromechanics
Simulated indentation composites
Finite element meth
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