1,720,990 research outputs found
Editorial Board Members’ Collection Series: Improving Structural Integrity of Metals: From Bulk to Surface
No full textFSW of AA2024: effects of tool wear on energy consumption
No full textThis study shows that the progressive adhesion of weld material to the tool in friction stir welding AA 2024-T3, up to tool saturation, brings about a decrease in power consumption until a plateau is reached. The cause of this behavior is the hindering of the stirring action of the tool due to the material accumulated on it. The built-up material changes the nature of the tool/material interaction and then the friction condition at their interface. The direct consequence is a decrease in the shearing strain and therefore in the heat generated by friction. Bits of this adhering material break off from the tool at intervals. Macro and micro detachments are identified. Micro-detachments happen continuously at small periodic intervals and produce vibrations. The amplitude of these vibrations increases in all their characteristic spectral components up to tool saturation. Macro-detachments generate oscillations in power consumption and leave galling on the weld bead
Peck drilling of CFRP/titanium stacks: effect of tool wear on hole dimensional and geometrical accuracy
No full textThe effect of tool wear on dimensional and geometrical accuracy of holes machined by peck drilling in carbon fibre reinforced plastic (CRFP) and titanium (Ti) stacks is studied. Coated and uncoated tungsten carbide drills of both fine and ultra-fine microstructures are employed to assess the importance of grain size and coating on hole accuracy. Hole profiles show two maxima: one at the hole entry and the other at the CFRP/Ti interface. Hole cylindricity as function of tool wear shows a minimum. It firstly decreases due to flank wear and subsequent reduction of the drill diameter. Then the rise of tool instability prevails with the result that an increase of the cylindricity with tool wear is brought about. Less wear-resistant drills attain this minimum in a shorter time of cutting
Scaling modelling of penetration in high productivity gas tungsten arc welding
No full textA novel semi-empirical equation in explicit form is presented for the estimation of weld penetration in high productivity Gas Tungsten Arc Welding (GTAW). The approach followed in developing the final expression is based on the methodology of scaling analysis applied to the description of the process according to the heat transfer theory. The equation developed is applicable under the condition of gouging penetration usually encountered in arc welding processes and accounts for heat absorbed by phase change, heat carried away by the molten metal, heat lost by conduction in the substrate, and the effect of penetration on arc length. The equation proposed requires as inputs: specific and latent heat, density, and solidus temperature of the substrate and welding speed, current, voltage, and stand-off distance. Welding experiments on five classes of materials (ASTM A36 structural steel, AISI 304 stainless steel, CP aluminium, AA 5083, and CP titanium) were performed to validate the model proposed under welding speed ranging from 3.9 to 19 mm/s and current going from 240 to 700 A. Predictions of penetrations calculated by the final model result in an mean percentage error of −0.87% with a standard deviation of 9.52%. The ultimate purpose of this model is to provide a simple and accurate expression useful for the selection of process parameters when using high productivity GTAW, especially to join novel alloys
Predicting Fatigue Lifetime of Glass Fibre-Reinforced Composites from Residual Strength Data
No full textIntegration of Neural Network Material Modelling into FEM Simulation Of Metal Cutting
No full textIschia (ITALY
Integration of Neural Network Material Modelling into FEM Simulation Of Metal Cutting
No full textIschia (ITALY
Dimensional errors in longitudinal turning based on the unified generalized mechanics of cutting approach. Part II: Machining process analysis and dimensional error estimate.
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