Analysis Of Thermodynamic Properties For Composite Materials With Unidirectional Fibers

Composite materials with unidirectional fibers, as a new type of material, are increasingly used in different fields, including the aerospace, automotive, civil construction industries, high-speed trains and even luxury cars. It has the advantages of low density, high strength, strong design, prominent anti-penetration capability. Moreover, uncertainty such as randomness always appears during the manufacturing of the composite materials. Therefore, the study of stochastic effective properties of composite materials with unidirectional fibers has important significance in the design and optimization of composite materials. Generally, the randomness of micro-structural properties and morphology as well as their correlation has a great impact on random effective properties of the composites since a small change in microstructure parameters may result in a greater change in the effective macroscopic properties. Therefore, during the calculation of the effective properties of fiber-reinforced composite materials, it is very important to consider the uncertainty in the microstructure of composites.In this work, the uncertainty of material such as the randomness of thermal expansion coefficients, Young’s moduli and Poisson rations of fiber and matrix, the volume fraction of fiber and matrix, the randomness of geometric dimension of fiber as well as the correlation among these random microstructural parameters is fully considered, the random homogenization analysis for effective thermal mechanical properties of composite materials as effective thermal expansion coefficients and effective elastic properties is addressed based on the equivalent inclusion method and random analysis method. The numerical characteristics of stochastic effective thermal mechanical properties such an mean value and mean square deviations as well as variation coefficient of random properties are firstly derived by Random Factor Method, and the results are simulated and compared with those from Monte-Carlo Method. The impact of randomness and correlation of the microstructural parameters on the random homogenized effective results are inspected by two methods. In addition, the correlation among these effective properties is obtained by Monte-Carlo Method. The results from two methods indicate that Random Factor Method is found to deliver rapid results with comparable accuracy to the Monte-Carlo approach.