Applied Mechanics and Materials Vol. 137

Abstract: In this paper, the micromechanical finite element method based on Representative Volume Element has been applied to study and analyze the macro mechanical properties of the carbon black filled rubber composites by using two-dimensional plane stress simulations and three-dimensional axisymmetric simulations under uniaxial compression respectively. The dependence of the macroscopic stress-strain behavior and the effective elastic modulus of the composites, on particle shape, particle area/volume fraction and particle stiffness has been investigated and discussed. Additionally, the simulation results of the two-dimensional plane stress model and the three-dimensional axisymmetric model are evaluated and compared with the experimental data, which shows that the two-dimensional plane stress simulations generate poor predictions on the mechanical behavior of the carbon black particle reinforced rubber composites, while the three-dimensional axisymmetric simulations appear to give a better prediction.

Abstract: The annual occurrence of hip fracture increases very rapidly, which cause a heavy public health burden. From a biomechanical perspective, hip fractures are thought to be caused by different directions of load. Fifteen different load conditions were studied here to simulate various falling configurations, the directions of which were defined by angle γ, δ. The purpose of the current study was to clarify the influence of load direction on strength and fracture site of the proximal femur using FE method to determine the load direction under which the proximal femur is most vulnerable to fracture.

Abstract: Temperature field and stress field of a concrete slab in a ship lock chamber are calculated, considering the influence of layered casting. And the influence of water pipe cooling at the early period of constructing, and at the period after constructing, sunshade, pre-cooled concrete etc are taken into account. The expression of finite difference method considering the effect of water pipe cooling is deducted for temperature analysis. Thermal stress calculation results show that the water pipe cooling at the mid-late period is a comparatively effective measure to reduce tensile stress of chamber mass concrete. And an effective temperature control measure is recommended in summer casting, which is that: sunshade + pre-cooled concrete + water pipe cooling (both at early period and at mid-late period). Mid-late period water pipe cooling must last for three months. Combined with other temperature control measures such as summer cover maintenance, winter cover preservation etc, the concrete cracks can be reduced, and the occurrence of large area run through cracks can be avoided.

Abstract: Based on Melan’s theorem, an improved numerical solution procedure for evaluating shakedown loads by non-linear superposition method is presented, and the relationship between the classical non-linear programming formulation of shakedown problem and the numerical method is disclosed. The stress term in classical optimization problem is replaced by the element bearing-ratio (EBR) in the procedure, and series of residual EBR fields can be generated by the D-value of the elastic-plastic EBR fields and the elastic EBR fields at every incremental loading step. The shakedown load is determined by performing the incremental non-linear static analysis when the yield criterion is arrived either by the elastic-plastic EBR fields or residual EBR fields. By introducing the EBR, the proposed procedure can be easily used to those complex structures with multi-material and complicated configuration. The procedure is described in detail and some numerical results, that show the efficiency and effectiveness of the proposed method, are reported and discussed.

Abstract: The study obtains the parameters of the formula of pressure caused by cylindrical charge’s explosive shock wave through experiments in a pool firstly. Through testing cylindrical charge exploding in concrete specimen, the study then gets blasting strain wave’s propagation law and formula’s parameter of exploding cylindrical charge in concrete specimen.

Abstract: This paper investigates the failure modes of serially connected isolation system that the rubber bearing connected with the basement column, under large deformation. Base on Haringx theory and Timoshenko beam modal, the geometrically non-linear equations of serially connected isolation system with one end clamped and the other glided, subjected to a terminal force, are formulated. By using differential quadrature element method (DQEM), the non-linear equations are solved numerically and the configurations of the deformed column are presented. The results show that the large deformation of serially connected isolation system mainly occurred in the rubber bearings. The buckling of rubber bearing is the main failure mode of the serially connected isolated system.

Abstract: Base on the principle of nonlinear calculation, the mechanical models and the method of models experiment, we have provided a numerical analysis method of fitting hyper-elastic material constitutive relations. The method educed material spacial constitutive relations expressed by tensor through strain energy theory. After that, deduced material uniaxis constitutive models and use BP neural network to fit coefficients. Constitutive relations are the base of material deformation research. However we just paid attention to deformation experimental result before, rather than theoretical analysis. The theoretical analysis method this paper researching is convenient and precise and scientific, so it has theoretical meaning and practical value.

Abstract: Defects like surface crack often appear in steel structures. To ensure the structural integrity and security, the new material such as fiber reinforced polymer (FRP) was adopted for strengthening and repairing. In this paper, three dimensional semi-elliptic surface crack in steel tension specimen strengthened with carbon fiber laminate (CFL) was studied, and numerical analysis was undertaken by Abaqus finite element software to study the stress intensity factor (SIF, KI) of the surface crack for CFL reinforcement effect. The results showed that, strengthening effect of CFL in front side was better than the back side of the steel plate; Crack shape ratio, a/c, had greater influence on strengthening effect in front side compared with little effect in the back side; The changes of crack relative depth, a/B, affected strengthening effect.

Abstract: The motion performance of Spar platform and dynamic characteristics for the mooring lines under different mooring configurations have been studied both in static analysis and coupled dynamic analysis. First, 3D hydrodynamic finite element model is built and the effects of the mooring system are taken into account by giving the specified pre-tension, angle and stiffness of the mooring lines on the fairleads. And hydrodynamic analysis of Spar platform is performed by the way of utilizing potential flow theory in frequency domain in order to calculate the hydrodynamic coefficients. Then, static analysis is applied to obtain restoring stiffness curves for the mooring system, structure displacements and mooring line tensions etc.. At last, coupled time domain analysis of the motion response of Spar is conducted for the coupled system and the dynamic tensions of mooring lines are calculated. The research results can be served as a reference for the selection and the performance study for mooring systems during preliminary design.