Experimental Study On Physical Characteristics And Mechanical Damage Of Jujube During Crisp Ripening Period

During harvesting,sorting and transportation of jujubes during brittle maturity period,the surface and interior of the jujube will be damaged to a certain extent.The mechanically damaged jujube will shorten the storage time and will perish and deteriorate,causing huge economic losses to the jujube farmers.Hinder the sustainable development of its industry.Different varieties of jujube have different physical properties and mechanical damage.The existing mechanical compatibility related to jujube harvesting,sorting and transportation is poor.Therefore,this paper focuses on the physical characteristics and mechanical damage of different varieties of jujubes in Xinjiang crisp ripe period The experimental research provides a certain theoretical basis for the research and development of red jujube mechanized equipment and structural optimization.The main conclusions are as follows:(1)Research on jujube planting mode and growth.Conduct field investigations on the planting patterns and growth conditions of different types of jujube trees in the eight,ten and twelve jujube orchards in Alar City,Xinjiang Characteristics(height of jujube height,height of main pole,diameter of main pole and height of tree)are used for size measurement,statistical analysis of relevant geometric parameters such as planting patterns and growth conditions of three types of jujube trees,which can provide relevant information for the mechanical damage characteristics of red dates Parameter basis.(2)Jujube physical characteristics test determination and analysis.The Grey jujube,Jun jujube,Dong jujube at the brittle maturity period was taken as the research object,and the physical property parameters such as water content,triaxial size,density,porosity and friction characteristics were measured experimentally.Result analysis:Moisture content of jujube is 66.13%,Junzao is 63.71%,Dongzao is71.55%;the mass and triaxial dimensions are subject to normal distribution,the quality of Dongzao is greater than that of Huizao and Junzao,and there is not much difference between Huizao and Junzao The sphericity of Dongzao is close to a sphere,and the gray and Junzao ellipsoids are much smaller than Dongzao;the surface area of Dongzao is greater than Junzao,and Junzao is greater than Huizao;the average density of Dongzao is greater than that of Huizao and Junzao,which are larger than Junzao,individual There are differences between them;the porosity of Junzao is greater than that of Huizao and Dongzao,Dongzao is greater than that of Huizao,the filling quality of Junzao is smaller than that of Huizao and Dongzao;the angle of repose is smaller as the geometric mean diameter increases,and the angle of repose is greater than that of Junzao and Dongzao and Junzao are larger than Dongzao;the size of sliding friction coefficient in contact with steel plate,organic plastic plate and soil plate is gray jujube,Junzao and Dongzao in sequence.(3)Experimental determination and analysis of jujube suspension speed characteristics.An air-blown suspension velocity test and measurement device was developed,which consisted of three parts:a wind power adjustment device,an air flow transmission line,and a measurement device.Using the principle of equal area concentric rings,when the frequency of the inverter is adjusted at 20 Hz and 50 Hz,the reliability of the airflow velocity of each cross section in the conical observation tube is verified.%,2.923~3.861%,the flow field uniformity is 0.019~0.352%,0.211~0.449%,all meet the stability of the air flow pipeline flow field and device performance requirements.The test obtained a linear regression equation between the jujube's suspension speed value and the frequency of the inverter,and analyzed the relationship between the particle size and water content of the Dongzao jujube and the suspension speed during the brittle ripening period.At 32.00 m/s,it is the optimal airflow velocity parameter for red jujube suspension;when the moisture content and particle size of red jujube are determined,the correction coefficient S of the theoretical suspension velocity shape is optimized from 0.565 to 0.679.(4)Experimental study on static load compression characteristics and crush damage of red dates.Taking the red jujube in the crisp ripe period as the test object,the single-factor test and the orthogonal test were used to analyze the test factors(red date variety,loading speed,compression direction)on the static pressure damage test indexes(surface hardness,elastic modulus,fruit softening rate and Surface damage volume)and the relationship between the degree of influence and change.The test results show that there is a significant relationship between the jujube variety,loading speed,compression direction and surface hardness,elastic modulus,fruit softening rate and surface damage volume during the crisp ripe period.The average surface hardness is 4.11 MPa;the average elastic modulus is 0.81 MPa;the average fruit softening rate is 14.32%;the average surface damage volume is 11.57×10~-66 m~3.The relevant multivariate linear regression equation is obtained to establish the mathematical model of the relevant indicators,and the establishment of the mathematical model can predict and evaluate the experimental indicators.(5)Experimental study on falling impact characteristics and collision damage of red dates.Taking the red jujube at the brittle maturity period as the test object,the drop collision test was conducted with different factors to explore the drop characteristics(peak acceleration,surface hardness)and damage evaluation(quality damage rate,surface damage)of the test factors(drop height,collision material and red date variety)Volume)correlation.The test results show that the drop height has the greatest impact on the drop characteristics and damage evaluation,and the impact material has the second largest impact.Acceleration value,mass loss rate and surface damage volume have significant effects on jujube damage:drop height>collision material>variety category.The correlation coefficient of acceleration value and mass damage rate is 0.908;the correlation coefficient of surface hardness and mass damage rate is-0.875;the correlation coefficient of acceleration value and damage volume is 0.729;the correlation coefficient of surface hardness and damage volume is-0.707;the mass damage rate and damage volume The correlation coefficient is 0.702.