The point beyond which the deformations of a structure or material are no longer purely elastic . An object is in equilibrium if the resultant of the system of forces acting on it has zero magnitude. See static equilibrium and dynamic equilibrium . External forces are sometimes called applied forces . A fixed connection is sometimes called a rigid connection or moment-resisting connection.
Flexibility is the inverse of stiffness .
High flexibility means that a small load produces a large displacement. Bending deformation, i.e., deformation by increasing curvature. A directed interaction between two objects that tends to change the momentum of both. A deformation of a structure or material under load is described as inelastic when the deformation remains after the load is removed. The term plastic is often used with the same meaning.