The Study On The Non-Destructive Testing Instrument For Residual Stresses Of Crankshaft

Crankshaft is the one of the important components of internal-combustionengine. Along with the improvement of the power performance ofinternal-combustion engine, working load of crankshaft becomes stronger andstronger. In order to improve the reliability of it, crankshaft manufacturers carryout unremitting efforts in the aspects, such as material and production technologyto produce high-strength crankshaft. On the other hand, automobile factories andmaintenance manufacturers try their best to make measurements and harmassessments for crankshaft.As the research of the relative experts, the major damage of crankshaft comesfrom the fatigue fracture of transitional round angle between crank-arm andmain-shaft, crank-arm and the axle of connecting rod. This position hassignificant influences in the stress state in running on the exhausted strength ofcrankshaft. Through technology improvement and certain methods (For examplerolling press to angle position, spray pellet), the manufacturers have thecrankshaft keep the state of compression stress, so as to reduce its working stressand raise its exhausted strength. But now in remaining stress detections, there arenot enough to suit the method of the transitional round angle detection. Especiallythe fast online detection method that can realize nondestructive of this position ismuch deficient. The crankshafts manufacturers can only carry out determining thenature assessment, or do sample crankshaft destructive quantitative measure inlaboratory. All are nearly impossible to guarantee 100 per of the production underrequirement. The exhausted damage appraisement of crankshaft gets muchharder. Therefore the technical research of crankshaft residual stressnondestructive detection has been paying much attention.In this thesis, according to the theory of Barkhausen effect, the mechanismsof the accruing of Barkhausen Noise signal (abbreviation "BN") and the influenceon BN signals caused by the material internal stress and microstructure areanalyzed. The handling technology of BN signals that have been captured isstudied.and the design of crankshaft residual stresses instrumentation is offeredaccording to rules of the Barkhausen effect.