Papers by Author: Vincenzo Tagliaferri

Abstract: The aim of this paper is to investigate the behaviour in terms of drilling forces and roughness of Metal Matrix Composites (MMC) in hot drilling machining. In particular, Al2009/(SiC)_w, Al6061/(SiC)_w, and Al6061(Al₂O₃)_p metal matrix composites were used, and the adopted temperature were in the range 20°C-160°C. A comparison with drilling at room temperature has been discussed. The results have shown the sensible influence of the working temperature on drilling forces and on surface material properties. In the case of Al2009/(SiC)_w a minimum in the drilling forces has been found, making possible the dry machining and improving the cutting conditions. Instead, for Al6061/(SiC)_W and Al6061(Al₂O₃)_p in the used temperature range no minimum appears.

Abstract: A process innovation is proposed by the authors to weld aluminum alloy tubes by means of a high power diode laser. In order to make the temperature profile uniform along the entire welding line, multiple passes of the laser source along the welding path can be performed at very high scan speeds. In the current study, this effect is achieved by focusing the standstill laser spot on the external surface of the aluminum alloy tubes which were put in rotation at high speed. The tubes were clamped together by using a threaded rod passing inside the tubes. Experimental tests were performed by changing the aluminum alloy heat treatment (6060 T1 and 6060 T5), the length of the samples to weld (80 and 100 mm), and the laser power (ranging from 800 to 950 W). The outer diameter of the tube was 10 mm, the thickness was 1 mm, and the rotational speed was kept constant at 1000 rpm. The welding time was monitored during the tests and ranged from 30 to 100 s in dependence on the material and process parameters. Specimens were extracted from the joints to perform tensile tests so as to measure the tensile strength. In the best condition, a high tensile strength was obtained (about 140 MPa).

Abstract: In this paper a neural network approach is used to model the diode laser assisted forming process. In particular thin sheets of Aluminum alloy AA 6082 were bended in the elastic range and then treated with a diode laser with the aim to reduce the spring back phenomenon. Experimental tests were performed to study the influence of the process parameters such as laser power, laser speed and starting elastic deformation on the evolution of forming process. In particular the heating effects on the elastic properties of the material was studied. A statistical approach is used to define the experimental plan and discuss the experimental results. Interesting trend of the effects of the diode laser on the forming process were found. Subsequently in order to predict the residual inflexion, during the laser forming, a multilayer feedforward artificial neural network has been implemented. A sensitivity analysis on the artificial neural network model is used to show the significance of all the input data employed. As a result of sensitivity analysis, a check between experimental and calculated trends for each investigated variables was performed, which revealed an appreciable fit between data displayed.

Abstract: This paper deals with a definition of a relatively novel technique to improve the fatigue behavior of high strength aluminum alloys, namely, Fluidized Bed Peening (FBP). Fatigue samples made from AA 6082 T6 alloy were chosen according to ASTM regulation about rotating bending fatigue test and, subsequently, treated by varying FBP operational parameters and fatigue testing conditions. First, a full factorial experimental plan was performed to assess the trend of number of cycles to rupture of fatigue samples varying among several experimental levels the factors peening time and maximum amplitude of alternating stress applied to fatigue samples during rotating bending fatigue tests. Second, design of experiment (DOE) technique was used to analyze the influence of FBP operational parameters on fatigue life of AA 6082 T6 alloy. Finally, ruptures of FB treated samples and untreated samples were discussed in order to evaluate the influence of operational parameters on the effectiveness of FBP process and to understand the leading process mechanisms. At any rate, the fatigue behavior of processed components was found to be significantly improved, thereby proving the suitability of FBP process as alternative mechanical technique to enhance fatigue life of components made from high strength aluminum alloy.