Thickness Definition and 349 Threads

In the field of industrial ultrasonic testing, ultrasonic thickness measurement (UTM) is a method of performing non-destructive measurement (gauging) of the local thickness of a solid element (typically made of metal, if using ultrasound testing for industrial purposes) based on the time taken by the ultrasound wave to return to the surface. This type of measurement is typically performed with an ultrasonic thickness gauge.
Ultrasonic waves have been observed to travel through metals at a constant speed characteristic to a given alloy with minor variations due to other factors like temperature. Thus, given this information, called celerity, one can calculate the length of the path traversed by the wave using this formula:





l

m


=
c
t

/

2


{\displaystyle l_{m}=ct/2}

where




l

m




{\displaystyle l_{m}}
is the thickness of the sample



c


{\displaystyle c}
is the velocity of sound in the given sample



t


{\displaystyle t}
is the traverse time
The formula features division by two because usually the instrumentation emits and records the ultrasound wave on the same side of the sample using the fact that it is reflected on the boundary of the element. Thus, the time corresponds to traversing the sample twice.
The wave is usually emitted by a piezoelectric cell or EMAT sensor that is built into the measurement sensor head and the same sensor is used to record the reflected wave. The sound wave has a spherical pattern of propagation and will undergo different phenomena like multipath reflection or diffraction. The measurement does not need to be affected by these since the first recorded return will normally be the head of the emitted wave traveling at the shortest distance which is equivalent to the thickness of the sample. All other returns can be discarded or might be processed using more complicated strategies.

View More On Wikipedia.org
  1. G

    Determine the thickness of aluminium using γ-rays

    Homework Statement [/b][/B] Hi all, I have been given a mini-project to complete which involves a block of aluminium which is stuck to a piece of wood and taped so that where the aluminium and wood touch is unknown. I have been told that I need to design an experiment to measure the thickness of...
  2. R

    Equipment Drawings and thickness of lines

    Warning: Rant ahead I get more and more drawings from vendors where all lines seem to be of the same thickness. Makes it awfully hard to tell if a line's a dimension line, a leader, a projection or a real part outline. Do others share my annoyance? Is this an evil of the post-AutoCAD era...
  3. V

    How Thick Should Steel Be for a 20-Foot Water Cylinder with a Piston?

    What i want to do is have a cylinder that is made of steel (don't know what types there are but i guess regular) with a height of 20 ft or so, filled with water. for the bottom of the cylinder i want a piston that would move 6 inches. the volume of the water on top of the piston is about...
  4. G

    LCD cell thickness - why is this restricted?

    Hi, I have read loads on LCD operation and in particular NT-LCD and understand the twisting of the light by the LC. Everywhere i read it states that "the thickness of the cell is crucial for correct operation" but does not say why! Why is this? Is it to do with the pitch of the LC helix...
  5. Saitama

    Thin film interference - Minimum thickness

    Homework Statement A lens (##\mu##=1.5) is coated with a thin film of refractive index 1.2 in order to reduce the reflection from the surface at ##\lambda=480 nm##. Find the minimum thickness of the film which will minimize the intensity of reflected. [Assume near normal incidence]Homework...
  6. A

    Minimum thickness n/wavelength equation?

    Homework Statement White light is incident normally on a thin soap film (n = 1.33) suspended in air. 1. What is the minimum thickness of the soap film that will constructively reflect light of wavelength 477 nm? 2. What is the next minimum thickness of the soap film that will...
  7. S

    Crystal Thickness for particular phase difference

    1. Hey, the question I believe should be fairly simple to solve but it's been a while since I've looked over such content. There are two light waves that enter a crytstal at the same time, one linearly polarised parallel to the optic axis and one perpendicular to the optic axis, they have...
  8. M

    Finding Minimum Thickness Problem

    A polymer coating has a n=1.30 and a base of n=1.50. What is the minimum thickness of the coating to reflect 500 nm least strongly?
  9. M

    Optimizing Polymer Coating Thickness for Reflectivity at 500 nm Wavelength?

