We live in the time domain and things change all around us as time marches perpetually forward. We typically notice how things change with respect to time.

For example, consider this car crash footage from a test run. If we were to study the effects of this crash, it would be in the time domain — how does the damage increase as time goes on?

But sometimes we need to change to a different domain, specifically the frequency domain. A windmill, a bridge, an aircraft or even your bicycle or washing machine all have long operating cycles. Simulating their response to dynamic forces over such a long time will overwhelm our computers because we have to solve for each small increment of time.

Lecture

To speed things up and save our computers, we can transform vibrations that happen in the time domain to the frequency domain by extracting all the vibration frequencies and the amplitudes of the load. We can then solve over the desired frequency range, exciting the structure with a variety of loading conditions. This allows us to solve these complex problems very efficiently!

In this lesson, we will discuss the concepts of time and frequency domains and explore their advantages and limitations.