Effects of carriage flexibility on friction force in linear ball guides

This paper presents the effects of carriage flexibility on the friction force in linear ball guides, which includes hydrodynamic rolling friction, elastic hysteresis friction, slip friction, and drag friction. To this end, we developed a computational model for the friction force in linear ball guides that accounts for the carriage flexibility. The model was validated through experiments, and the results prove that it provides more accurate friction-force estimates than the conventional model under the assumption of a rigid carriage. Subsequently, we examined the effects of external load, preload, and speed on the friction force. Among several friction components, hydrodynamic rolling friction makes a major contribution to the total friction force. Ball contact loads, which significantly vary with carriage flexibility, were found to influence the hydrodynamic rolling, elastic hysteresis, and slip friction forces. The proposed model considering carriage flexibility in linear ball guides is expected to find use in the design and operation of linear-ball-guide systems.

Structural optimization of ultra-thin leaf spring for weakening elastic hysteresis effect and enhancing fatigue life

Small-size ultra-thin leaf spring as the key elastic sensitive member is widely used in the precision electro-mechanical products. However, owing to the unavoidable elastic hysteresis effect of leaf spring, it always suffers from a significant graceful degradation of designed deflection and subsequently fatigue fracture under the condition of cyclic loading. In order to weaken the elastic hysteresis effect, structural optimization according to sequential quadratic programming method for reducing stress concentration of leaf spring was first carried out by simulations, and then the identification of elastic hysteresis effect for optimal leaf spring was carried out by experiments. Compared with the original design, the maximum deflection deviation for single cycle is decreased from 0.026 mm to 0.002 mm. For the sake of predicting the fatigue life of optimal structure of leaf spring being on the service, a loading block with multistage variable stress amplitudes was experimentally recorded and fitted by normal probability density function, and then a statistical probability method by mathematical analysis was proposed. Compared with the original design, the predicted fatigue life of leaf spring is 736000 loading blocks, which is ten times than that before structural optimization. A structural optimization for reducing stress concentration can significantly weaken the elastic hysteresis effect and enhance the fatigue life, which is benefit for the elastic stability of leaf spring during engineering application.

DETERMINATION OF THE MAIN CHARACTERISTICS OF THE PARTICLE TRIBOCONTACT AND THE ELASTOMER SURFACE UNDER SHOCK

In the course of the studies carried out, it was theoretically proved and experimentally confirmed that the elastic-hysteresis properties of elastomers determine the trajectory of particle motion upon impact on their surface, the magnitude of the velocity loss and the angle of rebound. The presence of three zones of angles of attack has been experimentally established, up to approximately 300, from 300 to 600 and over 600. Depending on the elastic-hysteresis properties of elastomers, the effect of these properties on the value of the rebound angle and the loss of speed is inverted

Enhancement of elastohydrodynamic friction by elastic hysteresis in a periodic structure

Lubricated friction of soft contacts is enhanced by periodic variation of substrate compliance.