Papers by Keyword: Short Fiber Composite

Abstract: An experimental study was conducted to evaluate notch effects on fatigue behavior of a neat polymer (PP impact co-polymer) and a composite made of 30 wt% short glass fibers in polybutylene terephthalate (PBT). A plate-type specimen geometry with a central circular hole was used. The experiments were conducted at room temperature in uniaxial tension-tension (R = 0.1) and tension-compression (R = -1) loading conditions. Some analytical methods including Neubers rule and the method of critical distances were used in addition to FEA to predict fatigue life of notched specimens. Neubers rule commonly used for metallic materials proved to be an accurate method for predicting the notched fatigue life of the thermoplastics considered.

Abstract: With the strong emphasis on environmental awareness, it has brought much attention in the development of recyclable and environmentally sustainable composite materials since the last decade. Environmental legislation as well as consumer demand in many countries is increasing the pressure on manufacturers of materials and end-products to consider the environmental impact of their products at all stages of their life cycle, including recycling and ultimate disposal. Silk fibers, spun out from silkworm cocoons, consist of a fibroin core surrounded by a protein layer called "sericin", and these fibers are biodegradable and highly crystalline. It has been known that these fibers have higher tensile strength and are more predictable in failure than glass and synthetic organic fibers. Recently, few preliminary studies have reported that the use of these silks, as microreinforcements to replace un-recyclable carbon and glass fibers for polymeric-based structural composite materials can enhance their mechanical and thermal properties, with reducing the amount of un-decomposable wastes and pollutants. In this paper, the mechanical properties of silk-based epoxy composites formed by different controlled manufacturing parameters are elaborately studied.

Abstract: A micromechanical model based on continuum analysis has been investigated by using finite element analysis (FEA) in discontinuous metal matrix composites (DMMC). To assess the tensile and compressive constitutive responses, a cyclic stress-strain behavior has been performed. For analysis procedure, the elastoplastic FEA and the regularly aligned axisymmetric single fiber model have been implemented to evaluate the internal field quantities. Accordingly, the fiber and matrix internal stresses were investigated for the constrained representative volume element (RVE). Further, the local plasticity in the matrix were described during loading and unloading precesses, which can predict the damage mechanisms as well as strengthening mechanisms. On the other hand, a thermoelasto- plastic analysis has been performed using FEA for the application to the continuum behavior in a discontinuous metal matrix composite. The internal field quantities of composite as well as overall composite behavior and an experiment was demonstrated to compare with the numerical simulation. As the procedure, the reasonably optimized FE mesh generations, the appropriate imposition of boundary conditions, and the relevant postprocessing such as elasto-plastic thermo-mechanical analysis were taken into account. For micromechanical model, the temperature dependent material properties and precipitation hardening effects have been employed to investigate field quantities. It was found that the residual stresses are induced substantially by the temperature drop during heat treatment and that the FEA results give a good agreement with experimental data.