The Optimization Of The Leaf Spring Suspension Of A Wheeled Transporter In The Mountainous Orchard Based On Road Spectrum

The cultivation of the fruit in South China mainly concentrates in hill orchard.The site conditions of the hill orchard is poor,resulting that the normal machinery is difficult to enter the hill orchard.With the development of a wheeled transporter in the mountainous orchard,the efficiency of the fruit transportation has been improved.An energy-saving,simple and secure,low speed but high torque hill orchard wheeled transporter for farm goods transporter was developed.But the study of a wheeled transporter in the mountainous orchard is currently foc used on the research of mechanical structure,such as the research frame,self loading structure and transmission and so on,and the research on the road roughness effect on a wheeled transporter in the mountainous orchard is very rare.Road roughness is o ne of the main inputs to the fatigue damage of the structure or parts of a wheeled transporter in the mountainous orchard,which is the fundamental factors affecting the fatigue life of the structures in a wheeled transporter in the mountainous orchard.The suspension is one of the most important parts of vehicle,and it has great influence on ride comfort and stability of vehicle.In order to study the influence of road surface roughness signal on the leaf spring suspension of a wheeled transporter in the mountainous orchard,this paper studies the following three aspects.(1)The system of the road surface roughness excitation signal acquisition was designed to acquire the different road surface roughness excitation signal.The acquisition system takes Lab VIEW as the host computer platform.The test platform was designed with the NI chassis 9174,NI data acquisition card 9234 and uniaxial acceleration sensor PCB 352C33.The signal collected by the system was the acceleration signal,and then the original acceleration signal was denoised by wavelet de-noising.The acceleration signal after de-noising was converted into displacement signal by the integral transformation.The displacement signal was converted into the displacement power spectral density curve,and through orthogonal analysis,it has concluded that the speed and load have significant influence on the road roughness signal.And the slope has the greatest impact on the road roughness,followed by the speed,and finally the load.(2)The influence of the road roughness excitation signal on the leaf spring suspension was discussed.The establishment of a wheeled transporter in the mountainous orchard model was built in ADAMS,and then the road power spectral density curve of excitation signal was imported into ADAMS,in order to get theamplitude frequency characteristic curve of leaf spring suspension.Thus we could get that the frequency of the road roughness on the leaf spring suspension is 2~10Hz.(3)The finite element analysis and optimization of the leaf spring suspension was carried out.The finite element analysis of the original leaf spring suspension was carried out to obtain the original plate spring suspension in the first eight order mode.The first natural frequency of the leaf spring suspension was 5.9522Hz,which was within the frequency range of the road roughness excitation signal,10z.Therefore,the original leaf spring suspension was optimized.And the first order natural frequency of the optimized leaf spring suspension was 18.598Hz,which was beyond the frequency range of the road roughness excitation signal,10z.And through the analysis of random vibration function in ANSYS,the fatigue life analysis of the leaf spring suspension before and after optimization was carried out,the life of the leaf spring suspension before and after optimization was 9.4×10~4,3.5×10~5 respectively.