Out of balance rotating system

AI Thread Summary
The discussion focuses on calculating the out-of-balance mass and angular position for a rotor assembly with unbalanced discs in different planes. For part (a), the user seeks guidance on determining the values of mBrB and ΘB, specifically using moments about point A and constructing a moment polygon. The user expresses confusion regarding how to find the closing vector necessary for these calculations. For part (b), the objective is to achieve dynamic balance by adding masses in planes A and C, requiring further calculations for their values and angular positions. The conversation emphasizes the need for clarity in applying moment theory to solve the problem effectively.
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Figure Q4. illustrates a rotor assembly with out-of-balance rotor discs in planes A, B
and C. The out-of-balance mass x radius products in planes A and C are as
indicated in the figure. The out-of-balance mBrB in plane B and its angular position \ThetaB
are such that the system is in static balance.

(a) Determine the values of mBrB and \ThetaB.


(b) If the system is to be dynamically balanced by adding balancing masses m1r1
and m2r2 in planes A and C, respectively, determine their values and angular
positions \Theta1 and \Theta2.

Any help is much appreciated!
 

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What don't you understand about part a?
 
well how to do it, in my lecture notes I says to take moments about a point, so I chose to go about point A. so from that I drew a moment polygon. I need to find sommething called a closing vectpr, I presume so thwt from point C I cwn return to point A therefore using some angles and other maths calculate a values for the question. I just don't know how to ge the closing vector.
 
sorry for the horrid spelling my tablet keyboard is crap
 

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