鲜枣应力松弛特性试验及虚拟样机仿真分析
Stress relaxation properties test and virtual prototype simulation for fresh jujube

为预测鲜枣在特定应变状态下的机械响应，减少其机械损伤和结构缺陷，以甘肃省敦煌市产鸣山大枣整果为研究对象，进行应力松弛试验，并对其应力松弛特性进行仿真分析。通过试验获得横向、纵向及常变形量为2 mm、3 mm时的应力-时间关系曲线和松弛特性数学模型，并应用ADAMS建立鲜枣动力学仿真模型。研究结果表明：鲜枣的应力松弛特性可用三元件Maxwell模型描述，相关系数R2>0.95；鲜枣纵向压缩的松弛应力任意时刻都大于横向压缩，且压缩变形量越大，平衡应力越大；松弛特性参数弹性模量之间和松弛时间之间都具有显著的相关性；鲜枣纵向受压松弛仿真值与试验值最大偏差为9.0%，验证了仿真数值解的正确性。
The stress relaxation experiment and the simulation analysis of the stress relaxation properties of jujube from Dunhuang Mingshan,Gansu were carried out in order to predict the mechanical response of fresh jujube in particular strain state and to reduce the mechanical damage and structural defects.The stress-time relation curve and mathematical model of relaxation characteristics in different compression direction (horizontal and vertical) and deformation (2 and 3 mm) were obtained through tests,and the dynamics simulation model of fresh jujube was set up using ADAMS.The stress relaxation properties of fresh jujube could be described using three components available Maxwell model,which correlation coefficient reached more than 0.95.The stress relaxation of longitudinal compression with fresh jujube in any time was greater than lateral compression,and the greater the stress compression deformation,the greater the balanced stress.The relaxation parameter included elastic modulus and relaxation time,and each had a significant correlation between these two parameters.The maximum deviation between relaxation test value and simulation value was 9.0% under longitudinal compression of fresh jujube,which verified the accuracy of simulation values.