Papers by Keyword: Contact Condition

Abstract: The oil lip seal operation is affected by the kinematics of the relative motion of the lip surface with respect to the shaft during both assembly and operation. Moreover, the variable position of the contact area along the sealing edge determines the contact pressure distribution and hence the wear rate of the lip.

Abstract: In this study friction stir welding of Al-Cu laminated composites were carried out by two different tool geometries. Welding procedure was carried out from both sides of Al and Cu. Analyzing cross section of welds showed that different contact conditions between shoulder and material, offers different material flow behavior which is dependent on the tool geometry. SEM analyses showed that mixing of materials in nugget region is more pronounced in the advancing side. Also XRD results indicated that welding from Cu side, leads to intermetallic formation in mixed regions.

Abstract: To investigate surface stress distribution of rectangle piston ring, method of increment loading based on energy variational principle is used to ascertain contact state and solve elastic contact problems by iteration. Calculation results show that the central section of the first sealing surface is subjected to lower stress while two sides higher stress. The theoretical analysis and experimental results indicate that appearance of stress peak on surface is related to movement direction of piston ring. Relatively critical wear regions of piston ring are consistent with finite element analysis results. Wear width of both sides is 0.2mm more or less. The section of maximal stress appears at position near ring groove of the first sealing area.

Abstract: Five-axis-grinding is a process, which merges high surface quality and high shape accuracy for high precision machining of multiple curved surfaces. Until now, characteristic parameters, which describe the interaction of the grinding tool and the workpiece are not available. In the present paper models for the analytical determination of the contact condition for surface normal grinding of double curved surfaces with toric grinding wheels are introduced to evaluate and configure the machining parameters.

Abstract: The mechanics of metal flow through long choked die channels have been investigated in unlubricated hot aluminum extrusion. Experiments were performed in a laboratory press at an earlier occasion by letting a grid pattern introduced into the billet flow down into the choked die channel to appear adjacent to the channel wall. The grid pattern was then revealed to characterize the metal flow in the channel. A 2D-model of the extrusion process was made. The model was applied to study the conditions in the extrusion experiments and in this model good similarity was obtained with the experiment. New knowledge regarding the metal flow through a choked die channel have been obtained this way, such as; contact conditions, presence of sticking and sliding zones, friction conditions in the sliding contact zone and the velocity profile over the cross-section of the channel.

Abstract: Until now, the complex kinematics and geometries as well as high quality requirements have prevented the use of all-ceramic prostheses for the medical treatment of knee joints. High-precision grinding and polishing processes for free-formed ceramic surfaces are essential for this purpose. Constantly changing contact conditions have to be considered to ensure a constant material removal. Within this work, appropriate tools are introduced which are able to adjust to the form variation of the component contour.

Abstract: The numerical simulation of the Single Point Incremental Forming process (SPIF) is time consuming due to the necessity to take into account various non-linearity such as the material behaviour, large strain deformation and the evolution of the tool-flange contact. Classical contact algorithms give good agreement with experimental results, but are time consuming. In this paper, we investigate the development of a procedure to simplify the management of the contact interface between the tool and the sheet. Nodes with imposed displacements are determined by a geometrical approximation of the deformed sheet. In order to have a better approximation of the local stresses in the flange, a pressure is applied on the tool side of the elements in the contact zone. The pressure value is obtained by an analytical model. A classical contact algorithm and the present simplified approach are compared in terms of an incremental forming benchmark. It has been shown that, for the benchmark problem studied here, a CPU time reduction of approximately 65% can be achieved while at the same time have good simulation results.

Abstract: Knowledge on the contact condition at the tool/workpiece interface is essential for understanding many aspects of FSW. In the present study, FSW experiments were conducted using aluminium alloys followed by metallographic examination focusing on the tool shoulder-workpiece interface region. It was observed that an interfacial intermetallic layer and hence metallurgical sticking/soldering readily formed. Temperature measurements have suggested the presence of interface liquid, hence suggesting a mechanical sliding contact condition dominant. This has been supported by the observation on material flow within the shear layer.

Abstract: The effect of the flow stress of solid lubricant for cold forging on the tribological conditions was investigated using a rigid-plastic finite element method. The thickness of lubricant film decreases with decreasing flow stress of the solid lubricant and then decreases rapidly. The apparent friction coefficient also decreases with the decrease in the flow stress of the solid lubricant. The thickness of lubricant film tends to decrease with decreasing friction shear factor. When flow stress of solid lubricant is low, the thickness of lubricant film decreases remarkably with increasing tool stroke. We can observe a good correlation between the flow stress of solid lubricant, friction shear factor, minimum film thickness and apparent friction coefficient.