Operating Deflection shape
Operating Deflection Shape (ODS) analysis is a method used for visualisation of the vibration patterns of a machine or structure caused by unknown operating forces.
The operating forces for machinery can typically be influenced by engine speed, load, pressure, temperature, flow, etc. For civil engineering structures the operating forces may be due to ambient forces from waves, wind or traffic.
Vibration measurements are taken at different points and directions on a structure.
The resulting vibration patterns are displayed as an animated geometry model or a table of values.
This helps visualize and analyze the structural behavior under various conditions.
Types of ODS Analysis
Time domain ODS
Frequency domain ODS
Running modes ODS (run ups /run downs)
Running orders ODS (run ups /run downs)
Time Domain ODS are used to investigate the vibration of a structure as a function of time. They useful in showing how the overall deflection shape changes step-by-step for both stationary and non-stationary (transient) signals.
Frequency or Spectral ODS are used to investigate the vibration patterns of a structure at specific frequencies under stationary conditions.
Running Modes ODS are used to investigate the vibration patterns of a structure at specific frequencies as a function of rotational speed.
Running Orders ODS are used to investigate the vibration patterns of a structure at specific orders as a function of rotational speed.
Modal Analysis
Modal analysis is the study of the dynamic properties of linear structures, based on structural testing or finite element analysis-based simulation. These dynamic properties include resonance frequencies (also called “natural frequencies”) and structural modes.
Modal analysis performed through either structural testing or finite element analysis-based simulation helps you to,
- Understand how a structure vibrating
- Correlate and update simulation models
- Speed up structural, vibro-acoustic and durability calculations
- Include flexibility in multibody simulation models