Contact problem on indentation of an elastic half-plane with functionally-graded coating in presence of tangential stresses on the surface

Plane contact problem on indentation of an elastic half-plane with functionally graded coating by a parabolic punch is considered. The surface of the half-plane is additionally subjected to distributed tangential stresses in a certain region different from contact area. The contact area is assumed to be asymmetric with respect to the center of the punch. Tangential stresses are represented in the form of Fourier series. The problem is reduced to the solution of two dual integral equations over even and odd functions describing distribution of normal contact stresses. The bilateral asymptotic method is used to solve these equations. Approximated analytical solutions asymptotically exact for both the small and large values of relative coating thickness are constructed

Study on mechanical and microgeometric characteristics of ion-plasma deposited TiN coating on 40Cr steel substrate

The ion-plasma sprayed titanium nitride (TiN) coating on the prepared 40Cr steel substrate is investigated. A part of the coating surface was covered by the copper foil mask to measure its thickness afterwards. The properties and characteristics of the sample surface microtopography before and after coating deposition are studied by the atomic-force microscopy (AFM). The technique for the high-precision determination of the coating thickness using the results of the AFM scanning of the transition area between the substrate and the coating on the sample surface is described and applied. The calculated uncertainty of the measured value of thickness is significantly less than in other methods. Mechanical properties of the coating are measured by the instrumental indentation method; the significance of an accurate determination of the correct thickness for measuring the coating characteristics by the indentation technique is shown

On a method for determination of Poisson’s ratio and Young modulus of a material

On the base of modernized NanoTest 600 Platform 3 indentation method is proposed to determine elastic parameters – Poisson’s ratio and Young’s modulus – of a material while loading in an elastic region. The experiment is based on procedure: lateral surface of indenter tip with the shape of parabolic cylinder penetrates into the specimen. NanoTest 600 was equipped by additional optics, backlight and device for spatial orientation of the specimen. This modernization allows to control the process of the indenter penetration both along its length and from the edges, so that one can observe and measure the width of the contact area and control the depth of the indentation area in a sample material. Mathematical modeling of the indentation process was conducted within the framework of plane theory of elasticity. This required solution of the contact problem on indentation of a rigid indenter with a parabolic shape into an elastic strip coupled with a non-deformable substrate. The fulfilment of condition of zeroing the contact stresses at the edges of the indenter with a known width of the contact area allows to determine the Poisson’s ratio, and condition of static equilibrium of the contact problem helps to find Young’s modulus of a strip material

On a method for determination of Poisson’s ratio and Young modulus of a material

On the base of modernized NanoTest 600 Platform 3 indentation method is proposed to determine elastic parameters – Poisson’s ratio and Young’s modulus – of a material while loading in an elastic region. The experiment is based on procedure: lateral surface of indenter tip with the shape of parabolic cylinder penetrates into the specimen. NanoTest 600 was equipped by additional optics, backlight and device for spatial orientation of the specimen. This modernization allows to control the process of the indenter penetration both along its length and from the edges, so that one can observe and measure the width of the contact area and control the depth of the indentation area in a sample material. Mathematical modeling of the indentation process was conducted within the framework of plane theory of elasticity. This required solution of the contact problem on indentation of a rigid indenter with a parabolic shape into an elastic strip coupled with a non-deformable substrate. The fulfilment of condition of zeroing the contact stresses at the edges of the indenter with a known width of the contact area allows to determine the Poisson’s ratio, and condition of static equilibrium of the contact problem helps to find Young’s modulus of a strip material