Search results for "Friction."
showing 10 items of 350 documents
ELECTROCHEMICAL ANALYSIS ON FRICTION STIR WELDED AND LASER WELDED 6XXX ALUMINIUM ALLOYS T-JOINTS
2007
Friction Stir Welding (FSW) and Laser Welding (LW) can be successfully employed to weld aluminium alloys, in many cases overcoming the difficulties encountered with more conventional welding processes like MIG or TIG. The corrosion resistance of the welded joint remains, however, an important issue, especially in applications (like in aircrafts), where corrosion can induce structural failure: the weld region has often lower mechanical resistance in comparison with the parent material and a decrease in its corrosion resistance, especially when the corrosion damage can represent a potential crack initiation site, can be unacceptable in components design. In this work the corrosion resistance …
Damping of rotor conical whirl by asymmetric dry friction suspension
2009
Abstract A new technique for the rotor whirl damping in rotating machinery, based on the elastic suspension of the journal boxes and the use of dry friction surfaces normal to the shaft axis between their supports and the frame, is here analysed theoretically for several cases of rotor systems characterized by mass and constraint asymmetry, where gyroscopic effects are to be expected and conical whirl motions may grow up. The critical flexural speeds can be easily cut off by an adhesive state of the supports and the whirl amplitude can be minimized as well throughout the remaining sliding range. Confining the operative angular speed of the rotor in the range of adhesive contact between the …
Experimental Investigation on the Use of Argon to Improve FMEP Determination through Motoring Method
2019
In the ever increasing challenge of developing more efficient and less polluting engines, friction reduction is of significant importance and its investigation needs an accurate and reliable measurement technique. The Pressurized Motoring method is one of the techniques used for both friction and heat transfer measurements in internal combustion engines. This method is able to simulate mechanical loading on the engine components similar to the fired conditions. It also allows measurement of friction mean effective pressure (FMEP) with a much smaller uncertainty as opposed to that achieved from a typical firing setup. Despite its advantages, the FMEP measurements obtained by this method are …
Using a neural network for predicting the average grain size in friction stir welding processes
2009
In the paper the microstructural phenomena in terms of average grain size occurring in friction stir welding (FSW) processes are focused. A neural network was linked to a finite element model (FEM) of the process to predict the average grain size values. The utilized net was trained starting from experimental data and numerical results of butt joints and then tested on further butt, lap and T-joints. The obtained results show the capability of the AI technique in conjunction with the FE tool to predict the final microstructure in the FSW joints.
Continuous dynamic recrystallization phenomena modelling in friction stir welding of aluminium alloys: A neural-network-based approach
2007
The current paper focuses on the continuous dynamic recrystallization phenomena (CDRX) occurring in friction stir welding processes of AA6082 T6 aluminium alloys. In particular, in order to predict the average grain size, a properly trained neural network is linked to the finite element method (FEM) model of the process. The utilized net, which takes as inputs the local values of strain, strain rate, and temperature, was trained starting from experimental data and numerical results. The obtained results show the capability of the artificial intelligence (AI) technique in conjunction with the FE tool to predict the final microstructure in the joint section.
Mechanical and microstructural properties prediction by artificial neural networks in FSW processes of dual phase titanium alloys
2012
Abstract Friction Stir Welding (FSW), as a solid state welding process, seems to be one of the most promising techniques for joining titanium alloys avoiding a large number of difficulties arising from the use of traditional fusion welding processes. In order to pursue cost savings and a time efficient design, the development of numerical simulations of the process can represent a valid choice for engineers. In the paper an artificial neural network was properly trained and linked to an existing 3D FEM model for the FSW of Ti–6Al–4V titanium alloy, with the aim to predict both the microhardness values and the microstructure of the welded butt joints at the varying of the main process parame…
Experimental Comparison of the MIG and Friction Stir Welding Processes for AA 6005 Aluminium Alloy
2015
In this study, the mechanical properties of welded joints of AA 6005 aluminum alloy obtained with friction stir welding (FSW) and conventional metal inert gas welding (MIG) are studied. FSW welds were carried out on a semi-automatic milling machine. The performance of FSW and MIG welded joints were identified using tensile and bending impact tests, as far as the environmental aspects are also included in the discussion. The joints obtained with FSW and MIG processes were also investigated in their microstructure. The results indicate that, the microstructure of the friction stir weld is different from that of MIG welded joint. The weld nugget consists of small grains in FSW than those found…
Comparative analysis of bonding mechanism in solid state metal working processes
2016
The Piwnik and Plata pressure-time bonding criterion was applied to Friction Stir Welding, Linear Friction Welding, Porthole Extrusion and Roll Bonding. A neural network was set up, trained and used to predict the bonding occurrence starting from the main field variable distributions calculated through specific numerical models developed for each process. The analysis of the results permitted to predict the occurrence of solid bonding and to highlight differences and analogies between the processes in order to obtain sound solid welds.
A three-dimensional cohesive-frictional grain-boundary micromechanical model for intergranular degradation and failure in polycrystalline materials
2013
Abstract In this study, a novel three-dimensional micro-mechanical crystal-level model for the analysis of intergranular degradation and failure in polycrystalline materials is presented. The polycrystalline microstructures are generated as Voronoi tessellations, that are able to retain the main statistical features of polycrystalline aggregates. The formulation is based on a grain-boundary integral representation of the elastic problem for the aggregate crystals, that are modeled as three-dimensional anisotropic elastic domains with random orientation in the three-dimensional space. The boundary integral representation involves only intergranular variables, namely interface displacement di…
Numerical simulation of linear fiction welding (LFW) processes
2011
Solid state welding processes are becoming increasingly important due to a large number of advantages related to joining ''unweldable'' materials and in particular light weight alloys. Linear friction welding (LFW) has been used successfully to bond non-axisymmetric components of a range of materials including titanium alloys, steels, aluminum alloys, nickel, copper, and also dissimilar material combinations. The technique is useful in the research of quality of the joints and in reducing costs of components and parts of the aeronautic and automotive industries.LFW involves parts to be welded through the relative reciprocating motion of two components under an axial force. In such process t…