Multi-objective Evaluation of Sealing Performance for High-Power-Density Diesel Engine Block-Cylinder Head Joint Surface

Based on the analytic hierarchy process (AHP), this paper constructs an objective-criterion-indicator evaluation model for the sealing performance of the engine block-cylinder head joint face in diesel engines. Judgment matrices for the objective-criteria and criteria-indicators were established according to actual expert ratings, and the weights of four types of design parameters relative to the overall sealing performance objective were calculated. Combined with finite element analysis of the assembly stress characteristics, precise quantitative ranking of the sealing performance for six different design schemes was achieved. Taking a certain type of V10 highly reinforced diesel engine as an example, the computational results indicate that the circumferential stress fluctuation around gas holes in the gasket is the most significant, with the peak stress reaching 19.42MPa, reflecting more pronounced non-uniformity of circumferential stress around gas holes. The stress distribution around water holes and oil holes is more uniform, with circumferential stresses mostly concentrated in the range of 15 - 20MPa. Oil hole 1 exhibits the highest average contact stress of 19.42MPa, while water hole 2 shows the lowest average contact stress of 15.04MPa, indicating that the region around oil hole 1 bears stronger loading. Among the six assembly schemes, both the criterion layer and indicator layer evaluations rank Scheme 6 as having the best overall sealing performance and Scheme 4 the worst, verifying the consistency between the evaluation model (criterion and indicator layers) and the instance-based computational results, which aligns with the physical principles of sealing and engineering experience.