Applied Mechanics and Materials Vols. 249-250

Abstract: A simulation of deep drawing process on the sheet metal was done by using Dynaform, the influence of blank holder force, deep drawing speed and friction coefficient on the forming speed of sheet metal in the deep drawing process were got. The forming speed of sheet metal determines the quality of deep drawing, in the deep drawing process the blank holder force and the deep drawing speed are controllable parameters, the friction coefficient can be intervened and controlled, and it’s a manifestation of the interaction of all parameters, the main factors which influence the friction coefficient just have blank holder force, deep drawing speed and lubrication except the material. The conclusion of this study provides the basic data for the analysis of the lubrication of mould, the study of lubricant and the prediction of the service life of deep drawing die.

Abstract: Pipelines being laying is subjected the high external water pressure, axial tension and bending moment, influencing the large deformation and the stability of pipelines. It is a key problem about the pipeline deformation and stress analysis under installation. The paper is focused on the analysis of the S-Lay method in deep water, modeling the deepwater S-lay installations considering interactions among the pipeline and stinger and the barge, which make the simulations more realistic. The large work of the paper issues the sensitivity analysis in the installation procedure, several examples are presented to calculate the pipeline configuration and mechanical analysis for different laying water depth, pipe diameter, thickness of wall and concrete weighted coating layer and stinger radius. Some results are presented as well.

Abstract: Combining the advantage of 3D design software Pro/E in modelling with the ability of finite element analysis (FEA) software ANSYS in analysis and calculation, this article builds 3D solid model with Pro/E, then imports the model into ANSYS through interface technology, finally establishes the FEA mechanical model of the elevator link. The stress distribution of elevator link under rated load is achieved by using ANSYS to analyze and calculate. The calculated results can be used to revise the design, improve the specific structural parameters, check and analyze the improved elevator link, thus improve the tensile and bending property of elevator link, provide reliable basis for reasonably designing and retrofitting the ring structure.

Abstract: In this study, we analyzed transverse cracks in rails using eddy current testing. Quantitative analysis was performed on transverse crack defect signals ascertained by actual flaw detection and finite element simulation of the rail that had developed a central transverse crack. The conductivity and width of the finite element model were equivalent to those of the actual rail. By analyzing the distribution of eddy current on the rail surface, the relationship between the variation in the density of eddy current and size of transverse crack was obtained. Experimental and simulation results indicated that the application of eddy current testing in quantitative analysis of a rail flaw was feasible and would be a valuable reference in future research.

Abstract: Multi-parameter description of crack behavior in quasi-brittle materials offers still enough space for investigations. Several studies have been carried out by the authors in this field [1-3]. One part of the publications by the authors (this work included) contain analyses of the accuracy, convergence and/or tuning of the over-deterministic method that enables determination of the coefficients of the higher-order terms in Williams expansion approximating the stress and displacement fields in a cracked body without any complicated FE formulations. These intermediate studies should bring together a list of recommendations how to use the ODM as effectively as possible and obtain reliable enough values of coefficients of the higher-order terms. Thus, the stress/displacement field can be determined precisely even in a larger distance from the crack tip, which is crucial for assessment of the fracture occurring in quasi-brittle materials.

Abstract: In order to reveal the characteristics of surface erosion of transmission line in sand and dust conditions in the northwest of China, an approach of simulating sandstorm flow field and impact on transmission line is proposed. Based on FLUENT model of two phase flow, the velocity flowing around the line and impacting direction between sand and line are analyzed. Simulation results show that the maximum sustained wind speed amounts to 20.9m/s at up and down side of line when the air velocity keeps at 15m/s. The simulation of impacting process based on LS-DYNA shows that the maximum displacements are 0.45×10^-3mm, 4×10^-3mm and 10×10^-3mm and maximum stresses are 0.25Mpa, 7MPa and 16MPa in the three processes which sand size is 0.25mm, 0.50mm and 0.75mm respectively.

Abstract: Coal and gas outbursts are a kind of dynamic phenomena seriously threatening subsurface mining safety in coal mines. A precise prediction of outburst hazard in rock crosscut coal uncovering directly depends on whether or not its prediction index can be accurately determined. Measurement uncertainty reflects the degree of uncertainty of a measured result. In this paper, the authors studied the sources of measurement uncertainty of prediction index K₁ for rock crosscut coal uncovering outburst hazard, built corresponding mathematical model and carried out a great number of laboratory experiments to evaluate the measurement uncertainty of the prediction index K₁ . At a confidence probability of 95%, the expanded uncertainty of the index K₁ is obtained to be 33.3%, far greater than 5% allowed in engineering. To analyze the uncertainty sources, a table of uncertainty components of index K₁ was made, and it’s found through analysis that the mass of desorbed coal sample and the accuracy of pressure sensor are the main factors inducing measurement uncertainty in determination of index K₁ , and corresponding improvement measures were put forward to create conditions for using this index to accurately predict rock crosscut coal uncovering outburst hazard.

Abstract: For the purpose of reducing the drift of the Quartzes Flexible accelerometer outputs in different temperatures, an improved BP algorithm based on GA (Genetic Algorithm) for temperature drift compensation of Quartzes Flexible accelerometer is studied in this paper. Based on the theory analysis and the simulation, the GA model has less training steps and better fitting precision compared with BP Neural Network. The results show that this method on temperature drift compensation of quartz flexible accelerometer has achieved good effect.

Abstract: It is known that the fluctuating structural load is caused by turbulent eddies flowing past or impinging upon the structure in case of turbulence buffeting. The prediction of the response of a structure to turbulence buffeting may be very important. In this paper the buffeting response of square cylinder with constant damping ratio (5%) based on FSI theory proposed by Zhe Liu [6] is simulated. And the movement of bluff body is controlled in the across-flow direction, and two types of inlet boundary conditions are considered to compare the different influence of them on the flow around the square cylinder, one is the steady inlet boundary and the other is the unsteady one.

Abstract: For Ramberg-Osgood elasto-plastic material, under the premise that integration path is limited through the Gaussian integration points, the finite element expressions of the J- integral were deduced in detail. Using the method of coordinate transformation, integration was conducted through the plane rs of the shell element local coordinate system rst (t for shell element thickness direction). The integration points on mid-surface of the shell element were considered. Thus the finite element expressions of the J- integral can be applied to shell elements, the J- integral calculation problem of the shell structure with crack can be solved. A lot of standard sample results comparisons show that the calculation precision of the method proposed in this paper meet the requirements of engineering. Finally, the J- integral of a pressure vessel (a cylindrical shell with a hole and unilateral axial crack) was calculated. The obtained results are recognized by a pressure vessel research institution and referenced in the design. In the conventional finite element calculation, users can, at the same time, obtain the J- integral of the component with crack. So the method in the paper has strong practicability and high engineering application value.