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Dynamics cheat sheet

my dynamics notes - 12000.org

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One degree freedom<br />

linear system unforced<br />

response<br />

y t c m y t k m yt 0<br />

y t 2 n y t n2 yt 0<br />

Some<br />

defintions<br />

k<br />

n m rad/sec<br />

damping ratio<br />

c c c<br />

r<br />

c<br />

2 km 2 n m<br />

Solution roots<br />

s 1,2 n n 2 1<br />

3 cases<br />

d n 1 2 30<br />

Defined only<br />

for under<br />

damped<br />

case(else zero)<br />

1 1 1<br />

Underdamped<br />

2 roots,<br />

complex<br />

conjugate<br />

Critical damped<br />

(one real root,<br />

double<br />

multiplicity)<br />

Over damped,<br />

2 real roots,<br />

distinct<br />

yt e nt Acos d t Bsin d t<br />

A y0, B y 0A n<br />

d<br />

yt A Bte nt<br />

A y0, B y 0 A n<br />

T d 2<br />

d<br />

1<br />

n<br />

Nasser M. Abbasi<br />

May 25, 2011<br />

One_DOF_system.vsd<br />

Damped period of oscillation<br />

Time constant<br />

yt Ae 2 1 n t Be 2 1 n t<br />

A y 0y0 n<br />

2 n<br />

B y 0y0 n<br />

2 n<br />

2 1<br />

2 1<br />

2 1<br />

2 1

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