Search results for "Tecnologie"
showing 10 items of 1379 documents
Application of a rheological Model for Phase Transformation Prediction in Beta Processing of Titanium Alloys
2013
The paper shows a description of a numerical model able to simulate a complete forming process of Ti-6Al-4V titanium alloy that is a multi-phasic alloy composed, at room temperature, by two main different phases, namely Alpha and Beta, which evolve during both cooling and heating processes. The characterization of the material behavior concerns both the thermo-mechanical and metallurgical data in order to set a valid tri-coupled thermo-mechanical-metallurgical analysis systems taking into account the effects and interactions of all the phenomena resulting from the coupling of thermal, mechanical and metallurgical events. The numerical model was used to simulate a double numerical campaign r…
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…
A simple inverse procedure to determine heat flux on the tool in orthogonal cutting
2006
The applications of numerical simulation to machining processes have been more and more increasing in the last decade: today, a quite effective predictive capability has been reached, at least as far as global cutting variables (for instance cutting forces) are concerned. On the other hand, the capability to predict local cutting variables (i.e. stresses acting on the tool, temperature distribution, residual stresses in the machined surface) has to be furtherly improved, as well as effective experimental procedures to validate numerical results have to be developed. The aim of this paper is the proposition of an innovative approach, based on an simple inverse procedure, in order to identify…
Key factors for industrial applicability of friction stir welded t-joints of different materials
2010
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…
Material Flow in FSW of T-joints: Experimental and Numerical Analysis
2008
In the paper the authors present the results of both an experimental and a numerical campaign focused on the analysis of the occurring material flow in the FSW of T joints of aluminum alloys. In particular to investigate the metal flow experimental tests and observations has been developed utilizing a thin foil of copper as marker placed between the skin and the stringer. In this way, the actual metal flow occurring during the FSW of T-joints has been highlighted together with the real bonding surface. The acquired information is definitively useful in order to choose effective set of process parameters, improving the process mechanics and avoiding the insurgence of defects.
Shape distortion and thickness distribution during SPIF processes: experimental and numerical analysis
2011
Single Point Incremental Forming (SPIF) is a quite new sheet forming process which offers the possibility to deform complex parts without dedicated dies using only a single point tool and a standard 3-axis CNC machine. The process mechanics enables strains much higher than traditional sheet forming processes, but particular attention must be given to the final part geometrical accuracy. In this paper the capabilities of a dedicated explicit numerical model are quantitatively analyzed on pyramid-shaped parts. In particular a comparison between experimental and numerical results is reported. Three different shapes at the varying of the stamping angle were considered and the final shape was ac…
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…