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Vibration attenuation by means of tuned mass dampers is a common practice in engineering since many years. Usually, their dynamic features are chosen so that a tuning on the modal characteristics of the system to control is achieved. Although such components can be very effective in reducing vibrations, they suffer of some drawbacks. The main one is that they cannot change their dynamic features in...
The analytical solution of a plane problem for a bimaterial plane with a crack in the shape of the circular arc located near an interface is obtained. On the crack edges external load is applied. At infinity stresses and angles of rotation are given. Method of complex potentials of Kolosov — Muskhelishvili together with a superposition method is used for solving the problem. The boundary problem is...
This paper describes how remote and virtual laboratories can support students in material properties study. The structure of the course and division of the study materials are described. The educational environment used for virtual and remote laboratories is presented.
In the field of the micro/nano operations, like micro, assembly engineering, biological engineering, ultraprecision machining and military needed precision operation and control , we need to use with micron, sub-micron or even nanometer resolution of micromanipulator. Micro positioning platform is an important carrier of precision positioning technology. The purpose of this paper is to design a flexible...
This paper proposes a design and control method for high-speed parallel robot. Improvement of several components of a robot is conducted from the previously designed prototype and thus better performance can be achieved. Stress analysis is conducted to improve the stability and reliability of the newly designed parallel robot.
The aim of this study was to check the load resistance factored design (LRFD) codes for Korean softwood species. Three representative structural timber Lazix Kaempferi, Pinus koraiensis, and Pinus densiflora, in the northeastern South Korea were selected. For evaluating the bending strength, a full-sized specimen was used. In the test results, it seemed that the KFRI grading rule was suitable for...
The springback is mainly an elastic deformation which occurs after sheet metal forming processes. This paper analyzed the mechanism of deep drawing springback of sheet metal forming, and the springback compensation was studied. Based on this, taking the stiffener parts of auto as an example, the paper analyzed the trend and distribution of springback and its distribution under different conditions...
This paper addresses the problem of heterogeneous deformable model accuracy using the finite element methods (FEM). Classic FEM uses predefined shape functions for interpolation and does not account easily for regions of discontinuities. Extended finite element methods (XFEM) use enrichment functions to compensate for the change in an element degrees of freedom (DoFs) in deformable objects. The XFEM...
Cold-formed steel channel sections had been widely recognized as lightweight material and its application in construction industry seen to be unlimited because it has proven in minimizing the building cost while satisfying the required strength. This paper investigates the structural behavior of cold-formed steel channel columns (without or with stiffeners) subjected to axial thrust. Computer aided...
This paper presents a modal analysis method of the base of welding robot by using the finite element analysis software ANSYS release10.0. The base suffers large dynamic stress as shock and vibration while welding robot works, which on the one hand lead to lower precision of welding, on the other hand, may cause the base damaged. Thus dynamic analysis is necessary for design of the base of welding...
Interfacial fracturing is the most important failure mode of solder joints. In this paper, interfacial stresses of Cu pad/solder interfaces are evaluated based on the theory of interfacial mechanics and the finite element method. Effects of solder joint shapes and solder materials on the stress intensity are investigated. The results show that Sn37Pb/Cu interface has greater stress intensity than...
Multi-head stretch forming(MHSF) is a new flexible technology for manufacturing sheet metal, and its multiple adjustable grippers substitute for integral structure grippers in the traditional stretch forming, it has the characteristics that these grippers can real-time adjust displacement and rotation according to variety of die curvature. The MHSF forming principle is introduced and corresponding...
This paper presents conceptual ideas for an ultra-high speed spinning ball motor with a target speed in the range of several tens of million rotations per minute. The research should prepare the next generation of ultrahigh speed motors. The focus of this work is to investigate physical limitations and discuss feasible concepts for the realization of such drive systems. One major issue is the analysis...
This paper gives an accelerated evolutionary algorithm for structure topology optimization. It combines the merits of level set method and Evolutionary Structure Optimization (ESO) for structure topology optimization. The traditional level set algorithm has some drawbacks, for instance, its resultant optimal topology configuration depend on the initial configuration of the structure. Additionally,...
In order to solve a series questions at present existing in machining technology of the disc with complex shape such as long process flow, great affects among working procedures and high cost, according to the outline of the part, the drawing process has been finished by one process instead of two, which is on the basic of the finite element numerical simulation and the experiment on simple dies....
Extrusion process of a large diameter thin-walled aluminum profile was simulated by FEM based on Deform-3D software. The results show that the material flow velocity in the bearing exit of the original designed die is non-uniform. Three times modifications were performed and simulated. The optimal design with more uniform flow velocity in the bearing exit was obtained.
This paper presents the electromechanical flywheel energy storage system designed to enhance rural electrification in Sub-Saharan Africa. Most non-grid connected areas, mostly rural, are powered with solar home systems whose sustainability is limited by the short life span, low power density and low storage efficiency of the battery storage. The electromechanical flywheel rotor is made from glass...
This paper proposes a parametric simulation plan for UBM geometry with different UBM rim angles, diameters and thicknesses. The parameter plan for the solder bump with different heights and diameters, and different shapes is also investigated. The goal of this study is to understand the impact of the die shrinkage on solder joint reliability under electromigration failure, and to optimize the UBM...
The effect of thinning down the chip thickness, will affect the stress pattern in the chip and causes the chip to deform locally when the thickness of the chip is thinner than a certain critical value. Such a local deformation may cause sharp gradient of residual stress around the solder bumps and thus, various failures. This paper shows that by considering the effect of solder bumps on a 50 mum chip,...
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