The Fretting Fatigue Damage And Improvement Measures Of Engine Block-main Bearing Cap Interface

Fretting fatigue easily causes the decrease of the component fatigue life, resulting in aunexpected accident. The block as the main part in the engine parts, often stays in complexand harsh working environment, which is prone to fretting fatigue damage. In this paper,against to the fretting fatigue fracture failure phenomenon of the block crossbeam of a powerV6diesel engine, which is generated in the course of their work, launches a series of frettingfatigue damage and improve research.Against the block-main bearing cap contact model to have a finite element calculation,analyze the force and deformation of each component and the contact characteristics ofcontact surface in the contact model, determine the failure form of block crossbeam, select aapplicable fatigue damage parameter method, make a number of improvements which arereference to the major factors of fretting fatigue and the specific condition of the block, verifytheir improvement results by using the selected parameter method, get twelve effectiveimprovements. The twelve improvements have considerable practical value to productionpractices. And the set of calculation, analysis, judgment, improvement and validation methodsand processes with a considerable degree of reference for the future fretting fatigue andfretting damage protection researches. The main works include:1.Using Pro/E to establish a block-main bearing caps physical contact model, usingANSA to establish a finite element model of contact model by local mesh refinement methodand sub-regional meshing. Selecting five different sizes for the refined mesh of contactsurface, and proving the model has better grid independence when it’s refinement unit lengthis0.2mm.2.Having the static analysis of block-main bearing caps contact model and the stress and displacement distribution analysis of components, in preload and outbreak conditions. Havingthe contact state, contact pressure and contact friction analysis of contact surface, and findingout the possible reason of analysis results.3.Summarizing the differences between fretting fatigue and general fatigue and thedifferences between general wear and fretting to judge the fretting fatigue damage. Having thestructural failure mechanism analysis about block-main bearing caps supporting surface,based on the knowledge of fretting fatigue failure mechanism.4.Using initially selected five parameter methods, which are used to calculate frettingfatigue damage, to predict the positions of contact surface micro cracks. Selecting RUIZcomprehensive parameter method as the fretting fatigue evaluation criteria.5.Referencing the key factors of fretting fatigue and the study of the block’s actualsituation to make a number of improvements, and using RUIZ comprehensive parametermethod to verify them. In the ultimately, selecting twelve effective improvements for theblock crossbeam fretting fatigue damage.