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Elastomeric materials are used in daily applications, such as tires and conveyor belts. Sliding friction of elastomeric materials often produces a unique periodic wear pattern. In general, the periodic wear pattern has to be prevented because it generates surface instabilities and, as a result, vibration. Sliding contact between an elastomer and a rigid ball may cause the development of a periodic...
Deep drawing is one of the most widely-used forming processes to manufacture automotive body parts from sheet metal. In order to simulate deep drawing processes, a finite element (FE) method was used to predict formability. The accuracy of the FE simulation depends on the material models, numerical techniques, and contact algorithms. Despite the fact that the contact conditions between the tool and...
In Finite Element (FE) simulations of sheet metal forming (SMF), the coefficient of friction is generally expressed as a constant Coulomb friction. However in reality, the coefficient of friction at the local contact spot varies with the varying operational, deformation and contact conditions. Therefore, it is important to calculate the coefficient of friction under local contact conditions to better...
In many adhesive wear processes, transfer of material from the donor surface results in the formation of lumps or a continuous layer on the countersurface. The morphology of the transferred layer is important for the tribological behaviour of the resulting interface. If the lumps formed on the countersurface are harder than the donor surface, abrasion of the donor surface will be the consequence of...
In two body abrasion processes hard asperities plough through a soft surface. If the asperities can resist the forces that act on it, scratches will develop in the soft material. If the asperities cannot withstand these forces, they will break off and not cause direct abrasion damage. The same is the case for galling, where lumps develop on one of the surfaces because of material transfer. These lumps...
In Finite Element (FE) simulations of sheet metal forming (SMF), the coefficient of friction is generally expressed as a constant Coulomb friction. However in reality, the coefficient of friction at the local contact spots varies with the varying operational, deformation and contact conditions. Therefore, it is important to calculate the coefficient of friction under local conditions to better evaluate...
Abrasion by sand particles is an important factor causing excessive wear in machines operating in sandy environments. To prevent such machines from failing, knowledge about the abrasive wear process is required. This work focuses on the relation between abrasive particle properties and the wear they cause.Sand was taken from several locations around the world, with variations in particle size and...
In this study a model capable of predicting a mild wear map for boundary lubricated contacts is presented and validated using model experiments. Both the transition from mild to severe wear as mild wear itself is modeled. The criterion for the transition from mild to severe wear is a thermal one. The mild wear model is based on the hypothesis that for an additive to protect the surface against severe...
In aluminium extrusion processes, friction inside the bearing channel is important for controlling the surface quality of the extrusion products. The contact materials show a large hardness difference, one being hot aluminium, and the other being hardened tool steel. Further, the contact pressure is high, which means that contact at the bearing–aluminium interface is fully plastic. A load dependent...
During the running-in of surfaces a change in roughness takes place. The presented model predicts this change for concentrated contacts using an elasto-plastic contact model based on a semi-analytical-method recently developed. Combining this method with a local coefficient of friction, which is determined using a mechanical threshold on the protective nature of the lubricant, and a strain related...
In this paper the transition from mild wear to severe wear of lubricated, concentrated contacts is dealt with. It is suggested that this transition is thermally induced. The transition from a mild wear to severe adhesive wear occurs when more then 10% of the surface transcends a predefined, critical temperature. A method for determining this critical temperature is presented. Using a BIM based numerical...
A theoretical and experimental study to analyze the contact behavior of the repeated stationary deterministic contact of rough surfaces is presented in this paper. Analysis focuses on the contact of rough surfaces on asperity level without bulk deformation. Contact area and deformation of isotropic and anisotropic contacting surfaces were simulated for each loading cycle and were plotted along with...
Theoretical and experimental results are presented to evaluate the deformation behavior of the contact between a real rough flat surface and a smooth ball. There are three deformation responses: plastic deformation of the asperities only, plastic deformation of the bulk only and combined plastic deformation of both the asperities and the bulk. The effects of the surface roughness and the Hertzian...
A wear measurement technique based on the comparison of local surface heights has been developed. The method makes it possible to measure wear on asperity level. By comparing two roughness measurements before and after a wear experiment, the developed algorithms are used in a semi-online wear measurement system (an integration of a pin-on-disk and an interference microscope). The system consists of...
A model that describes the abrasive wear between a hard and rough surface and a softer and smooth surface is developed. The contact between these two solids is modelled based on micro-contacts [M.A. Masen, M.B. de Rooij, Abrasive wear between rough surfaces in deep drawing, in: Proceedings of the 6th Austrib Tribology Conference, Perth, Australia, 2002, pp. 601–608], instead of the more conventional...
The transition of mild to severe wear of ceramics depends on the operating conditions (normal load, velocity and temperature) and material properties (like grain size, mechanical and thermal material properties). Adachi et al. [Wear 203-204 (1997) 291] introduced the transition of mild to severe wear of ceramics by defining a mechanical severity parameter based on the work of Hamilton [Proc. Inst...
The lifetime of sheet metal forming (SMF) tools is often limited by galling, a wear type that affects the surface quality of the products and the lifetime of SMF tools. Since SMF tools represent high economical value, it is clear that improvement and prediction of tool life is of high industrial importance. Therefore, models are required that can predict friction and wear related phenomena in SMF-processes,...
The friction and wear of alumina and zirconia ceramics doped with various weight percentages (0.5, 1 and 5wt.%) of CuO was studied. Dry sliding tests by using a pin-on-disc tribotester were conducted on these materials against commercially available Al 2 O 3 , ZrO 2 , SiC, and Si 3 N 4 ceramic balls. The results show that CuO give a significant reduction of...
Wear of ceramics under dry sliding conditions is, besides mechanical overload, often governed by frictional heating. On the basis of this study a new thermal severity parameter is introduced and applied to an existing wear map as a function of mechanical and thermal loading introduced by Adachi et al. [Wear 203/204 (1997) 291]. The new map is valid for a wide range of material properties and operating...
Galling is a known failure mechanism in sheet metal forming (SMF) processes. As a result of this wear process, the amount of waste increases, the production process becomes hard to control and eventually expensive maintenance is required in order to continue production. Delaying or avoiding galling mechanisms by optimising the contacting materials and lubricant is therefore of high industrial importance...
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