THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Additive manufacturing of metallic components – Process, structure and properties

Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.

Additive manufacturing (3D printing): A review of materials, methods, applications and challenges

This paper reviews the state-of-the-art of an important, rapidly emerging, manufacturing technology that is alternatively called additive manufacturing (AM), direct digital manufacturing, free form fabrication, or 3D printing, etc. A broad contextual overview of metallic AM is provided. AM has the potential to revolutionize the global parts manufacturing and logistics landscape. It enables distributed manufacturing and the productions of parts-on-demand while offering the potential to reduce cost, energy consumption, and carbon footprint. This paper explores the material science, processes, and business consideration associated with achieving these performance gains. It is concluded that a paradigm shift is required in order to fully exploit AM potential.

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Metal Additive Manufacturing: A Review

Recent advances in friction-stir welding : Process, weldment structure and properties

Hybrid modelling of the contact gap conductance heat transfer in welding process

Design of an empirical process model and algorithm for the Tungsten Inert Gas wire+arc additive manufacture of TI-6AL-4V components

Effect of Hot Isostatic Pressing and heat treatments on porosity of Wire Arc Additive Manufactured Al 2319

Shielding gas nozzle diameter variation and its impact on the anodic power distribution of low-current tungsten inert gas arcs were investigated, while maintaining either shielding gas flow rate or flow velocity constant. In addition, the effects of anode surface condition and flow behaviour type (laminar or turbulent) caused by the shielding gas nozzle applied were studied. It was found that arcs of 50 amperes (A) welding current were highly unstable deploying the conditions used, while increasing the arc electrical current to 100 A led to improved arc stability. As found in previous investigations, non-Gaussian distribution profiles occurred at 50 A, even with improved shielding. The power density maxima were found shifted away from the arc axis.

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Influence of shielding gas nozzle design on power density distribution in low-current TIG welding arcs

Split anode calorimetry investigations of tungsten inert gas (TIG) arcs were conducted using a large-diameter shielding gas nozzle. Some conditions displayed arc symmetry whilst others proved distinctly asymmetric. The variation of welding current and electrode tip to workpiece distance (ETWD) was studied. Decreasing the ETWD was found to increase the current density towards the arc axis but similar to a previous study of the authors, Gaussian distributions were not observed. The gas nozzle was designed to produce laminar gas flow and sound shielding behaviour; however, anode surface oxidation was found after welding, presumably caused by shielding gas contaminated with oxygen through the welding sequence. Therefore, axial arc symmetry was influenced by random effects. The conditions and reasons for the observed phenomena are explored within this paper.

/pdf/arc-instabilities-during-split-anode-calorimetry-with-the-3wt1pwq6t6.pdf

Paul A. Colegrove

Papers

Hybrid modelling of the contact gap conductance heat transfer in welding process

Design of an empirical process model and algorithm for the Tungsten Inert Gas wire+arc additive manufacture of TI-6AL-4V components

Effect of Hot Isostatic Pressing and heat treatments on porosity of Wire Arc Additive Manufactured Al 2319

Influence of shielding gas nozzle design on power density distribution in low-current TIG welding arcs

Arc instabilities during split anode calorimetry with the TIG welding process