What Are Operating Deflection Shapes?
什麼是operating deflection shapes(ODS)?
Traditionally, an ODS has been defined as the deflection of a structure at a particular frequency. However, an ODS can be defined more generally as any forced motion of two or more points on a structure.
傳統上，ODS 定義為在某一特定頻率下一結構物之變形位移。 然而，ODS 通常被定義為一結構物的兩個點或兩個以上的點受外力而產生的任何移動。
Specifying the motion of two or more points defines a shape. Stated differently, a shape is the motion of one point relative to all others. Motion is a vector quantity, which means that it has location and direction associated with it. This is also called a Degree Of Freedom, or DOF.
An ODS can be defined from any forced motion, either at a moment in time, or at a specific frequency. Hence, an ODS can be obtained from different types of time domain responses, be they random, mpulsive, or sinusoidal. An ODS can also be obtained from many different types of frequency domain measurements, including linear spectra (FFTs), cross and auto power spectra, FRFs (Frequency Response Functions), transmissibilities, and a special type of measurement called an ODS FRF.