Study On Ultrasonic Assisted Cracking And Characteristics Of Classification Components Of Connecting Rod Dissection

The cracking process of automobile connecting rod is the most advanced processing technology of connecting rod,which causes the brittle fracture of the large end of the connecting rod,and then forms a natural staggered saw tooth form on the cross section.Finally,the connecting rod body and the connecting rod cover are meshed with the three-dimensional concave and convex structure.Although the technology has been introduced to China early,there are some defects that limit its development: the limitation of cracking materials and the lack of cracking processing technology.Although C70S6 BY can be used for cracking in cracking materials,the price of the material is more expensive and the toughness is lower,and there is no breakthrough and innovation in the processing methods and technology of the connecting rod,and it is still unable to improve a series of problems occurring during the cracking process of the connecting rod,such as the end of the round,the burst,the bag,the single.Edge fracture and crack propagation surface migration.In order to solve the two main problems existing in the cracking of the connecting rod,this paper uses the quenched and tempered 45 carbon steel as the test material.First,the influence of the cracking velocity,amplitude,frequency and depth on the stress and strain of the material and the distribution of stress cloud map are simulated.The relationship between the cracking velocity,amplitude and depth of the cracked specimen under the condition of the vibration frequency of 20 KHz was explored through the test.Finally,the change of fracture morphology of the specimen under different parameters was observed by scanning electron microscope.The main work and conclusions of this article are as follows:(1)Starting from the function and basic principle of ultrasonic generator,transducer and horn,the design of the horn and cracking sample is carried out by combining theory with simulation,and the size of the horn and cracking sample can be obtained to meet the requirements of the experiment.At the same time,the corresponding transducer and cracking sample should be designed according to the experiment.Fixed support to build an ultrasonic assisted cracking test platform.(2)Using ABAQUS simulation software to simulate the ultrasonic vibration cracking test.The effects of cracking rate,amplitude,frequency and groove depth on the maximum principal stress and strain and strain cloud diagram of samples were analyzed.The simulation results show that the cracking speed,amplitude,frequency and depth are all affected by the material: the maximum principal stress value of the material increases first and then decreases when the cracking rate increases,and the maximum main stress(tensile strength)decreaseswith the increase of the ultrasonic amplitude and the depth of the groove,and reduces the plasticity of the material,and improves the material.Brittleness breaks the material in advance.When the ultrasonic frequency increases,the maximum principal stress of the material decreases first and then increases.(3)The vibration cracking test of the velocity,amplitude and depth of the cracking was carried out by the designed ultrasonic vibration cracking test platform and device.The influence of the ultrasonic frequency of 20 KHz,the velocity of cracking,the amplitude and the depth of the groove on the change of the stress value after the cracking of the material and the fracture morphology were emphatically analyzed.The test results show that the tensile strength of the specimen increases first and then decreases with the increase of the cracking speed,and the plasticity of the material decreases and the brittleness increases,but the fracture is still plastic fracture,and the tensile strength and plasticity of the material decreases with the increase of the cracking rate.When the amplitude is 15?m,the fracture of the specimen is typical brittle fracture,and when the amplitude is 30?m,the material occurs fast fatigue fracture.When the amplitude increases,the plasticity of the material decreases and the brittleness increases with the increase of the cracking rate.(4)Explored the effect of different groove depths on the fracture of vibratory cracking.The results show that when the specimen is not notched,the specimen has no obvious necking,the fracture rise and fall,the plasticity of the material and the brittleness increase,but the fracture is still the fracture of the dimple.With the same amplitude,the brittleness of the material increases with the increase of the trough depth(stress concentration coefficient),and the fracture is even flat.