Articles written in Sadhana
Volume 33 Issue 4 August 2008 pp 367-384
The paper describes an analysis of adhesion at the contact between non-Gaussian rough surfaces using the Weibull distribution with skewness as the key parameter to characterize asymmetry. The analysis uses an improved elastic–plastic model of contact deformation that is based on accurate Finite Element Analysis (FEA) of an elastic–plastic single asperity contact. Large range of interference values is considered starting from fully elastic through elastic–plastic to fully plastic regime of contacting asperities. The well-established elastic and plastic adhesion indices are used to consider the different conditions that arise as a result of varying load and material parameters. The loading and unloading behaviour for different combinations of the adhesion indices and skewness values are obtained as functions of mean separation between the surfaces. Transitional values of adhesion indices and skewness at which the inﬂuence of surface forces becomes insigniﬁcant are found to depend on material and surface parameters. Comparison with studies using previous elastic–plastic model that was based on some arbitrary assumptions shows signiﬁcant differences in loading behaviour.
Volume 33 Issue 4 August 2008 pp 403-432
The aim of this paper is to develop a simulation model of large deformation problems following a semi-analytical method, incorporating the complications of geometric and material non-linearity in the formulation. The solution algorithm is based on the method of energy principle in structural mechanics, as applicable for conservative systems. A one-dimensional solid circular bar problem has been solved in post-elastic range assuming linear elastic, linear strain hardening material behaviour. Type of loading includes uniform uniaxial loading and gravity loading due to body force, whereas the geometry of the bar is considered to be non-uniformly taper. Results are validated successfully with benchmark solution and some new results have also been reported. The location of initiation of elasto-plastic front and its growth are found to be functions of geometry of the bar and loading conditions. Some indicative results have been presented for static and dynamic problems and the solution methodology developed for one-dimension has been extended to the elasto-plastic analysis of two-dimensional strain ﬁeld problems of a rotating disk.