جستجوی مقالات مرتبط با کلیدواژه "fsp" در نشریات گروه "مکانیک"

Al-Si alloys are widely used in the manufacture of automotive parts such as pistons and cylinders. Although it has desired properties for use in pistons, some microstructural properties of this alloy, such as dendrites or the presence of needle-like silicones, reduce the performance of the parts produced. In this research, to modify the microstructural properties and thus improve the mechanical properties of the alloy, the friction stir processing (FSP) method is used. Also, the effect of process parameters such as rotational and traverse speeds as well as the shape of the pin on the microstructural and mechanical properties of the samples, are studied. The results show that the FSP process improves the microstructural properties of the base metal, and thus improves its mechanical properties. Furthermore, by increasing the rotational speed or decreasing the traverse speed of the tool, the silicon particles become finer, and consequently, the microstructural properties are improved.

In this research, the multi-pass friction stir processing on AZ91 alloy has been simulated with the three-dimensional numerical modeling based on the ABAQUS/ Explicit. This simulation involves the Johnson-Cook models for defining the material behavior during this intense plastic deformation and investing the fracture criterion. Friction stir processing is a complex process that includes several issues such as high strain rate deformation, microstructure evolution, the asymmetric flow of material, and heat. Therefore, the modeling of this process is challenging. This model simulates the tool plunging and stirring phases in the two-pass process. In this paper, to prevent too much damage in the elements during processing, the Arbitrary Lagrangian-Eulerian technique for automatically remeshing of distorted elements has been used. This work shows that the numerical modeling can be an efficient method to study the effect of process parameters on the thermal evolution and the stress distribution. The thermal model was calibrated using the experimental results from the previous works. This model can predict the transient temperature distribution and residual stress field during FSP on AZ91. The results show that the maximum temperature in the advancing side is more than that in the retreating side. In addition, numerical results show that at the end-position of the process, the tool during the lift-up leaves the keyhole region in a compressive stress state.