马铃薯的弹塑性力学特性试验及其损伤分析

Elastic-plastic Mechanical Characteristic Test and Damage Analysis of Potato

研究马铃薯的力学特性,可以指导马铃薯收获、加工、运输装备的设计,有效减少机械损伤。传统的研究均将马铃薯作为线弹性材料,没有发现生物屈服点。为此,切取鲜食马铃薯圆柱形试样,使用质构仪进行压缩试验,通过马铃薯的力-位移关系,发现了马铃薯的弹塑性规律;同时,计算出马铃薯破坏应力、弹性模量、切线模量和泊松比,并据此进行了损伤的有限元分析。研究结果表明:马铃薯存在生物屈服点;试样压缩力达到生物屈服点后,压缩位移与塑性变形量近似呈正比例线性关系;马铃薯在受到碰撞作用时,塑性变形主要发生在以马铃薯碰撞点为切点的内切球范围内,即马铃薯内部。研究结果符合弹塑性材料的力学特性,与现有的损伤试验结果吻合。

The study of the mechanical characteristics of potatoes can guide the design of potato harvesting,processing and transportation equipment to effectively reduce damage of potatoes.Traditionally,potato is considered as a linear elastic material and no bio-yield point.In this paper,fresh potato samples are cut as a cylindrical specimen and conducted compression tests using a Food Texture Analyzer.The elastic-plastic characteristics of potatoes is discovered through the force-displacement relationship of potato specimen.The potato failure stress,elastic modulus,tangential modulus and Poisson's ratio are calculated from the compression tests,and the finite element analysis is conducted.The results show that there is a bio-yield point in potatoes.After the compression force of the potato specimen exceeds the bio-yield point,the compression displacement and plastic deformation are approximately proportional linear relationship.When potatoes are impacted,damage is more likely to occur inside the potato and occurs mainly within the inner tangent sphere with the potato collision point as the tangent point,which is consistent with the mechanical characteristics of elastic-plastic material and with the existing damage experimental results.