9269

8571

كارشناسي ارشد

مكانيك-طراحي كاربردي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مكانيك

1393

بيست،153ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

محمود سليمي

محمود فرزين

1/9/93

محمود كدخدايي، مهدي سلماني تهراني

مهندسي مكانيك

ID8571

154 Modeling and Experimental Investigation of Friction Force in Metal Forming Processes with Ultrasonic Vibration Davoud Shahgholian Ghahfarokhi d shahgholian@me iut ac ir Date of Submission 2014 09 16 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Mahmoud Salimi Salimi@cc iut ac irAbstract Friction is created when two bodies slide on each other If the contact surfaces are examined at microlevel it is seen that the surfaces have asperities In fact the asperities get in the way and cause friction Bysuperposing ultrasonic oscillation to one of the bodies the friction force is reduced This phenomenon iswidely used in metal forming and metal cutting In recent years particular attention is paid to use such kind ofoscillations This phenomenon may be used as a replacement of lubricants in such processes due to its higherefficiency and less pollution effects In this research an elastic plastic model for the deformation of asperitiesduring the sliding of two surfaces is given which is capable of predicting friction force when ultrasonicvibrations are superimposed to macroscopic motion In this model area of asperities was considered as abeam and contact parameters were related to the dimensions of the beam and the equations related of thesurface area of the contact and the vertical and horizontal forces between asperities were obtainednumerically The advantage of this model over the other existing models is that the proposed model canpredict the friction force based on completely theoretical consideration without any experimental results Tovalidate the proposed model it was required to have reliable experimental results An experimental set upwas designed and built for this verification This set up have many segments The most important segmentsare a generator a transducer and a horn The horn that is used in this study is designed using the Abaqussoftware The tests for validation of the model presented in this research were carried out in longitudinal andtransverse modes on Aluminum and Steel samples of different surface roughness and different speed Comparison of experimental results with results from the theoretical model was made in three differentlongitudinal transverse and bidirectional modes The experiments show that the reduction in friction forcevalue due to superimposition of the ultrasonic oscillations in the longitudinal direction is 100 and for thevertical direction is 32 and for the bidirectional mode is 50 The maximum error of the model forlongitudinal direction vertical direction and bidirectional case is 22 14 and 10 respectively Thesevalues demonstrate the high accuracy of the model The proposed model was compared with the Coulomband Dong model The comparison show that the present model is a more accurate as compared to that of theCoulomb and Dong model Keywords Modeling Friction Asperity Ultrasonic Oscillation Set up Horn

محمود سليمي

محمود فرزين

محمود كدخدايي، مهدي سلماني تهراني