【作者】 王佳；

【导师】 李建平； 王建合；

【作者基本信息】 河北农业大学 ， 机械硕士（专业学位）， 2023， 硕士

【摘要】 苹果采摘后从果园到分拣库的短途运输是果园作业中的重要环节,针对园内果实运输过程中苹果与果筐、苹果与苹果间的碰撞损伤率高等问题,基于矮砧密植苹果园的果实采摘低损运输的要求,对具有缓冲材料的转运筐进行减损性能分析与试验,实现苹果采摘后运往分拣库损伤率低的目的。通过称重法测定了富士苹果的密度为0.862 kg/m~3,通过压缩和拉伸试验测得果皮、果肉和果核的弹性模量和破坏应力分别为11.3 MPa和0.44 MPa、3.9 MPa和0.29 MPa、6.4 MPa和0.37 MPa。利用ANSYS软件仿真分析了苹果果皮、果肉和果核的受力阈值,仿真结果表明当苹果轴向载荷大于20 N时,果皮和果肉会受到机械损伤;当苹果径向载荷大于10 N时,果皮和果肉均会收到机械损伤。以富士苹果-果筐为研究对象,缓冲材料、缓冲材料厚度和苹果排列方式为试验因素,采用单因素试验和响应面试验,分析了转运筐在模拟运输过程中苹果损伤体积和果筐底部所受压力。单因素试验结果表明,珍珠棉作为缓冲材料对苹果的保护作用最好,苹果损伤体积与果筐底部所受压力随着缓冲材料厚度的增加而减小,当排列方式为有序时苹果损伤最小。响应面试验结果表明:珍珠棉厚度为10 mm,苹果排列方式为有序时,苹果损伤体积为67.26～69.38 mm~3,苹果所受压力为10.13～10.39 N。对富士苹果进行碰撞理论分析,得到苹果损伤主要发生在苹果与果筐碰撞阶段。利用EDEM软件对苹果在有序和无序排列、不同加速度值下仿真运输车减速过程中苹果受力并进行单因素试验分析,当有序排列方式下加速度小于2.5 m/s~2时未超过苹果的损伤阈值,当无序排列方式下加速度小于2 m/s~2时未超过苹果的损伤阈值。以缓冲材料、缓冲材料厚度和苹果排列方式为试验因素,以刹车时的水平撞击力和苹果损伤体积为响应值,通过响应面试验分析得到不同速度水平下的最优缓冲组合参数为:缓冲材料为珍珠棉、缓冲材料厚度为10 mm、苹果排列方式为有序时,运输车初速度从5～20 km/h减速时水平撞击力为2.42～11.17 N,苹果损伤体积为13.27～103.97 mm~3。对不同减速过程的最优参数组合进行验证试验,苹果水平碰撞力和损伤体积的绝对误差均小于5%。在河北省顺平县苹果园基地进行了苹果采摘后从果树行间运输到分拣库的碰撞减损试验,与对照试验相比低损转运筐在最优缓冲组合参数条件下,采用低损转运筐的苹果损伤体积为40.12 mm~3;无任何保护的对照试验苹果损伤体积为184.42 mm~3。低损转运筐的减损性能好、果实损伤小,为苹果从果树行间运往分拣库的低损运输设备提供技术支撑。更多还原

【Abstract】 Short-distance transportation of apples from orchard to sorting warehouse after picking is an important link in orchard operation.Aiming at the problem of high collision damage rate between apples and fruit baskets and between apples during fruit transportation in orchard,based on the requirement of low-loss transportation for fruit picking in close-planted apple orchards with low anvil,the loss reduction performance of transfer baskets with buffer materials was analyzed and tested.The aim is to reduce the damage rate of apples after being picked and transported to the sorting warehouse.The density of Fuji apple was measured by weighing method as 0.862 kg/m~3.The elastic modulus and breaking stress of peel,pulp and core were measured by compression and tensile tests as 11.3 MPa and 0.44 MPa,3.9 MPa and 0.29 MPa,6.4 MPa and 0.37 MPa,respectively.ANSYS software was used to simulate and analyze the stress threshold of apple peel,pulp and core.The simulation results showed that when the axial load of apple was greater than 20N,the peel and pulp would suffer mechanical damage.When the radial load of apple is greater than 10 N,both the peel and pulp will be mechanically damaged.Taking Fujifilm apple basket as the research object,the buffering material,the thickness of the buffering material and the arrangement of apples as the test factors,the single factor test and response surface test were used to analyze the damage volume of apples and the pressure on the bottom of the basket during the simulated transport process.The results of single factor test showed that pearl cotton as buffer material had the best protective effect on apples.The damage volume of apples and the pressure at the bottom of fruit basket decreased with the increase of buffer material thickness,and the damage of apples was the least when the arrangement was orderly.The response surface test results show that when the thickness of pearl cotton is 10 mm and the arrangement of apples is orderly,the damage volume of apples is 67.26～69.38 mm~3 and the pressure of apples is 10.13～10.39 N.The collision theory analysis of Fuji apple shows that the damage of apple mainly occurs in the collision stage between apple and fruit basket.The EDEM software was used to simulate the force of apples in the deceleration process of transport vehicles under ordered and disordered arrangement and different acceleration values,and single factor test analysis was conducted.The damage threshold of apples was not exceeded when the acceleration was less than 2.5 m/s~2 in the ordered arrangement mode,and was not exceeded when the acceleration was less than 2 m/s~2 in the disordered arrangement mode.With buffer material,buffer material thickness and apple arrangement as test factors and horizontal impact force and apple damage volume during braking as response values,the optimal buffer combination parameters at different speed levels were obtained through response surface test analysis as follows:When the buffer material is pearl cotton,the thickness of the buffer material is 10mm and the arrangement of apples is orderly,the horizontal impact force is 2.42～11.17 N and the damage volume of apples is 13.27～103.97 mm~3 when the initial speed of the transport vehicle decelerates from 5～20 km/h.The absolute error of horizontal impact force and damage volume of apple is less than 5%.A collision loss reduction test was carried out in Shunping County apple Orchard base of Hebei Province.Compared with the control test,the damage volume of apples using low loss transfer basket was 40.12 mm~3 under the optimal buffering combination parameters.The damage volume of an apple without any protection was 184.42 mm~3.The low loss transfer basket has good loss reduction performance and little fruit damage,which provides technical support for the low loss transportation equipment of apples from the tree rows to the sorting warehouse.更多还原