• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.1
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• pp.1-10
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• 2017

In reverse engineering, one of the main tasks is reconstructing the mechanical properties of used materials. For an isotropic material, it could be defined by a single tensile test using a coupon extracted from the structure. In contrast, CFRP composites require many tests and complex procedures to define all the material properties because CFRP is an orthotropic material and a stacked laminate. In this paper, the procedure to reconstruct composite material properties is studied by using the classical lamination theory and the test data of three different laminates from a composite structure. A sample reconstruction of composite material properties using a composite car body is introduced to verify the method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2407-2414
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• 2015

This paper presents analytical expressions for the determination of out of plane thermo-elastic properties for conventional laminated composite plates. The approach follows that commonly accepted for in-plane properties. Results over a variety of lay-ups reveals that it is poor assumption to use transverse tape lamina properties to represent out of plane laminate properties for laminates with more than 10% plies oriented off-axis($90^{\circ}$) from uniaxial or for laminates with angle plies of $15^{\circ}$ or greater.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.393-401
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• 2014

In this paper, we propose an evaluation scheme of the coefficients of thermal expansion (CTE) of constituents in composite materials using an inverse analysis. The size of constituents typically is about a few micrometers, which makes the identification of material properties difficult as well as the measurement results inaccurate. The proposed inverse analysis scheme, which is combined with the Mori-Tanaka method for predicting an equivalent CTE of composite materials, provides the CTE of the constituents in a straightforward manner by minimizing the cost function defined in lamina scale with the steepest descent method. To demonstrate the effectiveness and accuracy of the proposed scheme, the CTEs of several fibers (glass fiber, P75, P100, and M55J) embedded in matrix are evaluated and compared with experimental results. Furthermore, we discuss the effects of uncertainty of laminar and matrix properties on the prediction of fiber properties.

• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.76-85
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• 2014

In this paper, the equivalent coefficient of thermal expansion (CTE) of fiber reinforced plastic composite material is investigated with various CTE prediction schemes. Although there are several methods for predicting the equivalent CTEs, most of them have some limitations of are not much accurate when comparing prediction results with test results. In the framework of computational homogenization, a representative volume element is taken from the predefined fiber-volume ratio, and modelled with finite element mesh. Finally, the equivalent CTEs are obtained by applying periodic boundary condition. To verify the performance of the proposed method, the results obtained are compared with those by the existing methods and test results. Additionally, the thermal pointing error analysis for star tracker support structure is conducted and its accuracy is estimated according to CTE prediction schemes.