Can ultrasound pass through metal?

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    Metal Ultrasound
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Discussion Overview

The discussion centers around the ability of ultrasound to pass through metal, exploring the extent to which it can penetrate and the factors influencing this capability. Participants examine various applications, including industrial and medical uses, and the implications of different frequencies and coupling methods.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants inquire about the ability of ultrasound to pass through metal and the thickness of metal that can be penetrated.
  • One participant mentions that ultrasound cleaning tanks are made of metal with transducers positioned outside the metal skin, suggesting that ultrasound can penetrate at least thin layers of metal.
  • Another participant argues that if ultrasound is coupled correctly to metal, it can travel quite far within it, drawing an analogy to sound traveling through metal.
  • It is noted that the attenuation of ultrasound in metals is significantly lower than in water or soft biological tissue, with extensive use in nondestructive testing of metal parts.
  • Participants highlight that attenuation varies with frequency, indicating that specific applications and frequency ranges are crucial for determining penetration capabilities.
  • One participant emphasizes the importance of matching ultrasound energy at interfaces to ensure effective transmission through metal, mentioning that different transducers are required for various applications.
  • There is a discussion about the use of coupling gels in both industrial and medical applications, noting that while the same transducer can be used, the designs differ based on the medium being tested.

Areas of Agreement / Disagreement

Participants express differing views on the specifics of ultrasound transmission through metal, with no consensus reached on the exact conditions or limitations. Multiple competing perspectives on the effectiveness of ultrasound in various contexts remain evident.

Contextual Notes

Limitations include the dependence on frequency and application specifics, as well as the need for proper coupling methods to facilitate ultrasound transmission through metal.

physea
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Hello

Can ultrasound pass through metal?
How much of it can pass and how thick the metal can be?

I couldn't find anything online, I only found some contradicting and unclear information.
 
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physea said:
Hello

Can ultrasound pass through metal?
How much of it can pass and how thick the metal can be?

I couldn't find anything online, I only found some contradicting and unclear information.
Ultrasound cleaning tanks are made of metal and the transducer is outside the (thin) metal skin.
 
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sophiecentaur said:
Ultrasound cleaning tanks are made of metal and the transducer is outside the (thin) metal skin.
I don't understand what you are saying
 
physea said:
I don't understand what you are saying
He is using the coupling method for those cleaning tanks as an existence proof that ultrasound energy can go through at least a thin layer of metal.

And if you couple it correctly to the metal, it can go quite far in metal. It's not all that difference from sound traveling in metal. I can hear a local commuter train (BART electric trains) coming from the sounds the tracks make long before the train shows up... :smile:
 
Attenuation of ultrasound in metals is much lower than in water (or soft biological tissue). Ultrasound nondestructive testing is used extensively for metal parts.
However the attenuation varies strongly with frequency. Ultrasound can range from tens of kHz to almost terahertz so to get an answer regrading how thick the metal and other details you should specify the application and the frequency range of the ultrasound.
 
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nasu said:
Attenuation of ultrasound in metals is much lower than in water (or soft biological tissue). Ultrasound nondestructive testing is used extensively for metal parts.
However the attenuation varies strongly with frequency. Ultrasound can range from tens of kHz to almost terahertz so to get an answer regrading how thick the metal and other details you should specify the application and the frequency range of the ultrasound.
There is another issue here, though. The ultrasound energy has to be Matched at any interface. This is necessary between the source and the destination of the waves or very little energy will pass through into and out of the metal. Different transducers must be used for different applications - body tissue, metal, air etc.
 
The same type of coupling gel can be used for both industrial and medical applications. The medical one has some antiseptic components. A thin layer of water will work too. And the same transducer will work for both, in principle. In medical imaging they use arrays of transducers whereas in industrial nondestructive testing they can use both single transducers and arrays.
The air coupled ones are indeed of a different design. But the question was not about ultrasound going through air.
 

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