The Influence of Structural Design Parameters on the Retention Force and Interference-Fit Reliability of Connecting Rod Bushings

Connecting rod bushings are core friction-pair components in diesel engine crank-connecting rod mechanisms, and their loosening failure—causing lubrication failure, accelerated wear, and even catastrophic damage. To address this critical issue, this study systematically investigates the influence of key structural parameters (inner diameter, wall thickness, width) on the retention force of the bushing’s interference fit. Through a combination of theoretical analysis, finite element analysis (FEA), and experiments, the safe interference range for typical bushing geometries is determined to be 0.08–0.11 mm (corresponding to a retention force range of 33.61–46.25 kN). Further parametric studies reveal that the retention force decreases with increasing inner diameter while increasing significantly with greater wall thickness and width, with wall thickness identified as the most influential parameter. For bushings featuring a large inner diameter, thin wall, and narrow width, stricter interference tolerance is required to ensure connection reliability. These findings establish a reliable parametric design framework, providing actionable engineering guidance for optimizing bushing structural design, controlling assembly processes, and mitigating loosening risks in similar heavy-duty equipment components.