Effects of Environmental Factors on Composite Materials

Abstract

Some of the environmental factors which affect the structural performance of composite materials are discussed. Various possible mechanisms of environmental factors ar examined, together with relevant experimental da.Finally, an analytical approach for predicting environmental effects, based on rate theory, is considered.

Macro and micromechanics analysis of short fiber composites stiffness: The case of old newspaper fibers–polypropylene composites

“…While Hirsch model doesn't explicitly incorporate the aspect ratio in the equations, Tsai-Pagano model (Eq. 7) and Halpin-Tsai equations [30,31] do, and they were also used to predict the intrinsic tensile modulus of the fibers. The stiffness in the fiber direction is given by:…”

“…The most common one's are based on the rule of mixtures (ROM) and can be used to back calculate the intrinsic properties of the reinforcing fibers [2,25,26]. In the case of short fiber semi-aligned composites, the most commonly used models to predict the Young's modulus or the intrinsic Young's modulus, are modified rules of mixtures (mROM) [27], Hirsch model [28], and Halpin-Tsai equations with Tsai-Pagano methods [2,[29][30][31].…”

“…The moduli were analyzed from a macromechanical point of view, and their micromechanical aspects were evaluated. The values of the intrinsic Young's moduli of the fibers were obtained by means of Hirsch model [28], and also by means of Halpin-Tsai equations with Tsai-Pagano methods [29][30][31] and then compared, to assess the influence of the aspect ratio of the fibers on the values. By means of Cox-Krenchel equations [32,33] were studied the length efficiency factors, and also were deduced the fiber orientation factors.…”

Estimation of the reinforcement factor ξ for calculating the transverse stiffness E2 with the Halpin–Tsai equations using the finite element method

“…The H-T equations were developed in the late sixties [5] with the aim of providing a simple but an effective way of calculating the elastic properties of a fiber reinforced lamina, since previous developments led to equations difficult to use. Halpin and Tsai developed an interpolation procedure attempting to gather the main results of those micromechanics analyses.…”

Theoretical prediction of dynamic composite material properties for hypervelocity impact simulations

“…To identify the elastic micromechanics theory best suited for predicting the properties of spacegrade CFRP composite laminates, six of the most common theories are subject to a critical review: mechanics of materials [13]; semi-empirical approach [14]; self-consistent field [15]; equivalent inclusion method [16]; method of cells [17], and; bridging method [18].…”