James D. Walker
B.S., M.A., and Ph.D. from The University of Utah
Dr. Walker is Director of the Engineering Dynamics Department of SwRI, where he oversees and manages a multi-disciplinary effort to investigate the dynamic response of materials and structures. His research is in wave propagation, plasticity, penetration mechanics, blast loading, and the dynamic response, fracture and failure of materials. He utilizes large scale numerical simulations, analytical techniques, and experiments. He wrote the chapter "Impact Modeling" in the Report of the Space Shuttle Columbia Accident Investigation Board. He is a developer of the Walker-Anderson penetration model. He is the author of Modern Impact and Penetration Mechanics (Cambridge University Press, 2021). Dr. Walker’s work includes survivability of ground vehicles, naval vessels, and spacecraft. In 2004 he was included in Popular Science’s "Brilliant 10" scientists list. He was awarded the 2005 ASME Holley Medal and the 2014 TAMEST O’Donnell Award in Technology Innovation. He received the Distinguished Scientist Award from the Hypervelocity Impact Society (HVIS) in 2024. Dr. Walker was an AIAA Distinguished Lecturer. He has taught mechanical engineering and mathematics at the graduate level at the University of Texas at San Antonio. He is a past president of the International Ballistics Society (IBS), a past president of HVIS, and is a Fellow of AIAA, a Fellow of ASME, and a Ballistics Science Fellow of the IBS.
Sidney Chocron
M.S. and Ph.D. from Polytechnic University of Madrid
Dr. Chocron has experience in low and high strain rate testing and constitutive models for ceramics, composites, metals, and foams applied to analytical and numerical computations. An emphasis of his research has been the fundamental study of ballistic fabrics (woven and nonwoven) and composites, focusing on carbon-carbon the last few years. Dr. Chocron has been active in the field for almost 30 years, most of the time in Madrid and San Antonio but performing occasional research in other centers such as University of Oxford (England), US Army Natick (Massachusetts), Technion (Israel), and UT-Austin (Texas). Dr. Chocron now heads the Computational Mechanics Section. He has coauthored 60 technical papers in peer-review journals and 100+ full papers in proceedings. After co-chairing the International Ballistics Symposium in Tarragona, Spain, he joined the International Ballistics Society in April 2007 and became Treasurer and Secretary. From 2017 to 2022 he served as the President of the Society. Dr. Chocron is Adjoint Professor at the University of Texas at San Antonio, where he teaches continuum mechanics and other classes, supervised a Ph.D. candidate and is advising other students.
Stephen R. Beissel
B.S. from The University of Washington and M.S. and Ph.D. from Northwestern University
Dr. Beissel has more than 25 years of experience as a developer of finite-element software for computational solid mechanics. His primary role has been co-developer of the EPIC code, which models the dynamic large deformations and failure of solid materials subjected to the extreme loads from high-velocity impacts and explosive detonations, and which is widely used throughout the DoD and the defense industry for the design of weapon systems and armor. Dr. Beissel has developed many of EPIC’s algorithms, including those for elements, contact boundary conditions, time integration schemes, and the ballistic responses of materials such as ceramics, fabrics, and fiber-reinforced composites. Dr. Beissel has been an active participant in the computational mechanics community, having contributed over 40 technical papers and organized symposia on computational methods for impact and penetration.
Scott A. Mullin
B.S. from The University of Texas at El Paso; and M.S. from California Institute of Technology
Mr. Mullin is a Senior Program Manager for Southwest Research Institute. Formerly, he was the Manager of the SwRI’s Ballistics and Explosives Engineering Section. He has more than 35 years of experience in impact phenomenology, penetration mechanics, explosive and ballistic sciences, scale modeling, and instrumentation. He has served as project manager and principal investigator on over 50 experimental programs at the SwRI ballistic range, where he has been responsible for design, instrumentation, data gathering, and analysis. Mr. Mullin has been actively involved in scale (similitude) modeling, applying the technique in many diverse areas of experimental design and data analysis. He is also an instructor in the SwRI short course, Scale Modeling in Engineering Dynamics.
