MAE Seminar: “Laboratory-Scaled Experiments on Impulsively Loaded Structures in a Fluid Environment”

Thursday, October 18, 2018
2:00 - 3:00 pm
SEH, B1220

Speaker: Dr. Christine Gilbert, Virginia Polytechnic Institute and State University

Abstract

A summary of fluid-structure experiments at the laboratory scale will be presented with a focus on high-speed slamming of small craft in waves and shockwave propagation through soft materials. Slamming water impact occurs frequently on high-speed craft and restricts the operating envelope of a vessel. One approach of understanding the hydroelastic nature of this phenomena is to study the vertical impact of a V-shaped wedge on calm water, which models a single slamming event after a vessel has become partially air- borne. The dynamic structural response of the bottom plate of a wedge dropped vertically (drop height = 7.9 cm) is investigated both experimentally and computationally. The experiments were conducted with a flexible bottom V-shaped wedge. Pressure on the wedge bottom, rigid body kinematics, and full-field out-of-plane deflection were measured. The out-of-plane deflection was measured using Stereoscopic-Digital Image Correlation (S-DIC). Discussion of future experiments using the VT towing tank facility will also be discussed.

Shockwave propagation and the resulting stress wave through axons located in the brain can cause traumatic brain injury. An experimental study was conducted using scaled-up cylinders under a longitudinal impact load in both air and water. The material properties of the axons are modeled by ballistic gelatin molded into slender cylinders. Each cylinder is given an impulse to simulate an arriving shockwave and filmed with a high-speed camera at 14,000 frames per second to capture the soft material deformation. An in-house image-processing code was written to measure the surface profiles of the cylinder’s top and bottom surface waves and to track the displacement of embedded bubbles/particles to understand the internal strain field resulting from the impulse load.

Biography

Dr. Christine Gilbert (formerly Christine Ikeda) is an assistant professor in the Kevin T. Crofton Department of Aerospace and Ocean Engineering at Virginia Polytechnic Institute and State University. Dr. Gilbert received her Ph.D. from the University of Maryland in Mechanical Engineering in 2012 under the supervision of Dr. James Duncan. Dr. Gilbert was an assistant research professor at the U.S. Naval Academy from 2012 to 2014 in the Naval Architecture and Ocean Engineering Department. From 2014 to 2016, Dr. Gilbert was an assistant professor in the School of Naval Architecture and Marine Engineering at the University of New Orleans. She joined the faculty at Virginia Tech in Fall 2016. She is a 2015 ONR Young Investigator. Her research interests include experimental fluid-structure interaction as related to Ocean and Naval vessels as well as problems that involved impulsive loadings. Dr. Gilbert’s research group is currently developing new methods for performing non-traditional tow tank experiments for slamming of small craft in waves.