PRODUCTS
Acoustic Load on Composite Air Inlets
Vibration analysis
Composite materials are increasingly used in aerospace applications due to their high tensile strength, lightweight composition, and resistance to fatigue and environmental stress. These qualities make them ideal for structural parts like air inlets. However, composites often exhibit lower durability under vibrational and acoustic loading, which poses potential performance issues. Conducting vibration analysis is essential to assess their behavior under such dynamic conditions and to improve aircraft reliability, performance, and safety.
Objective
This case study explores the application of Digital Image Correlation (DIC) for vibration analysis of composite materials subjected to acoustic loading. The primary goal was to evaluate vibration parameters and deformation on composite air inlets used in trainer jets when exposed to sound-induced excitation replicating jet engine noise.
Description of the Case Study
To simulate real-world operating conditions, a composite air inlet from a jet trainer aircraft was placed in a specially designed acoustic chamber and subjected to acoustic excitation using four high-powered speakers. The goal was to simulate the vibrational stress caused by engine noise and determine the vibration mode shapes.
❖ Excitation Source: Four speakers set to key resonant frequencies: 84 Hz, 118 Hz, and 238 Hz
❖ Cameras: 2× Phantom High-Speed cameras
❖ Resolution: 1200×800 pixels
❖ Frame Rate:
❖ 2,000 fps for 84 Hz and 118 Hz
❖ 3,000 fps for 238 Hz
❖ Calibration Grid: 4 mm
❖ Lighting: Single strong LED light
❖ Software: MercuryRT with 3D DIC and Vibrography modules
Optical Measurement Results
❖ Using 3D DIC, the full-field displacement and strain fields were captured. Displacement in the Z-direction (out-of-plane) was measured across all three test frequencies.
❖ 84 Hz
❖ 118 Hz
❖ 238 Hz
Vibrography Results
❖ The Vibrography module in MercuryRT enables full-field, non-contact vibration analysis using DIC and high-speed cameras. It visualizes Operational Deflection Shapes (ODS) and offers tools like spectral graphs and Campbell diagrams for detailed insight into dynamic structural behavior.
The images presents the amplitude and phase response at the selected frequency. On the left, you see the Amplitude Graph and Phase Graph, plotting displacement in the Z-direction across frequency. On the right, color maps overlay the reference image with computed amplitude (top) and phase (bottom), displaying the deflection shape and vibration phase distribution at the selected frequency.
|
Speaker frequency
|
Resonant frequency - DIC
|
Deviation
|
|---|---|---|
Advantages of Using 3D DIC in Forming Limit Curve Analysis
❖ Non-contact, full-field measurement of displacement and strain, eliminating the need for physical sensors on the specimen.
❖ Accurate Operational Deflection Shapes (ODS) visualization for identifying dynamic behavior at specific frequencies.
❖ Detailed frequency domain analysis, including amplitude, phase, power spectral density, and energy spectral density graphs.
❖ Campbell Diagram support for evaluating eigenfrequencies and resonance in rotating or oscillating systems.
❖ High-speed compatibility with synchronized cameras for capturing rapid vibrations.
❖ Ideal for validating aerospace components under realistic acoustic loading conditions.
This study highlights how MercuryRT’s 3D DIC and Vibrography tool provide powerful insights into the vibrational behavior of aerospace components. The non-contact, high-resolution measurement approach makes it ideal for analyzing critical parts under operational stress.
For more information about 3D DIC and Vibrography, please Contact us through email info@mercury-dic.com.
By Purchasing Our Products, Customer Care Is Not Over.
We’ll install your measurement system and help you solve your measurement problems. Our software and application engineers are here to help!