Dynamic stiffness of a lift mechanism for forklift truck

摘要

This article investigates the over constraints and dynamic stiffness of a spatial multi-link lift mechanism for forklift trucks. It focuses on the stiffness of the mechanism whose structural parameters are uncertain. Therefore, the interval analysis method is adopted to establish the stiffness. The forces and moments exerted on the fork frame and connection rods are firstly discussed via coordinate transformations between different Cartesian coordinate systems. The elastic deformation of rods and compatibility equations, and the rigid displacement of frame are then analyzed. An equation system is ultimately established to describe the dynamic stiffness of the mechanism. Considering the uncertainty of some parameters in engineering, the trend and interval area of the equivalent stiffness during work is investigated with interval analysis method. Numerical simulations show that this kind of mechanism can provide very good stiffness intervals in both vertical and torsional directions for engineering applications.