For example the elasticity equation in the case of stiff structures would be the governing differential equation.
A stiff structure is one that has the least possible displacement when given certain set of boundary conditions.
Subaru has redone the Legacy for 2000, with a stiffer structure to improve ride and handling.
The stiffer structure is designed for improved protection in a crash, more responsive handling and a better ride.
There wasn't the stiff structure that existed elsewhere in the hospital, with physicians implacably at the top.
With a structure so stiff, the independent suspension doesn't have to compensate for twisting, so its various parts are tuned for quick, precise handling.
Sandwich panels like these are the lightest, strongest, stiffest structure we can use.
This generates a very stiff triple-helical structure in water.
Some of the extra weight reflected a stiffer unitized structure with more sound-deadening.
Any stiff structure is going to have a resonant frequency that it wants to vibrate at.