Research On The Fatigue Characteristics Of The Bulldozer Ripper

Since the reform and opening up, chinese overall national strength has beendeveloping rapidly，the level of urbanization has made great progress, so theconstruction of infrastructure facilities has been further speeded up. Heavy industry, avery important index that measures a country industrial level, has constantly gotattention and development, the cradle of machine and equipment of manufactureindustry has gone through stages of rapidly developing. The development ofengineering machinery has also made a great contribution to urban development andinfrastructural construction. As an important tool in basic engineering construction,bulldozers have been used frequently and played an increasingly important part in allengineering construction field. The level of design and manufacture of bulldozershave been developing rapidly.Because of urgent need of engineering construction, the level of design andmanufacture of bulldozers have been greatly improved. However, compared withwell-known international manufacturer of construction machinery, there is still a biggap. Currently, the traditional design methods have always been used by most ofresearch institutions in domestic, which have disadvantages of long developmentperiod and high cost, and compared with foreign advanced level there is a large gap.Bulldozer ripper is often used as an important device in break ground operation,especially peeling to gravel, frozen soil and hard soil pavement. Due to roadirregularities,hard soil, confounding of soil components and adverse circumstances inworkplace, device often suffer major and uncertain impact load, therefore, the deviceis subject to damage easily. The damage of bulldozer working device or componentnot only affects the efficiency of the construction, but also generates additionalmaintenance costs. So the research of force and fatigue characteristics of ripper toothlever has practical significance.Currently, there are two categories of computing the fatigue life of rack, the testmethod and analysis method. The so-called test method is a series of experiments thatcan obtain the required fatigue data through simulating the actual situation. Althoughthis method is reliable, but it takes a great manpower and material resources. Theanalysis method analyzes fatigue properties and fatigue life of the part based on theperformance analysis of the material. Load history obtained by the finite element analysis software is the basis of the analysis method. This method effectively reducesthe dependence of large numbers of tests, and therefore has been got widely used. Atpresent, fatigue analysis softwares that are most commonly used in engineering arenSoft and MSC-Fatigue.Based on the characteristics of the research object and the theory of fatigueanalysis, this paper selected the appropriate fatigue analysis methods and then didcorrelation calculation. Due to the limit of experimental conditions, laboratory costsand other factors, the experiments and data of ripper and gear lever load spectrum arevery limited, and the references that can be learned from are also very rare. Therefore,this paper accomplished co-simulation of machinery-hydraulic system for the ripperby using the virtual prototyping technology and rigid coupling technology, and got thedynamic load data in the working process of the rack by considering the dynamiccharacteristics of the hydraulic system. In addition, the paper has completed theanalysis of fatigue life combined with nSoft fatigue analysis software.Through theoretical analysis and simulation research of ripper, the paper got thedynamic characteristics in its work process of the ripper and the intensity in variouscircumstances of the gear lever, and analyzed the destruction form under the sufferedload of gear lever and its fatigue life. The content of this study has a certaintheoretical reference value for the overall performance of large crawler bulldozerripper and the optimization and improvement of the gear lever structure.