- #1

fog37

- 1,568

- 108

- TL;DR Summary
- force density or pressure

Hello,

Forces can be concentrated (when acting at a single point) or distributed (when acting over a surface or line).

In the case of distributed forces, we can find the resultant concentrated force by calculating a surface or line integral of the force density ##f(x)## w.r.t. an area or length differential.

This is equivalent to adding together small products of force times infinitesimal areas. Statics books show these types of calculations. For example, $$\int \sigma dA$$

Is the force density ##\sigma =f(x)## to be considered a pressure density or a force density? Pressure is fundamentally normal force per unit area. Is ##\sigma## a pressure density only when the force direction is exactly perpendicular to the surface? The force density may be at an angle at different points on the surface with both a parallel and normal components relative to the surface.

Thanks!

Forces can be concentrated (when acting at a single point) or distributed (when acting over a surface or line).

In the case of distributed forces, we can find the resultant concentrated force by calculating a surface or line integral of the force density ##f(x)## w.r.t. an area or length differential.

This is equivalent to adding together small products of force times infinitesimal areas. Statics books show these types of calculations. For example, $$\int \sigma dA$$

Is the force density ##\sigma =f(x)## to be considered a pressure density or a force density? Pressure is fundamentally normal force per unit area. Is ##\sigma## a pressure density only when the force direction is exactly perpendicular to the surface? The force density may be at an angle at different points on the surface with both a parallel and normal components relative to the surface.

Thanks!