Identification And Numerical Characterization Of Static Pressure Damage Of Korla Fragrant Pear Based On Electrical Characteristics

Korla fragrant pears have thin skin and crisp flesh and rich juices.They are characteristic agricultural products of Xinjiang.However,Xinjiang is located in the northwestern border of my country,and it is inevitable to suffer static pressure damage in a series of links from picking at the origin to sales in the interior.After the fruit is damaged by static pressure and the tissue cells are ruptured,it is very easy to be infected by pathogens,causing the fragrant pear to rot,and the quality of the fruit is reduced.Therefore,reducing the static pressure damage of fragrant pear can greatly reduce the economic loss of farmers.For this reason,this article takes Korla fragrant pears as the research object.First,a non-destructive testing system is designed.The system is used for weighing and measuring electrical characteristics.Secondly,it explores the mechanical properties of fragrant pears during the picking period,the change rule of damage area,and the microstructure.The rupture of damaged cells in Xiaxiang pear.This part of the research helps to reveal the cause of fragrant pear hydrostatic damage and provides a theoretical reference for reducing fragrant pear hydrostatic damage;then establish a quantitative evaluation method of fragrant pear static pressure damage area based on electrical characteristics Realize fast,simple and accurate screening of fragrant pears damaged by static pressure;finally,use the finite element method to simulate the static pressure damage process of fragrant pears,simulate and predict the static pressure damage area of fragrant pears,and quantify the static pressure damage area of fragrant pears based on electrical characteristics The evaluation methods were compared,and the optimal evaluation method to quantify the static pressure damage area of fragrant pear was proposed.The main conclusions of the study are as follows:(1)During the picking period,the mechanical parameters of the fruit all decrease with the increase of the picking period.During the picking period,the limit yield strength of the fruit varies from 53.8 N to 148.37 N,and the deformation energy varies from 51.12 N?mm to 322.52 N.?mm,the limit destructive force varies from 78.28 N to 209.91 N,and the destructive energy varies from 96.91N·mm to 693.1 N·mm.During the picking period,the static pressure damage area of the fruit increased with the increase of the amount of deformation.During the picking period,the overall hardness of the fruit showed a downward trend.According to the decline rate of the fruit hardness curve,the picking period could be from September 1st to September 9,September 9th to September21,and September 21th to September 29th.It is divided into three stages:Ⅰ,Ⅱ,andⅢ.When picking fragrant pears at stage I and stage III,the fruit is affected by static pressure damage and fluctuates less.When picking fragrant pears at stage II,the fruit is affected by static pressure damage.More economic losses.(2)During the picking period,the parallel equivalent resistance Rp and complex impedance Z of the fragrant pears damaged by static pressure are both smaller than the Rp and Z of the normal fragrant pears.During the same picking period,the difference between Rp and Z before and after the damage The values all increase with the increase of the fragrant pear static pressure damage area.Under the same damage area,the difference between Rp and Z before and after the damage decreases with the increase of the frequency.Under the influence of different frequencies during the picking period,the frequency 100k Hz and the electrical parameter Z were selected to establish a quantitative evaluation method for the static pressure damage area of the fragrant pear.The mathematical model R~2established by this combination has an average value of 0.99 and a standard deviation of 0.0057,which is based on electrical characteristics.The best evaluation method to quantify the static pressure damage area of fragrant pear.(3)The error range of the best evaluation method for quantifying the static pressure damage area of fragrant pear based on electrical characteristics is 0.94%～5.77%,and the error range of the best evaluation method for quantifying the damage area of fragrant pear based on finite element is2.88%～13.44%.The comparison shows that the quantitative evaluation method of fragrant pear damage area based on the electrical characteristic method is more accurate.