Abstract: A comparative study of the girder damage identification of Jintang Cable-stayed Bridge in Zhoushan Island-Land Project using the deflection index, the cable tension index, the beam bottom bending stress index, the modal curvature index and the modal flexibility matrix is introduced. By means of finite element method, a series of damage cases associated with the box girder are analyzed. The result shows that, for different damage types, the best effect of the girder damage identification is the modal curvature index, followed by the cable tension index, the beam bottom bending stress index is nearly of the same effect as the modal flexibility matrix index, and the worst is the deflection index.
Abstract: This paper proposes to model cushioning materials by combining hyperbolic tangent function and tangent function together. Based on the proposed model, the kinetics equations for cushion packaging system under excitation of half-sine acceleration pulse shock have been derived, where the rotation due to product’s eccentricity in center of mass has been taken into account. The law for coupling between rotation and translation is discussed. Numerical analysis shows that it may lead to a certain degree’s excessive packaging and thus causes waste if the rotation effect is not considered in design. The proposed model and the established kinetics equations with consideration of coupling between translation and rotation provide much better description regarding the characteristics of practical cushion packaging systems, and thus can be taken as reference in design optimization for packaging structure. The proposed approach can also be directly applied in analyzing the shock responses of packaging systems with multiple degrees of freedom.
Abstract: One of necessary prerequisites to design cushioned package is the determination of product shock fragility, which is so far obtained by means of destructive method on shock testing machines. This paper presents a non-destructive method--power flow method to predict the product fragility. The transport package system was first divided into two subsystems to simplify analysis. The energy of critical component of the product was then calculated by applying a power flow equilibrium equation. And finally, the parameters of the transport package system, such as the input power, the internal loss factor and the coupling loss factor, were discussed.
Abstract: In order to obtain simple formulae of cable dynamic behavior for numerical computation, the Chebyshev series method for the free vibration analysis of a cable considering boundary condition and flexural stiffness is utilized. The differential eigenvalue problem is reduced to an algebraic system which gives approximate eigenfrequencies and mode shape functions for a cable. These simple and approximate formulae are of value in the analysis of cable dynamic response and may be proved useful in the design of cable structures. The proposed approach is applicable to a wide range of cables.
Abstract: In order to meet the requirements of research on steer-by-wire force feedback, a MRF- damper-based experimental system was developed. In the paper, the necessity of the experimental system was analyzed, the general structure and hardware components were introduced. The design of the rotary MRF dampers was illuminated in detail. Experiments showed that the MRF-damper-based haptic system can be used for the study of automobile steer-by-wire system.
Abstract: This paper first establishes the model for a 2-DOF non-linear cushion packaging system with strong hysteresis and then derives its vibration equations. The vibration equations are transformed into ones using dimensionless variables and parameters. The influence of mass ratio and stiffness ratio on the system under excitation of trapezoidal pulse shock has been analyzed based on the response spectra obtained by applying the fourth order Runge-Kuntta method to the transformed equations. Results show that the mass ratio is the key design parameter.
Abstract: In this paper, the structure similar to the connection of two connecting rods of human elbow joints is proposed to construct coordinates of connecting rods and the transformation matrix of pose. Lagrange’s equation is used to build dynamic equations including the feature of dynamic equations of musculotendon. Simulation results show that the proposed model is effective and reasonable.
Abstract: In this paper, the Poisson problem with homogeneous Dirichlet boundary conditions on the bounded open domain is considered and the superconvergence property of 3D tensor-product block finite elements is analyzed by using a computer-based test.