Lecture 19 Balancing

Question 1

machine is balanced if

Answer 1

sum of dynamics force is zero

Question 2

what is the acceleration of single out of balance mass m located at radius r from axis of rotation

Answer 2

under constant velocity rotating

a = -w^2 r

Question 3

Force applied to rotor with single out of balance mass m located at radius r from axis of rotation

Answer 3

F = m w^2 r

needs to be equal and opposite

Question 4

To balance a single out of balance mass what should be done

Answer 4

a balance mass M can be added diametrically opposite at distance R
where mr = MR

Question 5

moment vector of out of balance masses in multiple planes what is this system

Answer 5

M = d x F = d x mw^2 r = dk x mw^2 ri = dmw^2r j

dynamically unbalanced

Question 6

Draw out the tabular form table

Answer 6

see book

Question 7

what will mrd always equal for one of the bearings

Answer 7

0 as d = 0

Question 8

Once the tabular method table is complete how are the final values of mrd calculated

Answer 8

using sum of mrd = 0 graphical
close force polygon in horizontal direction
mrd1 * cos(theta1) + mrd2 * cos(theta2) + mrd3 * cos(theta3) = 0
close force polygon in vertical direction
mrd1 * sin(theta1) + mrd2 * sin(theta2) + mrd3 * sin(theta3) = 0
solve for values of mrd and theta that are unknown
draw sketch to check if theta needs + 180

Question 9

How do you obtain bearing loads from tabular method

Answer 9

mag F = mrw^2 angle will = theta