近日，课题组在JCR力学一区期刊“European Journal of Mechanics A/Solids”第65卷（2017）上发表题为“Surface mechanics induced stress disturbances in an elastic half-space subjected to tangential surface loads”的研究论文，论文官方网页和简要内容如下。
论文官方网页：
Highlights
An elastic half-space subjected to surface tractions was semi analytically analyzed.
Gurtin and Murdoch's complete model of surface mechanics was taken into account.
Although extremely localized, the effects of surface mechanics are significant.
Proper design of surface properties can render desired displacements and stresses.
Surface mechanics introduces length scales into the classical Cerruti's problem.
Abstract:
To better understand the impact of surface stress effects on frictional contact mechanics, a three-dimensional stress analysis is presented for an elastic half-space subjected to arbitrarily distributed shear tractions in a circular portion of its plane boundary. The method of Boussinesq displacement potentials is used to address the problem, where local elastic field including displacements and stresses right on the loading surface is semi-analytically determined by solving a set of integral equations. Numerical results are presented to examine effects and the stress disturbances caused by the coupling of surface loads and surface mechanics. The results show that a metallic layer with properly designed mechanical behavior coated on the free surface of a half-space substrate of even the same material can function as a stiffener and stress reliever. Surface stress effects also result in unexpected rise of adhesive forces near the loading perimeter, although the traction loads are purely tangential. The results suggest a means of optimizing the local displacements, strains and stresses by controlling the material properties of the half-space boundary.
Keywords:
Surface mechanics; Half-space; Surface load; Stress analysis; Cerruti's problem
Conclusions:
In the context of Gurtin and Murdoch's model of surface mechanics, we developed a general method of solution for an elastic half-space subjected to an arbitrarily distributed shear traction load in a circular portion of its plane boundary. Semi-analytical solutions in terms of improper integrals were developed for four example traction loads. A few observations and conclusions can be drawn on the basis of combined analytical and numerical investigations.
Surface effects play an important role in the determination of the elastic field in and near the loading area. Although only the region within a couple of times the loading size is affected, the influence of surface mechanics is significant. In every case, the strength of surface effects is in proportion to the magnitude of the corresponding classical solution.
For a half-space coated by a nickel [111] layer, the model of surface mechanics functions as a stiffener and stress reliever. When compared to their classical counterparts, lower magnitudes in both displacements and stresses were found. The asymmetric displacement gradient terms in the surface constitutive law are responsible for the unexpected rise of adhesive forces near the circular loading perimeter.
Surface effects induce intrinsic length scales into the classical Cerruti's solution. Local displacements and stresses in the region within approximately one intrinsic length scale are significantly affected. The otherwise zero shear stress becomes non-trivial in the immediate vicinity of the point load.
