Shear flow

The term shear flow is used in solid mechanics as well as in fluid dynamics. Loosely speaking, shear flow is defined as:

• the gradient of a shear stress force through the body (in solid mechanics);
• the flow induced by such a force gradient (in a fluid).

In this article the first definition from solid mechanics is used. See Viscosity for a fuller treatment about the term from fluid dynamics.

Dimensions

In solid mechanics, shear flow is given in dimensions of force per length. This corresponds to units of newtons per meter in the SI system and pound-force per foot in the English Engineering and British Gravitational systems.

Shear flow in semi-monocoque structures

The equation for shear flow in a particular web section of the cross-section of a semi-monocoque structure is:

$q = \frac{V_y Q_x}{I_x}$

where

q - the shear flow
Vy - the shear force perpendicular to the neutral axis x through the entire cross-section
Qx - the first moment of area about the neutral axis x for a particular web section of the cross-section
Ix - the second moment of area about the neutral axis x for the entire cross-section