This study uses experimental and numerical methods to examine the impact of average fatigue force, amplitude fatigue force, and internal pressure on the ratcheting behavior of SS316L concentric and eccentric reducers. The material of the samples was first verified through mechanical analyses. Subsequently, the samples were fatigue tested at controlled force and room temperature (25 ◦C), and strain reading was done at the critical points of the samples by the digital image correlation (DIC) method. Numerical simulations with Abaqus software were conducted to validate the experimental results, confirming the experimental tests’ accuracy with an acceptable margin of error. Finally, after ensuring the reliability of the numerical results, the influence of the changes in the parameters mentioned above was numerically investigated. It was observed that as these variables increase, the ratcheting strain also increases in the axial and circumferential directions, with greater sensitivity to the increase in average force and amplitude force.
