Applied Mechanics and Materials Vol. 697

Abstract: A simple method for measuring and calculating the finger joint angular displacement was proposed to serve as the basis for designing dexterous hand and rehabilitation robot hand. The direct kinematics model and the inverse kinematics equation of the finger were established at the beginning of this paper. Then, the trajectory of the fingertip, from which the coordinates of the fingertip were extracted by using AutoCAD, was captured by camera. Finally, the trajectory coordinates of the fingertip were substituted into the inverse kinematics equations to solve the angular displacements of the proximal interphalangeal (PIP), distal interphalangeal (DIP) and metacarpophalangeal (MCP) joints. The calculating precision testing of the finger joint angular displacement needs to substitute the angular displacements calculated before into the direct kinematics equations of the finger to calculate the trajectory of the fingertip. Then, the average Euclidean distance between the calculated trajectory and the real trajectory was computed to test the calculating precision of the finger joint angular displacement. The average Euclidean distance of each fingers is less than 0.05mm, which proves the high calculating precision of the finger joint angular displacement and the efficiency of the method presented in this paper.

Abstract: A dynamic model of tractor-semitrailer cornering braking was established in this paper. The accuracy of the model was tested and verified by comparing model output with data of tractor-semitrailer test. By model simulation of the cornering braking process, initial speed such as 20km/h, 25km/h, 30km/h, 35km/h, 40km/h was chosen to analyzed the changing curve of braking distance, articulation angle, yaw rate and lateral acceleration. The result shows that during cornering braking of tractor-semitrailer, with the increasing of initial speed, braking distance greatly increased, articulation angle, yaw rate and lateral acceleration are all increasing. Thus, when braking in a turn, the vehicle speed must be reduced to ensure the stability of tractor-semitrailer cornering braking.

Abstract: The principle and application of rapid prototyping technology were presented. Several typical rapid prototyping technology were introduced, such as the Stereo Lithography Appearance, Laminated object manufacturing, fused deposition modeling, selective laser sintering, three dimensional spray adhesive technology. The rapid prototyping technology was used in manufacturing, clinical surgical, defense technology, ceramics, dental, and so on. The choke point of rapid prototyping technology application was analyzed, such as molding materials, precision error, and the performance of data sharing software. The future development trend of rapid prototyping technology is prospected also.

Abstract: This paper discuss the possible fault about AMT. By using the information redundancy between those parts, the faults of sensors and actuators can be found. In addition, the corresponding tolerant is put forward. Based on the fault diagnosis method, Matlab/Simulink mathematical model of engine, clutch and transmission is built. The simulation results show that the model can satisfy the requirement of fault diagnosis, and has certain tolerances.

Abstract: The erosion and wear mechanism for drilling equipment is studied in this paper, which is for the problem of unstable performance of drilling system and short lifetime caused by the erosion of drilling equipment by drilling fluid. The flow field, surface pressure of the erosion prone parts and drilling fluid flow rate are calculated by the finite element method. The results demonstrate the parts eroded seriously by drilling fluid appear in where the curvature of the curve of the wall changes suddenly and where the rate of change in the stress field is greater, which provide a theoretical basis on design, optimize, repair of drilling equipment.

Abstract: For the complexity of its space surface,the rapid measuring technology of machining errors for roller gear cam has always been a difficulty.In this paper, the NC machining technology of roller gear cam is introduced first, then a rapid measuring method for roller gear cam center distance error is put forward,and a error analysis model is established, last the machining experiment is done to verify the feasibility of the method.

Abstract: Investigation of mechanical state of shape memory alloy pipe-coupling had an important significance in engineering field. Theory of plastic deformation was used to analyze the coupling force in the tube connecting process of NiTiNb shape memory alloy, in this paper. Based on the analyzed results a mechanical modeling and formula calculation were carried out, the radial pressure of the SMA tube was calculated, in this paper. The results show that, when the temperature doesn’t reach to contact temperature, the pipe coupling of TiNiNb shape memory alloy has no radial pressure; when the temperature reaches to inverse martensite phase transformation temperature, the radial pressure increases; with the decreasing of temperature, the radial pressure increases a little. The radial pressure and push-out force increase with the increasing of the wall thickness. Thus, to improve the strength of connection, the wall thickness of pipe coupling can be properly increased.

Abstract: With the increasing use of composite materials in aviation structures, stability and weights of wing-box are important projects that engineers care about. In this paper, the genetic algorithm is chosen to deal with the conceptual design problems of composite wing-box. For the more excellent capabilities in optimization computation of multi-dimensional functions, particularly when overcoming local-best solutions, genetic algorithm is presented to determine the design variables of complicated wing-box. Optimization algorithm is realized with MATLAB software, which calls the finite element program MSC.Nastran to get buckling load factors, and structural layout, thickness of plies and minimum weight of wing-box are obtained simultaneously. The results show that the approach proposed is available, effective to preliminary design of the mainly aeronautical structures.

Abstract: The current status of nanofabrication briefly reviewed, then molecular dynamics model of poly-silicon is founded on micro-nanoscale with molecular dynamics method, in which several typical defects are distributed reasonably. Molecular dynamics simulation of nanocutting process is conducted according to the simulation model. Keeping the other conditions remain unchanged, simulating calculation is made by reasonably changing cutting parameters such as cutting velocity and cutting depth, through which the changes of the morphology structure of workpiece surface,cutting force and system potential energy are observed. The simulation results are compared and studied, then the influence laws of each parameter on morphology structure of workpiece surface, cutting force and system potential energy are analyzed. Based on this, the mechanism of poly-silicon nanomachining is discussed .

Abstract: As road traffic becomes more and more crowed nowadays, rear impact has become one of the most common forms of traffic accident. According to a survey, up to 78.2% of rear impact can cause occupant neck injury. Up to now, E-NCAP, J-NCAP, IIHS and C-NCAP have set whiplash test in officially. But because of the uncertainty of injury mechanism, none of the countries has reached an agreement on the evaluation method of occupant neck injury. Comparison and analysis of whiplash evaluation methods are made, from aspects of collision waveform, speed, evaluation criteria, calculation method, criteria limit, etc. The annual C-NCAP whiplash tests are set as statistical sample and an analysis of the relationship between lost points and influential factors is carried out in order to find the part that needs to be perfected. Finally, effective suggestions are put forward for the improvement of evaluation method of occupant neck injury in whiplash test.