Modal Analysis

The process of determining a set of generalized coordinates for a system such that the equations of motion are both inertially and elastically uncoupled. More commonly, it is a process of determining the natural frequencies, damping factors, and mode shapes for a structure. This is usually done either experimentally through frequency response testing or mathematically using finite element analysis.

Excitation techniques

Mechanical

• Hammer or impacting device
• Easy to use
• Control of force pulse difficult

Electrohydraulic

• High forces
• Low frequency only
• Very high harmonic distortion
• Equipment is heavy

Electrodynamic

• Wide range of forces
• Wide frequency range
• Low harmonic distortion
• Equipment is portable

See also: Circle Fitting, Mode Shape, Natural Frequency, Real Modes, Vibration.