Abstract
Understanding the characteristics of granular materials remains one of the challenges for engineering science and practice. Granular agricultural materials complicate this challenge further due to the added problems of variation in moisture content and deformability at the micro-, meso- and macro- scales. This study attempts to improve this understanding by modelling maize en masse as viscoelastic using the Maxwell-Weitchert model and establishing the viscoelastic constitutive parameters for the same.Uniaxial stress-relaxation experiments were conducted under cyclic loading conditions using the Instron uniaxial loading machine for three maize varieties at an initial bulk density of 800kg/m3. Each test was repeated three times. Experimental results were then compared to theoretical predictions under the MaxwellWeitchert conditions. The coefficient of determination R2 for Relaxation Modulus, E(t), ranged between 0.84 and 0.90 for the three maize varieties at 800kg/m3. The standard error for residual stress was 1.17, 0.95 and 1.82MPa for the three varieties, V1, V2 and V3 respectively. From these results, it was concluded that granular maize en masse can be adequately described as being viscoelastic under the Maxwell-Weichert model predictions.
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