Applied Mechanics and Materials Vols. 117-119

Abstract: The finite element modeling methods of a passenger car exhaust system’s flexible parts are introduced. A finite element (FE) model of the exhaust system is established with the finite element software and modal analysis of the FE Model is carried out. Through changing both automotive exhaust hangers’ Z direction of stiffness and bellows’ each direction of stiffness, the data of natural frequencies and vibrating modes of the exhaust system were obtained respectively. Comparing and analyzing the results indicates how the stiffness of exhaust hangers and bellows influences the modal of passenger cars’ exhaust system.

Abstract: While hydraulic retarder installed on the transmission shaft, both ends of rotating shaft and transmission shaft are directly connected. It needs bracket to be fixed on the automobile frame, deformation of the bracket directly influenced the normal work and life span of the hydraulic retarder. So we must pay more attention to the strength of the bracket during our design. This paper obtained the stress state and the structural deformation situation under different structures, and confirmed the dangerous parts of the bracket by designing two different projects of the bracket and using ANSYS software to analyze the finite elements. It also provided a theoretic basis for further structure optimization and could be a reference for the similar product design.

Abstract: Three-dimensional finite element analysis should be used in stability analysis of slope because it can overcome the short advantages of two-dimensional finite element and can simulate the complex topographic and geological conditions. Based on the large-scale triaxial shear test, the modified Duncan-Chang model is established. Based on strength reduction elasto-plastic finite element, stability of high fill embankment was studied with three-dimensional finite element method considering the complex terrain conditions. Study results suggest that plastic strain and displacement mutant of slip surface node can be a sign of slope instability as a whole. At the same time calculation of three-dimensional finite element also does not converge. Therefore, it can be slope instability criterion calculate whether the finite element static analysis converges or not. On the other hand, stability safety factor of high fill embankment under three-dimensional conditions is larger than that of two-dimensional conditions, which shows that boundary conditions of high fill embankment enhance its stability.

Abstract: Through the method of three-dimensional analytical photography, the paper acquired and analyzed the kinematical parameters of movement of the technology of overhead smash in badminton and tennis for the purpose of pointing out the kinematical characteristics of the technology. The study shows: while hitting the ball and springing off the ground, the way of using force begins at the top and in the order of thigh, lower leg and feet; during the whole hitting process, shoulder, elbow and wrist are basically at the same moving speed with the peak of angular velocity appearing first from the shoulder, and the time for the elbow and the wrist appearing almost in a synchronous manner.

Abstract: Hydrostatic testing is an important step in pipeline construction. This test ensures the integrity of newly-constructed pipelines. Testing pressures used by Chinese construction contractors are lower than that in foreign countries. Nowadays, higher testing pressure is considered safer for pipeline operation. But what is testing pressure we should apply Basing on fracture mechanics theory, this paper addresses the effects of testing pressure on pipeline materials, and calculates the maximum safe testing pressure. Also, experiments validate the theoretic conclusions.

Abstract: The letter focuses on studying Noether symmetry and conserved quantity of discrete nonconservative and nonholonomic Hamiltonian system. Firstly, the discrete Hamiltonian canonical equations and discrete energy equations of nonconservative and nonholonomic Hamiltonian systems are derived with discrete Hamiltonian action. Secondly, based on the quasi-invariance of discrete Hamiltonian action and equation of lattice under the infinitesimal transformation with respect to time, generalized coordinates and generalized momentums, the discrete analogue of Noether’s identity and determining equation of lattice are obtained for the systems. Thirdly, the discrete analogues of Noether’s theorems and conserved quantities of the systems are presented. Finally, one example is discussed to illustrate the application of the results.

Abstract: In this paper, asymmetric twin tower high buildings with large bases were studied and the FEM model of asymmetric twin tower high building with large bases was established. Then the structural dynamic characteristics was analyzed, the x-direction and y-direction level seismic excitation were input separately with the help of time-domain analysis method, and the acceleration time-domain curve of the top of the structure was obtained, the reference of structural design was provided.

Abstract: Abstract: Based on the Miner′s linear accumulative damage theory and the low cycle fatigue damage parameter that is relative to the total strain amplitude and the mean stress of the plastic zone near crack tip, a new numerical simulation method to predict the fatigue crack growth (FCG) of materials is presented. The numerical FCG results for middle-cracked tension (MT) specimens of Cr2Ni2MoV steel, TA12 and TC4 alloys by ANSYS are closed to those by tests. Therefore, the new method has capability to give good FCG prediction accuracy for different materials. Furthermore, the Paris FCG models of TA17 and TC11 alloys were predicted by this method and can be referred to the key engineerings.

Abstract: High strength concrete consisting of binary and ternary blended cementitious systems based on ordinary Portland cement, pulverised fuel ash and silica fume were investigated for carbonation. PFA up to 40% was used and to these blends 0, 5, 10, and 15% SF was incorporated as partial cement replacement. Results of carbonation of concrete cured in mist and air are reported. It was found that carbonation linearly increases with an increase in PFA content. Concrete with OPC only and concrete with 10% SF content showed insignificant change in carbonation when comparing air cured and mist cured concrete. The maximum carbonation depth observed for air cured concrete (containing 40% PFA) was less than 4 mm while in the case of mist cured concrete it was less than 2 mm. This depth is still far less than the cover of reinforced steel bars to cause corrosion.

Abstract: By using the high purity Cu samples as the study objects and based on the experimental measurement results of the interface thermal resistance, the study on the relations between the interface thermal resistance, the laser modulation frequency and the phase lag under different temperatures has been carried out through the Matlab numerical simulation. It is shown that the corresponding phase lag is increasingly bigger but the interface thermal resistance is increasingly smaller while the interface temperature become higher at a certain pressure; furthermore, the study on relation between the interface thermal resistance and the temperature variation has been carried out and it may be concluded based on the analysis that the interface thermal resistance changes remarkably while the temperature scope is from 20K to 60K and the interface thermal resistance varies slightly while the temperature scope is from 60K to 120K.