Applied Mechanics and Materials Vols. 166-169

Abstract: The distinctive paper is devoted to correct wavelet-based multilevel numerical method of local solution of boundary problems of structural analysis. Operational and variational formulations of the problem (particularly with the use of wavelet basis) are presented. Computer-oriented algorithms of fast direct and inverse discrete Haar transforms are described. Due to special algorithms of averaging within multigrid approach, reduction of the problem is provided.

Abstract: In order to reduce seismic responses of structures, low-yield point steel has been used for dampers due to its excellent energy dissipation capacity. However, few researches about the low-yield point steel dampers have been conducted in China so far. This paper mainly presents an experimental study on two buckling-restrained braces (BRBs) which take an in-line steel plate as the core and a double-web wide flange steel member as the outer unit. Low-yield point steel LY100 is taken as the core material and conventional steel SN400 is taken as the outer material. Uniaxial cyclic loading tests of two low-yield point steel BRBs (LYS-BRB) were conducted to investigate their hysteretic behavior and energy dissipation capacity. The two LYS-BRBs yielded at rather small displacement and their accumulated plastic deformation ratios reached 1639 and 1437, respectively. Significant strain-hardening behavior can be observed in the hysteresis curves of LYS-BRBs and the maximum cyclic stress reached 3.85 times the yield stress.

Abstract: A technique to assemble global stiffness matrix stored in sparse storage format and two parallel solvers for sparse linear systems based on FEM are presented. The assembly method uses a data structure named associated node at intermediate stages to finally arrive at the Compressed Sparse Row (CSR) format. The associated nodes record the information about the connection of nodes in the mesh. The technique can reduce large memory because it only stores the nonzero elements of the global stiffness matrix. This method is simple and effective. The solvers are Restarted GMRES iterative solvers with Jacobi and sparse appropriate inverse (SPAI) preconditioning, respectively. Some numerical experiments show that the both preconditioners can improve the convergence of the iterative method, and SPAI is more powerful than Jacobi in the sence of reducing the number of iterations and parallel efficiency. Both of the two solvers can be used to solve large sparse linear system.

Abstract: The fundamental frame units were taken from the multi-ribbed composite wallboard. 1/2 scale model specimens including bare frame (FD Series) and infilled frame (IFD Series) were loaded in the diagonal direction. By changing the section size of a frame beam and column, the mechanical properties of multi-frames under vertical and horizontal loads were studied. Through comparing and analyses, contributions and interaction between frame and infilled block were investigated. The results show that the frame section stiffness influences the mechanical properties remarkably and the interaction between frame and infill is significant.

Abstract: In order to find the cause of the cracked intermediate axis in a transmission,the characteristic of the bending vibration，torsional vibration and bending-torsional coupling vibration were studied through the analysis of the nature frequency and modal shape based on prestress.The results show that the fatigue fracture of the axis is mainly due to the resonant torsional frequency and bending-torsional coupling vibration and It is basically demonstrated by experiment.It has been found that the fundamental frequency is increase with the increase in spin axis velocity because of the centrifugal load i.e.prestress.The effets can be accounted for by an adjustment of the stiffness,and the dynamic equations are derived.In the end,it is made the optimized design on the axis,the low inherent frequencies are optimized in order to avoid resonance.The problem of the cracked intermediate axis has been solved.

Abstract: This article analyzes five concrete-filled double steel tubular column models based on the large finite element analysis software ABAQUS. An axial compression test was carried out on specimens with different diameter-thickness ratio of internal steel tube in order to get the whole longitudinal load-displacement curves and the whole load- strain curves for internal and external steel tube and concrete. We get the ultimate bearing capacity for five specimens, the result of simulation agree well with the theoretical calculation data, that provide reliable data for concrete-filled double steel tubular column in respect of finite element (FE) simulation.

Abstract: As m value is not an inherent property of soil and affected by many factors, limited to the current level of theorey and technology, m value of soil around each pile can not be accurately taken when using “m” method to simulate the pile-soil interaction in engineering. In this paper, finite element software is used for the systematic study on the influence of m value to internal force and deformation for transverse bent of high-piled wharf. By analysis, it is considered that the influence is little and can meet the project accuracy requirements when taking m value through experience.

Abstract: This investigation provides a hybrid Trefftz finite element approach for analysing orthotropic potential problem. For verification purpose, two examples are numerically investigated.

Abstract: There is the long periodicity attitude error between true attitude and measurement attitude using star sensor for spacecraft attitude determination system because of aberration of light. Aberration of light occurs because the spacecraft’s velocity has a component that is perpendicular to the line traveled by the light incoming from the star. The type of aberration is analyzed and their constants of aberration are calculated in this paper. According to the constants the aberration, the correction mathematical models of parallax of aberration of light of these types of aberration are derived. The parallax of aberration of light of the recognized stars in the FOV of star sensor is calculated with the mathematical models. Then the true vectors of recognized stars at image space coordinate system of star sensor are calculated. The measurement attitude of star sensor is calculated with the true vectors of recognized stars and their vectors at celestial sphere coordinate system. The simulations show the long periodicity attitude error is corrected with the method in this paper. At last the correction of aberration of light was successfully demonstrated using two star sensors with real sky experiment in 2011.

Abstract: A widely used organic polymer textile material, which is made of polyester fibers and then cured in the resin afterwards to fix the original pattern of the textile, is used to study the flaw’s influence in the mechanical properties as well as its influence in the failure behavior of the textile. This kind of textile is preferably applied and acts as the re-enforcement part or component in the composite design or composite manufacturing. To mathematically and theoretically analyze the relationship between the mechanical behavior of the polyester textile and the flaw within the material, a model based on the fracture mechanics is proposed to explain the experimental results from the mechanical tests of polyester textile specimens.