Understanding Ultrasound Attenuation and Reflection in Aluminum Sheets

[ChrisCOD]

Hello. I write this in regards to enquiring whether you can address various questions I have in relation to acoustics and the physics of sound. In particular, I am interested in ultrasound. I have various questions in relation to it.

In particular, I am interested in understanding the nature of attenuation of ultrasound through reflection and absorption due to aluminum, in particular a specific aluminum sheet that I can provide the details of. I would like to know, in particular, information pertaining to the ability of focused ultrasound beams to penetrate to the other side of an aluminum sheet, particularly the one I know the properties of.

In essence, I would like to know information pertaining to the scale of intensity reduction due to the sheet as a function of all phenomena that occur due to the interaction of the focused ultrasonic beam with a singular sheet, such as reflection due to acoustic impedance mismatch where the surrounding medium is air and also considering of absorption with the aluminum particularly as it relates to the additional intensity reduction due to repeated internal reflections due to the first reflection of the focused ultrasound at the back surface and so on.

I would like to know in addition the impact of trajectory due to penetration of such a sheet.

Additionally, I would like to know in detail the mechanics of the interaction of a focused ultrasonic beam with a particular arrangement of these aluminum sheets. The set up is as follows: First, 4 aluminum sheets are placed one after the other, with each having equivalent material properties which I can specify. They are spaced out relative to each other by 1cm. Then, we propose that a device emits focused ultrasound towards the sheets such that its trajectory intersects with all four sheets. In this situation, I would like to know in detail the mechanics of the interaction of the focused ultrasonic beam with this configuration of material, with a particular interest in how the configuration impacts intensity reduction of the focused ultrasound due to the overall mechanics of the interaction of the focused ultrasonic beam with the sheet configuration.

I am also interested in a description of all other impacts on the focused ultrasound due to its attempt to penetrate to the other side of the sheets. Note, I stress that when I refer to intensity reduction, I specifically make reference to the reduction in ultrasonic energy that is able to pass to the other side of the sheets due to the fact that it would seem that reflection doesn't decrease the ultrasonic energy as it persists in the environment.

So, in conclusion with respect to the last point, I want to know the intensity reduction in so far as it is concerned with the computation of the total amount of ultrasonic energy able to penetrate to the other side of the sheet/sheets. In regards to the computation, it can be expressed as a percentage, or alternatively as a number where we consider the initial intensity of the focused ultrasonic beam to be 100 million watts per square meter.

In addition, a general description of the efficacy of aluminum sheets and aluminum in general in regards to reflection of focused ultrasound and in particular if the reflection is consistent irrespective of variation in the properties of the ultrasound due to all ways in which it can exists, whether it be extremely high intensity of consideration of all other parameters or properties of focused ultrasound. Any additional information which you think would be useful to know or understand is also appreciated.

Note, the properties of each sheet can be found here: https://www.aluminiumwarehouse.co.u...-x-1000-mm-x-0-9-mm-1050a-h14-aluminium-sheet

Thanks.

 

[DaveC426913]

Paragraphs!

(OP has been edited by the Mentors)

 

[Baluncore]

Why do you need to do this?
Are you considering a continuous ultrasonic sine wave, or an explosive step transient?

100 MW/m² is beyond metal deforming and cutting.
Laminated armour is used on military vehicles.

You are asking us to give you a lifetime of education in a forum post.
What you ask would take at least one textbook, and one year of study.

https://en.wikipedia.org/wiki/Composite_armour

 

[ChrisCOD]

Why do you need to do this?
Are you considering a continuous ultrasonic sine wave, or an explosive step transient?

100 MW/m² is beyond metal deforming and cutting.
Laminated armour is used on military vehicles.

You are asking us to give you a lifetime of education in a forum post.
What you ask would take at least one textbook, and one year of study.

https://en.wikipedia.org/wiki/Composite_armour

It seems like a rather simple question. In pure physics terms, explain the mechanics of the interaction of a focused ultrasound beam with such an arrangement purely as a function of attenuation due to reflection and absorption and the resultant intensity reduction without regard to anything else such as precise understanding of the geometric properties of the ultrasound over time or anything additional.

