Advances on Mechanics, Design Engineering and Manufacturing III

This open access book gathers contributions presented at the International Joint Conference on Mechanics, Design Engineering and Advanced Manufacturing (JCM 2020), held as a web conference on June 2–4, 2020. It reports on cutting-edge topics in product design and manufacturing, such as industrial methods for integrated product and process design; innovative design; and computer-aided design. Further topics covered include virtual simulation and reverse engineering; additive manufacturing; product manufacturing; engineering methods in medicine and education; representation techniques; and nautical, aeronautics and aerospace design and modeling. The book is organized into four main parts, reflecting the focus and primary themes of the conference. The contributions presented here not only provide researchers, engineers and experts in a range of industrial engineering subfields with extensive information to support their daily work; they are also intended to stimulate new research directions, advanced applications of the methods discussed and future interdisciplinary collaborations

Residual stress and fatigue crack growth life prediction in fastener holes cold-worked by uniform indentation in 2024-T351 aluminium alloy

This thesis concerns primarily the residual stress characterisation in fastener holes coldworked by a novel StressWave process, and the prediction of the fatigue crack growth under the influence of such residual stress. Aerospace 2024—T351 aluminium alloy plate of 6.35 mm thickness containing a nominal 06.35 mm hole was used. Using neutron and laboratory X-ray diffraction measurements, a large compressive residual stress was found in StressWave and split-sleeve cold-worked holes. Detailed stress mapping indicates that a StressWave hole contains a highly symmetric residual stress field with a wider compressive region. Conversely, the split-sleeve technique generates a complex asymmetric stress variation through the specimen thickness and around the hole. Independently, a comprehensive finite element study was conducted to reveal the residual stress development associated with the two distinct cold-working techniques at various stages. Favourable agreement was achieved between the experiment and simulations. The deformation mechanism associated with the cold-working process is decisive to the behaviour of the residual stress field created. The symmetric crack growth behaviour observed in StressWave specimens permits a through-thickness crack geometry to be considered. Accordingly, Green’s functions for a single crack and two symmetric cracks originating from the edge of a circular hole were developed. These solutions were verified using weight function and finite element analysis and are therefore appropriate for subsequent study of fatigue crack growth. A theoretical framework was proposed to explicate the interaction of residual stress with the superimposed loading at the crack tip, which was mathematically expounded as a function of stress intensity factor and stress ratio. This analytical framework provides a reasonable correlation between the mean stress and crack closure criteria. As a demonstration, a finite-width plate containing a centre hole with a single crack, with surface residual stress measured by X-Ray diffraction was analysed. It was revealed that for a predictive task, both the mean stress and crack closure definitions necessitate different requirements of material database and parametric definitions. Next, the fatigue testing suggested that the fatigue durability of fastener holes treated by the StressWave method generally outperformed those observed for split-sleeve samples. Prediction according to the unified theory produced encouraging results matching the experimental fatigue crack growth measurement. Detailed analysis showed that suitable parametric calibration and the appropriate use of crack models were imperative to achieve reliable prediction. Future efforts necessary for accuracy of prediction work for StressWave cold-worked holes are discussed

Advances in Bio-Inspired Robots

This book covers three major topics, specifically Biomimetic Robot Design, Mechanical System Design from Bio-Inspiration, and Bio-Inspired Analysis on A Mechanical System. The Biomimetic Robot Design part introduces research on flexible jumping robots, snake robots, and small flying robots, while the Mechanical System Design from Bio-Inspiration part introduces Bioinspired Divide-and-Conquer Design Methodology, Modular Cable-Driven Human-Like Robotic Arm andWall-Climbing Robot. Finally, in the Bio-Inspired Analysis on A Mechanical System part, research contents on the control strategy of Surgical Assistant Robot, modeling of Underwater Thruster, and optimization of Humanoid Robot are introduced

Aeronautical Engineering. A continuing bibliography, supplement 115

This bibliography lists 273 reports, articles, and other documents introduced into the NASA scientific and technical information system in October 1979