Lecture 3 SDOF Systems Flashcards
1
Q
SDOF
A
single degree of freedom
2
Q
what does SDOF mean
A
just consider one directions of motion, very simplified system
3
Q
there are as many vibration modes as there are
A
DOFs
4
Q
on a frequency response graph what does the number of peaks refer to
A
the number of degrees of freedom (just count peaks, not troughs)
5
Q
what can you treat a system with multiple degrees of freedom as SDOF
A
in the frequencies around a single peak
approximate motion around a resonance
6
Q
force equivalent of mass
A
fm = m x..
7
Q
force equivalent of spring
A
fk = kx
8
Q
force equivalent of damping
A
fc = c x.
9
Q
equation of motion of free vibration
A
mx.. + kx = 0
10
Q
general solution to free vibration equation
A
x(t) = C1 e^jwnt + C2 e^-jwnt
11
Q
SDOF general equation
A
x(t) = Acos(wnt) + Bsin(wnt)
12
Q
undamped natural frequency
A
wn = sqrt (k/m)
