تحليل رفتار ارتعاشي جاذب ارتعاشي ساخته شده از آلياژ حافظه دار

چكيده انگليسي :

Vibration Analysis of a Shape Memory Alloy Adaptive Tuned Vibration Absorber ATVA SeyedBashir Shokrani sbshokrani@me iut ac ir Date of Submission 06 05 2009 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 8311 IranDegree M Sc Language FarsiSupervisors H Nahvi Assoc Prof hnahvi@cc iut ac ir M Kadkhodaei Assist Prof kadkhodaei@cc iut ac ir Abstract Vibration is a phenomenon that has been studied extensively due to its destructive effects such as causingthe neurosis and noise and destruction of machinery parts to eliminate vibrations various techniques have beenimplemented including design of new structure and using vibration absorbers Among these solutions vibrationabsorbers have received special attention due to their application oriented essence Vibration absorbers have agreat variety Among these tuned vibration absorbers TVA are capable to be adjusted with the system whenchanges take place in the system Tuned vibration absorbers may be categorized into active passive andadaptive types ATVA among which the adaptive type has received special attention due to its adaptivity withthe system Smart materials have special characteristics that make them suitable for utilization in tuned vibrationabsorbers Among smart materials shape memory alloys SMA are under the spotlight due to their phasechange and super elastic characteristics In this thesis an adaptive tuned vibration absorber made from shape memory alloy has been analyzed Inthis analysis an aluminum beam with support motion is considered as the objective system and a SMA beam isconnected to the end of the aluminum beam as a vibration absorber First specific behaviors of shape memoryalloys are simulated using constitutive equations A code is also developed for simulation of vibration of thebeam with support motion and a concentrated mass on its other end For vibration analyzing of a shape memoryalloy beam first it is tried to analyze it with ABAQUS But it is cleared that because of the special beam elementin ABAQUS that it does not have any control on cross section for deriving the results this method is not usable Then the vibration equations is derived with noticing that the module of elasticity changing with stress and istried to solve this equation with finite difference but it is showed that with this method the results are diverged So it is considered that the module of elasticity does not change with stress and just change with temperature Results show that the shape memory alloy beam has less deflection due to super elastic property and hysteresiscycle that dissipates energy and by exciting the shape memory alloy via heating and consequently changing thephase from Martensite to Austenite which results in a change in system s stiffness the natural frequency of thesystem can be altered to avoid resonance Considering the results shape memory alloys seem to be appropriatefor using as absorbers Then a system consisting of an aluminum beam as the objective system and another one made from shapememory alloy with a mass an end mass which is connected to aluminum beam is analyzed Results examination demonstrates that shape memory alloy has a satisfactory performance as an absorber In addition by exciting the shape memory alloy wires which results in a change in their phase the system s stiffness ischanged and the natural frequency of the system is relocated This may be used to avoid resonance in thesystem Key Words Vibration Shape Memory Alloy Absorber Tuned Damping

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تحليل رفتار ارتعاشي جاذب ارتعاشي ساخته شده از آلياژ حافظه دار

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