Stiffness of the Roller Screw Mechanism by the Direct Method

In this paper, the direct stiffness method is used to construct a stiffness model of the roller screw mechanism. This method models the entire roller screw mechanism as a large spring system composed of individual springs representing the various compliances. In addition to predicting the overall stiffness of the mechanism, the direct stiffness method can calculate the distribution of load across the threads of the individual bodies. With the load on the individual threads known, the contact stresses can be calculated. This allows for a better understanding of the sensitivities of stiffness and contact stresses in the mechanism with various design parameters and can ultimately be used to design roller screws that are stiffer and with lower contact stresses.