Design and Stress Analysis of Extraterrestrial ... - The Black Vault

External loads during blade vibration are, the forces of inertia.
The linear load from the force of iflertia is
expressed by. equality
f0¢2 (a)
or,
q = --QFtj,
(a')
where opF is2 the linear mass of the blade (the mass of a unit
length of a blade);
ýp, is- the; dens!ity, of the b2!ade;,materia-1l-;
F is- the area .of the current blade cross section;
= n(z, t) is the bending func~tion (the equation of an elastic
line) o2 the blade.
The externf.l force of inertia is
ba~anced by- the internal
elastic forces.
As we know,
the bending moment during bending of a beam is
l-f
A ,dz2 (b)
or
•"M, "E IEV (b",
w.'ere E is the elasticity modulus of the first kind;
I is the moment of inertia of the cross sectional area of
a blade relative to the ý ax1s.;
1 nr is the second derivative with respect to z of the function
of deflection.
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