Design And Experimental Study Of Specimen In Ultrasonic Fatigue Test Of Materials

In recent years,higher requirements have been put forward for the performance of materials and components by the development of aerospace,transportation,nuclear industry,machinery and other fields.The traditional fatigue test has low load vibration frequency.It will not only takes a lot of time and cost,but also impossible to draw S-N curve when the material high cycle and super high cycle fatigue tests are completed.By means of ultrasound,the test time and cost are saved to a great extent.By adjusting the test device,the fatigue tests of tension,bending and torsion can be completed.In this paper,the design of specimen in the ultrasonic fatigue test device as the key point,completes the specimen size precalculation with the help of Microsoft Mathematics software,and uses the Ansysworkbench software to assist in the dynamic optimization design of the specimen.Find out the most important dimension in the specimen design,and give the tolerance range,reduce the machining precision of the specimen,reduce the processing time,and save the processing cost.When the stress value of the specimen is less than the stress value required for fatigue fracture,the condition analysis under the ultrasonic fatigue test of the specimen is given,and the test fracture requirement is achieved by optimizing the design of the specimen without replacing and adding the variable amplitude rod.The two-arm cantilever beam model is used to complete the ultrasonic fatigue bending test,which avoids adding bending loading bar and static load loading device to the traditional three-point bending test device,and enriches the specimen model ofultrasonic fatigue bending test.In this paper,the analytical calculation results of the specimen are given and the simulation analysis and dynamic optimization design are completed.Based on the existing ultrasonic fatigue test equipment,the test-bed is built and debugged,and the material ultrasonic fatigue tension test and bending test are successfully completed.Complete the statistical data carding,give the material ultrasonic fatigue tension,bending test from the design of the test to the test results carding of the complete process.In order to complete the ultrasonic fatigue test of precious metal and super-hard metal,the design method of central mosaic specimen is put forward,and the connection between the clamp and the test material is realized by the way of interference connection.The superhard metal 18 Ni maraging steel(250)was used as the test material and 30 CrMnSi steel as the clamp.The theoretical analysis of the specimen,the design of the excess interference and the design of the assembly process were completed,and the dynamic optimization design were carried out to complete the modification.In order to ensure the accuracy and feasibility of specimen design.The concept of dynamic optimization of specimens proposed in this paper has perfected the design and machining methods of specimens in the field of ultrasonic fatigue.Shorter processing time and less energy loss contribute to the popularization of ultrasonic fatigue test;The double-arm cantilever beam model makes up for the single defect of the bending test model;It also provides a feasible method for the selection and treatment of test materials in ultrasonic fatigue test of precious metals and superhard metal materials.