Modal analysis is an experimental approach for investigation of the dynamic characteristics of a structure, such as the natural frequencies, damping factors and modal shapes of a structure.  From this experimental technique, the structures vibration patterns as well as it』s dynamic weakness is discovered. These results will guide engineers to resolve the structural resonance problems.

Modal test usually refers to the testing procedure of modal analysis.  During modal testing, the structure is subjected to an external excitation, usually performed by a person swinging an impact hammer striking the structure at a predefined point. The responding vibration signals are measured by accelerometers also located at predefined points and then the data is acquired by an analyzer which then performs cross channel analysis.  The Analyzer then performs a FRF (Frequency response function) for each measured point.  Once each FRF is collected for each point measured, the data is then sent to a post analysis software for proper mathematical calculation to show natural frequencies, damping factors and modal shapes.