Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Gears are machine elements used in most engineering applications, mainly in the automotive and aerospace industries. When designing gear drives, the available standardised procedures are usually used for that purpose. However, the available computational methods are also often applied to obtain the load capacity of gears considering different fatigue design approaches (i.e. the stress-life approach, the strain-life approach and the fatigue crack growth approach). This book consists of five chapters. The first chapter introduces the reader to the fundamental magnitudes of gear drives concerning cylindrical gear pairs, bevel gear pairs, and worm gear pairs. The second chapter explains the theoretical background of the load capacity of gears; surface pitting load capacity and tooth root load capacity are described in detail. The third chapter focuses on the strength analyses of metal gears. Chapters four and five describe the strength analyses of sintered and polymer gears, including some typical practical examples.

Computational mechanics is a scientific discipline that marries physics, computers, and mathematics to emulate natural physical phenomena. It is a technology that allows scientists to study and predict the performance of various productsâ€"important for research and development in the industrialized world. This book describes current trends and future research directions in computational mechanics in areas where gaps exist in current knowledge and where major advances are crucial to continued technological developments in the United States.

The papers in this book deal with computational methods for predicting material processing defects. Using recent advances in finite strain plasticity and viscoplasticity, damage modelling, bifurcation and instability theory, fracture mechanics and computer numerical techniques, new approaches to mechanical defect analysis are proposed. Appropriate methods for explaining and avoiding the defects leading to fracture, high porosity, strain localization or undesirable geometrical imperfections are presented. In addition, some papers are devoted to new formulations and new calculation algorithms to be used for solving the forming problems. Finally, two papers deal with physical description of defects occurring in forming and cutting operations, focusing on the academic and practical interest of these topics.This is the first book to deal with the prediction of defects occurring in material forming processes; it contains much of interest from both a theoretical and a practical viewpoint.

Until recently, engineering materials could be characterized successfully using relatively simple testing procedures. As materials technology advances, interest is growing in materials possessing complex meso-, micro- and nano-structures, which to a large extent determine their physical properties and behaviour. The purposes of materials modelling are many: optimization, investigation of failure, simulation of production processes, to name but a few. Modelling and characterisation are closely intertwined, increasingly so as the complexity of the material increases. Characterisation, in essence, is the connection between the abstract material model and the real-world behaviour of the material in question. Characterisation of complex materials therefore may require a combination of experimental techniques and computation. This book publishes papers presented at the Third International Conference on Computational Methods and Experiments in Material Characterisation.Topics covered include: Composites; Ceramics; Alloys; Cements and Cement Based Materials; Biomaterials; Thin Films and Coatings; Advanced Materials; Imaging Analysis; Thermal Analysis; New Methods; Surface Chemistry, Nano Indentation; Continuum Methods; Particle Models; Damage Mechanics; Innovative Techniques; Stochastic Methods.