Department of Engineering

# The dynamics program

## Introduction

 dynamics is a program used in the 1B course to model simple spring-dashpot systems. Start the program by typing ``` dynamics ``` It's a matlab-based program, so you can use the usual matlab methods of producing output. Details on particular features are described below. To enlarge the screen-dumps in this document, just click on them.

## Model

 Use this panel to choose how many bodies will be in the system and change system values Use this panel to set initial conditions

## Time Domain

 Use the Time Domain panel to select parameters. A default step force (15kN) is already loaded - the 'Show Default Step force' button display it. Then press the 'Run time analysis' button. Output will be like the picture on the right when there are 2 degrees of freedom.

## Frequency Domain

 Use the Frequency Domain panel to select parameters. Then press the 'Run frequency analysis' button. Output will be like the picture on the right when there are 2 degrees of freedom.

## Utilities

• Printing - Use the "Print..." and "Page Setup" menu options. To save images into files use the "Save as" menu option.
• Zooming - The "Tools" menu includes a Zoom option which you can sometimes access using buttons under the menubar. When zoom is on, click the left mouse button in a figure to zoom in on the point under the mouse. Click the right mouse button to zoom out.
• Points - to obtain numerical values from graphs, click on the graph's button then click on the point of interest. The coordinates displayed will be of the point of the graph whose x-coordinate is nearest to the x-coordinate of your cursor.
• Save/Restore sessions - lets you save and restore system parameters.

## Background

The code is partly a conversion of Fortran code written by Dr Ruth Thomas, partly an adaption of matlab code written by Cristian Gutierrez Acuna (from the Matlab Central archive) and partly written by Will Hoult (CUED). Some of the theory is on our Matlab and 1B dynamics page.

Mail bug reports to Tim Love (tpl)

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