Applied Mechanics and Materials Vols. 94-96

Abstract: Brief development process of the finite element method, foundation of quasi-conforming element has been analyzed from weak formulation generalized compatibility equations and its weak continuity condition in this paper. The quasi-conforming element methods are the exact solution of generalized compatibility equations and satisfy the weak continuity requirement naturally. The quasi-conforming element methods do not satisfy stress equilibrium conditions and concision calculating process of matrix’s athwart. The discrete precision can be predicted in prior. It also extends space of original finite element method and is landmark in computational mechanics.

Abstract: Extended finite element method (XFEM) has been applied to the crack propagation problems. A standard displacement-base approximation is enriched near a crack by incorporating both a discontinuous field and the near crack front asymptotic fields through a partition of unity method. This technique allows the entire crack to be represented independently of the mesh, so remeshing is not necessary to model crack growth. Applications of the proposed technique to beam subjected to three-point bending have been presented, results shown the location of the crack imposes important effect on the crack propagation direction.

Abstract: In this paper, with the ANSYS, stress distribution and safety factor of crankshaft were analyzed by using 3D finite element method. The results show that the exposed destructive position is the transition circular bead location of the crank web and the crankpin. Maximum stress is 121 MPa. Safety factor is 3.12. Maximum deformation is 0.0719 mm. Crankshaft satisfies the design requirement.

Abstract: In this paper, the aerodynamic effects of high-speed train passing in tunnels are investigated in numerical calculation method of hydromechanics. According to the actual situation of flow filed when the train through the tunnel, the flow geometry model is set up. The flow problem is described by Navier-Stokes equations of unsteady viscous compressible fluid and k-e two equations turbulent model. Thereby the aerodynamic effects of the train through the tunnel are analyzed comprehensively. The changes of the air pressure in tunnel caused by high-speed train entering into the tunnel are mainly analyzed. In addition, the mechanical characteristics of carriages when two train in the tunnel passing through each other are analyzed.

Abstract: In this paper, a general finite strip is developed for the static and vibration analyses of folded plate structures. The geometric constraints of the folded plates, such as the conditions at the end and intermediate supports, are modelled by very stiff translational and rotational springs as appropriate. The complete Fourier series including the constant term are chosen as the longitudinal approximating functions for each of the displacements. As these displacement functions are more general in nature and independent of one another, they are capable of giving more accurate solutions. The potential problem of ill-conditioned matrices is investigated and the appropriate choice of the very stiff springs is also suggested. The formulation is done in such a way to obtain a unified approach, taking full advantage of the power of modern computers. A few numerical examples are presented for comparison with numerical results from published solutions or solutions obtained from the finite element method. The results show that this kind of strips is versatile, efficient and accurate for the static and vibration analyses of folded plates.

Abstract: Experiments have been performed to observe the kinematics of multi-droplet moving in a stationary emulsion exposed to a horizontal electric field of different magnitude. The droplet motion is recorded by a high-speed CCD camera. A Lagrangian framework is outlined to simulate the kinematics of multi-droplet by means of cluster integration method. The droplet size distributions computed are qualitatively consistent with the experimental picture. It is clarified from computation that the effect of the electric field intensity and the viscosity of the oil on the droplet motion. Experiments have been performed to observe the kinematics of multi-droplet moving in a stationary emulsion exposed to a horizontal electric field of different magnitude. The droplet motion is recorded by a high-speed CCD camera. A Lagrangian framework is outlined to simulate the kinematics of multi-droplet by means of cluster integration method. The droplet size distributions computed are qualitatively consistent with the experimental picture. It is clarified from computation that the effect of the electric field intensity and the viscosity of the oil on the droplet motion.

Abstract: The Lagrangian analysis method is re-analyzed. It is shown that when a series of stress profiles (or strain profiles, or particle velocity profiles) are measured to determine the strain-stress relation. In this paper, the stress histories at different Lagrange positions are measured by one dimensional SHPB experiments. The variation histories of various physical quantities are fitted to least square cubic B-spline function with a sufficient accuracy definite condition. The path lines of these quantities are constructed in terms of a least square quadratic polynomial. A program for inert flow of Lagrangian analysis (IFLA) is worked out. Taking the data of experiments as the input for the IFLA, the flow field information is solved. The error analysis shows that such a method has a definite reliability and stability.

Abstract: Considering strongly nonlinear characteristic of iced conductor rotating around its center of mass in the wind-deviation plane, two dynamic equations are constructed by using Den. Hartog criterion and O. Nigol criterion, and galloping characteristics between them are studied, which can provide references for constructing correct iced conductor galloping models. By comparative analysis of two models, the vibration frequency of O. Nigol model is slightly higher than that of Den. Hartog model, and the amplitude of O. Nigol model is smaller. Then the stability of iced conductor galloping and the effects of parameters on galloping amplitude are discussed, from which can conclude that the trends of two models varying with parameters are basically identical. But for numerical, O. Nigol model is more accurate.

Abstract: Thin-walled cylinder, circumferential crack, pure bending, J-integral, stress intensity factor

Abstract: In this paper, a new approach is proposed and addressed for designing vehicle suspension systems based on the scheme of multi-objective programming. For complicated vehicle random vibration, a linear model is used to describe the dynamic behavior of vehicles running on randomly profiled roads. The road irregularity is regarded as a Gaussian random process. Pesudo excitation method has been used to solve the dynamic responses. And a Kriging model is introduced to build the approximate mapping relationship between the design variables and the responses. Optimal solutions are derived by means of the method of centers for structural optimization with multiple objectives. Numerical examples are given, and compared with other optimization methods.