    Homework Statement A polymer coating has a n=1.30 and a base of n=1.50. What is the minimum thickness of the coating to reflect 500 nm least strongly? Homework Equations The Attempt at a Solution
  10. I

    Thickness of lead required for 200 keV x-rays?

    is this correct? mass attenuation coeff. = 8.636 cm^2/g 8.636 * (density of lead: 11.3 g/cm^3) = 975.868 per cm thickness (mm): t= 9.21 / 975.868 = 0.009 cm = 0.09 mm
  11. P

    Calculation of thin film thickness from complex refractive index

    Hello, I want to ask how can one calculate the thickness of a thin film (or each of the thin films in a stack of 3-4 thin films on one another) when - complex refractive index of each thin film is known (n and k). This refractive index is obtained from a single wavelength ellipsometer and...
  12. D

    Calculate Steel Pipe Thickness for Oil Transportation | Safety Factor 1.5

    1. Homework Statement A 1.2m diamater steel pipe carries oil of relative density 0.822 under a head of 70m of oil. What minimum thickness of 120MPa (yield stress) steel would be required for a safety factor of 1.5? 2. Homework Equations Head = pressure/rho.g thickness = (safety...
  13. A

    How Do I Determine the Minimum Thickness for a PVC Board?

    Right now I am working on a small project. I have a board (made of PVC) that is nearly 3ft long (1ft wide) and supported on each end. Mounted to the board will be various items. To save money and weight I am looking to calculate the minimum thickness I need so that the board can support...
  14. A

    Calculate electric field at position x given ρ and thickness d?

    Calculate electric field at position x given ρ and thickness d?? Homework Statement Two large uniformly charged slabs, I and II, are stacked together as shown in the picture. Suppose the thickness of each slab is d= 0.2 μm. The volume charge densities in the negatively charged slab (I)...
  15. T

    Lenz' Law copper tube thickness question

    For the classic Lenz law demonstration using a neo. magnet dropped down a copper pipe, is the magnetic force generated correlated to the thickness of the copper pipe? Ergo, will the magnet go slower down a thick copper pipe vs. a standard size plumber pipe?
  16. K

    Thickness of Graphene: Theory & Measurement

    Hello, I was just wondering what the theoretical thickness of single layer graphene is? Thanks in advance for any feedback.
  17. E

    Expression for Torsion Constant of Varying Thickness Box Section

    Hello Everyone, I am after an expression for the torsion stiffness constant of a rectangular hollow section (RHS) with varying wall thickness. I have done some research into finding an expression that allows for four varying wall thicknesses but have not found anything as of yet. The only...
  18. V

    Calculating Insulation Thickness

    I'm trying to calculate insulation thickness for a foundry, and can't figure it out after spending a few hours searching. Refractory: Kast-O-Lite Material Required: 1.44g/cm^3 Thermal Conductivity: 0.65 W/m*C Maximum inside temperature is 1648*C I figured there would be a minimum of...
  19. R

    How to arrive the glass thickness ?

    I have a glass which will act external water pressure of 10ATM and it is fully housed with the center opening(Consider wrist watch). What is the formula to get the required thickness. Say your diameter of the glass or area of the glass is fixed. And the formula required for different profiles...
  20. W

    Finding the Thickness of Polystyrene in a Capacitor

    Homework Statement Homework Equations Capacitance = k(epsilon zero) (Area) / (distance) Length (thickness) = (Volt)(Area) / (Current * Resistivity) The Attempt at a Solution Given: Capacitance : 480 * 10 ^ -12 Farad Radius: 24 * 10 ^ - 2 m Area: pi * r ^ 2 dielectric constant of...
  21. S

    Thickness of AntiReflection Coating for destructive interference

    Homework Statement Glass, despite being transparent, still reflects a little bit of light. When making lenses and such, you'd rather not waste any light with stray reflections. Fortunately, you can use destructive interference to suppress those reflections. The picture below shows a piece of...
  22. S

    Potential of infinite sheet with thickness

    Homework Statement Describe the potential inside and outside an infinite insulating sheet with uniform density ρ and thickness d, as a function of x (distance from the center of the sheet). zero potential has been set at its center. What is the potential on the surface of the sheet?Homework...
  23. R

    Solving a Slab Design for Proper Thickness & Reinforcement

    [b]1. Homework Statement [ Here is the question that I am struggling with. I am told that my answers are not correct, but I do not know where I went wrong? Any suggestions would help greatly! I attached a paper with all my work shown. Thanks! A solid one-way, continuous slab is used...
  24. O

