input sine wave for 3 seconds

I am trying to simulate a 1DOF structure response to an earthquake (sine wave) input using ode45.

I can input: earthquake = A*sin(w*t), but how do I make this equal zero after a certain time has passed? i.e. 3 seconds. And then see how the structure response dissipates after the sine wave (earthquake) has stopped?

Thanks a lot :)

Answer 1

[Star Strider]

You can probably do this by simply thresholding with respect to time. This creates a discontinuity, so multiplying it by a second sine curve with a period of 6 seconds (to give a more gradual envelope) would likely work best. It would also be best to give your ODE a ‘tspan’ vector of discrete times rather than a two-element range.