Composite pressure vessel CNG made of epoxy – carbon material with nonmetal liner is 60% lighter than aluminum vessel under the same conditions. One of the important parameters in the pressure vessels design is their resistance against impact and prevention of explosion. In this paper, the effects of low velocity impact on composite pressure vessel are investigated using FE analysis. The vessel reactions under velocity impact with different velocity, impact angle, and ply angle are studied based on Chang-Chang composite failure criterion. Finally, the effect of gas pressure inside the vessel before and after impact are analyzed. تفاصيل المقالة

Production and preparation of many parts of the aircraft body including wings with long length, smooth form, and large radius of curvature are amongst the most important challenges in this industry. In this paper, the effective factors in the rubber pad forming method on a pieces contain curvature radius have been investigated by finite element method. The effect of variables such as curvature radius, sheet thickness, rubber pad thickness, rubber hardness, lubrication condition, spring back phenomena have been analyzed. To validate the finite elements simulation, the experimental results were compared. Then, other above-mentioned variants were studied. The obtained results indicate that there is a close differentiation between the numerical and experimental works. Moreover, the cited parameters have different effect on part quality تفاصيل المقالة

The basic trait in the ceramics is their high brittle or low fracture toughness, and the main criteria in the design and application is specifying the fracture toughness in ceramics. In this paper, a new method is proposed to determine the fracture toughness of ceramics, which is enhanced in lowering the cost of fracture toughness determination relative to the previous methods. Hence due to the low cost and case of access of alumina (Al2O3) which is extensively used in ceramics industry, it is applied as the most important source for achieving the objectives. Pure alumina has excellent properties such as refractory and high hardness on one hand, and has disadvantages such as low fracture toughness on the other hand. In order to improve its mechanical properties, various additives such as nano scale silicon carbide (SiC) powder are used. In this paper, alumina micro powder having 5% nano magnesium oxide by weight were mixed separately with silicon carbide nano particles of 2.5%, 5%, 7.5%, 10% and 15% to construct various types of ceramics, with different physical and mechanical properties. Semi experimental equation for their fracture toughness determination was presented and used for other brittle materials. This equation has minimal cost of experiments for determining fracture toughness of different brittle materials. تفاصيل المقالة

Injection molding is one of the most important and common plastic formation methods. Combination of modeling tools and optimization algorithms can be used in order to determine optimum process conditions for the injection molding of a special part. Because of the complication of the injection molding process and multiplicity of parameters and their interactive effects on one another, analytical modeling of the process is either impossible or difficult. Therefore Artificial Neural Network (ANN) is used for modeling the process. Process conditions data is needed for modeling the process by the neural network. After modeling step, the model is combined with the Genetic Algorithm (GA). Based on the injection molding goals that have been turned into fitness function, the optimized conditions are obtained. تفاصيل المقالة