Application of Impact-Acoustics to Detect Tile-Wall Bonding Integrity
Date Issued
2016
Date
2016
Author(s)
Zhang, Nan
Abstract
The objective of this study is to perform impact-acoustics to detect the tile-wall bonding integrity. Impact-acoustics is based on impacting vibration of the object surfaces, making the sounds caused by surrounding pressure of air vibration. We can see the differences between debonded and undebonded tiles and structure when we performing impact-acoustics on the surface of tiles. The differences came from the different vibration modes after impacting the surface of tiles. Therefore, we can analyze the frequency domain from the acoustic signal to recognize if the tile-wall bonding is debonded or not. Compared to the previous study, most of them use experimental data to get conclusion, we process parameter analysis to impact-acoustics by numerical simulation. We analyzed the response of sounds and physical phenomena from every kind of tile-wall bonding situation, then verified by model experiment. From the results of numerical simulation and model experiment, we found that no matter the tile is debonded or not, as long as the impact location is on the undebonded part, the frequency of undebonded tile is identical with the debonded one. Both of them are equal to the frequency of thickness of structure, which is estimated by the formula of impact-echo. When the debonded part is impacted, flexural vibrations will perform. Different vibration modes will be excited by impacting different debonded location. The closer impacting location to the middle of debonded part, the larger energy of first mode will excited. While changing the impact location to the edge of debonded part, the second mode or the higher mode energy will be excited, even exceed the first mode. Generally, the frequency of debonded tile is lower than undebonded tile, but if the area of debonded is very small, the frequency may even higher than undebonded one. Traditional impact-acoustics is using the reduction of frequency as a judgment of debonded tile, which belongs to the highest frequency peak on the frequency domain. However, according to the result of this study, the way of judgment is kind of inadequate. This study recommends not to adopt the highest peak on frequency domain, but the first one. The inspection process is as follows: First of all, sampling on site or estimating frequency of undebonded part, then processing impact-acoustics to each test tile. If the first peak on the frequency domain is close to the frequency of structure thickness, we can conclude this impact location of tile is undebonded. If the frequency of first peak is higher than the frequency of structure thickness, the impact location may have a small debonded below. If the frequency of first peak is lower than the frequency of structure thickness, the impact location may have a larger debonded underneath. To further understand the distribution area of debonded parts on the larger tile, performing impact-acoustics experiment with grid on the surface of tile is recommended. Utilizing frequency domain, each point of grid would be judged on the undebonded part, the middle of the debonded part or the edge of debonded part, then we can depict the rough shape of debonded part.
Subjects
Impact-Acoustics
Tile
One-Way Fluid-Structure Interaction
Nondestructive Testing
Type
thesis
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