Thermo-mechanical deformation control of a cylinder liner using segmented pre-compensation design

The thermo-mechanical deformation of cylinder liners significantly affects the structural integrity and tribological performance of internal combustion engines. However, the strong coupling among thermal loads, assembly constraints, and material responses makes it difficult to control the working geometry of liners under operating conditions. In this study, a fully coupled thermo-mechanical finite element model of a non-road diesel engine assembly is developed to investigate the out-of-round deformation behavior of a wet cylinder liner at the firing moment under rated condition. The axial and radial deformation characteristics of the liner are systematically analyzed, revealing a pronounced axial segmentation of deformation induced by spatially varying thermal and mechanical constraints. Based on these findings, a segmented inner-surface pre-compensation strategy is proposed, incorporating radial honing depth, axial conicity, and ellipticity as design variables. To efficiently identify the optimal combination of pre-compensation parameters, a self-directed online learning optimization (SOLO) algorithm is employed, with liner straightness and roundness jointly considered as the optimization objectives. The results demonstrate that the proposed segmented pre-compensation approach effectively counteracts thermo-mechanical deformation. Compared with the original liner, the optimized design achieves a maximum reduction in axial straightness of approximately 18% while maintaining nearly unchanged roundness across all characteristic cross-sections.