An Investigation of the Contact Fatigue Characteristics of an RV Reducer Crankshaft, Considering the Hardness Gradients and Initial Residual Stress

Abstract

The crankshaft is one of the core components of a Rotate Vector (RV) reducer. The fatigue life of the RV reducer is severely hindered by fatigue failure on the eccentric cylindrical surface of the crankshaft. The hardness gradients and residual stress in the crankshaft, associated with machining operations, exert an enormous impact on the rolling contact fatigue (RCF). In this work, a finite element method (FEM)-based three-dimensional elasto-plastic contact model is established to calculate the stress–strain field by taking hardness gradients and initial residual stress into account. The RCF characteristics of an RV reducer crankshaft is investigated by applying modified Fatemi–Socie (FS) multiaxial fatigue criterion. The results indicate that initial residual stress plays an influential role in the fatigue damage by altering the distribution of the maximum normal stress near the contact surface. The modified FS fatigue criterion could better consider the effect of initial residual stress and the shear stress, which significantly improves the prediction accuracy of the contact fatigue life model. The contact fatigue performance could be considerably improved by designing appropriate shot peening parameters to obtain optimized residual stress distribution. Therefore, the technique presented may serve as an important guideline for the anti-fatigue design of an RV reducer crankshaft.

A novel adaptive blind deconvolution algorithm: application to feature extraction of weak faults in RV reducer gears

“…Set both the maximum number of iterations Z and the size of populations N in SCSSA to 30. According to the signatures of the fault signal, the optimization parameters are defined within a certain value range: L is [100, 650], T is [50, 350] and M is [1,7]. Subsequently, SCSSA is utilized to optimize these three critical parameters of MCKD.…”

“…Firstly, taking the root crack fault as an example for analysis, set both the maximum number of iterations Z and the size of populations N in SCSSA to 30. According to the signatures of the fault signal, the optimization parameters are defined within a certain value range: L is [100, 500], T is [50, 150] and M is [1,7]. Subsequently, SCSSA is utilized to optimize these three crucial parameters of MCKD, and the iterative curve for optimizing the root crack fault signal is shown in the figure 11.…”

“…With the continuous advancement of industrialization in recent years, mechanical equipment is developing towards largescale, precision, and intelligence, and industrial robots are receiving more and more attention. As a pivotal component in industrial robots, RV (rotate vector) reducer is widely used in key parts such as robot joint drive, its performance seriously affects the operation status of rotating mechanical equipment [1].…”

Rheological characteristics and behaviour prediction of lubricating grease for RV reducer across a wide temperature range

“…Grease is the key element that affects its performance. Ideal operating temperatures allow the reducer to exhibit appropriate efficiency and service life during service [1][2][3]. At low temperatures, grease viscosity is high and the internal frictional resistance of the flow process is high, requiring the aid of sufficient external force to overcome the resulting resistance [4][5][6].…”

A Novel Method for the Analysis and Optimization of End Face Stress in Cycloidal Gears Based on Conformal Mapping

“…Furthermore, specific fatigue forms, like rolling contact fatigue in RV reducer crankshafts, have been investigated. Li et al introduced a 3D elasto-plastic contact model, factoring in hardness gradients and initial residual stress for better fatigue life prediction [12]. Additionally, Feng et al examined the breakdown of a secondary driving helical gear in electric vehicles, linking the failure to elevated contact stress and impact load caused by subpar material properties [13].…”