Research On The Mechanical Components Fatigue Design Method And Its Application Under Impact Load

With the rapid economic development, construction machinery used more widely in the social production, which suffers severe working condition and randomness loads, such as mining machinery and earthmoving machine. The existing brief and strong impact load may occurs in a working cycle during the work. Along with the ongoing impact load, fracture damage appears at some high stress domain and the crack expands, which lead to the mechanical component rapidly damaged and losing its working ability. It has an important implication to research on the fatigue strength design to search the impact load suffered fatigue analysis method to improve product competitiveness.The impact load suffered fatigue design method is researched and applied to the fatigue analysis of scraper movable arm in this paper. The reason of rapid failure is analyzed and an improved program is proposed. The researches in this paper are as follows.The existing theory of fatigue analysis and related knowledge of fracture mechanics fatigue crack propagation are introduced at first. The influences of initial crack caused by impact load on fatigue crack propagation life of mechanical parts are analyzed. The effects of different fracture toughness on fatigue crack propagation life is also analyzed. The impact load suffered fatigue design method of mechanical component as well as the design process and implementation steps are concluded.The damage reasons of scraper movable arm are analyzed. The fatigue life problem is analyzed and optimization improved with the proposed fatigue analysis method, where the scraper movable arm is calculated and finite element analyzed and the damage domain of the arm is fatigue strength checked. Based on the linear and nonlinear fatigue cumulative damage theories, fatigue life estimation of the arm is accomplished regardless of impact-load.Based on the nonlinear finite element analysis software, impact dynamics of the scraper movable arm is analyzed. The force situations of the damage areas under impact load are obtained. With the related knowledges of fracture mechanics, the fatigue crack propagation life of damage areas are estimated and the possible initial crack length is forecast. According to the analysis of the effect of impact load on movable arm injury, preliminary optimization improvement program of the movable arm is proposed.