A Hybrid Finite Element Analysis Of Shot Peen Contour Forming Using Residual Stress Measurements

In order to develop surfaces that have the proper curvature for aerospace structures, it is sometimes necessary to use shot peen forming, also known as contour forming, to create the desired shape in a piece of metal. Since the preferred metal in aerospace continues to be aluminum and its alloys, this study will concentrate on the effects of shot peening on aluminum. Typically, shot intensity is measured using standard Almen strips made from cold rolled SAE 1070 spring steel. Since the effects of the shot on aluminum is the chief concern of this study, aluminum strips of the same size and thickness will be used to determine the intensity of the shot on aluminum parts. These strips will be exposed for different amounts of time to different intensities, measured using the steel Almen strips, and then the intensity (or arc height) will be measured on the aluminum strips. The residual stresses in these strips will then be measured using the hole drill method (ASTM E837). The stresses from the residual stress test will then be used to develop a finite element model that simulates the aluminum strips and the deformation in them. The model will then be calibrated with the empirical data. From there, it will be the goal of this study to be able to predict the deformation of aluminum parts when exposed to certain shot peen intensities. This will enable more efficient contour forming processes with less rework. Furthermore, the trial and error of a manual process can be avoided with the use of robotics. Robotics/Automation can also help in creating more consistent results.

Residual Stress, Thermomechanics& Infrared Imaging, Hybrid Techniques and Inverse Problems, Volume 9 of the Proceedings of the 2015SEM Annual Conference & Exposition on Experimental and Applied Mechanics, the ninth volume of nine from the Conference, brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on a wide range of areas, including: Inverse Methods Inverse Methods in Plasticity Varying Length Scales Harsh Environments Opto-Acoustical Methods Hybrid Experimental Residual Stress Modelling and Advances in Measurements Thermomechanics General Material Response Infrared Imaging

Residual Stress, Thermomechanics & Infrared Imaging, Hybrid Techniques and Inverse Problems, Volume 9 of the Proceedings of the 2016 SEM Annual Conference & Exposition on Experimental and Applied Mechanics, the ninth volume of ten from the Conference, brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on a wide range of areas, including: Damage Analysis from Thermal Measurements Quantitative Visualization Stress Analysis from Thermal Measurements New Approaches to Residual Stress Measurement Residual Stress & Optical Methods Non-homogeneous Parameters Identification General Inverse Methods Residual Stress Measurement by X-Ray Diffraction

Shot peening is a cold working manufacturing process designed to induce residual stresses in the surface of the treated material. Theoretical and experimental studies have demonstrated the beneficial effects of shot peening on the fatigue resistance of materials that is a result of the layer of compressive stresses produced in the treated material. Many published studies have used finite element analysis modeling of the peening process to investigate the effects of various peening input parameters on the depth and magnitude of this compressive layer. In the current study, the LS-DYNA code is used to perform 3D dynamic finite element analyses of multiple cast steel high hardness shots impacting a titanium target in an overlapping manner. In contrast to other published analyses, the current work investigates combinations of peening process parameters and their effects on residual stresses. In addition, the current study includes design of experiments to develop regression equations to predict surface stress, maximum residual stress, depth of the maximum residual stress, and the zero-crossing depth using combinations of the peening process input parameters which are shot size, shot velocity, and shot impact angle. Finite element analyses for several different shot peening input parameters are then used in a comparison of results with the regression equations to assess their applicability.

The service performance and life of metal parts are closely related to the surface integrity of materials. Shot peening (SP) is a well-known surface strengthening technique and is widely used for the improvement of the component surface integrity in industrial fields, such as aerospace,vehicle, construction machinery and etc. With the rapid development of science and technology, numerous new SP techniques have been developed from the conventional mechanical shot peening, such as the laser shock peening (LSP), ultrasonic shot peening (USP),surface mechanical attrition treatment (SMAT) and etc. Different from the other mechanical processing techniques, a considerable number of process parameters have an influence on the surface strengthening effects of shot-peened metal parts. Therefore, the selection of the SP process parameters with respect to the different metal parts has always been a challenge. With the rapid development of the computer technology, the numerical simulation has increasingly attracted the more and more attentions both from the academy and the industry. Compared to the experimental investigations, the numerical simulations are not only timesaving and economical, but also can provide an insight into the surface strengthening mechanisms of SP.

Research goal of the present monograph is the establishment of an efficient engineering approach, which will include straightforward but accurate simulation models, in order to estimate the residual stress fields of welded joints introduced during welding and their post-weld treatment with High Frequency Hammer Peening. The present subject lies on the intersection of structural engineering, material science and computational mechanics.

This book presents the proceedings of the International Conference on Residual Stresses 10 and is devoted to the prediction/modelling, evaluation, control, and application of residual stresses in engineering materials. New developments, on stress-measurement techniques, on modelling and prediction of residual stresses and on progress made in the fundamental understanding of the relation between the state of residual stress and the material properties, are highlighted. The proceedings offer an overview of the current understanding of the role of residual stresses in materials used in wide ranging application areas.

Comprehensive Materials Processing, Thirteen Volume Set provides students and professionals with a one-stop resource consolidating and enhancing the literature of the materials processing and manufacturing universe. It provides authoritative analysis of all processes, technologies, and techniques for converting industrial materials from a raw state into finished parts or products. Assisting scientists and engineers in the selection, design, and use of materials, whether in the lab or in industry, it matches the adaptive complexity of emergent materials and processing technologies. Extensive traditional article-level academic discussion of core theories and applications is supplemented by applied case studies and advanced multimedia features. Coverage encompasses the general categories of solidification, powder, deposition, and deformation processing, and includes discussion on plant and tool design, analysis and characterization of processing techniques, high-temperatures studies, and the influence of process scale on component characteristics and behavior. Authored and reviewed by world-class academic and industrial specialists in each subject field Practical tools such as integrated case studies, user-defined process schemata, and multimedia modeling and functionality Maximizes research efficiency by collating the most important and established information in one place with integrated applets linking to relevant outside sources