Using piezoelectric patches the stress concentration around a hole on a plate under tension is reduced and controlled. To attain the reduction in stress two placements for piezoelectric patches is investigated. The first location is top/bottom of the hole with compression induced strain and the second is left/right of the hole with tension induced strains to control the stress flow. The result for two above condition is presented for host plate and piezoelectric patches and by comparing the results the advantages of locating the piezoelectric patches to control the stress flow in the host plate is investigated. The results show that locating the piezoelectric patches at left/right of the hole, to control the stress flow and stress concentration is more effective than locating them at the top/bottom of the hole. تفاصيل المقالة

The roll forming process plays a critical role in producing various sections used in industries. Also, the quality of these products is strongly affected by the thickness of the strip, the distance between stands, the section web, the flower pattern, and the plastic anisotropy. Therefore, the influences of practical factors on the bowing defect of the symmetrical U-section are experimentally and mathematically characterized in the present research. The investigated material is DC03 (1.0347) steel. Different prediction models such as linear and non-linear model based on the general full-factorial design of experiment are used to predict the effect of following factors on the bowing defect. Accuracy of the analytical model was verified by comparing the output results with the practical data. Results show that the strip thickness of investigated material, the flower pattern, and the section web have the most significant effect on the bowing defect. Also, the anisotropic properties of the investigated material and the inter distance have the minor impact on the bowing defect, but the effect of material with considering the anisotropic properties on increasing the accuracy of process simulation results is very impressive and increases the accuracy of simulation results from 84% to 91%. Finally, the predicted bowing defect using the modified two-factor model was in 91% agreement with the experimental results. تفاصيل المقالة

This article has studied the effect of ratio of stiffness and thickness between piezoelectric actuators and host plat has been explored on optimal pattern for placement of piezoelectric work pieces around a hole in thin isotropic plate under static loading to reduce stress concentration. The piezoelectric actuators reduce directly or indirectly the stress concentration by applying positive and negative strains on the host plate. For this purpose, various modes as the thickness/stiffness ratios of the plate to the piezoelectric patches as ≥1 or ≤1 were considered. Then, a Python code was developed using particle swarm optimization algorithm in order to achieve the best model of piezoelectric actuators around the hole for maximum reduction in stress concentration factor. Also, the maximum stress concentration on the top and bottom of the hole was moved to another point around the edge by changing the location of piezoelectric patches. The results obtained from software solutions were confirmed by experimental tests. تفاصيل المقالة

A powerful optimization method is proposed in this study for the minimal dimensional designproblem of gearbox. It is a general model that is suitable to use for any series of gear drives systemand can extract both dimensional and layout of components-limited optimization design together.The objective function in this study has many local extremes so for avoiding this situation, variousconstraints have been determined Then, Particle swarm optimization algorithm has beenimplemented to speed up the convergence of optimization and elitist particles searched in problemspace to find optimum value of goal function until all of them converge to the similar set of values.At the end, Results have been presented in the utilitarian diagrams to obtain optimal parametersfrom useful diagrams. The results display that the proposed method in this study is better than otherreported in last works and it shows optimum volume of gearbox being related to a decrease of notjust space but costs, material used to make gearbox component, etc. تفاصيل المقالة

Distortion and deformation of tubes during machining operations are very important. In this study, a tube used in magnetic drum separator under concentrated load (machining load) is considered. Using finite element simulation, deformities and their dependence on parameters such as the thickness of the tube and the place of concentrated force are observed and predicted. To compare and confirm the results, some experimental tests are considered. The results show that there is good agreement between the numerical and experimental data. The results of this study indicate the amount of residual stress in the tube by changing the location of the load, the effect of residual stresses in the tube, indentations at different levels of thickness and location of the load. Results show that the values and location of force affect the stress and residual stress in the thickness of tube. In addition, increasing the thickness of tube decreases the residual stress area in longitudinal and circumferential direction of tube. Also, the maximum residual stress in tube is occurring under the force area and by increasing the thickness of tube, the displacements of area under the force is decreased. تفاصيل المقالة