AEM Seminar: Pushing the Boundaries: From Detonations to Auto-injectors
Joseph Shepherd, C.L. "Kelly" Johnson Professor, Aeronautics and Mechanical Engineering, Caltech
2:30 PM on 2017-11-03
Detonation of explosives, pressure transients in pipes, and mechanical impact. These all have in common the coupling of fluid motion and structural deformation that creates an intriguing field of study that scientists and engineers have been exploring for more than a century. Particularly challenging is the analysis of the excitation of wave motion in the structure by the "traveling load" created by pressure waves. Motivated by a wide range of technological problems, we have used laboratory experiments, numerical simulation and analytical methods to explore the rich range of phenomena occurring in these situations. Our studies have used detonation in gases and shock waves in gases or liquids to create a wide range of responses including vibration, plastic deformation, rupture, and buckling in metal, plastic and composite tubes. Our most recent work examines the mechanics of auto-injectors used for self-administering viscous drug solutions contained in prepackaged syringes. Using a combination of instrumented devices, scaled-up models and numerical simulation, we demonstrate how large pressures and associated strains in the syringes result from the transient dynamics of device operation.
Biography
Prof. Shepherd is the C. L. “Kelly” Johnson Professor of Aeronautics and Mechanical Engineering at the California Institute of Technology in Pasadena, CA. Since 2015, he has also been the Vice President for Student Affairs, and was Dean of Graduate Studies from 2009-2015. He has been on the faculty at Caltech since 1993 and served on the faculty of Rensselaer Polytechnic Institute from 1986 to 1993. Prior to that, he was a staff member at Sandia National Laboratories from 1980 to 1986. He earned his PhD in Applied Physics from Caltech in 1981, and his BS in Physics from the University of South Florida in 1976. Prof. Shepherd’s research interests are in thermodynamics, molecular processes, fluid and solid dynamics with applications to explosions, propulsion, high-speed flight and re-entry into planetary atmospheres, energy technology and medical devices. As the Vice President for Student Affairs, he oversees the operation of the co-curricular programs and student services for Caltech undergraduate and graduate students.