The Mechanical Properties Analysis And Study On Thickness Optimization Method Of An Excavator’s Boom

Hydraulic excavator is a main type of construction machinery, which completes excavation with the working device, while the boom is the main stressed components of working device. While working, the boom often cracked and fractured due to the poor and uncertainty working conditions. The design accuracy of the boom directly affects the efficiency and service life of the excavator.In this paper, a small hydraulic excavator boom was selected as the research object, the simulation analysis of the mechanical properties of the environment under actual excavation was conducted, and a rapid optimization method for complex plate and shell thickness was put forward. Finally, the thickness of boom plate was optimized design using the proposed optimization method. The specific contents and the main conclusions are as follows:(1) The typical working conditions (the maximum digging force, the maximum digging depth, the maximum digging height and the maximum digging radius) of the hydraulic excavator’s working device was determined and rigid dynamics analysis was conducted. The force curves of each boom’s hinge points were obtained. Selecting the dangerous moment of the four conditions and taking into account the partial and lateral forces, statics and transient dynamic of the excavator boom was analyzed with the finite element method theory. Finally, the fatigue life of the boom was analyzed based on the static strength calculation, which determined the weak position of the boom.(2) A rapid optimization method has been put forward combined with the shell theory and the finite element method theory. The optimization mathematical models were established based on the maximum equivalent stress and the total maximum displacement. And then, the corresponding theoretical formulas have been derived respectively. Finally, a quickly optimized design implementation method was proposed based on ANSYS. According to analyze the impact of the complex loads, constraint ways, load types and complexity of the structure to the design accuracy, the validation results demonstrate the accuracy of the proposed rapid optimization design method.(3) The thickness of the boom’s plate was been optimized with the proposed rapid optimization method. First, sensitivity of the boom was analyzed. For simplifying the model, design variables with smaller sensitivity were ignored. And then, the thickness of the board was optimized by the corresponding formula. The final optimization results showed that the proposed optimization method is effective.Avoiding cracking and fracture of the boom, and improving the product reliability, this paper provided a theoretical basis and practical tools for the design of an excavator’s boom and a certain guidance value to optimize design.