Applied Mechanics and Materials Vols. 229-231

Abstract: This article presents conclusions of machinability tests on new austenitic stainless steels DIN 1.4301 and verified with software of CA-X systems. This article presents the results of experiments that concerned the verification of machined surface conditions of workpieces from a austenitic stainless steel DIN 1.4301 and cutting tool wear. The results of cutting zone evaluation under cutting conditions (cutting speed v_c=50 m/min, depth of cut a_p= 2.75 mm and feed f= 0.06 mm per rev.) are a definition of shear level angle and the texture angle. For DIN 1.4301 steel Φ₁ is 38°. The acquired results are interesting in that for the defined conditions we can achieve a quality outer surface after cutting with roughness parameters down to around 0.82 µm.

Abstract: A conjugate heat transfer study was undertaken using STAR-CD. The boundary conditions are given by vehicle operation and engine operation. All three mechanisms of heat transfer, i.e., convection, conduction, and radiation, were included in the analysis. The vehicle exhaust system components temperatures were analysized at certain several separate variables such as the velocity and temperature of the exhaust gases which depend on the engine operation conditions and the velocity and temperature of the external airflows which depend on vehicle operations. The results showed all three mechanisms of heat transfer and increased quantitative understanding of the flow conditions surrounding vehicle exhaust system.

Abstract: Using the random model, the vibration control problem of structures with uncertain parameters is discussed, which is approximated by a deterministic one. The feedback gain matrix is determined based on the deterministic systems, and then it is applied to the actual uncertain systems. A method to calculate the standard deviations for responses of the closed-loop systems with the uncertain parameters is presented by using the random perturbation. This method is applied to a vibration system to illustrate the application. The numerical results show that the present method is effective.

Abstract: A novel and simplified method, which is useful in calibrating instantaneous acceleration and cushioning time of accelerometers after impacted by an object under different parameters’ condition, is proposed in this paper. An investigation on cushioning time, which is usually difficult to be quantified during the process of collision, has also been conducted. Firstly, by mathematical inference on a physical model, we obtained two formula conclusions. Next, numerical simulation suggests that the instantaneous acceleration and cushioning time, to different extent, are sensitive to six factors. Then, influences produced by each of them are studied one by one. By analyzing these influences, the method and results are proved to be correct and practical.

Abstract: To achieve high density and high performance, through-Silicon Vias (TSVs) have recently aroused much interest because it is a key enabling technology for three-dimensional (3-D) integrated circuit stacking and silicon interposer technology. In this study, a 3-D 1/8th symmetrical nonlinear finite element model of a stack die TSV package was developed using ANSYS finite element simulation. The model was used to optimize the package for robust design and to determine design rules to enhance 3-D stack package in view of bump reliability. An L₈(2×7) Taguchi matrix was developed to investigate the effects of interposer thickness, TSV diameter, insulation (SiO₂) thickness, chip thickness, substrate thickness, bump height, and bump diameter on bumps reliability. A temperature cycling test in the range of 0 °C to 100 °C was conducted by three cycles. The mechanical property of SAC leadless solder included time independent plastic and time dependent creep behaviors. The parameter of inelastic strain range of the third cycle was used to evaluate the bump life prediction. Two levels were chosen for each parameter to cover the ranges of interest. The results show that the smaller insulation (SiO₂) and substrate thickness and the larger dimension for the other factors provide the best combination. These could be used as guides for further similar 3-D stack packages design.

Abstract: This paper researches on the levitation and drag forces of Halbach permanent-magnet electrodynamic suspension. First, construct an analytical model to calculate the magnetic field in the air gap and the current in the secondary conductor plate, thus deducing analytical expressions of the levitation and drag forces. Second, establish a 2D and a 3D finite element model, using ANSYS. Finally, at different speeds, from 0 to 250 km/h, compare the forces calculating results through the above three methods. Results generating from the 2D-FEM and the analytical algorithm have less than 3% of relative error, but for having not taken the horizontal components of eddy current in the reaction plate into consideration, thus 10% more than the 3D-FEM calculating results.

Abstract: The conical inflated beams have steady bending stiffness before wrinkles appear according to experimental load-deflection curve, then the deflection distribute function is derived based on the differential function of deflection with variable bending stiffness. The equivalent bending stiffness is presented while the conical inflated beam equates to cylindrical inflated beam, according to the deflection formula of beam, the model of equivalent bending stiffness of conical inflated beams is obtained. Comparing the equivalent bending stiffness of conical inflated beams between theoretical model and Experiment results, it is found that they agree with each other well.

Abstract: This paper taking the high strength of WN gears drive as target, which makes the WN gear device has light weight and compact size. The WN gears drive optimization design model of actual project is put forward by multiple-factor comprehensive failure analysis. The research is to solve nonlinear constrained optimization problems by the method of sequence quadratic programming (SQP) in MATLAB optimization toolbox. Using the optimization program of engineering design examples to analyze the relationship about gear drive parameters on contact and bending fatigue strength, thus the engineering design method of the WN gears drive is improved. This research not only achieved the optimization design of WN gears drive, but also revealed that the interactions between transmission parameters and strength design of the gear, which improved design efficiency and provided application foundation for CAD design of WN gears driving.

Abstract: Rotary slender column in cylinder is a special structure in oil engineering. It contacts with outer cylinder and interacts with its inner pipe fluid and outer annular fluid. A partitioned coupling model was founded by dispersing slender column into beam element, dividing fluid domain into some sections, dispersing fluid section into hexahedron unit and transfer method of the information of coupling interface was described. Dynamics experimental device of column-liquid interaction was built to do column rotating test with considering the displacement and force boundary conditions of rotating column and testing axial excitation force of bottom column, axial acceleration of head column, transverse displacement of columns and collision and contact forces between inner columns and outer pipeline. The maximum absolute error between experimental results and numerical results is 0.31mm and this research provides the methods of numerical simulation and experimental study.

Abstract: Meshing is playing an important role in the large complex structural FEM simulations; it has a direct effect on calculating precision of structural simulations. For increasing the calculation accuracy and analysis accuracy of complex structure, the finite element meshing problems is proposed on the finite element analysis of large complicated structures. The effects caused by element type, mesh density and intergradations on calculating precision are studied and discussed. A research argues that with length-width ratio of 1~2 and length-thickness ration of 1.5~4.5 of two-dimensional rectangular element, the quality of meshing method of two-dimensional element is above normal. As the height of one-dimensional element is equal to the sum of reinforcing rib height of outer panel and half the thickness of panel, more accurate results can be obtained.