http://doras.dcu.ie/17608/1/Final_Version%2C_Review_paper.pdf

Optimization of different welding processes using statistical and numerical approaches - A reference guide

AlSi10Mg cellular lattice structures have been fabricated by selective laser melting (SLM) using a range of laser scanning speeds and powers. The as-fabricated strut size, morphology and internal porosity were investigated using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray microtomography (micro-CT) and correlated to the compressive properties of the structure. Strut diameter was found to increase monotonically with laser power while the porosity was largest at intermediate powers. Laser scanning speed was found to thicken the struts only at slow rates while the porosity was largest at intermediate speeds. High speed imaging showed the melt pool to be larger at high laser powers. Further the melt pool shape was found to vary cyclically over time, steadily growing before becoming increasingly instable and irregularly shaped before abruptly falling in size due to splashing of molten materials and the process repeating. Upon compressive loading, lattice deformation was homogeneous prior to the peak stress before falling sharply due to the creation of a (one strut wide) shear band at around 45° to the compression axis. The specific yield strength expressed as the yield stress/(yield stress of the aluminium × relative density) is not independent of processing conditions, suggesting that further improvements in properties can be achieved by process optimisation. Lattice struts failed near nodes by a mixture of ductile and brittle fracture.

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Influence of processing conditions on strut structure and compressive properties of cellular lattice structures fabricated by selective laser melting

The single weld bead geometry has critical effects on the layer thickness, surface quality, and dimensional accuracy of metallic parts in layered deposition process. The present study highlights application of a neural network and a second-order regression analysis for predicting bead geometry in robotic gas metal arc welding for rapid manufacturing. A series of experiments were carried out by applying a central composite rotatable design. The results demonstrate that not only the proposed models can predict the bead width and height with reasonable accuracy, but also the neural network model has a better performance than the second-order regression model due to its great capacity of approximating any nonlinear processes. The neural network model can efficiently be used to predict the desired bead geometry with high precision for the adaptive slicing principle in layer additive manufacturing.

Bead geometry prediction for robotic GMAW-based rapid manufacturing through a neural network and a second-order regression analysis

Hybrid Layered Manufacturing is a Rapid Manufacturing process in which the metallic object is built in layers using weld deposition. Each layer built through overlapping beads is face milled to remove the scales and scallops and ensure Z-accuracy. The formations of single beads and overlapping multiple beads are modeled in this paper. While the individual bead's geometry is influenced by the size of the filler wire and the speeds of the wire and torch, the step over increment between the consecutive beads additionally comes into the picture for the multiple bead deposition. These models were validated experimentally. They are useful not only to predict the bead's shape but also to optimize the three process parameters.

Weld bead modeling and process optimization in Hybrid Layered Manufacturing

Artificial neural network modeling of weld joint strength prediction of a pulsed metal inert gas welding process using arc signals

Prediction of weld bead geometry and penetration in shielded metal-arc welding using artificial neural networks

The chapter aims to briefly discuss the various stages of the medical device development life cycle, beginning with the conceptualization stage through the engineering design and development, design validations and verification, and preclinical and clinical strategies, followed by the regulatory approval processes in India, Europe, and the United States. 

Overview of medical device development

List of contributors

Thermo regulated infant warming wrapper with infrared light emitting diodes for prevention of hypothermia in preterm low birth weight babies

Thin sheets of phosphor bronze are utilized for the manufacturing of a number of small components used in electrical and electronics products. The prevailing joining methods pose restrictions on their applicability and are less supportive of the environment due to the formation of the by-products. Ultrasonic metal welding can bridge this gap owing to its numerous unique features. The present study is executed to explore the ultrasonic weldability of thin phosphor bronze sheets. The experiments are performed according to the Box–Behnken design of the response surface method to investigate the effect of major parameters on the responses such as tensile–shear load, weld area, and interface temperature. The weightage of the parameters and their mutual interaction is analyzed by ANOVA and response surfaces. Two different approaches have been employed to calculate the weld area, and a fairly good correlation of weld area is observed with the weld strength. A regression model has been developed to predict the weld strength, and the parameters are optimized using the simulated annealing algorithm. Further, a study related to the mechanical, thermal, and microstructural characterization of the joint has revealed some more interesting findings of the process and its utility for the applications. Finally, it is concluded that phosphor bronze is a perfect candidate for ultrasonic metal welding. The process can produce sound, flawless, and sufficiently strong joints within the prescribed range of the parameters. 

D.S. Nagesh

Papers

Prediction of weld bead geometry and penetration in shielded metal-arc welding using artificial neural networks

Overview of medical device development

List of contributors

Thermo regulated infant warming wrapper with infrared light emitting diodes for prevention of hypothermia in preterm low birth weight babies

Ultrasonic Metal Welding: A Novel Joining Technique for Phosphor Bronze Sheets