ETA Experimental Modal Analyses Kit

Modal analysis is practised for machine tool chatter, Automobile & ship NVH (Noise Vibration & Harshness), Civil (Building, Bridges) structural damage & Aircraft flutter. Modal analyses find shapes and frequencies at which structure will amplify the effect of load and is a major tool in the design of safe optimal structures.

The analyses :

  • Directs the focus on the weak elements in the structure limiting capacity power utilisation.
  • Identifies critical dangerous operational rotation speeds.
  • Indicates where to constrain or load a structure.
  • Suggests methods to move an inconvenient operating frequency
  • Experimental modal analysis verifies the theoretical finite element analysis (FEM) and is the only way to measure the structural damping factor.

The EEMAK (Experimental Modal Analyses Kit)
This kit consists of

  • EH Force exciter with its Hydraulic supply.
  • Controller with Sensors (Accelerometers).
  • Modal analyses software.

The EH Force exciter superposes heavy dynamic forces over static forces over a wide frequency range. EH force exciter is compact and light , a major advantage over electrodynamic exciters. It consists of a Tandem actuator, EH Servo valve , Integral Loadcell & Position Transducer. The control with amplitude modulation, enables the force level to be maintained as the frequency is swept. The exciter functions in Sinusoidal, Swept Sine & Random modes.

The response of the load to the excitation is measured at multiple points on the structure , by accelerometers whose outputs are then analysed by the Modal Analysis software. The software extracts the modal parameters of frequencies and damping factors of the structure under study.

It generates the Geometrical model and displays the animated mode shapes of the structure. This software also provides an "IF/Then" solutions to any structural design change.

Exciter, Controller

Force Frequency Spectrum

Frequency Response Function (FRF)

Frequency Response Function (FRF)

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