<p>Hydrogen is an environmentally friendly alternative to fossil fuels; its only combustion byproduct is water. Demand for hydrogen fuel is increasing exponentially in many industries, including the transportation sector. Due to its large availability and an excellent source of clean energy, hydrogen is being used in many applications. Hydrogen gas can be produced with zero carbon footprint by using renewable electricity to electrolyze water. Unlike electricity, this “green hydrogen” can be very efficiently stored for later use. The most economical and easiest way to store the hydrogen used as fuel is storing hydrogen gas under high pressure. However, the materials used in the infrastructure of hydrogen storage and distribution systems are vulnerable because of exposure to high-pressure hydrogen can lead to mechanical damage and property degradation. Metals form brittle hydrides when exposed to hydrogen, which can lead to crack formation. Some materials, such as polymers, are chemically inert to hydrogen but can undergo mechanical failure due to a phenomenon wherein hydrogen gas diffuses through the polymer chains and occupies preexisting cavities or voids inside the polymer material. If the hydrogen gas pressure is reduced more quickly than hydrogen can diffuse back out of the polymer (which is necessary for some applications), the trapped hydrogen gas instead escapes by rupturing the material, causing surface blistering or permanent damage. This is commonly referred to as rapid decompression failure (RDF) or explosive decompression failure (XDF).</p><p>In this study, simulations on a micro-scale are performed to obtain the damage criterion for macro-scale simulations. The hyperelastic material model, along with the maximum principal strain failure theory, was chosen for this study as it represents the nonlinear material response with brittle failure observed in uniaxial tensile tests perfectly. A continuum mechanics-based fully coupled diffusion-deformation model with a damage is then developed to predict the stress distribution and damage propagation while the polymer undergoes rapid decompression failure. Simulations were performed using the finite element method (FEM). The simulation results are also compared with the experimental observations to examine the validity of the modeling.&nbsp; EPDM polymer was chosen for study because of its commercial availability and common use in&nbsp;hydrogen storage and distribution system. It has superior mechanical properties, high heat resistance, and a&nbsp; chemically inert nature towards hydrogen gas. Two additional variants of pure EPDM were also studied to understand the effect of adding carbon black fillers and plasticizer to the damage evolution in the EPDM polymer.&nbsp;</p>

A Fully Coupled Diffusion-Deformation Model With Damage for Polymers

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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