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The application of modeling theories and the choice of failure criteria are difficult in part because they are too varied and must be validated by biaxial tests, which are expensive to be performed. This article is devoted to the nonlinear modeling and failure criteria which are employed in the design and analysis of anisotropic materials. Indeed, in this work, a study of the macroscopic and microscopic behavior of a graphite epoxy under a three-point bending test is conducted, and the successive failures are also predicted. Experimentally, the damage progression and the effect of geometrical parameters are followed and identified in detail. The analytical modeling is based on a recently developed approximation for isotropic materials. This approximation is also valid for the studied quasi-isotropic laminated composite. A software program has been elaborated for the application of the most general failure criteria. The results obtained by this analytical modeling show a good correlation with those of the experimental study.

In order to ensure structural integrity in such applications of composites materials, it is important to understand the material behaviour under mechanical loadings and predict correctly its responses. In this paper, the authors perform several three-point bending tests on a typical stacking sequences used in composite structures. Inspection techniques involving a digital microscope are used to study the successive failures and the effect of the thickness ratio (l h −1 ) on nonlinear behaviour. It was found that successive failures depend on the stacking sequence where the orthogonal sequences have a significant effect on the delamination between the plies. To describe the nonlinear behaviour observed, Von-Karman's large deflection theory and classical plate theory (CPT) are employed in the formulation of analytical modelling used in this work. The Riccati equation obtained leads to predict the experimental nonlinear curves with good accuracy. However, a slight dispersion between the experimental and analytical curves less than 11% was observed at large deflection.

The liquid composite molding family (LCM) includes several processes like RTM ("Resin transfer molding") and VARI ("Vacuum assisted resin infusion"), to satisfy the requirements of each industry. The objectives of recent years in the automotive and aerospace industries tend towards better control of production costs by using of new materials, shorter manufacturing cycles, a higher level of performance and safety and better environmental respect. In the automotive sector, a short cycle time and a lower cost equipment are the most criteria to determine a suitable process, while the quality of the part is the primary parameter for aeronautical process selection. The main objective of this paper is to propose and discuss a new design of LCM mold, allowing at the same time to facilitate the manufacturing process, in particular to reduce the cycle time and to respect the material's health by obtaining a part with minimum defects. This innovation is achieved by using the TRIZ theory (theory of inventive problem solving), in order to eliminate the contradictions that exist between the requirements of the two sectors.

Relaxation-compression resin transfer molding under magnetic field is a new variant of VARTM (“vacuum assisted resin transfer molding”) process, which uses a flexible magnetic membrane controlled by a magnetic force, in order to govern the relaxation and compression phases by changing the permeability of the fabric preform. Thus permits to the resin to enter easily into the mold and to increase the resin impregnation velocity and the fiber volume fraction. This innovation is based on the application of the TRIZ theory (“the theory of inventive problem solving”), which allows us to answer to the shortcomings and the conflict links exist inside the VARTM processes. The objective of this paper is to present this new process and to study the effect of the current intensity and the separated gap between the flexible magnetic membrane and solenoid on the permeability of the preform.