Simulation And Experiment Of Magnetic Memory In Gear Damage Testing

With the characteristics of stable transmission ratio, large bearing capacity, highmechanical efficiency, gear box has become one of the most widely used mechanicaltransmission device. The single tooth defects especially creep damage induced byfatigue crack is the major cause of failure in gear transmission. Currently, the vibrationanalysis method is the most common method in gear fault detection and diagnosis.While vibration analysis can only detect the macroscopical defects, it cannot fulfill thetask of determining the stress concentration area caused by the fatigue damage. Thenondestructive detection method based on metal magnetic memory can detect stressconcentration areas effectively. This article presents the magnetic memory testingprinciple firstly, and then the magnetic dipole model and the magnetic force couplingmodel are established. Based on these two models, the simulation of magnetic memoryphenomenon from simple flat model to complex gear model is completed. The failureprocess and magnetic memory phenomenon are analyzed through the gear bendingfatigue test. The main contents are as follows:(1)The theory of magnetic memory testing technology is introduced. Base on thethe magnetic properties of ferromagnetic material, the magnetic dipole model andstress-magnetization coupling model are established. The magnetic memorycharacteristics are caused by the joint action of the two models, which providingimportant theoretical basis for the finite element simulation and the design of testprogram.(2)Two types of plane models with different defects (the crack defect and the earlyfatigue damage) are established. The magnetic memory signal around the defect area issimulated respectively based on the model of magnetic dipole and stress-magnetizationcoupling model. And the characteristics of magnetic flux leakage signal with differentdefect parameters are analyzed.(3)The gear3D finite element model is established by using Solidworks@software.The stress distribution of gear tooth under the bending stress and meshing process isanalyzed by means of finite element method, respectively. Based on the model ofstress-magnetization coupling model, the magnetic flux leakage signals around the gear tooth crest are simulated, and the characteristics of magnetic memory signal arepresented.(4)The gear bending fatigue test platform is constructed. The gear failure processunder bending fatigue and variation characteristics of metal magnetic memory signal arestudied. Then, the metal magnetic memory signal evaluation guidelines of gear bendingfatigue failure are extracted. And the research results provide the useful references forthe application of metal magnetic memory method in early detection of gear damage.