The nonlinear features of the squeeze-film problem between two parallel long strips driven by the relative harmonic oscillation of the strips is studied via the regular perturbation and numerical calculation for ∈ < 1 and σ = O(1)- O(103), where ∈ is the dimensionless amplitude of the oscillation, and σ is the squeeze number. The fluid film behaves as a (nonlinear) spring for large σ and as a (nonlinear) damper for small σ, which are qualitatively similar to the linear analysis. However, a steady state force is generated even though the driving mechanism is purely oscillatory due to the nonlinear effect. Furthermore, the dimensionless quasi-steady rate of energy dissipation within one cycle of the plate oscillation, E, is not zero (zero for linear analysis), and is maximized at σ ≈ 10. Also the rate of increase of E with ∈ is greater than ∈2. The present study may be helpful for the design of some accelerometers and vibration absorbers.

Adopting the DEFORM software for the finite element analysis, this study simulated steady-state plastic deformation of the sheet at the roll-gap during asymmetrical sheet rolling. Using FEM code DEFORM, the effects of roll speed ratio, roll radius ratio, friction factor ratio upon the curvature of the rolled product and rolling force were systematically discussed. With a view to verifying the validity of the study simulated, a series of experiments on asymmetrical cold sheet rolling using Aluminum sheet as specimen are carried out. The comparisons between numerical and experimental results show good agreement. Therefore, this numerical model using DEFORM software can offer useful knowledge for designing the pass-schedule of asymmetrical sheet rolling.

In this paper, the EndoFEM incorporated with a node duplicated and then unloaded crack extension methodology, is employed to produce the CT specimen of A1 2024-T3 with initial fatigue crack and then to simulate its stable crack growth under Mode I condition. Using the experimental P-LLD data, the P-Δa diagram can be estimated by the effective compliance method. This results in a further simulation of crack extending procedures which can obtain the stress-plastic strain distributions of growing crack front and their crack opening profiles, CTOD and CTOA vs. Δa Diagram, COD and COA measured at 5 positions behind the original crack tip vs. Δa diagram. The results mentioned above have excellent agreements with results of related experiments and other computational simulations.

In consequence, the paper proposes a single fracture parameter of crack growth which can be casted in the future studies of EndoFEM simulation: (1) Within the crack initiation range whose crack extension rates da/dP has the lowest constant value, the COA measured at 0.5mm behind the original crack tip is takes as 5°; (2) Within the stable crack growth region whose crack extension rates are nonlinearly and monotonically increasing with finite values, the COA measured at 1mm behind the current crack tip is also taken as 5°.

This paper describes a model using boundary element and finite element methods for the solution of three-dimensional incompressible viscous flows in slow motion, using velocity-vorticity variables. The method involves the solution of diffusion-advection type vorticity equations for vorticity whose solenoidal vorticity components are obtained by solving a Poisson equation involving the velocity and vorticity components. The Poisson equations are solved using boundary elements and the vorticity diffusion type equations are solved using finite elements and both are combined. Here the results of Stokes flow with very low Reynolds number, in a typical cavity flow are presented and compared with other model results. The combined BEM-FEM model has been found to be efficient and satisfactory.

The stress-strain relationship of the sand and asphalt concrete materials is one of the most important research subjects in the past, and many conctitutive laws for these materials have been proposed in the last two decades. In this study, the Vermeer plasticity model is modified and used to predict the behavior of the sand and asphalt concrete materials under different stress path conditions. The results show that the predictions and test results agree well under different stress path conditions. However, the orignal Vermeer model can not predict the stress-strain behavior of the asphalt concrete. Finally, the modified Vermeer plasticity model is incorporated with the pavement rutting model to predict the rut depth of pavement structure under traffic loadings.