Impregnation of the multi-layered fiber preform with injected resin was analyzed by using the control volume finite element method for three-dimensional mold filling simulation of the resin transfer molding (RTM). Numerically predicted flow fronts were compared with experimental data to validate accuracy of the numerical results and applicability of the numerical code developed in this study. Since isothermal Newtonian flow was assumed, Darcy's law and continuity equation were used as governing equations and permeability tensors employed for each layer. Flow simulation was conducted for the two types of mold geometries, i.e., rectangular plate and hollow cylinder. It was proven by comparing numerical results with experimental data that the simulation code is accurate enough to predict the flow patterns, especially when multi-layered preforms were placed in the cylindrical mold. It was also found that the filling time was reduced by using outer gates compared with the case of inner gates. Three-dimensional numerical simulation provided useful information for mold filling and can be used to design an optimum mold and make the RTM process efficient.

The warpage in a glass fiber-reinforced polyamide molded part caused by the sharp corner effect and differential shrinkage could be effectively reduced by optimizing the injection process parameters using numerical simulations. The results showed that adopting a three-gate injection method could effectively minimize the warpage caused by the sharp corner effect by more than 66% due to better fiber orientation and compensation of the shrinkage deviations. Simple equations were used to obtain the optimized packing profile, and the overall warpage could be reduced by more than 43%.

Through acoustic emission on-line monitoring system, the effective value of acoustic emission is measured, which produces in the grinding of fiber reinforced ceramic matrix composites. The mapping relationship, grinding parameters and the effective value of acoustic emission, is discussed qualitatively. And the influence of different grinding directions on the effective value and spectrum also is studied. These could be significant guidance for controlling the grinding process to improve the machining quality.

Resin transfer molding (RTM) is a very important category of low cost fibre reinforcement composite material manufacturing technique. But void which mainly formed at the process of filling and infiltration is able to reduce the performance of products. This paper first introduced how harmful the void is, and then formation theory, finally focus on the technical feature and resent evolution. Numerical simulation is always a mature and efficient research method for this field of investigation. Formerly, scientists also attribute their effort to such investigation, but, at that time, their simulation was 1D or 2D which can not represent the process accurately enough. Therefore the results are not so significant. Recently most studies pay attention to 3D simulation and how factors (such as injection pressure, structure of preform and so on) work. With the development of mathematic theory and simulation software some new numerical simulation methods present itself. Researchers may copy the course of resin’s filling in RTM more integrity to make their relation close to reality. Based on their achievement, the technique of RTM also improved to eliminate void’s emergence. However the real flow of resin is more than complex, more work should be done to avoid it and then set up a controllable industrial production system.

As the inductance of magnetic cores is the most important parameter for their service performance. Four coupling models of EE-type ferrite cores are established to analyze the relationship between surface quality and the inductance of ferrite cores. Besides, 3D FEM simulation of different models is made by ANSOFT MAXWELL software. The results show that the surface quality has a direct influence on the service performance of ferrite devices.