OS-E: 0335 Measure Sound Radiation from Impacting Plates

Explicit Analysis of the impacting plates to extract the contact forces and performing Frequency Response Analysis using these forces as input to study the sound radiation by the plates.

Model Files

Refer to Access the Model Files to download the required model file(s).

The model files used in this example include:

  • Impact_Test.fem
  • Acoustic_Analysis.fem
  • Acoustic_Analysis.h3d
  • Compose_Script.oml

Model Description

Two plates (Figure 1) are meshed with first order CHEXA element. Both the plates are constrained at one end in all DOF’s and time dependent load is applied on upper plate, which causes it to impact with the lower plate. Explicit Analysis is performed for the setup and contact forces are requested as an output.

Figure 1. Finite Element Model of Impacting Plates with the Boundary Conditions and Analysis Procedure
The frequency response setup has a smooth acoustic mesh (in this case a cylinder with hemispherical faces) around the impact plates. The ends of the acoustic mesh (surface of the cylinder) have infinite elements. Perform the Frequency Response Analysis to calibrate the sound radiated by the impacting plates at a distance of 1.5m and 2.5m (location of mic points).

Figure 2. FE Setup for Frequency Response Analysis
Material Properties: Polycarbonate (Plates)
Young's modulus
1E+03 MPa
Poisson's ratio
1E-09 ton/mm3
Material Properties: Air (Acoustic Mesh)
Sound velocity
343000 mm/s
1.2E-12 ton/mm3

Contact Force Conversion (Time to Frequency Domain)

Contact forces obtained from explicit analysis are in time domain, to convert the time domain results into frequency domain with help of Compose Script. These frequency dependent forces are fed as an input for Frequency Response model where the sound radiation is checked, due to this impact phenomenon.

Figure 3. Contact Force Time to Frequency Domain Conversion


Figure 4. Sound Pressure Level at a Mic Point(N1395) . 2.5m far from the sound source with a maximum of 34.43 DB

Figure 5. Sound Pressure Level at a Mic Point(N1396) . 1.5m far from the sound source with a maximum of 38.41 DB