Alexander J. Carpenter
B.S., M.S. and Ph.D. from The University of Texas at Austin
Dr. Carpenter is a Lead Engineer in the Engineering Dynamics Department at Southwest Research Institute. He performs high-rate numerical simulations, particularly of ballistic and blast events, using various Lagrangian finite element solvers and Eulerian hydrocodes. He also analyzes material characterization data obtained under a variety of conditions and stress states (e.g., tension, compression, shear, plate impact) to fit both material models and equations of state for use in simulation codes. His interests include modeling deformation and fracture of a variety of engineering materials including metals, ceramics, foams, soils, and composites. Dr. Carpenter has created novel material models for reproducing the directional failure and subsequent response of metals, ceramics, and composites which have been implemented in various numerical solvers for use in complex impact-loading problems. He has co-authored fourteen refereed journal articles and over thirty conference papers.
James T. Mathis
B.S. and M.S. in Mechanical Engineering from The University of Texas at San Antonio
Mr. Mathis is a Staff Engineer in the Ballistics and Explosives Engineering Section at Southwest Research Institute where he manages and supports experimental and computational programs involving dynamic response due to explosive blast and ballistic impact. His primary area of focus is high-speed diagnostics and customized instrumentation for dynamic events to support collection of high-quality data for analysis of impact events and validation of computational models. He utilizes his knowledge and experience in diagnostics for the proper selection, design, and application of transducers, data acquisition equipment, and post processing tools. In addition, Mr. Mathis conducts full-scale bird strike tests to develop bird-impact-resistant aerospace structures and for FAA/EASA certification tests.
Christopher Sorini
B.S. and Ph.D in Mechanical Engineering from Arizona State University
Dr. Sorini is a Research Engineer in the Computational Mechanics Section of the Engineering Dynamics Department at Southwest Research Institute. He has worked at SwRI since 2023, where he performs numerical simulations of thermomechanical deformation and material failure in support of impact physics, protection, and space systems research. He has experience with Lagrangian, Eulerian, and ALE methods and regularly uses LS-DYNA, CTH, and EPIC in his work. He has implemented user material subroutines in LS-DYNA and EPIC. His work at SwRI has involved simulating the dynamic behavior of various materials, including metals, foams, and composites. He has prior experience in multiscale modeling of composites, including polymer matrix composites under impact loading and creep in high-temperature ceramic matrix composites. Aside from a general interest in computational solid mechanics, he is interested in the use of optimization theory to automate the calibration of material constitutive models and has developed tools to do so for several viscoplasticity models, including the Johnson-Cook, Steinberg-Guinan-Lund, and Preston-Tonks-Wallace models.
Donald J. Grosch
B.S. in Mechanical Engineering from The University of Texas at San Antonio
Mr. Grosch is the Senior Manager of the Ballistics and Explosives Engineering Section. He has worked at SwRI for over 35 years. His work is mostly experimental, managing technical programs that utilize all the Department’s Ballistics and Explosive Ranges. He conducts hypervelocity impacts and other hypersonics-related research using SwRI’s two-stage light gas gun facilities. He conducts small arms ballistic tests and large caliber ballistic experiments with guns up to 50mm. Mr. Grosch also conducts explosive experiments to include the use of linear and conventional shaped charges, 155-mm artillery shells, 500-pound Mk-82 general purpose bombs, explosively formed projectiles (EFP’s), and large bare explosive charges up to 1250-pounds. Over the years, his work has supported programs with the US Army, Navy, Air Force, DARPA, NASA, the Department of Energy, and commercial firms. Mr. Grosch was the project manager of the Columbia Accident Investigation program at SwRI, in which the cause of the Space Shuttle Columbia disaster was proven to be a foam impact during launch that resulted in a hole in the wing leading edge. Mr. Grosch is a past chairman of the Aeroballistics Range Association and maintains an active role in that organization.
Or call Janet Banda at +1 210 522 2386.