Vibration Mode Analysis And Structural Optimization Of The Handrail Of SR1Z-80 Handheld Tiller

With the advantages of small volume, light weight, simple structure and easy transfer in the fields, handheld tiller is widely used in hilly lands, greenhouses and orchards in South China. During the working process, vibration, generated by the engine, couples with the vibration resulting from blade roll soil-cutting, and it transfers to the operator’s hands through the handle and its contact. The hands subject the local vibration, and if the operators are localized the vibrations for a long period, it may cause bad disorders to hands, resulting in high risk of vibration-induced white finger(VWF). Meanwhile, the vibration of the handrail can cause fatigue failure, accelerate damage to some parts of the machine and shorten the life of the machine.By taking the handrail as the research object, based on Computational Modal Analysis and Experimental Modal Analysis, the 3-D model of handrail was established by UG software. Through ANSYS Workbench, the Finite Element Method(FEM) Model of handrail was obtained after meshing. Through modal analysis module in Workbench ANSYS, model parameters such as natural frequency and vibration type of ten modalities in the free state were obtained. Vibration test system of handrail was established, using LMS Test.lab Experimental Modal Analysis, the natural frequency, vibration modal, damping ratio of handrail in the ten models were obtained as well. Computational Modal Analysis results were compared with Experimental Modal Analysis results, by selecting main dimension parameters having serious impact on vibration at positions under the natural frequency as follows: handle, cross bar and handrail rod. By combining the orthogonal test and Computational Modal Analysis, the vibration of each combination was analyzed. The main conclusions of the study are as follows:(1) Each vibration mode of Computational Modal Analysis and Experimental Modal Analysis had a largely same trend, and the relative error value of each natural frequency was relatively small. The results showed that the FEM model of handrail could truly reflect the inherent vibration characteristics of handrail. The simplification of FEM model was correct and effective. It was useful for Computational Modal Analysis to study the vibration characteristics of handrail.(2) From the ten order modal vibration patterns of the handrail, obtained by Computational Modal Analysis and Experimental Mode Analysis, the results showed that handle, cross bar and handrail rod are the three main parts that have great influence on the vibration of handrail under the natural frequency.(3) Taking the dimensions of handle, cross bar and handrail rod as variables, the vibration of each combination was analyzed by means of combining orthogonal test and Computational Modal Analysis. The optimized dimensions of the handrail are as follows: handle length 17 cm, cross bar length 39 cm and handrail rod length 47 cm.