Fatigue life simulation of rotary tiller blades synthetic using experimental and finite elements analysis tools

Abstract

Rotary tiller blades are usually required to achieve the performances of more efficient and longer lifetime. Shapes and processing techniques play a key role in their fatigue life. A Simulation model and data of field experiments were conducted to use are used synthetically for on the evaluation of fatigue life, which is related with the geometric features of rotary tiller blades and their working conditions. In simulation model, the weakest section of rotary tiller blade was identified by the finite element method with ANSYS software. The weakest section was loaded by statistical random load spectrum using severe conditions in the working environment including sandy soil and clayey soil. The modal analysis method was adopted in studying dynamic effects. Fatigue analysis methods (SN curves, rain flow counting and mean stress theory) were used to determine the fatigue damage imposed on the components. The simulation model analyzed the fatigue sensitivity of input parameters to obtain a discrete fatigue life, and important factors affecting the fatigue life. The comparisons between rain flow matrix and damage matrix reveal corresponding relationship between loading cycle and fatigue damage. Based on these, cumulative fatigue damage was calculated by the software (ANSYS Workbench) according to linear damage theory, and the fatigue damage was evaluated. The predictions were based on linear elastic fracture mechanics theories combined with the finite element method. The results indicated that it can be used to anti-fatigue design of rotary tiller blades in the designing stage of product, and provide technical support for further optimization and evaluation of rotary tiller blades.