Search results for "Friction"
showing 10 items of 352 documents
Design of Numerical Simulations of Linear Friction Welding Processes: Issues and Difficulties
2015
In this paper, a critical analysis of the technical difficulties and numerical issues in running simulations of linear friction welding processes is carried out. The focus of the paper is the comparison of different modeling strategies of a numerical analysis for the LFW process of Ti-6Al- 4V titanium alloy, for which the thermal aspect strongly influences the mechanical behavior due to the phase transformation, taking place over a definite range of temperature. A 3D simulation campaign, conducted using the FEA code DEFORM™, was considered in order to show advantages and disadvantages of each approach, including the most critic limitations and complexity in a correct simulation design using…
On the effectiveness of Finite Element simulation of orthogonal cutting with particular reference to temperature prediction
2007
Abstract Finite Element simulation of orthogonal cutting is nowadays assuming a large relevance; in fact a very large number of papers may be found out in technical literature on this topic. In recent years, numerical simulation was performed to investigate various phenomena such as chip segmentation, force prediction and tool wear. On the other hand, some drawbacks have to be highlighted; due to the geometrical and computational complexity of the updated-Lagrangian formulation mostly used in FE codes, a cutting time of only a few milliseconds can be effectively simulated. Therefore, steady-state thermal conditions are not reached and the simulation of the thermal phenomenon may be ineffect…
Micro and macro mechanical characterization of friction stir welded Ti–6Al–4V lap joints through experiments and numerical simulation
2013
Abstract Lap joints of Ti–6Al–4V were produced and the effect of the main process parameters was studied through macro and micro investigations highlighting mechanical resistance, microhardness profiles, grain size and phase distributions. A dedicated numerical model was used to link the input process parameters to temperature and strain distributions and to the final microstructure in the welded joint. It is found that the strain produced in the stir zone by proper combination of process parameters plays a fundamental role in the final microstructure and mechanical properties of the joints.
CDRX modelling in friction stir welding of AA7075-T6 aluminum alloy: analytical approaches
2007
Abstract Friction stir welding (FSW) is an energy efficient and environmentally “friendly” (no fumes, noise, or sparks) welding process, during which the workpiece are welded together in a solid-state joining process at a temperature below the melting point of the workpiece material under a combination of extruding and forging. Significant microstructural evolution takes place during FSW: in particular continuous dynamic recrystallization (CDRX) phenomena result in a highly refined grain structure in the weld nugget and strongly affect the final joint resistance. In the paper two different analytical models aimed to the determination of the average grain size due to continuous dynamic recry…
Experimental and Numerical Analysis of Microstructure Evolution during Linear Friction Welding of Ti6Al4V
2015
Abstract Linear Friction Welding (LFW) is a solid state welding process used to joint bulk components. In the paper, an experimental and numerical study on LFW of Ti6Al4V titanium alloy is presented. A laboratory designed LFW machine has been used to weld the specimens with different contact pressure and oscillation frequency. The joint microstructure has been experimentally observed with SEM and EDS. A dedicated numerical model, able to predict temperature, strain and strain rate distribution as well as the phase volume fraction evolution, has been utilized to predict the final microstructure in the welded parts. It was found that complete transformation of the alpha phase into beta phase …
Influence of process parameters on the product integrity in friction stir extrusion of magnesium alloys
2016
Friction Stir Extrusion is an innovative direct-recycling technology for metal machining chips. During the process a specifically designed rotating tool is plunged into a cylindrical matrix containing the scraps to be recycled. The stirring action of the tool prompts solid bonding related phenomena allowing the back extrusion of a full dense rod. This process results to be particularly relevant because allows the reuse of the scrap without any previous treatment. Experiments have been carried out in order to investigate the influence of the process parameters on the extrudes quality and a numerical model has been developed in order to simulate the evolution of the material flow.
Numerical modelling of the linear friction welding process
2010
Linear friction welding (LFW) is a solid-state joining process applied to non-axisymmetric components. LFW involves joining of materials through the relative reciprocating motion of two components under an axial force. In such process the heat source is given by the frictional forces work decaying into heat determining a local softening of the material and proper bonding conditions due to both the temperature increase and the local pressure of the two edges to be welded. In the present work the authors present a numerical model of the linear friction welding process of AISI 1045 parts. The numerical model allowed to highlight the process mechanics and the physical conditions which must be r…
Towards Tool Path Numerical Simulation in Modified Friction Stir Spot Welding Processes
2009
Spot welding can be considered a very common joining technique in automotive and transportation industries as it permits to obtain effective lap-joints with short process times and what is more it is easily developed through robots and automated systems. Recently the Friction Stir Spot Welding (FSSW) process has been proposed as a natural evolution of the already known Friction Stir Welding (FSW) process, allowing to obtain sound spot joints that do not suffer from the insurgence of typical welding defects due to the fusion of the base material. In the paper, a modified Friction Stir Spot Welding (FSSW) process, with a spiral circular movement given to the tool after the sinking stage, is p…
Comparison between FSW and bonded lap joints - A preliminary investigation
2017
Difficult to weld aluminium alloys can be effectively joined by different alternative processes. Friction Stir Welding (FSW), among the solid-state processes and adhesive bonding represent two very attractive techniques. They allow the production of highly resistant joints avoiding the formation of the typical fusion weld defects. The aim of this work is to identify, analyse and compare the mechanical properties of AA6016 aluminium alloy joints made out of 1 mm thick sheets. FSW lap joints were and epoxy bonded joints were produced. Using the FSW results as benchmark, the overlap required in the bonded joint was identified to ensure the same static strength. Once the geometric configuration…
Metallurgical Phenomena Modelling in Friction Stir Welding of Aluminium Alloys: Analytical vs. Neural Network Based Approaches
2008
In this paper, the metallurgical phenomena occurring in friction stir welding processes of AA6082-T6 and AA7075-T6 aluminum alloys are investigated. In particular, to predict the local values of the average grain size, either a simple analytical expression depending on a few material constants or a properly trained neural network is linked to the finite element model of the process. The utilized tools, which take as inputs the local values of strain, strain rate, and temperature, were developed starting from experimental data and numerical results.