| The presence of internal boundaries or discontinuities is a common feature of many engineering problems both in stress analysis and heat transfer analysis. To analyze such problems by the Finite Element Method, special interface elements are developed to model discontinuities. Since contact is often localized, these elements are of the grading type so as to allow fine meshes in the contact region. To model the interactions between stress and heat transfer, a fully coupled analysis is developed. A computer programme is developed and tested for both 2D and 3D static and dynamic contact, on curved surfaces.;The normal stress distribution for a long cylinder on a semi-infinite flat plate compares well with the closed form solution from Hertz's equations. Wheel-rail interaction problems particularly in sliding contact are examined.;Heat transfer across contacts is also modelled. The thermal properties and boundary conditions are specified carefully so as to mimic as accurately as possible the dependence of contact thermal resistance upon interface pressure, surface quality and gap size, as indicated by experimental results.;Practical application of interface elements in heat transfer is examined by modelling heat transfer across contacts and across layers of materials with different thermal properties. Specific problems of heat transfer across contacts and small air gaps in spring-loaded and bolted electronic circuit components are examined including a discussion of possible means of reducing contact thermal resistance based upon interacting geometries. A coupled thermal-stress analysis using contact elements is demonstrated by modelling the peening of welds. The analysis suggests that it is possible to produce welds that are nearly free of residual stress and distortion. This result could be important to industrial applications.;Testing is done by solving simple test cases, based on elasticity theory or heat transfer theory respectively, whose solutions are known or can be verified before attempting practical engineering problems. |
