Volume 4, Issue 2

Experimental studies were made on isotropic cylindrical panels made of Aluminum 7075-T6 under uniaxial compression. The experimental values of the critical buckling load were determined using four different methods. The critical buckling load was also determined using MSC/NASTRAN and CQUAD8 finite element. The experimental values of the critical buckling load obtained by different methods were compared with the finite element solution. The effects of the panel angle, panel length and panel thickness on the critical buckling load of isotropic cylindrical panels made of Aluminum 7075-T6 were studied. It is found that the Method III (based on a plot of applied load versus average axial strain) yields the highest value for critical buckling load and Method II (based on a plot of applied load versus square of out-of-planede deflection) the lowest value for critical buckling load. The experimental values given by Method III are seen to be closest to the finite element solution. Critical buckling load increases monotonically as panel angle increases.

This paper addresses a linearization technique for a linearizable nonlinear SDOF system based on block pulse (BP) transform. BP transform method is a useful tool for giving a solution of difference equations with less computational costs. The main goal of this work is on reducing the costs of linearizing computation. It is necessary to compare the results obtained using this method with other traditional methods to verify the effectiveness of the proposed method. Therefore, the efficiency of BP transform method is compared with the traditional equivalent linearization (EL) method, used to linearize nonlinear systems. Two numerical simulations are applied to the Duffing oscillator system to demonstrate the feasibility of the proposed method based on BP transform. Finally, the results of comparison between existing approaches that have applied to the considered problem depicted the proposed method base on orthogonal functions is able to approximate the nonlinear system’s behavior and shows the superiority of the proposed approach in the sense that it is more accurate by computational advantageous.

Vehicle crash-can transfers the kinetic energy into strain energy stored in the structure via a sequential deformation wall crushing process. The performance of the crash can FEA model and its ability of predicting mechanical behaviours in a crash event is assessed and verified via the FEA analysis and corresponding experiment data. Compression tests are performed to validate the FEA simulation results. Wall tolerance sensitivity is also investigated via FEA simulation in order to examine if and how the manufacturing defect could impose impact on crash can energy absorption capability. It is found that the performance of crash-can with manufacturing tolerances can be predicted by the FEA model derived in this paper. Internal energy analysis indicates the wall thickness is tolerance insensitive and manufacturing defect can be disregarded under the manufacturing tolerance standards.

The delamination growth may occur in delaminated piezoelectric shell subjected to external dynamic load and it will further cause structural failure. Based on the variational principle of moving boundary and considering the contact effect between delamination regions, in this paper, the nonlinear governing equations for the delaminated piezoelectric shell under hygrothermal condition are derived, and the corresponding boundary and matching conditions are given. At the same time, according to the Griffith criterion, the formulas of energy release rate along the delamination front are obtained and the delamination growth is studied. In the numerical calculation, the energy release rate and delamination growth of axisymmetrical piezoelectric cylindrical shell are analyzed, and the effects of geometric nonlinear, voltage, temperature and humidity, mechanical load, delamination length and depth, geometrical parameter and boundary condition on delamination growth are discussed.

Exact analytic solutions for the motion of second grade fluid between two infinite coaxial cylinders are established. The motion is produced by the inner cylinder that at time t = 0+ applies torsional and longitudinal oscillating shear stresses to the fluid. The exact analytic solutions, obtained with the help of Laplace and finite Hankel transforms, and presented as a sum of the steady-state and transient solutions, satisfy both the governing equations and all associate initial and boundary conditions. In the special case when a1 to 0 they reduce to those for a Newtonian fluid. Finally, the effect of various parameters of interest on transient parts of velocity components, velocity profiles as well as comparison between second grade and Newtonian fluids is discussed through graphical illustration.

In this paper, we present the homotopy analysis transform method (HATM) to solve fractional Lotka- Volterra equation, which describes the long term servival of species. The HATM solutions, denotes less error compare with their respective exact solution for alpha = 1. In addition to non-proposed techniques, HATMis valid for both small and large parameters, it also provides us with a simpleway to adjust and control the parameter hbar and auxiliary function H(t), which play effective role for convergence solutions of fractional differential-difference equations (FDDEs).