Finite Element Modeling And Analysis Of Pressure Characteristics Of Tractor Seat Based On ABAQUS

It is a significant feature of agricultural mechanization to complete the agricultural production with the tractor as the power source.As an important product in the process of agricultural modernization,tractors are more and more widely used in agricultural mechanized production.In order to meet the rapid development of agricultural production demand,tractors are developing in the direction of high efficiency and intelligence.The tractor has a more complex working environment,with large fluctuations in the road,vibration and noise,and sometimes it is necessary to work for a long periods of time when the farmer is needed.These factors can easily lead to driving fatigue that affecting the quality and the efficiency of the work.A study shows that 80%of the tractor drivers are varying degrees of suffering from low back pain,sore sores and other occupational diseases.Tractor seat as a direct contact with the driver,can support the driver’s body and the role of vibration,many scholars at home and abroad use the pressure distribution between drive and seat to assess the static comfort.The geometric parameters of the seat,the characteristics of the material and the profile of the shape of the tractor seat can be affected by the pressure distribution characteristics between drive and seat.A comfortable seat design allows the body to be reasonably distributed in the seat,to avoid excessive compression of the lower thigh nerve tissue and numbness,to ensure that the hip blood circulation,reduce the incidence of hip tissue ulcer disease and other occupational diseases for the tractor driver,provide good driving conditions,reduce work fatigue,to ensure the quality of operations,improve working efficiency.The key to obtain accurate simulation result of the pressure distribution between the drivers and seat lies in two aspects:one is the accuracy of the model,including the seat model and the driver’s biomechanical model.In this paper,we obtain the tractor seat cloud data by REOMER absolute joint arm measuring machine,and establish the 3 dimensional model of tractor seat through CATIA reverse engineering method.Based on the 3DsMAX software model library,the human biomechanical point cloud data were obtained.And build the driver’s soft tissue and skeleton model.Another key factor is the accuracy of the model properties.The mechanical properties of the polyurethane foam were evaluated by referring to the D3574 standard and the related research literature.The main contents of this paper are as follows:(1)The mechanical Properties Test of seal filling material-Polyurethane FoamA static uniaxial compression test was carried out at 3 strain rates for the polyurethane foam samples of the tractor seat filler with reference to the American Society for Testing and Materials ASTM D3574-01.The pitting hardness test of the seat material specimen was carried out with reference to the method for measuring the hardness of a flexible foamed polymeric material.The constitutive model of the second-order strain energy function of the seat filling material and the 3 strain rate models are established.The stress-strain characteristics under the condition of uniaxial compression are analyzed,and the information of the compression strength of the seat packing material is obtained.(2)Seat surface data acquisition and modelingUsing ROMER absolute joint arm measuring machine and ScanWorks V3 laser probe on the tractor seat point cloud data collection,This paper introduces the working principle and data acquisition method of joint arm measuring machine,analyzes the key technologies of reverse engineering,including point cloud data preprocessing,model curve and surface reconstruction.Based on CATIA reverse engineering technology establish the seat 3 dimensional model.(3)Tractor driver body soft tissue and skeleton model establishmentReference to China’s adult anthropometric size of the human body model of the larger impact of 32 major human body measurement data,Choose to meet our tractor driver requirements 18 to 60 years of age with a typical representative of the 50th percentile body size data,Based on the 3 dimensional modeling software 3DsMAX human body model library,the human body model and the skin point cloud data are imported into CATIA software,and the CATIA reverse engineering module is reconstructed by scaling and adjusting the human body model.(4)Research on pressure characteristics distribution between drive and seatBased on ABAQUS,the numerical analysis of the pressure distribution between the driver and the seat of the tractor is carried out.With HyperMesh for finite element pretreatment,The stress distribution between the driver and the seat interface is analyzed by ABAQUS,and the stress distribution of human soft tissue is obtained.In this paper,the study of the pressure distribution characteristics of the tractor-seat contact interface is helpful to improve the comfort of the tractor seat,improve the working efficiency and reduce the incidence of occupational diseases.It is provided for the development and optimization of the tractor seat.