Applied Mechanics and Materials Vols. 444-445

Abstract: This paper focuses on Fluid-structure interaction dynamics for laminated plate\shell topology optimization. Based on ICM method, the filtering function of the element weight, the element mass matrix and the element stiffness matrix are established. Through Fluid-structure interaction boundary element integral formula, and Taylor expansion of Rayleigh quotient which is described by the filter function, the frequency constraint is approximately expressed as an explicit function and the mathematical formulation of the optimal problem refer to weight as objective and subject to multiple frequency constraints. Finally, the topology optimization problem is solved by dual sequence quadratic programming (DSQP). Numerical examples are provided to demonstrate the validity and effectiveness.

Abstract: In this paper, based on the bidirectional B-spline QR method (BB-sQRM), the mechanical properties of the shear-wall with opening were studied. The cubic B-spline function (CB-sF) was used to construct the basis function of the BB-sQRM for its good properties. The new computational scheme of the BB-sQRM for structural analysis was established with quadrilateral element. Numerical example was given to illustrate the validity of the proposed algorithm for the shear-wall with opening. The reliability of the proposed algorithm was verified by comparing with the results of ANSYS. The effects of the opening size on lateral displacement and stress of the shear-wall with opening were discussed. The numerical results show that, square hole and rectangular vertical hole are more conducive to bearing capacity of the shear-wall with opening.

Abstract: The spline finite point method (SFPM) that is based on the classical laminated plate theory is introduced to investigate the natural vibration of smart FGM plate, which is integrated with piezoelectric layers. The spline basic function that meets different boundary conditions is constructed by the generalized parameter method, and a new dynamic computational scheme for smart FGM plate is established to analysis the natural frequency that considering influence of the axial force, which is generated by the electric field. To demonstrate the less computational cost and higher accuracy of the SFPM, several numerical examples are calculated. The effects of the electric field and the influence of the thickness ratio of piezoelectric layer and substrate on the fundamental frequency are also discussed.

Abstract: Grid-stiffened cylindrical shells are widely applied in aviation and aerospace engineering. Bearing capacities of grid-stiffened cylindrical shells will be reduced by local heating. In this study, numerical simulation method is applied to deduce the temperature distribution of the grid-stiffened cylindrical shells subjected to high power laser irradiation. Temperature dependent aluminum alloy properties are fully considered in the process of numerical simulation. Comparing to smooth thin-wall cylindrical shells, the effect of ribs size to temperature distribution is studied. As the material properties varying with temperature, the temperature rising rate is higher at the initial period when cylindrical shell is subjected to laser irradiation. The temperature rising rate gradually reduces with irradiation time increasing. Buckling analysis was performed to obtain the buckling bearing capacity and the effect of local heating on grid-stiffened cylindrical shells subjected to local heating.

Abstract: The extended finite element method (XFEM) allows the entire crack to be represented independently from the mesh, which means re-mesh is unnecessary in model crack growth, reduces the computational time drastically. However, fatigue crack growth simulation has been computationally challenged by lots of analog computations in crack growth. Therefore, a new reanalysis algorithm based on incremental Cholesky factorization is derived. In this paper, we consider a variant of XFEM in which an exponent discontinuous function is used to simulate the crack through unit. Then the corresponding formula of XFEM with inclusion and crack problem with a new reanalysis algorithm is derived. In the end, we use the new reanalysis algorithm and an optimization algorithm to predict the angle of crack initiation from a hole in a plate with inclusion. It shows that the algorithm is effective.

Abstract: Convex meshfree approximation with non-negative shape functions yields strict positive mass matrix and is particularly favorable for dynamic analysis. In this work, a kernel-enriched quadratic convex meshfree formulation with adjustable local approximation feature is presented. This formulation is built upon the generalized meshfree approximation with a relaxed quadratic reproducing condition. The resulting shape functions of the kernel-enriched quadratic convex meshfree formulation are presented in detail. The convergence behaviors for both static and vibration problems are discussed. Numerical results show that better accuracy can be achieved with the present formulation.

Abstract: Bolted connection technology has been widely used in steel structure engineering. Conventional structural analysis softwares solve related problems with the assumption of regarding the bolted connection as a rigid joint connection. Thus the calculated internal forces of the structure members are bigger than those of real measurements, and the calculated displacement are smaller than the experimental ones under the same load. One of the main reasons is the bolt slippage. In the lattice structure, there are a large number of bolted connections with thin connection members and small-diameter bolts, however, their clamping forces are relatively small. These characteristics have significant effects on the static response of the lattice structure. In this paper, in comparison with the test results, the deformation-load curves of the bolt connections are introduced into the finite element simulation, revealing the effect of bolt slippage on the static response of lattice structure. The simulation and test results show that the bolt slippage causes the redistribution of the member internal forces of the lattice structure and increases the displacement of the lattice structure,thus the simulation results with bolt slippage are more close to the real values. The proposed algorithm and simulation results would provid good reference for further engineering applications.

Abstract: The extended finite element method (X-FEM) is reviewed and some new developments for fracture analysis of structures is presented. The X-FEM is an extension to the classical finite element method (FEM), using the concepts of partition of unity and meshless approaches. It is specifically designed to improve the performance of the conventional finite element method, while keeping the computational costs at an acceptable level, and avoiding the cumbersome remeshing of FEM in crack propagation problems. The simplicity, flexibility in handling several cracks and crack propagation patterns on a fixed mesh, and the level of accuracy with minimum additional degrees of freedom have transformed X-FEM into the most efficient numerical procedure in the arena of computational fracture mechanics.

Abstract: As a new type of composite material, particle reinforced composite materials, which has good mechanical properties and secondary machining, have been widely used in mechanical, biological, aerospace, military, motor and other important industrial areas. With the development of science and technology lots of research and numerical simulation have been carried on at home and aboard. Because of the reinforcements, the overall mechanical properties have been significantly improved. At the same time, fracture properties and fatigue characteristics are lower. This paper, based on the VCFEM, lead in the traditional FEM to research particle reinforced composite materials, tending to get a better result in simulating the mechanical property. The principle of the voronoi unit Based on the particle composites as the research object, combine four node isoparametric element with the voronoi cell mesh together to complete the structure calculation.to make the description of the distribution of high stress of the interface of inclusion particles more accurate. As we know that due to the reinforcement, the original features of the material have changed. To a certain extent, reduce its applicability. The interface layer is the important reason of the damage. As Fig1-1, Contact interface between particle and matrix cracking cracks. This makes a third crack boundary. means crack boundary, means inclusion particles, crack boundary, means substrate crack boundary, so we can find that at it still satisfy: (1) Fig 1 Containing inclusions, consider interface debonded voronoi cell At and because of the cracking, the two boundaries have no restraint, so satisfy the following boundary conditions (on border) (2) (on border) (3)

Abstract: This paper presents the series solutions in Hamiltonian form for plane sectorial domain of the nonlocal linear elasticity originally proposed by Eringen [. Based on the Hamiltonian governing equations of plane elasticity for sectorial domain, the variable separation and eigenfunction expansion techniques were employed to obtain these solutions. These solutions can be used to develop a nonlocal analytical finite element for the model I crack in nonlocal fracture mechanics.