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The potential for use of Hydrogen fuel in aviation and ground transportation industry is growing, and along with it, the need for light-weight tanks to store liquid & sub-cooled hydrogen. Fiber-reinforced composite materials, especially, carbon-fiber composites, are widely used in aerospace industry and have replaced Aluminum, Steel and in some cases Titanium in aircraft and engine components. However, the use of composites in cryogenic applications for aviation and ground transport has started to gather interest only recently. Unique challenges exist for composite structures and materials under cryogenic conditions, in aviation and ground transport, given the long length of service, lasting years.
The RTX Technologies Research Center (RTRC) is designing and manufacturing a tank to store liquid Hydrogen (LH2) for heavy duty ground transport applications [1], through a DOE-HFTO program. This is a dual-tank concept, with an inner tank storing liquid Hydrogen under pressure, and an outer tank at atmospheric pressure. The final design follows a conformal geometry allowing for increased usage of cubic space with a largely circular tank geometry. A preliminary test article of this tank involves a cylindrical geometry. This paper describes the thermo-structural response of this cylindrical tank under pressure and thermal loading.
The inner tank, holding liquid hydrogen under pressure, is made out of carbon-fiber composite. A finite element (FE) model of the entire composite tank is set up in the commercial finite element software Abaqus [2] to assess thermal stresses in composite, which arise due to a thermal mis-match between the fiber and polymer, and also due to directional structural properties of individual plies in a composite. The inner tank is modeled with continuum shell and solid elements. A continuum damage criterion is applied to capture intra-ply damage. Inter-ply delamination is captured via the use of cohesive zone elements [3]. The applied load consists of a thermal cool-down to 20K, followed by a internal pressure in the tank. Composites are susceptible to micro-cracking due to cooling and this study examines the propensity for, and location of resulting damage. A localized model of the tank-boss interface with 3D hexahedral elements to capture stresses in more detail is set up. Stresses due to cooling from room temperature to 20K are modeled. Locations of highest stresses and the margin of safety is assessed from the analysis, permitting an assessment of the structural failure modes of the tank.
- R K Ahluwalia, H.-S. Roh, J.-K. Peng, D. Papadias, A.R. Baird, E.S.Hecht, B.D. Ehrhart, A. Muna, J.A. Ronevich, C. Houchins, N.J. Killingsworth, S.C. Aceves; “Liquid hydrogen storage system for heavy duty trucks: Configuration, performance, cost, and safety,” IJHE, 48-35 (2023) 13308-13323
- ABAQUS/Standard User's Manual, Dassault Systèmes Simulia Inc., 2023
- S. R. Voleti, Prabhakar M. Rao and M. Periera “Impact response of thermoplastic composites – Experiments and modeling”, Journal of Composite Materials, https://doi.org/10.1177/00219983241304688, 2024
