234 Nanosensors: Physical, Chemical, and Biological
The only remaining normal stress σ
x
can be written as
σ
x
ky=
(4.2)
where
k is a constant
y = 0 lies in the center of the beam
The total internal force has to be zero, and it is given by
F dA
x
A
int
= =
∫
σ 0
(4.3)
A bending moment is a term used to describe the force or torque exerted on
a material and leads to the event of bending or exure within that material.
Moments, internal or external, are rotation equivalents of forces, equal to
force times distance. The bending moment in a beam is the moment, internal
to the beam, necessary to counteract externally applied moments. The bend-
ing moment at a section through a structural element is dened as the sum of
the moments about that section of al ...