بررسي پديده جيغ ترمز و پارامترهاي موثر بر آن

چكيده انگليسي :

Modeling of disc brake squeal and the parameter are influenced on it Bahram Shahin Varnosfaderani b shahin@me iut ac ir bahram6283@gmail com March 14 2010 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisors Ziaie Rad Saeed Professor Email szrad@cc iut ac ir Esfahanian Mohsen Assistant Professor Email mesf1964@cc iut ac irAbstractBrake squeal is an annoyance noise caused during brake operation In brake operation three types of noisedepending on the frequency range may occurred When the frequency of noise is less than hundred Hertz it isnamed brake judder while for frequency less than thousand is named brake groan It is called Brake squealwhen the frequency is less than twenty thousand The focus of this work is on the brake squeal This noise is irritating to both vehicle passenger and passerby This problem has become principal issue forautomotive industrials increasingly in recent years Decreasing this noise causes increasing of vehicle quietness passenger comfort and quality of automobile and decreasing of warranty cost It is noticeable that onlyautomobile industries in North America spent one billion US$ a year to recognize and decrease the squeal The reason and source of generating brake squeal is not understood exactly because the mechanism ofgenerating this noise is so complicated Scientists that working in the field brake squeal accept that instabilitydue to the friction force leading to self excited vibration cause brake squeal Engineers and scientists commonlysuggest three possible reasons for the onset of instability namely the change of the friction coefficient withchange of relative speed between pad and disk change of the relative orientation of the disc and the frictionpads leading to a modification of the friction force and two modes which are close to each other in thefrequency range and have similar characteristics may merge as the friction contribution increases All of thetheories were studied in this thesis For the first two of these theories Matlab Software was utilized and somemethods were suggested for decreasing the brake squeal noise For decreasing the first theory first dither signalwas applied to system and the influenced of it was studied and at last two nonlinear controls sliding mode andcomputed torque method applied to system for suppression of stick slip For decreasing the affect of twisttheory at first linear control was utilized to decreasing out of plane vibration of disc and a nonlinear system wasintroduced for the brake squeal and nonlinear control computed torque method applied to four degree offreedom system of brake squeal for suppression of out of plane vibration The third theory was studied withAbaqus Software A finite element model of the Samand brake system was constructed in software and thensolved in several steps Finally the behavior of the model was analyzed with respect to the variation ofimportant parameters such as coefficient of friction brake force stiffness of the brake system and its materialcharacteristics The effect of slots on the pads was also investigated Key WordsBrake squeal Dither Friction induced vibration Sliding Mode Computer torque method Finite element Matlab Abaqus

شاهين ورنوسفادراني، بهرام

بررسي پديده جيغ ترمز و پارامترهاي موثر بر آن

دايتر , ارتعاشات خود تحريك , مودهاي لغزان , گشتاورهاي محاسبه شده , المان محدود , آباكوس , متلب