Mitigation of shock loading on structures using aqueous methylcellulose solution

Abstract

Shock mitigation performance of aqueous methylcellulose hydrogel and water for structural applications was investigated through two dynamic loading instruments: Instrumented bar and shock tube. While aqueous methylcellulose solutions have previously been found to attenuate impact-induced forces passing through them by a unique liquid-to-solid phase transition, this is the first time studied as shock mitigators to structural elements. The results obtained with aqueous methylcellulose as mitigator were compared with an equivalent experiment conducted with water as damping medium. The liquid was loaded into a specially designed hollow aluminum box, built to allow transmission of dynamic stress waves to a thin back plate. Determination of the liquid's attenuation performance was based on the 3D Digital Image Correlation technique with high-speed photography to obtain the full-field real-time deformation data of the back-face plate throughout the dynamic loading event. It was found that upon high rate loading with the instrumented bar, the aqueous methylcellulose solution decreases the maximum out of plane displacement resulting from the dynamic loading by as much as 40% compared to water, and significantly damps the structural vibrations of the back-face plate. On the other hand, upon relatively low rate loading with shock tubes, water and aqueous methylcellulose solutions provide the same magnitude of out of plane displacement, however, the damping ratio (Logarithmic Decrement) of the structure through aqueous methylcellulose solutions is 45% greater than through water. The findings are analyzed and rationalized in terms of imparted mechanical power.