Improving resonant frequency and damping analysis at high temperatures via laser Doppler vibrometer sensor

This paper on Laser Doppler Vibrometry investigates how to better measure the stiffness (elastic properties) and energy loss (damping) of refractory materials when they are heated to very high temperatures. Traditional acoustic sensors struggle at high temperatures because the vibration signals become weak and heavily damped. The authors compare a standard electret microphone with a laser Doppler vibrometer (LDV), an optical sensor that measures vibration without touching the sample. They test several alumina-based refractory materials, each with increasing microstructural complexity and higher damping behavior. The LDV consistently captures clear vibration signals even when the acoustic sensor fails, especially above 1100–1400 °C. This allows continuous tracking of resonant frequencies and damping during phase transformations, sintering, microcracking, and liquid-phase formation. The study shows that LDV enables reliable measurements through extreme microstructural events that normally disrupt acoustic detection. As a result, researchers can directly link microstructural changes to mechanical behavior at high temperature. The work expands the usable temperature and damping range of the impulse excitation technique (IET). Overall, the LDV significantly improves high‑temperature material characterization for refractories.

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