The present study investigates a novel two degrees of freedom (2DOF) modeling of hybrid-bistable vibration energy harvester (VEH) considering nonlinear magnetic interaction and elastic magnifier to improve the efficiency and expand the action bandwidth. The main part of harvesting mechanism is a composite cantilever beam consists of three layers of magnetostrictive, piezoelectric and a metallic core with internal damping. Such a novel architecture generates more electrical power and operates at larger bandwidth than common piezoelectric or magnetostrictive energy harvesting systems. In the present work, a coupled 2DOF model is developed to investigate the vibration behavior and energy harvesting rate of the harvester. The harmonic balance method is used to obtain the frequency responses and then the Runge-Kutta method is utilized to calculate the dynamic responses. A parametric study is done to investigate the effects of the key features of the harvester such as magnets distances, base acceleration level and excitation frequency on the rate of electricity generation. تفاصيل المقالة

In the deep drawing process, the optimal design of the initial blank shape has many advantages such as reducing the cost of production and waste and improving the quality of the process and thickness distribution. The deep drawing process is highly nonlinear due to the large deformation, plastic deformation of the material and the contact phenomenon. Therefore, the general solution to such problems is to use iterative methods based on numerical simulation. The present study implements a similar approach and presents a new algorithm to make geometrical corrections to the external boundaries of a blank, as well as its internal boundaries, in several iterations. A computer program was developed to automatically run these iterations to study the features of the proposed algorithm. Next, an example problem was solved, and the results are compared with other studies. The results showed that the proposed algorithm is sufficiently robust against the initial guesses for the blank, which is an advantage of the present algorithm over those from other algorithms. Because in other algorithms presented in the articles, if the appropriate initial guess is not selected, the algorithm will not converge to the answer. The proposed algorithm also has a higher convergence speed in achieving optimal blank. تفاصيل المقالة

Today, metal forming is considered one of the essential methods of manufacturing and producing parts. Therefore, the more accurate knowledge of it leads the industrialists to produce higher quality parts. Deep drawing is one of the most important methods in metal forming processes used to produce cup-shaped products. In this paper, numerical simulation of the deep drawing process based on the finite element method is performed using Abaqus software for a cylindrical cup. Then, the results obtained from numerical simulation are compared with the experimental results in the sources, and the validation of the simulation is performed. In the deep drawing process, effective parameters such as circumferential strain distribution, thickness strain distribution, and radial force distribution are extracted from numerical simulations and compared with experimental results in the sources. The effect of friction coefficient, blank holder force, and punch radius on the deep drawing process has also been investigated. Because experimental methods based on trial and error are time-consuming and costly to achieve the shape of the primary blank, researchers use numerical methods to simulate and design metal sheet forming processes such as deep drawing. It is necessary to compare the results with experimental works to validate the simulations performed by numerical methods. تفاصيل المقالة

Deep drawing is a popular process in sheet metal forming. The goal of shape optimization of the initial blank which is considered in the present work is to find the shape of the blank in a manner in which after a deep drawing process the contour of the edges of the produced part meets a target contour. Such problems are highly nonlinear because the simulation consists of large deformation, plastic deformation, and contact. Therefore, the general approach to solving such problems is using iterative methods which are based on numerical simulation. Such an approach is also followed in the present work and a new algorithm for geometry modification of initial blank in each iteration is proposed. In the proposed algorithm, the normal distance between the final contour and target contour is used as a criterion to modify the initial blank. To evaluate the proposed algorithm a computer program is developed and to automatically execute the iterative process. One numerical example solved and the results are compared with those reported in the literature. One of the benefits of the proposed algorithm is its insensitivity to the initial guess. Therefore, to evaluate the effect of the initial guess on its performance the example was solved using different initial guesses. The results show that the proposed algorithm is robust regarding the initial guess and convergence to the optimum shape will be achieved by starting from an initial guess. تفاصيل المقالة