Fatigue life modeling of linear actuators in robotics and automation

The wear and fatigue life of actuators is a topic of great interest in the field of Industrial Automation since linear actuators are essential components to many machine tools and robots. The fatigue life of a linear actuator closely relates to many factors such as loads lubrication, material properties, surface properties, pressure, and temperature. Therefore, the fatigue life cannot be modeled without a simultaneous consideration of solid mechanics, fluid dynamics, contact mechanics, and thermal dynamics. Despite of numerous publications in past 50 years, research is in a great demand in predicting fatigue life of linear actuators. We are motived to model and validate the fatigue life of lead screw actuators. Firstly, the theory of asperity contact and the Archard's model of sliding wear are applied to estimate the amount of wear under given circumstances. Secondly, a test platform is developed based on a standard ASTM test protocol, and the wear phenomenon at the ball-on-flat sliding is measured to validate the developed wear model. Thirdly, the finite element analysis is conducted to assess the contact stresses in the assembly model of actuators. The estimated data from three sources are merged to formulate a mathematical model in predicting the fatigue life of lead-screw actuators.