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dQ N dQ
 q  або  qR N ;
ds R d
dM dM
 Q або  QR .
ds d
Here ds  Rd - the length of the arc that has a radius of
curvature R and corresponds to the angle d . These
dependencies allow to verify the correctness of constructing
diagrams of the internal force factors:
1) in the final hinge pillar and on the free end of the console
when not loaded external moments, M  ;
0
2) in cross-section, which is applied to the beam focus point
on the diagram M will jump on the magnitude of the
moment and the tangent to the diagram before and after
the jump are parallel to each other;
3) in sections where the rod attached to the concentrated
force perpendicular to the axis of the rod (ie, directed
along the radius), the diagram Q will jump to the value
applied forces in the direction of their actions, and the
diagrams N and M - the kinks;
4) in sections which are applied concentrated forces
tangential to the axis of the rod, the diagrams N are
jumping, and the diagrams Q and M - the kinks;
5) in sections where Q  , diagrams N and M extremes
0
will occur;
0
6) in sections where N  , diagrams Q arise extremes;
0
7) in areas where Q  diagrams M of increases and
decreases N in the direction of diagrams reference angle
0
 , where, Q  diagrams M comes and N - is growing;
0
8) in areas where N  diagrams Q increases towards the
0
reference angle  , and where N  - decreases.

4.2 Calculation of stresses in cross sections of curved
beams. Conditions strength

Consider a flat curve with a radius of curvature of the beam axis
R , which is in a pure bending (fig. 4.4).

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