    Calculating optimum thickness of the insulation for composite wall

    Homework Statement A wall is required to be insulated by embedding wood within concrete. the total thickness of the concrete and wood are 10cm and 1 cm respectively and are fixed due to structural constraints. determine the minimum heat leak into the room if the location of the wood can be...
  25. U

    Thickness of steel required for a vacuum chamber

    I'm trying to build a vacuum chamber for chemistry purposes. This isn't exactly for school, but it's something I'm doing for fun and it's close enough to a school problem. Anyway, my vacuum chamber will be a prism 24" wide, 18" deep, and 18" in height. It will also have a 8"x6" Plexiglas window...
  26. Y

    Calculating Material Used in a Cylinder of given Thickness

    When given a cylinder with radius, height and thickness, how does one go about computing the amount of material used in making the cylinder? Initially I thought the amount would be: Material=2\pi r^{2}t+2\pi r h t where t is the thickness of the cylinder. Looking at this equation...
  27. I

    Research problem-photoresist thickness

    Greetings PF.In my lab, we are having trouble making correct photoresist films(over 100 microns, SU-8 photoresist). They typically are not hardening enough before exposure. We want to solve this problem quickly as this is starting to interfere with the project. I'm trying to find solutions to...
  28. N

    MATLAB Analyzing Wall Thickness vs Force Data Sets

    Attached are three figures. The problem in question essentially involves extracting data from a .CSV (MS Excel) file and .mdb (MS Access) file which I have done already but not correctly. Data set #1: gives me 'Wall Thickness vs. Time' ( [3400 - 8200] s , [0,1] in.) as shown in figure3.jpg...
  29. S

    Pressure vessels, wall thickness

    Homework Statement 20 m3 of gas at a pressure of 25 bar is to be stored in a cylindrical pressure vessel 2 m long. Given the following information : The yield strength of the vessel material is 14,000 psi If a factor of safety of 5 is to be used, determine: (a) Whether the vessel should be...
  30. K

    Extracting thickness of glass and index of refraction from Cartesian Graph

    Homework Statement I made a graph in Excel which graphs (1/x^2) vs (1/cos^2 (angle of incidence)). From the graph I am supposed to analyze the slope and intercept of the straight line. I made a trendline which came out to be y=mx + b = (-0.0084)x + 5.54. From this equation I'm supposed to...
  31. I

    Finding material thickness on cylindrical shells

    I have been tasked to find the material thickness needed for a cylindrical shell with open ends. I have been given the internal pressure, the cylinder inside diameter, the Poisson's ratio and the allowable tensile strength. I have used Birnie's equation to solve (see attached file in thread...
  32. D

    How is diffraction affected by grating thickness?

    I would like to talk to someone here who has either theoretical or practical experience with not-too-thin transmission gratings. I have the following problem. I want to compute the far-field diffraction image of an electromagnetic wave (with a wavelength in the visible spectrum) as it passes...
  33. C

    Finding area from volume and thickness

    Homework Statement How large a surface are in units of square feet will 1 gallon of paint cover if we apply a coat of paint that is 0.15 centimeters thick? Homework Equations There is no shape given that the paint must cover to know which volume and area equation to use. There must be...
  34. J

    Calculating thickness of a cast iron cylinder carrying pressure of 30Nmm^2

    1. Homework Statement A cast-iron cylinder of 300mm bore carries a pressure of 30 Newtons per square millimetre; what should be its thickness for a unit working stress of 25 Newtons per square millimetre? 2. Homework Equations ó1 = pd/2t t=pd/2tó1 3. The Attempt at...
  35. J

    Finding thickness of a cast iron cylinder

    Homework Statement A cast-iron cylinder of 300mm bore carries a pressure of 30 Newtons per square millimetre; what should be its thickness for a unit working stress of 25 Newtons per square millimetre?Homework Equations ó1 = pd/2t t=pd/2tó1The Attempt at a Solution t=pd/2tó1 t= 30*300/2*25...
  36. G

    How thick should a steel plate be to support a load of 1300 N in a 3 point bend?

