This study presents a finite element approach of a numerical model to investigate the profile of the deformed sprayed particles and the compressive residual stresses analysis at the interfacial zone of particle and substrate impact using cold gas dynamic spray (CGDS). The Lagrangian approach was used to analyze, in details, the material deformation behavior during impact, contact problems of single-particle impact process and the outputs of equivalent plastic strain and temperature to achieve a qualitative understanding of cold gas dynamic spray contact process of cold sprayed particle on the substrate. The evolution of residual compressive stresses during impact was also analyzed for multiple-particles impact process using the Lagrangian approach. It can be observed that the compressive residual stresses increase by increasing the preheating temperature and particle initial impact velocity.

Composite materials show different mechanical properties in different directions which leads to complications in the prediction of their behavior. In addition to being inhomogeneous, behavior of composite materials is highly dependent on the curing process and many studies have tried to address these issues. Residual stress can induce high errors in prediction of composite material properties and leads to a difference between theoretical and experimental results. It has been observed that the humidity of environment and the chemical properties of composite materials are also important. Fewer studies have addressed thick layer composites and no damage theory has been developed for these materials. In this paper residual stress in thick layer composites have been studied. Using numerical analysis, the curing process has been modeled and mechanical properties of a thick layer composite are obtained and the induced residual stress in these composites has been assessed. Unlike thin layer composites, the stress in each layer is not specific and a tensile and compressive stress field can exist simultaneously in thick layer composites.

This paper presents an approach of linking finite element method with artificial neural network to predict J-Integral parameter in desirable airfoil condition. Finite Element (FE) and Artificial Neural Network (ANN) have been employed for the purpose. In other words, a prediction of finite element results has been done using ANN. Ultimately results of two methods have been compared for different cases. Wing fracture is a well-known problem of the planes which depends on various parameters. The J-integral is a vital parameter in evaluations of structure fracture phenomena. On the other hand residual stresses play an influential role in fracture formation. In the current work, effect of residual stresses and crack depth on J-Integral has been investigated in a standard NACA0012-34 airfoil. As will be seen, residual stresses and crack depth influence J-Integral values. It also will be shown that predictions of ANN method are in a good agreement with those obtained by finite element method.

Cold working a hole decreases tendency of fatigue crack initiation and growth near the hole. It is due to creation of some compressive tangential residual stresses around the hole. But there are many uncertainties which affect the residual strain and residual stress field. In fact these uncertainties lead to have scatter in the test results and considering the residual strains and residual stresses as random variables. In this paper strains recorded by strain gages mounted around the hole during cold working process in seven pieces specimens, were analyzed by statistical tests and stochastic properties of mentioned random variables were obtained using SPSS software. The residual strains have been also distributed by normal probability distribution function.