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In this paper the extrusion process of a cross-shaped profile was investigated. In particular, the study was focused on the distortion of extruding profiles when the workpiece and die axis are not aligned. The process was simulated using the finite element method (FEM) and the natural element method (NEM), both implemented in an updated-Lagrangian formulation, in order to avoid the burden associated with the description of free surfaces in ALE or Eulerian formulations. Furthermore, an experimental equipment was developed in order to obtain reliable data in terms of deformed entity, required process load and calculated pressure. At the end, a comparison between the numerical predictions and the experimentally measured data was carried out. The main results are presented in the paper.

In the modern manufacturing scenario and, in particular, in sheet metal forming, the requirement of customised production is still growing. The introduction of incremental forming enables the production of customised components in small lots. In particular, single point incremental forming is characterised by the simplest equipment; any die, in fact, is avoided reducing the necessary tooling to a simple frame, able to clamp the sheet, and a hemispherical punch that imposes the required deformation. This tooling simplicity and the associated process mechanics, in turn, determine a sometimes relevant lack of accuracy. The paper is focused on the investigation of the influence of the process parameters on accuracy through a reliable statistical analysis. The obtained models permit to implement some effective actions to improve the accuracy taking into account a simple case study.

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 ineffective. In order to overcome such problem two different approaches are proposed in this paper. The former is based on a pure thermal simulation once the thermal flow on the tool is properly calculated. The latter, on the contrary, is based on an artificial modification of the heat transfer coefficient at the interface between the chip and the tool in the thermo-mechanical simulation. Both of the proposed methodologies are discussed in the paper, highlighting the advantages and the drawbacks of each of them.

The forming of the completed aluminium foam sandwich (AFS) panels would determine an improvement in the manufacturing of parts and panels. In this paper the authors have investigated the formability of AFS through experiments and numerical simulations. As far as the former are concerned, commercially prepared panels have been considered and bending and stamping processes have been taken into account. In addition, FEM analyses have been developed, utilizing a porous material model following the evolution of the material density throughout the forming processes.

In the paper the problem of optimal pass schedule design in multi-pass wire drawing process is investigated. An automatic design procedure based on an effective artificial intelligence (AI) technique, namely simulated annealing (SA), is proposed. The developed algorithm is aimed to achieve a satisfactory balance of the drawing stresses on the material along the reduction sequence, maintaining in the meantime the drawing stress at each pass below a safety value. In this way both the optimal number of passes and the optimal drawing sequence are determined. The effectiveness of the design procedure is tested through the comparison of the sequences suggested by the algorithm with a set of industrial sequences for wires of different materials.

The most advanced approach to the prediction of ductile fracture occurrence in metal forming processes is represented by a damage mechanics formulation. Such an approach requires a suitable evaluation of the parameters which appear in the yield condition for the damaging material and in the model which governs the evolution of microvoids (nucleation, growth and coalescence), which allow to calibrate the model with respect to the actual state and properties of the material. In the paper this aim is pursued employing an inverse identification approach based on an optimization technique which permits to adjust the material variables so that the numerical response matches the experimental one. In particular the load vs. displacement curve during a tensile test has been used to optimise the comparison between the numerical and the experimental results and to develop a full damage characterisation of the material.

Early studies of friction in cold forming of an aluminium alloy by the double cup extrusion technique are presented. The ratios between the heights of the cups, obtained by backward and forward extrusion, respectively, were related to the frictional conditions due to different lubricants by calibration curves obtained by means of a finite element analysis. The results have shown that the double cup extrusion process is strongly influenced by friction shear factor. The analysis on the investigated lubricants has shown friction shear factor values from 0.01 to 0.25. The comparison of computer simulation with experimental tests have shown excellent agreement.

The effects of metal-working temperature on the hot axisymmetric upsetting of AA 7012 aluminium alloy were investigated in the temperature range of from 250 to 400°C, at a strain rate of 4 s −1 . The material behaviour was studied by means of simulative methods based on the analysis of torsion-test results which have shown that when the strain increases, the flow stress increases to a peak value and then decreases to a fracture value. Furthermore, the flow stress decreases with decreasing strain rate and with increasing temperature. Constitutive equations, describing accurately the hot deformation behaviour of the material, were defined and used subsequently in a numerical model that allowed the coupled thermal-mechanical analysis of hot upsetting. The predictions of forging load versus ram travel and the overall shape changes of the workpiece were compared with experimental results: they were found to be in good agreement with measurements taken in laboratory experiments conducted under similar conditions.

In the present paper the isothermal forging has been computer simulated by finite element modelling in order to rationalize and optimize the process. The isothermal forging of AA 7012 aluminium alloy was investigated at temperatures ranging from 250 to 400°C, with strain rate of 0.05 s −1 . Hot workability of the material was investigated and constitutive equations were defined using torsion tests. Such equations were used in finite element modelling of isothermal forging. The numerical predictions were compared with isothermal experimental test results at the same conditions; an excellent agreement was observed.

Hot rolling processes are generally analysed by means of some simplifying hypotheses: most of the developed theories assume that the operation is conducted isothermally and that plane strain conditions occur. In the paper a full 3-D coupled thermal-mechanical analysis is carried out concerning some hot plate rolling processes in order to investigate the process mechanics: the obtained values of spread in width have been compared with some experimental data, revealing a significant predictive capability of the numerical model.

A finite element analysis has been applied to model the reverse drawing process. The influence of two different strain hardening behaviours and of some operating parameters has been investigated by means of the updated Lagrangian approach which allows taking into account large deformations and strains.