Influence Of Mechanical Behaviour Research Articles

Characterisation of out-of-plane shear behaviour of anisotropic sheet materials based on indentation plastometry

This paper presents a new methodology for characterising the out-of-plane plastic anisotropy behaviour of sheet metal, based on indentation testing. Conventionally, advanced yield criteria are used to describe plastic anisotropy, requiring multiple in-plane mechanical tests (such as uniaxial and biaxial tests) to calibrate a model. However, in certain forming applications (e.g. blanking, ironing and incremental forming), the influence of mechanical behaviour through thickness cannot be ignored, necessitating the characterisation of out-of-plane material behaviour. To do this, a 3D plastic anisotropy model must be used and calibrated for the out-of-plane shear parameters, which can be difficult to determine. Researchers often assume an isotropic case or equal shear parameters for in-plane and out-of-plane behaviour. More advanced calibrations involve the crystal plasticity model. In this work, we propose a two-stage calibration procedure. In the first stage, we calibrate the in-plane parameters of the YLD2004–18p yield function conventionally. In the second stage, after fixing the in-plane parameters, we determine the remaining out-of-plane shear parameters based on the results of the ball indentation test. We show for the first time that out-of-plane shear parameters can be determined from a macro-mechanical test for a 2.42 mm thick cold-rolled AA5754-H22 series aluminium sheet.

Nonlinear Behavior of Marine Soil on the Dynamic Stability of Upper Wharf Structures: A Numerical Simulation Approach

Shen, C.; Qian, J.; Chen, X.; Xie, F., and Zhu, J., 2021. Nonlinear behavior of marine soil on the dynamic stability of the upper wharf structures: A numerical simulation approach. Journal of Coastal Research, 37(1), 149–155. Coconut Creek (Florida), ISSN 0749-0208.This paper investigates the influence of mechanical behavior of marine soil on the dynamic stability of the upper wharf. A series of triaxial consolidation undrained shear tests and one-dimensional consolidation compression tests was conducted to analyze the influence of fine particle content on the nonlinear behavior of marine soil. It was found that the relationship between stress and strain, the undrained shear strength, and residual strength of soil samples strongly correlated with the content of fine particles. In addition, the content of illite soil had a significant impact on the characteristic of the stress–strain curves, with a threshold of about 10%. A numerical model of the foundation-pile-superstructure under wave load was established. The results showed that the dynamic response of a wharf under wave load depended on the strength and nonlinear behaviors of the marine soil foundation. The strain-softening foundation with high peak strength led to more damage on the wharf. However, the strain-hardening characteristics resulted in more damage on the wharf when the peak strength was low. This suggests that the mechanical properties of soil foundation should be taken into account for the long-term durability and stability in the design of the wharf.

Influence of mechanical behavior between the grains on stress fluctuation of aluminum alloy thick plate

The research on fl uctuation and inhomogeneity of internal stress of aluminum alloy thick plate is theoretical and technological base for stress control technology. By using X-ray diffraction technique and mechanical test method, aluminum alloy with typical fine sub-grains, coarse recrystallized grains, and second phase was analyzed; the interactive mechanical model between grains was built for analysis of variation of internal stress within the local micro structure by imitating the actual distribution of grains. The experimental result shows that the mechanical model can effectively explain the reason for fluctuation of microscopic stress, which also proves that the inhomogeneous distribution of metal organization is the cause for the complex distribution of microscopic stress. The model can well describe stress distribution of thick plate caused by thermal deformation. Besides, it well describes mechanism of stress fluctuation.

Influence of Mechanical Behavior of Adhesives on Shear Stress Distributions in the Single-Lap Adhesive Joints

This paper deals with the effects of mechanical behavior of adhesives on the shear stress distributions of single-lap adhesive joints under tension using the three-dimensional finite element analysis (FEA) technique. Numerical examples are provided to show the influence on the shear stresses of the joints using adhesives of different characteristics which encompass the entire spectrum of viscoelastic behavior. FEA solutions of the shear stress distributions in the adhesive layer have been obtained for four typical characteristics of adhesives. The results indicate that Young’s modulus and Poisson’s ratios of adhesives strongly affect the shear stress distributions of the joints.

Influence of stress–strain field on the dissolution process of polycrystalline nickel in H 2SO 4 solution: An original in situ method

Stress corrosion cracking (SCC) raises a lot of questions concerning complexity of stacked physical mechanisms. Synergy between electrochemical processes and mechanical field near the crack tip is now recognized. However, the influence of mechanical behaviour on corrosion processes is not well established and only few works dealt with this effect. Consequently, it seems to be necessary to determine the influence of the plastic strain on the surfaces reactivity in aqueous mediums. The great part of this work was devoted to the development of an electrochemical cell on a bench of mechanical test in order to carry out in situ measurements of current density. Three levels of interaction have been discussed taking into account the different expression of plastic deformation (dislocation density and distribution, slip bands emergence, stress field) in order to study the effect of mechanical state on dissolution, on passivation processes, and on stability of oxide film of polycrystalline nickel in H 2SO 4 solution.

Influence of mechanical behavior on the wear of 4 clinically relevant polymeric biomaterials in a hip simulator

The elastic and large-deformation mechanical behavior of 4 materials with known clinical performance was examined and correlated with the wear behavior in a hip simulator. Acetabular liners of a commercially available design were machined from ultra-high molecular weight polyethylene (UHMWPE), high-density polyethylene (HDPE), polytetrafluoroethylene (PTFE), and polyacetal and wear tested in a multidirectional hip joint simulator. Elastic and large-deformation mechanical behavior was directly measured from the wear-tested liners using the small punch test. The finite element method was used to compute elastic modulus from the measured small punch test initial stiffness, and the contact stress for the liners was calculated using the theory of elasticity solution. Positive, statistically significant correlations were observed between the hip simulator wear rate and the initial peak load, ultimate load, and work to failure from the small punch test. Negative correlations were observed between the wear rate and the elastic modulus and contact stress. The results of this study support the hypothesis that the large-deformation mechanical behavior of a polymer plays a greater role in the wear mechanisms prevalent in total hip replacements than the elastic behavior.