 

[ChrisCOD]

Why do you need to do this?
Are you considering a continuous ultrasonic sine wave, or an explosive step transient?

100 MW/m² is beyond metal deforming and cutting.
Laminated armour is used on military vehicles.

You are asking us to give you a lifetime of education in a forum post.
What you ask would take at least one textbook, and one year of study.

https://en.wikipedia.org/wiki/Composite_armour

Furthermore, I believe you make reference to different kinds of ultrasound. With respect to all such types, are you able to answer the question taking into consideration my previous reply?

 

[berkeman]

It seems like a rather simple question. In pure physics terms, explain the mechanics of the interaction of a focused ultrasound beam with such an arrangement purely as a function of attenuation due to reflection and absorption and the resultant intensity reduction without regard to anything else such as precise understanding of the geometric properties of the ultrasound over time or anything additional.

WITW? What research have you done so far? Have you worked with the math of Electromagnetic or Acoustic reflections between layers before? Please show us all that you have done on this question up to now. Thank you.

 

[ChrisCOD]

Why do you need to do this?
Are you considering a continuous ultrasonic sine wave, or an explosive step transient?

100 MW/m² is beyond metal deforming and cutting.
Laminated armour is used on military vehicles.

You are asking us to give you a lifetime of education in a forum post.
What you ask would take at least one textbook, and one year of study.

https://en.wikipedia.org/wiki/Composite_armour

Also, what do mean by an explosive step transient? Can you explain exactly what this is with respect to ultrasound? Thanks.

 

[berkeman]

Also, this looks a lot like your previous schoolwork question...

https://www.physicsforums.com/threa...late-interaction-factors-to-consider.1057392/

 

[ChrisCOD]

WITW? What research have you done so far? Have you worked with the math of Electromagnetic or Acoustic reflections between layers before? Please show us all that you have done on this question up to now. Thank you.

I know that aluminum is a highly effective reflector of ultrasound when the surrounding medium is air. However, I am particularly interested in how the described arrangement impacts the reduction in intensity as you consider the various mechanics of what is happening, namely the internal reflections which attenuate the ultrasound within the medium, and the intermittent transmission of ultrasonic energy in the direction of the next aluminum sheet due to the reflection at the back surface of the sheet and a continued analysis of this repeated process involving reflections and transmissions and attenuations.

 

[berkeman]

I know that aluminum is a highly effective reflector of ultrasound when the surrounding medium is air. However, I am particularly interested in how the described arrangement impacts the reduction in intensity as you consider the various mechanics of what is happening, namely the internal reflections which attenuate the ultrasound within the medium, and the intermittent transmission of ultrasonic energy in the direction of the next aluminum sheet due to the reflection at the back surface of the sheet and a continued analysis of this repeated process involving reflections and transmissions and attenuations.

You quoted my reply, but did not answer any of my questions. Show us your math working on this and tell us your background. Also address my question about your previous thread start on this as a schoolwork problem.

 

[Vanadium 50]

Paragraphs!

...are for sissies!

 

[dlgoff]

...are for sissies!

 

[Dale]

What material is between the transducer and the first sheet, and what material is between the sheets.

 

[Baluncore]

Also, what do mean by an explosive step transient? Can you explain exactly what this is with respect to ultrasound? Thanks.

If you do not know what the terms mean, you will not understand the answer.

I asked why you needed to do this.
YOU ANSWER FIRST.

 

[ChrisCOD]

What material is between the transducer and the first sheet, and what material is between the sheets.

Air is the intermediary substance in both cases.

 

[berkeman]

Air is the intermediary substance in both cases.

Wrong answer. You have multiple other questions queued up that we have asked you, and you choose only to answer this simple one that has no information about your background, your work on this problem, why you are re-asking a schoolwork question in a new thread, etc.

This thread is paused for Moderation -- if you want it re-opened, please send me a PM that addresses all of our other questions that we have been asking in this thread.