Dynamic Analysis And Equipment Development For Laver (Porphyra Yezoensis) Harvesting

Laver(Porphyra yezoensis)is one of the important cultivated and economical algae in China.The harvesting operation is an important part of the production chain of laver,due to the low technical level of harvesting equipment,there are still some problems in laver harvesting,such as high labor intensity,low production efficiency and high loss ratio.According to the biomechanical characteristics and harvesting technical requirements of laver,the three sections type hob harvesting equipment of laver were designed.Through the simulation research of ANSYS/LS-DYNA software,the optimal structure and working parameters of the harvesting equipment were determined,and the experimental study on the harvesting performance of the prototype has been completed.The harvest dynamics of laver was analyzed.In order to explore the cutting state of laver and reduce the damage and missing cutting of laver in the process of harvesting,the relationship between the motion path of the harvesting knife,the rotation cutting angle of the knife and the force on laver was studied.The result showed that shear stress is inversely proportional to the tensile stress.When the rotating cutting angle becomes smaller,the proportion of the laver being cut increases,and vice versa the proportion of pulling off increases,when the rotating cutting angle of the knife is 90°,the fracture state of laver is completely pulled off.The design of three sections type hob harvesting equipment for laver was completed.According to the technical requirements for harvesting and production of laver,combined with the biomechanical parameters of laver,an overall work plan of a three sections type hob harvesting equipment for laver was proposed.The knife mechanism,the stubble height adjustment mechanism,the mesh curtain support mechanism,etc.were designed,and the length of the three sections type hob is 2000mm,the number of knives was 9,and the turning radius was 240mm;the adjustable length range of stubble height adjustment mechanism was 3-7cm.The hydraulic system was selected and calculated,the gasoline engine was used as the power source,the hydraulic motor with a displacement of 20mL/r,a variable piston pump with a displacement of 18 mL/r.The simulation study on harvesting dynamics of laver was carried out.Based on ANSYS/LS-DYNA,a rigid-flexible coupling model of the interaction between the cutting device and the laver fronds was established,and the effect of different forward velocity,cutter revolving speed,knife extension length and inclination angle on the cutting force of laver was studied through response surface simulation experiments,the results showed that when the combination of the forward velocity,the cutter revolving speed,the knife extension length and inclination angle was 0.77 m/s,900 rpm,40 mm,and 110°,respectively,the cutting force on laver was the smallest,which was 4.21 N.This study provides a theoretical reference for the design and research of laver mechanized harvesting equipment.The performance test of laver harvesting equipment was completed.Through single factor experiment,the effects of different the forward velocity and cutter speed on the net recovery rate and loss ratio of laver were studied.It was found that the cutter revolving speed had a significant impact on the net recovery of laver,with the increase of the cutter revolving speed,the net recovery rate increases first and then gradually stabilizes,while the forward velocity had a significant impact on the loss ratio of laver,with the increase of the forward velocity,the loss ratio increases slowly and then increases sharply.When the cutter revolving speed and the forward velocity are 900 rpm and 0.77 m/s,respectively,the recovery rate and loss ratio are97.45%and 3.38%respectively.At the same time,the microscopic structure of laver was observed,the results showed that the cut-off proportion are 77.5%.The recovery efficiency of the harvesting equipment can reach 2160 m~2/h.This study proposed a new method for harvesting laver,revealed the influence law of the structural parameters and operating parameters of the three sections type hob harvesting equipment on the cutting force and harvesting effect of laver,and provided technical support for the harvesting of laver on the beach.