# Problem 11: Dynamic Analysis for Vibration of an Unbalanced Mass

## Objective

A 65 Kg industrial sewing machine has a rotating unbalanced mass of 0.15 Kg-m. The machine operates at 125 Hz and is mounted on a foundation of equivalent stiffness 2x106 N/m and damping ratio 0.12. What is the machine's steady state amplitude?

## Entities Validated

- Rigid body
- Revolute joint
- Translational joint
- Force_Spring damper – translational

## Type of Analysis

- Dynamic

## Reference

Schaum’s Outline of, Theory and Problem of Mechanical Vibrations, First Edition by S Graham Kelly: 82 (ISBN 0-07-034041-2)

## Model Files

- rotating_unbalance_mass.mdl - MotionView Model
- rotating_unbalance_mass.xml - MotionSolve Deck

## Graphical Results

## Result Comparison

Output | Analytical | MotionSolve | % Error |
---|---|---|---|

Steady state amplitude of machine (mm) | 2.43 | 2.43 | 0 % |

## Conclusion

MotionSolve results compare well with analytical results.