基于接触力学的蓝莓裹膜包装损伤机理及机构优化研究

Blueberries are soft and easily damaged, and expensive to pack artificially. When using the universal wrapping machine for fresh fruits and vegetables, the static pressure damage is serious and the shelf life is short as well. The static pressure damage of blueberry under the coupling of multi-layer stacking and packaging mechanism belongs to the non-linear problem of contact, slip and large deformation. It is necessary to apply contact mechanics to study the damage mechanism of blueberry in order to solve the problem of easy damage in mechanized packaging process. Based on this, the applicant intends to study the damage mechanism and mechanism optimization of blueberry wrapping based on contact mechanics. The specific research contents are as follows: Firstly, based on the biomechanical characteristics of blueberry, the non-linear constitutive mechanical model of multi-layer stacking caused by blueberry contact will be established to reveal the static pressure damage mechanism of blueberry multi-layer stacking. Secondly, the electromechanical integration testing system of longitudinal and transverse sealing mechanisms of blueberry packaging will be designed and constructed. We will obtain the spatial attitude change law and blueberry damage expression under the synergistic coupling of multi-components of packaging mechanism and the relationship between them. Furthermore, we will clarify the damage mechanism of blueberry under the synergistic coupling of packaging mechanism. And the design parameters and control theory of key mechanism for low-loss/non-destructive wrapping of multi-layer stacked blueberry will also be determined. Last but not least, the storage dynamics model of mechanized packaging blueberry will be established to evaluate shelf life. The research results will provide theoretical basis and technical support for the development and application of low-loss/non-destructive blueberry packaging machinery, further promoting the mechanization of blueberry packaging and the development of comprehensive quality of blueberry industry.

蓝莓柔软且易损伤，人工包装价格高昂，使用通用型果蔬裹膜装备包装时，静压损伤严重货架期短。蓝莓多层堆叠及包装机构耦合下的静压损伤属于接触、滑移、大变形的非线性问题，需应用接触力学对其损伤机理展开研究，以解决蓝莓在机械化包装过程中易损伤的难题。基于此，申请人拟进行基于接触力学的蓝莓裹膜包装损伤机理及机构优化的研究，研究内容为：基于蓝莓生物力学特性，建立蓝莓接触引起的多层堆叠非线性本构力学模型，揭示蓝莓多层堆叠静压损伤力学机理；设计包装机构机电一体化测试系统，得出包装机构多部件协同耦合作用下的空间姿态运动变化规律与蓝莓损伤表达形式以及两者之间的关系，阐明包装机构协同耦合作用下蓝莓损伤机理，确定多层堆叠蓝莓低损/无损裹膜包装关键机构设计参数及其控制理论；建立机械化包装蓝莓贮藏动力学模型，评估货架期。本项目研究成果将为低损/无损蓝莓包装机械的研发应用提供理论支撑，促进蓝莓产业收储运综合品质提升发展。

中国是全球第一大蓝莓生产国，其中蓝莓种植面积和产量均为世界第一。然而蓝莓果实柔软，机械化裹膜包装时因果实自身力学特性易造成静压损伤，阻碍了蓝莓产业的发展。因此，本项目开展基于接触力学的蓝莓裹膜包装损伤机理及机构优化研究，提出了多层堆叠蓝莓裹膜包装低损/无损抑制策略，以期提升蓝莓包装品质。.首先采用近红外高光谱反射成像对蓝莓瘀伤进行准确检测，获得了损伤率并建立了蓝莓损伤评价标准，将蓝莓静压损伤分为四个等级。以蓝莓单颗果实生物力学为基础，通过压缩试验和理论计算，首次获得了蓝莓的精确力学参数，弹性模量为0.225MPa，泊松比为0.35，利用有限元搭建了单颗蓝莓果实不规则弹性体模型。通过多层堆叠蓝莓静压试验获得了蓝莓力学本构关系，建立了蓝莓接触引起的多层堆叠非线性本构力学模型，同时结合有限元仿真，分析了载荷分布规律与静压损伤特性。为了研究多包装机构协同耦合作用下多层堆叠蓝莓裹膜包装损伤机理，设计了气力式横封装置和夹持卧带式供送成型装置等关键机构，并对机构进行了动力学分析，同时利用仿真软件和样机试验对关键部件进行了结构参数优化，搭建了蓝莓自动包装试验台，阐明了包装机构协同耦合作用下蓝莓损伤机制，确定了多层堆叠蓝莓低损/无损裹膜包装关键机构设计参数及其控制方法。最后通过机械化包装蓝莓货架期品质和动力学模型研究，评估了包装后蓝莓品质，为机械化裹膜包装蓝莓的贮藏提供理论依据。.项目研究成果揭示了蓝莓堆叠损伤力学机理，为其他类似浆果的堆叠损伤问题研究提供了理论基础；同时耦合包装关键机构运动与力学参数，形成了具有自主知识产权的蓝莓低损/无损包装技术与装备；本项目成果对提升蓝莓收储运综合品质，促进蓝莓产业发展具有一定的推动作用。