2008

Table Of Contents
Key Terms
DefinitionTerm
The moment of all forces that act on the member to the left of a section (a point
along the member where bending moment needs to be calculated) taken about
the horizontal axis of the section.
bending moment
A curve representing the vertical displacement of different points along the
member subjected to a load.
deflection line
A load or force that is exerted over a certain length.distributed load
A support that prevents translation as well as rotation about all axes.fixed support
Force or moment acting on a member or body.load
An important property of areas and solid bodies. Standard formulas are derived
by multiplying elementary particles of area and mass by the squares of their
moment of inertia
distances from reference axes. Moments of inertia, therefore, depend on the
location of reference axes.
A support that prevents rotation in all axes, but allows translation along one
axis.
movable support
A force that is concentrated on a point.point force
Calculating Moments of Inertia and Deflection Lines
The measurement unit for the moment of inertia is mm4 or inches4. These
are geometric values, which appear in deflection, torsion, and buckling
calculation. AutoCAD Mechanical uses the result of the moment of inertia
calculation for the deflection line calculation.
Moment of inertia calculations are performed on cross sections of beams or
on other objects that can be represented as closed contours. Calculations can
be performed on a cross section of any shape, as long as the geometry of the
cross section forms a closed contour.
318 | Chapter 15 Calculating Moments of Inertia and Deflection Lines