Synthesis / SEM Lectures on Experimental Mechanics – serie

This book describes the theory and practice of the Hole-Drilling Method for measuring residual stresses in engineering components. Such measurements are important because residual stresses have a "hidden" character because they exist locked-in within a material, independent of any external load. These stresses are typically created during component manufacture, for example, during welding, casting, or forming. Because of their hidden nature, residual stresses are difficult to measure and consequently are often ignored. However, they directly add to loading stresses and can cause catastrophic failure if not properly included during engineering design. Thus, there is an urgent need to be able to identify and measure residual stresses conveniently and reliably.The Hole-Drilling Method provides an adaptable and well-proven method for measuring residual stresses in a wide range of materials and component types. It is convenient to use and gives reliable results. Because of the hidden nature of residual stresses, the measurement method must necessarily be indirect, thus, additional care and conceptual understanding are necessary to achieve successful results. This book provides a practical introduction to the Hole-Drilling Method, starting from its historical roots and going on to focus on its modern practice. The various chapters describe the nature of residual stresses, the principle of hole-drilling measurements, procedures and guidance on how to make successful measurements, and effective mathematical procedures for stress computation and analysis. The book is intended for practitioners who need to make residual stress measurements either occasionally or routinely, for practicing engineers, for researchers, and for graduate engineering and science students.

The field of Experimental Mechanics has evolved substantially over the past 100 years. In the early years, the field was primarily comprised of applied physicists, civil engineers, railroad engineers, and mechanical engineers. The field defined itself by those who invented, developed, and refined experimental tools and techniques, based on the latest technologies available, to better understand the fundamental mechanics of materials and structures used to design many aspects of our everyday life. What the early experimental mechanician measured, observed, and evaluated were things like stress, strain, fracture, and fatigue, to name a few, which remain fundamental to the field today.This book guides you through a chronology of the formation of the Society for Experimental Mechanics, and its ensuing evolution. The Society was founded in 1935 by a very small group of individuals that understood the value of creating a common forum for people working in the field of Applied Mechanics of Solids, where extensive theoretical developments needed the input of experimental validation. A community of individuals who—through research, applications, sharp discussion of ideas—could fulfill the needs of a nation rapidly evolving in the technological field. The founders defined, influenced, and grew the field of what we now call Experimental Mechanics. Written as a narrative, the author describes, based on input from numerous individuals and personal experiences, the evolution of the New England Photoelasticity Conference to what we know today as the Society for Experimental Mechanics (SEM). The narrative is the author's perspective that invites members of the Society to contribute to the story by adding names of individuals, institutions, and technologies that have defined the Society over the past 75 years.Many of the key individuals who greatly influenced the advancement of the field of Experimental Mechanics are mentioned. These individuals are, in many ways, the founders of the field who have written textbooks, brought their teaching leadership and experiences to the classroom, worked on the Apollo project, and invented testing, evaluation, and measurement equipment that have shaped the fields of engineering. SEM's international membership is highly represented by those in academia, as you will read, although there has always been a powerful balance and contribution from industry and research organizations across the globe.The role of the experimental mechanician is defined, in many ways, through the individual legacies shared in the following pages….legacies that define the past and create the foundation for what is now and what is to come.

This book is designed to provide lecture notes (theory) and experimental design of major concepts typically taught in most Mechanics of Materials courses in a sophomore- or junior-level Mechanical or Civil Engineering curriculum. Several essential concepts that engineers encounter in practice, such as statistical data treatment, uncertainty analysis, and Monte Carlo simulations, are incorporated into the experiments where applicable, and will become integral to each laboratory assignment. Use of common strain (stress) measurement techniques, such as strain gages, are emphasized. Application of basic electrical circuits, such as Wheatstone bridge for strain measurement, and use of load cells, accelerometers, etc., are employed in experiments. Stress analysis under commonly applied loads such as axial loading (compression and tension), shear loading, flexural loading (cantilever and four-point bending), impact loading, adhesive strength, creep, etc., are covered. LabVIEW software with relevant data acquisition (DAQ) system is used for all experiments. Two final projects each spanning 2-3 weeks are included: (i) flexural loading with stress intensity factor determination and (ii) dynamic stress wave propagation in a slender rod and determination of the stress-strain curves at high strain rates.The book provides theoretical concepts that are pertinent to each laboratory experiment and prelab assignment that a student should complete to prepare for the laboratory. Instructions for securing off-the-shelf components to design each experiment and their assembly (with figures) are provided. Calibration procedure is emphasized whenever students assemble components or design experiments. Detailed instructions for conducting experiments and table format for data gathering are provided. Each lab assignment has a set of questions to be answered upon completion of experiment and data analysis. Lecture notes provide detailed instructions on how to use LabVIEW software for data gathering during the experiment and conduct data analysis.

The inelastic response and residual mechanical properties acquired from most shock compressed solids are quite different from those acquired from quasi-static or moderate strain rates. For instance, the residual hardness of many shock compressed metals has been found to be considerably lower than those loaded under quasi-static conditions to the same maximum stress. However, the residual hardness of shock compressed metals is much higher than those loaded quasi-statically to the same total strain. These observations suggest that the deformation mechanisms active during inelastic deformation under shock compression and quasi-static or moderate rates may be quite different. Therefore, the primary objective of this short book is to offer the reader a concise introduction on the Structure-Property Relationships concerning shock compressed metals and metallic alloys via shock recovery experiments.The first phase of the book, chapters 1 through 3 provides a brief historical perspective on the structure-property relationships as it pertains to shock compression science, then plastic deformation in shock compressed metals and metallic alloys is described in terms of deformation slip, deformation twinning, and their consequences to spall failure. Existing knowledge gaps and limitations on shock recovery experiments are also discussed. The fundamentals of shock wave propagation in condensed media are presented through the formation and stability of shock waves, then how they are treated using the Rankine-Hugoniot jump relations derived from the conservation of mass, momentum, and energy. The equation of states which govern the thermodynamic transition of a material from the unshock state to the shock state is briefly described and the elastic-plastic behavior of shock compressed solids is presented at the back end of the first phase of this book. The second phase of the book describes the geometry and design of shock recovery experiments using explosives, gas and powder guns. Then results derived from the residual mechanical properties, microstructure changes, and spall failure mechanisms in shock compressed metals and metallic alloys with FCC, BCC, and HCP crystal lattice structures are presented. Also, results on the residual microstructure of explosively compacted powders and powder mixtures are presented. Lastly, the book closes with the new frontiers in shock recovery experiments based on novel materials, novel microscopes, novel mechanical processing techniques, and novel time-resolved in-situ XRD shock experiments.