Applied Mechanics and Materials Vol. 778

Abstract: Based on the study of a car exhaust system, use HyperMesh Software and its build-in finite element software to build FEM , Analysis the free modal of exhaust system, Calculate its natural frequency, Then optimize the position of hook based on the ways of average degrees of freedom (ADDOFD), Makes its modal frequencies avoiding engine idling frequency. Finally, through the calculated constraint mode, Verify whether coupling with the excitation frequency of engine, and further verify the reasonableness of the position of the hook.

Abstract: Using the method of complex analysis, the paper investigates the plane elasticity problem of circular orifices with four-cracks through conformal mapping, and provides an exact analytical solution for the crack-tip stress intensity factor (SIF). From this we have simulated circular orifices with three-cracks, symmetrical four-cracks, asymmetrical collinear double-cracks, and symmetrical collinear double-cracks; as well as the crack problems of asymmetrical cross-shaped cracks, symmetrical cross-shaped cracks, and T-shaped cracks.

Abstract: Aluminum honeycomb is a lightweight material with high strength and strong capacity of energy absorption. In order to research energy absorption characteristic of aluminum honeycomb material, quasi-static and dynamic out-of-plane compression experiments are carried out on a double-layer aluminum honeycomb impact attenuator of one FSAE racing car. Plateau stress (PS), specific load (SL), mass specific energy absorption (MSEA), volume specific energy absorption (VSEA) and other parameters of the tested aluminum honeycomb under both quasi-static and dynamic impact conditions are analyzed. The results show that the tested aluminum honeycomb impact attenuator has good energy absorption capacity to meet the collision requirements. Furthermore, under the condition of dynamic impact, the energy absorption capacity of this honeycomb improves compared with that under the condition of quasi static compression.

Abstract: The free vibration along with the vertical direction of the symmetric double spring –mass system has been studied with experimental method. It is discovered that when the distance between two suspending points is not zero, the vibration of symmetrical double spring mass system along the vertical direction is nonlinear. The period of the system increases with the increase of the amplitude and distance of suspending points. The equivalent mass coefficient of the system vibrating nonlinearly is greater than that of the system vibrating harmonically and is related to inclination degree and relative elongation of the spring.

Abstract: Lathe bed is one of the important parts of machine tool, and its performance will affect the final machining accuracy of the machine tool directly. A numerical control lathe produced by a machine tool plant was taken as the research object, the finite element analysis and optimization method of the Lathe bed were studied. First of all, the external load of the bed was analyzed, static performance finite element analysis of the bed was implemented, and the corresponding analysis results were obtained. Then, the evaluation methods were discussed, and the deformations of junction areas were studied. At the same time, its effect on the performance of machine tool could also be analyzed. Based on the topology optimization method, the conceptual model of Lathe bed could be acquired, and also the rationality of the existing machine tool structure was discussed. The finite element analysis and optimization method of Lathe bed were concluded, which are helpful to obtain the static characteristics of the Lathe bed accurately. Moreover, there is an important practical significance to design the Lathe bed reasonably and to promote the machine tools comprehensive performance.

Abstract: A finite element model for the frame structure of mini-battery electric vehicle (mini-BEV) is established. The stress distributions of frame structure are calculated under three typical conditions. On this basis, the lightweight design of frame structure is presented, and then the new modified frame is carried out to take static analysis to validate the improvement program results show that the improved scheme is desirable.

Abstract: In this paper, based on the numerical simulation with RNG k-ε model by using commercial code of FLUENT, the effects of the structure size of the shell and tube heat exchanger, such as the baffle spacing and the gap height of baffle plate, on the pressure drop, the heat transfer coefficient and j-f Factor were investigated to obtain the relationship between the baffle spacing and the gap height of baffle plate using the same thermophysical conditions. The numerical simulation results exhibited that there was a non-monotonic relationship between the baffle spacing and the gap height of baffle plate. A better heat transfer performance could be observed under the condition of a smaller value of the baffle spacing and a higher value of the ratio of the gap height to the actual section, or under the condition of a higher value of the baffle spacing and a smaller value of the ratio of the gap height to the actual section. Moreover, under the optimum geometrical condition, the numerical simulation results showed that a smaller difference between the inlet section length and the baffle spacing could give a higher j-f Factor and a better heat transfer performance.

Abstract: MSC.Nastran is the popular large finite element structural analysis software. In order to combine the advantages of MSC.Nastran software and high-performance computers, the second development of the finite element software MSC.Nastran based on parallel computers is researched in this paper. This can improve MSC.Nastran application and calculating efficiency, finally a practical example is given to verify its correctness and efficiency.

Abstract: In this study, the hydraulic cylinder with internal non-slip safety locking device was designed and analyzed. From the market demand and fail-safety requirement, the hydraulic cylinder prototype specifications are developed. The dimensions and mechanisms of hydraulic cylinder model were initially designed to make sure parts combination as requirement. The stress and deformation of designed model with material properties were analyzed by Solidwork COSMOS module. The finite element analysis results showed that the clamp clip cutting seams help to uniform rod and clamp clip stress distribution. The bottom end and front end of the clamp clip with 16 cuttings have the best results in terms of stress and deformation. But the bottom end and front end of the clamp clip with 8 cuttings for rod holding effect would be better for reducing machining costs and increase durability. The stress concentration phenomenon of cut clip end can be rounded treatment; in order to reduce stress is too large in clip end.