Experimental, Numerical, and Analytical Studies of Stress and Displacement in Full-Scale Beds of Activated Alumina Granular Material for Space Life-Support Systems

Abstract

Granular beds made of activated alumina and magnesium oxide used for recycling/processing water in space life-support systems are usually compressed using a spring mechanism for effective functioning. The spring force is a critical factor in providing appropriate compaction to the entire length of the granular bed, and therefore, it is important to investigate and predict the axial stress and displacement along the bed. This paper presents results from experimental, numerical (finite-element), and analytical models of a full-scale dry granular material bed of activated alumina packed in a cylinder. The finite-element (FE) model, when used with proper contact model and properties, predicted both the axial stress and the displacement along the length of the granular bed well. Janssen’s one-dimensional model did not provide as accurate predictions for stress because of simplifications associated with the model. Because the system is long and slender, it is very important to properly model the wall friction in predicting the behavior of the granular bed. All the assessments used in this study indicated that the axial stress decays very steeply along the bed.