Damage characteristics and crack evolution regularity of cassava under cumulative impacts by micro-CT and discrete element method (DEM)

Le résumé fourni par la source

During post-harvest processing, storage, and transportation, repeated mechanical impacts on cassava ( Manihot esculenta ) induce the accumulation of internal microcracks, leading to accelerated decay and quality decline. Traditional macroscopic mechanical indicators are insufficient to dynamically characterize the cumulative damage evolution process under repeated impacts. This study constructed a coupled mechanical framework of the Tavares UFRJ continuous damage mechanical model and the discrete element method (DEM)-based Hertz-Mindlin with Bonding contact model. The compression tests and micro-computed tomography (CT) experiments collectively revealed the initiation, expansion, and penetration characteristics of internal cracks in cassava under 1–15 cumulative impacts. The results showed that the peak compressive force of cassava exhibited a non-linear decay trend with the increasing cumulative impact energy. The optimal model parameters were obtained, including the maximum fracture energy of 7.226 J/kg, cassava material constant of 0.639, damage accumulation coefficient of 4.863. The relative error between the simulated cracking rate (33.01%) and the Micro-CT measured cracking rate (34.90%) was only 5.42%, confirming the high accuracy of the model. Micro-CT revealed that under the influence of natural pith structure of cassava, the cracks after repeated impacts exhibited an uneven distribution with severe damage to the central pith cavity and periphery, and slight damage to the intermediate transition area, and the fracture evolution followed a three-stage pattern of initial germination-gradual expansion-local penetration. Our findings provide quantitative analysis tools and theoretical basis for assessing post-harvest mechanical damage risk, optimizing low-damage storage and transportation processes, and breeding impact-resistant cassava varieties.

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