Research On The Cutting Mechanism Of Green Pepper Branches And Cutting Device Based On Mechanical Numerical Model

With the production of green pepper rising year by year,the demand for efficient harvesting is expanding rapidly.However,it is still at the stage of manual harvesting,which is not very efficient.Therefore,there is an urgent need to develop a low cost,low energy consumption and high efficiency green pepper harvesting device to meet the current harvesting challenges.The harvesting agronomy of green pepper is to cut off branches for whole branch harvesting,but there is no mature branch cutting device for green pepper on the market at this stage,and the cutting mechanism for green pepper branches is not clear.In this study,after systematically analyzing the current situation of domestic and foreign research and combining the agronomic requirements of green pepper cutting and harvesting,a mechanism research process combining actual experiments and numerical simulations was realized;a high-efficiency and low-power green pepper cutting device was designed;the physical parameters of green pepper branches were calibrated;the mechanical intrinsic model of green pepper was constructed;the working conditions were simulated by finite element method,and the optimal structural parameters and working criteria of the green pepper cutting device were derived.Theoretical analysis and structural design of each component module of the device were carried out based on the simulation results and cutting mechanism;non-standard parts were drawn and processed,and standard parts were calculated and selected for purchase;after the device was prototyped according to the design idea,performance tests were started to test the operational performance of the device.The main research contents and conclusions are as follows:（1）Determination of basic mechanical parameters of green pepper.The basic physical parameters of the branches and their related mechanical parameters were determined by physical tests:density of 0.88 g/cm^（-3）,moisture content of 68.636%,longitudinal modulus of elasticity 288.67 MPa,tangential modulus of elasticity 26.14MPa,longitudinal shear modulus 107.552 MPa,tangential shear modulus 9.834 MPa The longitudinal Poisson’s ratio is 0.342,the tangential Poisson’s ratio is 0.329,the longitudinal tensile limit is 14.131 MPa,the tangential tensile limit is 8.57 MPa,the longitudinal compressive limit is 12.91 MPa,and the tangential compressive limit is11.835 MPa.The coefficient of friction with the steel plate is 0.676 in the transverse direction and 0.724 in the longitudinal direction.The above data can provide effective reference for the research of cutting characteristics and revealing the action mechanism of the related green pepper branches.（2）Numerical modeling of the branch mechanics of green pepper.The mechanical response of the branches is divided into three stages of elasticity,elasto-plasticity and plasticity,which are intertwined in time and effect.An intrinsic model that reflects the properties of branch transverse isotropy,tensile and compressive inequality,and damage manifestation was established.The model is also written by For language to realize the function of material model applied to computer software.The model can provide the basis for the mechanical simulation test of the branches of P.glauca,after which the simulation test can replace most of the mechanical tests of the branches of P.glauca and save time for the study of the mechanism of the branches of P.glauca.（3）Finite element test to optimize the design parameters and explain the cutting mechanism.Based on the established mechanical model and the measured mechanical parameters of the branches,a finite element model was established to simulate the working conditions of green pepper branch shearing.Single-factor tests were conducted to determine the degree of influence of the parameters on the efficiency effect,and then to determine the significant parameters and their working range.Within the selected parameter range,the quadratic regression response surface model of significant parameters and performance indexes was established by Box-Behnken test with the results of evaluating the performance of the device such as work efficiency and work effectiveness as indicators to obtain the key guidance of mechanical design.The optimal structure and working parameters were determined as follows:edge angle 16°,cutting angle 73.23°,and cutting rate 5.01 mm/s^-1.At this time,the theoretical maximum cutting force and optimal cutting completion were 803.35 N and 8.58%,respectively.According to the ANOVA results,the statistical RSM models all had R2 greater than 98%and the significance levels were all greater than 99%,indicating that the models were reliable.Another model was established to monitor the cutting process of green pepper,and the stress,change morphology,strain,and reference point displacement were linked together in time to reveal the cutting mechanism of the whole process of cutting of green pepper branches across the distance.By cross-referencing,the damage limit of the cutting stress of the green pepper branch under the better parameters of 16°and 5.01 mm/s^-1 is10.07±0.02 MPa,the bending limit stress is 2.14±0.01 MPa,and the limit stresses on the tool and the support member during the whole cutting process are 9.93±0.02 MPa and14.5±0.02 MPa,respectively,and the The maximum strain was 9.57E-7.The above findings have positive effects on the research of the devices for cutting and branch treatment of green pepper,such as the selection of materials,the determination of cutting structure,and the optimization of parameters.（4）Design and test of branch cutting device.According to the preliminary research on green pepper branches,i.e.,the relevant parameters and mechanism conclusions obtained from simulation tests,combined with the green pepper growth environment and harvesting agronomic requirements,the design requirements of the green pepper cutting device were clarified.The device was selected as the clamping and shearing type,and the overall structural design and operation flow of the device were determined.The device mainly consists of clamping parts,shearing parts,control module,sensing module,etc.According to the existing mechanism and conclusion,the design process of the control system is as follows:the human-computer interaction interface is built and written by APPInventor software,the Arduino core board is selected for software program writing and debugging,and the hardware modules of the control system are selected and wired according to the overall design idea.After each module was tested for communication and stability,it was assembled into a complete branch cutting device and tested for stability.During the test:the device was assembled and idle debugged to ensure that the components could operate stably according to the design objectives,and the automatic identification decision system identified accurately and made timely decisions.（5）Device performance test.The results show that the device can be stable for green pepper branch cutting test,and has a high efficiency,from reaching into the green pepper branch,to identify the branch,decision clamping,decision shearing,cutting the branch to achieve the full process at most only 10.9s,multiple branches at the same time cutting time gap is not large.After comprehensive cutting quality,3 branches were cut at the same time with higher efficiency and better degree of completion,which was more advantageous.The device was tested for fixed proportional power consumption,single branch single shear power consumption of about 10.29J,double branch single shear power consumption of about 10.90J,three branches word shear power consumption of about 11.68J,intelligent shear single shear power consumption of about 9.82J,a comprehensive comparison,the greater impact on power consumption is the number of cut branches.The overall power consumption of the studied device is not large and is economical.