Virtueel werk voor een systeem van verbonden starre lichamen

The principle of virtual work can be applied to machines with multiple connected rigid bodies under loads to solve problems involved in it.

Consider a toggle vise, where a force is applied at its midpoint, resulting in a reaction force exerted by the wooden block on the vise.

In the free-body diagram, friction is neglected, and a positive virtual displacement is considered.

Choose a system of coordinate axes, and define the positive and negative increments.

The reaction forces at the left point and the normal force do no work during this displacement.

As a result, only the virtual work done by the applied and reaction forces needs to be computed.

By expressing the coordinates in terms of the angle theta and differentiating, the total virtual work of both forces can be determined.

Setting the total virtual work to zero gives the equation for the reaction force exerted by the wooden block on the vise.