TRIMMED BODY NVH

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TRIMMED BODY NVH

 

VEHICLE DESIGN DISCIPLINE:

The vehicle design need to target the four discipline, They are…

·       MBD(multi body stimulation)

·       CRASH

·       DURABILITY

·       NVH(noise,vibration,harshness)

 

 

MBD(multi body stimulation):

It helps in studying the dynamic of moving parts,How load,force are distributed throughout mechanical system.

 

CRASH:



It is done to verify the structural integrity& crash worthiness of the vehicle.

In this particular design is more important,we can make a accidentand check it.whether,the passenger safe (or) not.

 

Durability:

To access the life time of  biw components for service load.

In durability,you have a repetitive load.

For example,

10 Kg load applying the particular part continuously,how many hrs the part will sustainand when the part will break down.

 

NVH(noise,vibration,harshness):



It is major priority in automotive design,because people feel fatique,vibration etc…

NVH pertains to measurement and reduction of excess sound and vibration in vehicle.

Car manufacturer focusing on reducing NVH to improve driving experience.

We can feel vibration by our touch and vision, and also feel noise by hearing.

People can feel the noise and vibration in different way,some feel annoying,some does not feel anything happens.

Vibration occurs at low frequency(30Hz -200Hz),if you ever felt steering wheel shake?

Noises occurs at high frequency(30Hz-4000Hz) and it can be high pitched sounds and it may be suddenly happens.

While noise and vibration are easily measured.harshnessis more relative item,harshness is how noise and vibration is intense inside the cabin.

 

WHY NVH IS IMPORTANT:

 


Imagine,we can built a bridge,if wind blows at high speed.and it also have own natural frequency depends on the stiffness of material and mass.when these two meet at a same value,then the bridge start oscillation.

Thus, while the nvh phenomenon is more important.when the high vibration takes place ,the bridge will collapsed automatically.

 Bridge collapsed video

AUTOMOTIVE FREQUENCY RANGE:


Global stiffness can br cured by CAE or FEA methods.

Local stiffness are cured by boundary element method.

                        Absorbtion,mass,stealing are cured by energy based method. 

STRUCTURE BORNE NOISE:

It is the sound,which spread in solid bodies like walls,houses etc…

Medium of transfer is structure because these sound travelled by structure.

Vibration is the resultant of structure borne noise.

Frequency range=uoto 1000Hz.

Feel as a vibration and heard as a noise.

In automobile,the vibration is first generated by friction of wheel and road and then it goes to shock absorber,it will reduce a vibration as much as possible but not 100%,then it reaches structure of automobile the the passenger feel the vibration.

 

AIR BORNE NOISE:

It can be carried via air.this can be heard by passenger’s ear from 20k Hz.

Sound pressure of noise is resultant of it.

Air borne noise falls in under high frequency.



 In this article,if u have such kind of doubts feel free to ask me 💬 INSTAGRAM@ ame_ir43

 

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