CG & moment of inertia - W.r.to co-ordiante transformation 1

[elogesh]

Dear all,

In a automotive vehicle, we got the CG as well moment of inertia of the power train(engine+clutch+gearbox..) about the vehicle co-ordinate system with zero degree of rotation.When the engine is fitted into the vehicle the engine is rotated -3 deg for connecting the propeller shaft with the rear axle.

We would like to have the revised CG and moment of inertia for this -3 deg rotation with respect to vehicle co-ordinate system.

Kindly let me know the procedure to convert CG and moment of inertia values from zero deg to 3 deg rotation.

Sample data:

CG X =-660 Y=-7 Z=144

Moment of inertia tensor

IXX= 72 IXY= 0.6 IXZ=-55
IYX-55 IYY= 410 IYZ=0.6
IZX=-55 IZY= 1.58 IZZ=385


Rotation of power train about Y-axis w.r.to Vehicle co-ordinate system.

Kindly let us know whether any other info required.... to calculate the new CG and moment of inertia.

I thought it has to be multiplied by below transformation matrix,but not sure

cos(-3) 0 -sin(-3)
0 1 0
sin(-3) 0 cos(-3)

I look forward for your expert comments for determining the new CG and moment of inertia of power train with respect to vehicle co-ordinate system.

Thanks in advance.

Elogesh

 

[zekeman]

Looks good to me.

 

[zekeman]

On second thought,if the engine is rotated -3 deg then the vehicle frame is rotated +3 degrees with respect to the engine frame, so the transformation should be

cos(+3) 0 -sin(+3)
0 1 0
sin(+3) 0 cos(+3)