0000000000457705
AUTHOR
Antonio Barcellona
Friction stir spot welding of aluminum alloys
Material flow behaviour in the Friction Stir Spot Welding of aluminum alloys
Friction stir spot welding (FSSW) is a technological process that it allows to obtain junctions characterized by good mechanical properties and to perform them in a simple and fast way. The detailed knowledge of material flow around rotating tool, and of the microstructural evolution occurring during this process, constitute the fundamental input to realize analysis and simulation models in order to determine a optimal tool design and high structural efficiency welds. In the present research, an integrated mechanical-metallurgical-morphological analysis has been performer, to evaluate the influence of the different technological parameters on the characteristics of the joint. The experiment…
Spot friction stir welding of aluminum alloys
Numerical Model for Shape Memory Alloy Actuators
In order to realize a control system for Shape Memory Alloy (SMA) actuators, that ensure high displacement precisions, a numerical model that simulates SMA wire behavior subjected to thermo-mechanical actions, up to high number of cycles, has been set up. In particular, the constitutive model of Brinson, 1993,[1] coupled by a suitable kinetic low has been used. Beginning from such model, some corrections have been performed to take into account the deviations, in term of characteristic temperatures and mechanical responds, due to a numerous thermo-mechanical cycles. Furthermore, in order to complete and check the numerical model, experimental tests have been performed; initially the employe…
Thermo-Mechanical Characterization of Ni-Rich NiTi Shape Memory Alloy
MICROSTRUCTURAL CHARACTERISAZTION OF THERMO-MECHANICAL TREATED TRIP STEELS
The increasing demand for the reduction of automobiles CO2 emissions for environmental preservation leads the automotive industries towards the mechanical components weight reduction. Sheet steels with multiphase microstructures exhibit favourable combinations of strength and ductility. The so called TRIP steels have a metastable microstructure that consists of a continuous ferrite matrix containing a dispersion of hard second phases martensite and bainite. These steels also contain retained austenite, at room temperature, that represents the source of the TRansformation Induced Plasticity effect. When the material is subjected to deformation step, the retained austenite transforms itself i…
Process parameters analysis in friction stir welding of AA6082-T6 sheets
Effect of intercritical annealing and of isothermal bainite treatment on microstructure, mechanical and bake hardening properties of TRIP 800 steel
Artificial Neural Networks to correlate Hot Deformation Cooling Rate and Deformation Temperature on Continuous Cooling Transformation of 22MnB5 Steel
The 22MnB5 steel is a hot stamping steel developed with the aim to satisfy the increasing request of the automotive industries to apply materials able to guarantee higher passive safety and weight reduction. The hot stamping process is an innovative forming technique in which the deformations are carried out at elevated temperature and allows to achieve high strength components. The experimental characterization of the material response, at different values of the main variables of process, may result both expensive and time consuming, but the mutual effects evaluation of the deformation parameters and the phase transformations are necessary to produce components within the desired properti…
New Characterization Methodology For Shape Memory Alloys
Thermal and thermo-mechanical treatments on shape memory alloys
Pin shape effect on friction stir welding af AA6082-T6 sheets
Electro Thermo Mechanical Characterization of NiTi Actuator Wire
Material flow analysis in dissimilar friction stir welding of AA2024 and Ti6Al4V butt joints
The complex material flow occurring during the weld of dissimilar AA2024 to Ti6Al4V butt and lap joints was highlighted through a dedicated numerical model able to take into account the effects of the different materials as well as the phase transformation of the used titanium alloy.
Multi-Layer Neural Network Application For Optimization of Thixotropic Aluminum Alloy Process Parameters
Thermo-mechanical treatments on aluminum alloys for microstructure improvements
A new control parameter to predict micro-warping-induced job failure in LPBF of TI6AL4V titanium alloy
Abstract Laser powder bed fusion (LPBF) includes a few printing techniques widely used, in recent years, concerning the additive manufacturing of Ti6Al4V alloys. These produced parts, typically utilized in sectors such as aerospace and biomedical, are characterized by very high added value. It is therefore fundamental to identify the influence of process parameters typical of LPBF technology on the occurrence of warping leading to process failure. This study deals with the characterization of single-track and “micro-scale” level warping phenomena which may lead to protrusion of material over the powder bed and process failure before normal termination. This phenomenon was investigated as a …