    I'm using the basic deflection equation to determine how thick a plate of steel would have to be to support a load of approximately 1300 N in a 3 point bend, with surface dimensions of of 420 x 630 mm. I = bh3/12; δ = FL3/(C1EI); Esteel = 200 GPa = 200 N/mm; δ = 50 mm (arbitrary); h3 =...
  37. M

    Is Acrylic Piece of 25mm thickness strong enough for shaft walls

    I am wandering if acrylic piece of 25mm thickness would be strong enough to be used as shaft walls that has 15kg radial force acting on it. If it's not, what material is the best to be used? For those who don't understand or want to know more, look at my picture.
  38. N

    Calculating Pressure Vessel Thickness with Given Data

    Homework Statement Problem: find the thickness of a Pressure Vessel. Given: Operating Pressure, Operating Temperature, Material type and Grade, and OUTSIDE Diameter/Radius Homework Equations q1. how to calculate Design Pressure/Temp. from Operating Pressure/Temp.? q2. how to calculate...
  39. G

    Calculate thickness of a pressurized vessel

    Hi guys. I am trying to figure out how thick should be an aluminium pressurized vessel with a internal pressure of 0.125 pa or 1/8 bar. The shape of the box is a cylinder 130cm base x 170cm height. The maximum pressure difference is 0.125 bar inside -> 0 bar outside. I know that i need to know...
  40. D

    Stress and Strain (Finding the thickness of truss members)

    Hi guys i have a exam coming up soon and stress is starting to kick in. I am good with stress and strain, but I am just confused on this question and don't understand what i need to be doing. I've tried every formula and i just can't seem to get question 5 out. The answears for this question is...
  41. D

    Stress & Strain (Finding diameter, extention & thickness)

    Hi guys i have a exam coming up soon and stress is starting to kick in. I am good withy stress and strain, but just confused on this two questions and don't understand what I am doing wrong. I've tried every formula and i just can't seem to get question 6 out. And question 5 same problem i...
  42. A

    How to calculate the minimum pipe wall thickness in this scenario

    Hey guys, Hope you can help me with the following practical problem I am facing right now. I plan to build a pipe system in which ethanol (vapor/liquid) is being conducted at pressures from 1 atm to 10^(-2) atm. What would the minimum pipe wall thickness be if the pipe material was a)...
  43. M

    Thickness of material to support a heavy load

    My situation is i have a 10kg battery that is mounted on top of a plastic material. How would i exactly calculate the right thickness for the plastic to support the 10kg battery?
  44. J

    Year 12: Cambridge Physics Problem (Rate of increase of ice thickness)

    Guys I'm weak in heat and kinetic theory, so I'm going to need extra guide and pointers from you guys to solve this and the coming questions. Thank you. Question: A pond of water at 0 degrees Celsius is freezing. The thickness of the ice layer is h and the top surface of the ice remains at a...
  45. M

    Trying to design a gear with minimum thickness

    Hello, I am blanking on the equations I should use to calculate the stress through a section of a gear. I would like to be able to calculate the thickness of trepanned gear. Hopefully the attachment helps show what I am looking for. The area between the arrows needs to be minimized...
  46. S

    What is the relationship between normal and shear forces in structural analysis?

    Homework Statement Given in uploaded file Homework Equations σallow=\frac{P}{A} τallow=\frac{V}{A} The Attempt at a Solution Given in uploaded file Answers are d=16mm, h=10mm I tried using methods used in previous questions but it didn't work out for me here, if anyone could...
  47. R

    Index of refraction and thickness of materials

    Hi, my current research is to determine the thickness and the index of refraction of semiconductor materials.. using reflectivity.. my adviser gave me the results of the sample by GRAPHS the reflectance percentage vs. the wavelength.. i know that i can measure the index of refraction.. if i...
  48. E

    Calculate the minimum thickness

    Homework Statement I have a large polymer plate of 45cm x 120cm, with Young Modulus 0.8 GPa and I want to calculate the safe thickness (before fracture) of that plate on a middle line force across the width of the plate with magnitude of 0.6 kN. The middle line force distribution is shown...
  49. N

    Thickness of 304 stainless sheet to avoid puncture

    Designing a cylinder using Stainless Steel 304 and am trying to figure out the minimum thickness of the outer wall of the cylinder to avoid being puncture by a 6in diameter steel bar after falling 1 meter onto the bar. Cylinder will weigh approximately 5500kg.
Back
Top