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Hi!! can any one tell me the free vibration occur in a buses mean that which components experience the free vibration which could be or could not be damped out !!! i have search alot but didnt get relevant matter on this topic!! it is my assignment which is given by my professor !! so plz help me !!!
From
Haris Aslam ,Student of Automotive Enginneering Frm NED University ,karachi,Pakistan  

Plz make it harry up !! is there no one who actually make any contribution in this regard & giving me a chance to thanks!! guys help !!  

i think that you are ahead of your self...   there are lots of components in a bus that can vibrate..   depending on the road surface... the engine isolation mounts... the suspension mounts...

there are NVH.. noise vibration and harshness microphone kits that can be attached to multiple parts of cars and trucks to measure the harmonic vibrations and noises... think of microphones on little clamps.. all hooked up to a recorder...

do you know what frequency the vibrations is happening at.. with the frequency.. you can look at other systems to see what is  causing it...  

thanks for reply!! dude i know there are alolts of part which are vibrate after expriecne bump from road and running engine !! but my concern is with free vibration (a body is said to be vibrate continuously after a small deformation or applied of forece initially)mean that which parts causing free vibration ???
what i understand is that spring in suspension , valves floating when engine run in red zone ,due to air noise the body is also vibrate !!!So you tell i m taking the concept in the right way ..Correct me if i m wrong !! Tell me parts name which exprience FREE VIBRATION!!
Haris Aslam ,Student Of Automotive Engineering, frm NED university ,karachi,Pakistan  

there is a natural frequency that automotive bodys will resonate at.. or flex at.. perhaps this is what you are talking about...

i think that you need to read up on a bunch of articles ... over at SAE.org...  they will have the answers you need...

but i have found some of the articles misleading...  so beware... but most of their data is good..

just because somebody wrote it down.. and got it published .. does not make it true...


in bus bodys....  more fasteners of the flat panels to the structure...    more triangulation in bracing.. will reduce flex...

but then you have to take into effect of the weight ...    and how much flex is acceptable...

out here in california... there was a brand of busses... that had a problem...  it had just a tad too much flex for the frames to withstand...    the potholes in the pavement when fully loaded caused the aluminum frames to fatigue and crack.. sometimes dropping the bus to the ground...    

are you designing a new bus????      is so... you really want to plan ahead...   if it is electric...  you may want to design in a removable battery pack.. that has spring loaded contacts...  so when the bus gets to one end of its route... it pulls into a depot..  the driver locks the brake... gets out...   pulls open a compartment...  flips a switch.. retractable wheels come down on the battery pack..   screw drive actuators lower the battery from it mount.. the battery can then be rolled out and into a charging stand... and another battery rolled in...  this prevents the need to park the bus for hours and hours while recharging the battery...

air conditioners for the busses need to be modular...  and hook up with low pressure liquid hoses...  like a heat pump...  

so they can be removed and replaced in minutes when problems arise..  by line personal..  then moved to specialists for repair...  

for liquid fueled motors... the drivetrain needs to be designed to swap out in an hour...   the whole engine transmission and rear axle roll out...   roll in another ... and the bus is ready for the road...     the chassis that supports the powertrain would weigh slightly more.. but the ease of service would make it really attractive to fleet owners...   the ability to roll the drivetrain out of the bus...  take it to a test stand... with a built in hydraulic lift... so the mechanics can repair it.. service it... test it... all without having to take a bus out of service...      with the ability to multiplex engine controls...  all the engine controls except for the air brake hoses can be plugged in quickly..

think of how this will change bus designs...   swapping in an electric motor power train... with the removable battery pack... or the city diesel power train... or the highway power train...  ...