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Study The Effect Of Die Corner Angle Of Equal Channel Angular Pressing (ECAP) on Cu-Zn-Al Shape Memory Alloys Processing
No full textReview of self-healing effect on Shape Memory Alloy (SMA) Structures
No full textSelf-healing has usually an emphasis on special materials that is metallic materials. When there is a minor damage, almost all biological organisms, even complex ones, have the ability to repair themselves. Recently, a novel field of materials science is constituted by self-healing in organic materials or material systems and it is rapidly expanding. These materials have a particular ability to heal themselves. The initial crack is healed to the point that upon reloading, a new crack is formed next to the original, rather than the original crack reopening. Only simple heating can reverse transformation and cause reinforcement for these cracks. The shape memory alloy wires are activated by heating the system and therefore the healing begins. Due to the heat, the wires relapse to their original shape at the shape change in martensite to austenite transition temperature. The concentration of most of the studies so far has been on polymers and ceramics and the reason is that it includes self-healing in non-metallic materials. Also, they are more convenient than including it in metallic materials. In this review paper the design principles of self-healing materials and their improvement methods are investigated
Laser-assisted bending of titanium grade-2 sheets: experimental analysis and numerical simulation
No full textExternal force laser-assisted bending of Titanium Grade-2 flat sheets to achieve sharp bending angles (>140°) with small fillet radii is herein investigated. In particular, the influence of the operational parameters, laser power, scan speed, number of passes, on bending angles and fillet radii of the metal substrates is analysed. The experimental results show that shaping of the substrates can be performed with great reliability, being springback largely minimised in broad operational ranges. Exploratory Data Analysis (EDA) allows the design of first approximation technological models and, in turn, the development of 3d processing maps. Based on the experimental findings, numerical modelling of the bending process by the Finite Element Method (FEM) through ABAQUS/Explicit software is also developed. The numerical model is found to match with great accuracy the experimental results, being it also extremely flexible and responsive to the change of the operational parameters
An artificial neural network model for laser transmission welding of biodegradable polyethylene terephthalate/polyethylene vinyl acetate (PET/PEVA) blends
No full textLaser transmission welding is a quick, easy, and viable method to join plastic materials for several industrial domains. The main challenge for manufacturers is still on how to choose the input process parameters to achieve the best joint performance. Joining between PET (polyethylene terephthalate) films does not make an exception, with quality strictly depending on laser joining parameters. The purpose of the present study is to estimate the weldability of a polymeric material couple according to their thermal and optical properties. This paper investigates an experimental study of laser transmission welding of PET 100% and PET-PEVA (polyethylene vinyl acetate) 5%, 10%, and 15% sheets by a diode laser. In the present work, laser power and scan speed were considered as operational parameters, which have a significant influence on the quality of the joint zone. Then, the influence of PEVA aliquots in PET/PEVA blends, which altered the mechanical properties, such as joining behavior, mechanical characterization, and degradation level, was analyzed. In addition, an artificial neural network model is developed to achieve the optimal laser parameters. The obtained results proved the advantage of this model, as a prediction tool, for developing laser welding parameters. [Figure not available: see fulltext.]
Optimal choice of Die in Cu-Al-Ni-Mn Shape Memory Alloys Produced Equal Channel Angular Pressing (ECAP) using FEM method
No full textStudy The Effect Of Die Corner Angle Of Equal Channel Angular Pressing (ECAP) on Cu-Al-Ni Shape Memory Alloys Processing
No full textDissimilar Laser Welding of NiTi Wires
No full textNiTi shape memory alloys are well-known due to their outstanding functional properties including superelasticity (SE) and Shape Memory Effect (SME). Laser welding is a viable technique for the joining of NiTi wires, which are employed in the design of smart structures. Joining of dissimilar wires can provide better flexibility using various alloys and, consequently, lead to multi-functional properties. However, this is really challenging due to the effect of temperature on microstructure and composition of the welded joints, since the thermal process alters the material microstructure and subsequently the transformation temperature of the heat affected area. Therefore, it is of utmost relevance to find the optimal laser operational parameters for this process. In this context, this study investigates the dissimilar laser welding of NiTi wires. The experimental investigation is based on several interconnected analyses that include optical microscopy (OM), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS) analysis. Thermal analysis by Differential scanning calorimetry (DSC) is also performed to check the matching between the thermal transition of the welded joints compared to the reference materials. Highest energy delivered during welding led to welded joints of better quality. Lastly, the identification of the optimal operational parameters of the laser welding process, such as laser power and scan speed, was found to be crucial to preserve microstructural properties of the welded wires, thermal transition temperatures and therefore avoid to affect the functionality of the materials
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