Abstract

The present study analyzes the best attachment of the propeller shaft of a submersible to his bearing, studying geometry of contact between those elements. A semi-analytical method based on the rules of the quadrature of the main values of Cauchy, the secant method and a numerical method for determining a tension map have been applied to the study of the contact surfaces between shaft and bearing. It is assumed that there are imperfections in the order of microns when machining the contact surfaces, which can produce subsurface damage that is possible, linked to pitting and the growth of fatigue cracks. Such failures not only will influence on the proper propulsive performance, but also on the watertightness conditions, which is related to the risk of ship integrity loss. The results let us to set design criteria, which account for the Youngs module and the importance of an adequate machining and further adjustment of clearances on the shaft-bearing system, thus improving the reliability of such elements.

Abstract

The knowledge of contact forces in teeth surfaces during mastication or para-functional movements can help to understand processes related to friction and wear of human dental enamel. The development of a numerical model for analysis of the occlusal contact between two antagonistic teeth is proposed, which includes three basic steps: the characterisation of the surface roughness, its homogenisation using an assumed distribution function and the numerical determination of the resulting forces. Finite element strain results for the main different asperities are statistically combined, deriving the predicted macroscopic behaviour of the interface. Axisymmetric and 3D numerical models with an elasto-plastic constitutive law are used to simulate micro-indentations and micro-contacts, respectively. The contact is allowed to occur locally in planes not necessarily parallel to the surface's mean plane, a problem for which there is no analytical solution. The three identified parameters, homogenised surface hardness (3.68 GPa), surface yield stress (3.08 GPa) and static friction coefficient (0.23), agree with the experimental values reported in the literature.

Abstract

We develop a fully coupled finite element solution for elastoplastic indentations of unsaturated granular soils by a rigid cylinder by using a mortar-type contact algorithm. In the presented solution, we have employed an advanced constitutive model that allows the inclusion of the effect of matric suction and induced anisotropy in the problem. Several numerical examples in both static and dynamic scenarios are provided for validation and demonstrating the capabilities of the presented framework.