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This work deals with the modeling and simulation of shock absorbing shells for ballistic vests and helmets to achieve optimal protection. Shock absorbing shell is modeled as a circular membrane with clamped edge. Symmetrical loading patterns were considered as follows: uniformly distributed pressure over the entire surface of the shell, uniformly distributed pressure over a part of the shell's surface,...
Wire bonding is the most popular interconnection technique that has been used in microelectronics packaging due to its maturity and cost effectiveness. The technology advances in the era of miniaturization and multifunction have urges the need for the smaller wire bond size to cope with the decrease of bond pad pitches. Ultimately, this will introduces al lot of technology challenges in the characterization...
The challenges for the companies involved in conception, development and/or manufacturing of electronic products are the lead-free technology with its increased melting temperature of the solder alloy and trend to reduce the solder materials cost by usage of lead-free solder pastes with low silver content. Defining the elements Pad-Paste-Pin-Process as Key Process Input Variables (KPIV) in terms of...
A simple, room temperature process was reported to fluidic assemble dense, vertically aligned SWNTs between two chips and connect them together. This technology has the potential capability to attach a die to its heat sink in packaging replacing the common available die adhesives by virtue of better mechanical and thermal properties. Two chips with trench about 2 μm deep on the pre-treated surface...
In this paper, we propose a novel haptic device that gives weight and friction illusions. Sensing a slip condition at a fingertip plays an important role to estimate the weight and friction properties of an object. This fact suggests that controlling the contact condition could yield weight and friction illusions. Based on this idea, a prototype device was developed that controls the contact surface...
Electric arc erosion during contact break/make cause contact resistance degradation, material transfer, non-closing and non-opening, above failure modes affect relay operation characteristics greatly. A relay model testing device which could simulate relay parameters of: initial contact force between N.C. contacts, contact gap and N.O. over-travel mechanical parameters assembly was used to study arc...
The reliability of a connector depends on the contact force generated by the spring in the terminal of a connector. The springs are commonly formed by stamping from a strip of spring material. Therefore, the prediction of the force - displacement relation by the finite element method (FEM) is very important for the design of terminals. For simulation, an accurate model of stress-strain (s-s) responses...
Rapid prototyping (RP) fulfills the current need in manufacturing industry to shorten the design cycle while improving its quality. Since there are various methods of RP process, this study focuses on the mechanical properties and microstructure of fused deposition modeling (FDM) RP specimens between two types of raster orientation which are cross (0°/90°) and crisscross (45°/−45°).The method of investigation...
The fracture energy release rate G∼C, which is the important parameter of ice pressure calculation model that is built on energy balance method, is the fracture mechanics performance of ice material. It is related with these factors such as ice material loading rate P•, which must be measured by experiment. It is the experimental method of fracture mechanics used in this paper. These ice specimens...
Crankshaft is one of the most important components if diesel engine, and its design and improvement are very important to engine design and improvement. So the crankshaft intensity checking system based on simply-supported beam method is programmed by VC++. Then a real crankshaft is checked using this system and the results show that this system can be useful to crankshaft checking.
Firstly, based on the Ottosen-four parameter failure criterion, establish material constitutive mode with damage factor. Then, in circumstance of large non-linear dynamic finite element software (ANSYS/LS-DYNA), build the combinative cutting model of advanced knife and scraper under different altitude difference. In addition, three-dimensional dynamic simulation of cutting characteristics is applied...
In this paper, a traveling wave type miniature ultrasonic motor using a foil type stator is proposed. The developed motor has a simple mechanism without being a piezoelectric vibrator in itself. Traveling waves from the vibrator source propagate to the foil type stator through the long-length waveguide. Unlike an ordinary ultrasonic motor, the developed motor rotates in the same direction as the traveling...
There has recently been a significant growth in interest in determining the mechanical properties of living human cells. Much of this work has centred around the application of the Hertz Contact Stress model to force/displacement curves that are obtained from atomic force microscopy. However, it is widely recognised that the conventional Hertzian approach, that is based upon a linear elastic model...
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...
Internal gear pumps have significant advantages over other types of pump, such like high operating pressure, efficient transmission of energy, long service life, little pressure ripples and low noise emissions. Due to the nature of water, such as, low viscosity, poor lubricity and high vapour pressure, the performance of water hydraulic internal gear pumps is totally different from the oil ones. Using...
Through the experimental study of Hydraulic Control System by 6800KN Brick Press, we obtain the displacement, pressure, characteristic curve about the up and down main cylinders and floating box cylinder. On the basis of the analysis of these characteristic curve, we can work out the powder compaction curve, ejection Friction coefficient the loss of positive pressure coefficient. The result of the...
Hydraulic servo pump is extremely important to achieve high dynamic performance and large power density of distributed actuation systems in modern aircrafts. In this study, a piezo-hydraulic servo pump (PHSP) with multiple piezoelectric stacks (PZT stacks) is proposed. The key feature of this design is the development of a mutual active valve rectification method. Based on the novel rectification...
Effects of retention groove location and dimensions of threaded glass fiber post on the maximum retention force of the restorative system and the maximum equivalent stress in the root were numerically investigated. Results show that the retention groove can effectively enhance retention ability and reduce the stress in the root. And the maximum retention force of the restorative system can be increased...
The paper puts forward a DEM design software employing OpenGL as back end display software, for improving the seed metering design precision in agriculture production, introducing the basic principle and modeling method of OpenGL. In the end, a practice design of precision seed-metering device is cited as an example for proving this method to be in effect.
This thesis expounds the action mechanism of scientific and technological progress to pig industry. Based on the statistical data of pig industry in Sichuan province since 1995 to 2009, this paper calculates the contribution rate of pig industry scientific and technological progress by using C-D production function model, and analyzes and compares with the other provinces. The result indicates that,...
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