Exact analysis of the orientation-adjusted adhesive full stick contact of layered structures with the asymmetric bipolar coordinates

The adhesion failure has become one dominant factor in determining the reliability and service life of miniaturized devices subject to loadings with arbitrary orientations.This article establishes an adhesive full stick contact model between an elastic half-space and a rigid cylinder loaded in any direction.Using the Papkovich-Neuber functions,the Fourier integral transform,and the asymmetric bipolar coordinates,the exact solution is obtained.Unlike the Johnson-Kendall-Roberts(JKR)model,the present adhesive contact model takes into account the effects of the load direction as well as the coupling of the normal and tangential contact stresses.Besides,it considers the full stick contact which has large values of the friction coefficient between contacting surfaces,contrary to the frictionless contact supposed in the JKR model.The result shows that suitable angles can be found,which makes the contact surfaces difficult to be peeled off or easy to be pressed into.

基于JKR模型的粗糙圆柱表面线黏着接触分析

利用粗糙平面接触模型,假定表面单个微凸体的接触采用JKR黏着接触模型,同时考虑圆柱体表面的整体变形,建立了粗糙圆柱表面线黏着接触模型,推导出表面等效压力分布方程。把压力方程量纲一化,采用修正Newton-Raphson法对方程进行迭代求解,计算出粗糙圆柱表面存在表面力作用下的等效压力分布曲线。结果表明外载荷不小于零时,接触中心压力为正,微凸体被压缩;而接触边缘处压力为负,微凸体被拉伸,表明黏着区域主要分布在接触边缘。同时计算出接触半宽随外载荷的变化曲线,当外载荷为拉伸力并大于某一临界值时,表面分开。并且与经典的接触模型进行了对比,发现低载时模型之间的差别较大,而载荷比较大时趋于一致。

Discrete element method for adhesion properties evaluation of deep-sea sediment from macro and micro perspectives

The adhesion between the mining machine and the deep-sea sediments will significantly affect the driving performance of the mining machine in the deep-sea environment.When the mining machine and the deep-sea sediment interaction simulation was carried out,the accuracy of the particle interaction parameters will directly affect the simulation results.This study proposed a method to systematically calibrate the interaction parameters between deep-sea sediment and grouser through the combination of experiment and simulation.The uniaxial compression test and macro adhesion test and corresponding discrete element numerical simulation were carried out,modifying the contact parameters until the simulation results are close to the experimental results.Then the micro-parameters of the JKR adhesion contact model were back calibrated with the test results,and the contact parameters between soil particle-soil particle and soil particle-metal are calibrated.Besides,the adhesion test shows that the adhesion forces were ranked in the order of 5052<STi80<TA2<TC4 under the same surface roughness,which indicates the aluminum alloy 5052 has the best anti-adhesion performance.The relationship between surface adhesion force and microscopic contact parameters was studied by discrete element numerical simulation,and the result shows that the coefficient of static friction and the coefficient of rolling friction has little effect on adhesion force.While it is mainly affected by the coefficient of restitution and surface energy,the surface adhesion force tends to decrease with the increase of the coefficient of restitution and increase with the growth of surface energy.The obtained parameters of soil particle to soil particle and soil particle to metal affecting the adhesion can contribute to the design optimization for the grouser of mining machines to decrease surface adhesion and enhance its movability and mining efficiency.

Adhesive contact of a rigid sphere to finitely stretched substrates

Exemplified by adhesive contact of a rigid sphere with equiaxially stretched elastomeric substrates, the effect of finite pre-strain on adhesion behavior is studied based on the JKR model. The analysis indi-cates that the pre-strain reduces the contact area between the sphere and the substrate, but does not alter the adhesion strength.

任意轴对称弹性体吸附接触的广义Maugis模型

通过线性叠加Sneddon方法和Lowengrub-Sneddon方法分别给出的解,得到了一个弹性半空间轴对称混合边值问题的一般解,进而研究了两个一般轴对称弹性体的正向无摩擦吸附接触问题．考虑任意有效的表面形状(要求中心部分首先进入接触)和任意的表面吸附作用,推广得到了广义Maugis模型．该模型是一个半解析的模型,它可以分解成表面形状和表面吸附作用的分别独立影响的两部分,以及一个关联变形和吸附作用的式子．利用Dugdale模型近似表面吸附作用,得到了具有任意有效的表面形状的广义M-D模型．它在强吸附或软材料条件下的极限形式是广义JKR模型,而在弱吸附或硬材料下的另一个极限形式是广义DMT模型．

Adhesion Performances Between Two Orthotropic Solids Influenced by Temperature Increment

The classical adhesive contact models belong to isothermal adhesion theories,where the effect of temperature on adhesion was neglected.However,a number of experimental results indicated that the adhesion behaviors can be significantly affected by temperature.In this paper,the two-dimensional non-slipping anisothermal adhesion behaviors between two orthotropic elastic cylinders are investigated within the framework of the Johnson-Kendall-Roberts theory.The stated problem is reduced to the coupled singular integral equations by virtue of the Fourier integral transform,which are solved analytically with the analytical function theory.The closed-form solutions for the stress fields in the presence of thermoelastic effect are obtained.The stable equilibrium state of contact system is determined by virtue of the Griffith energy balance.The effect of temperature difference on adhesion behaviors between orthotropic solids is discussed.It is found that the difference between the oscillatory and non-oscillatory solutions increases with increasing the degree of anisotropy of orthotropic materials.The oscillatory solution cannot be well approximated by the non-oscillatory solution for the orthotropic materials with relatively high anisotropy.