What is Strain: Definition and 461 Discussions

In organic chemistry, ring strain is a type of instability that exists when bonds in a molecule form angles that are abnormal. Strain is most commonly discussed for small rings such as cyclopropanes and cyclobutanes, whose internal angles are substantially smaller than the idealized value of approximately 109°. Because of their high strain, the heat of combustion for these small rings is elevated.Ring strain results from a combination of angle strain, conformational strain or Pitzer strain (torsional eclipsing interactions), and transannular strain, also known as van der Waals strain or Prelog strain. The simplest examples of angle strain are small cycloalkanes such as cyclopropane and cyclobutane.

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  1. Nemo's

    Stress Strain Curve: Explaining Beyond UTS

    Homework Statement Explain in terms of stress and strain what happens to the stretched material beyond the ultimate tensile stress. Homework Equations A curve similar to this The Attempt at a Solution I can see that the curve beyond UTS represents increasing stiffness but i can't...
  2. R

    Calculating stress, strain and Young's modulus?

    After a fall, a 77 kg rock climber finds himself dangling from the end of a rope that had been 15 m long and 9.1 mm in diameter but has stretched by 2.3 cm. For the rope, calculate (a) the strain, (b) the stress, and (c) the Young's modulus. strain = ΔL/L stress = F/A Young's modulus =...
  3. J

    Cross Sectional Area, Stress and Strain confusion

    Homework Statement For each material calculate the cross sectional area in m². Each sample is of rectangular cross section 20mm by 1mm. Produce Stress and Strain tables for the data. TEST DATA FOR X (N) EXTENSION (mm) 1000 0.48 2000 0.60 3000 0.70 4000 0.80 Homework...
  4. K

    Solving for Stress and Strain in Three Dimensions

    Homework Statement Knowing that the stress and strain for an isotropic media can be related with the following expressions: \sigma_{xx} = (\lambda + 2\mu)\varepsilon_{xx} + \lambda\varepsilon_{yy} + \lambda\varepsilon_{zz} \sigma_{yy} = \lambda\varepsilon_{xx} + (\lambda +...
  5. K

    Stress & strain for steel wire

    A 1.80-m long round steel wire with a cross-sectional diameter of 0.80 mm is placed over a light frictionless pulley, with one end of the wire connected to a 23.0-kg mass and the other end connected to a 14.0-kg mass. By how much does the wire stretch when the masses are in motion? S= F/A e=...
  6. R

    Shear modulus and shear strain relationship?

    If a shear force is acting on a rectangular beam, how do I use the value of the shear modulus to calculate if the force applied will fracture the beam? Below I've submitted the data involved. The shear force applied is 1000 N and the cross section area is 28 mm. So the shear force applied is...
  7. G

    Strain gage to measure drag in a wind tunnel?

    How would a strain gage be set up (on top of the model? around the sting?) to measure drag? I don't quite understand the connection between the force of drag and some sort of compression/tension force...? Thanks for the clarification.
  8. A

    What is the Difference Between Plane Stress and Plane Strain?

    Hello everybody, Can you please tell me what's the difference between plane stress and plane strain ? Does one imply the other ? For example, does plane stress imply the plane strain ? Thank you in advance.
  9. S

    How to connect strain gauge in the form of wheatstone bridge

    HAI I am SYED , i am doing my project using strain gauges. Problem description: I have 4 strain gauges bonded to an octagonal ring. The strain gauge i am using is METAL FOIL TYPE , GF(gauge factor) -2 and 320ohm resistance. The strain gauge has two terminals ,my question is (1) Can anyone...
  10. K

    Determining plain stress and plain strain

    In a delta strain rosette problem if normal strains are given and asked to find the six components of stress and strain , is it considered as a plain stress or plain strain problem.??
  11. P

    Calculate strain induced in a rubber(Elastosil 607) against applied force

    Hello Team, I have a rubber (harness A of 54 and elongation at break of 100%) on which 30N of force is applied over 45mm2 of ares. I would like to know the strain induced in the rubber against the force. The problem here is i could not find the exact Young's modulus value for this material. But...
  12. M

    Force measurement system - relating output voltage to Force - strain gauges

    Homework Statement I'm struggling with this, I have series of data for the deflection of a cantilever beam and the corresponding output voltages from a strain gauge, wheatstone bridge and amplifier circuit. I'm trying to find the relation between voltage output and force, i.e. Force = K x...
  13. M

    Permanent Offset (stress strain)

    Sorry for the inverted picture... "y" axis: top to bottom is 500 400 250 "x" axis: at B is .00125 at E is .05 modulus elasticity is E=200GPa so from AB=.00125 from CD=.002 calculated: epsilon=400x10^6/200x10^9 I need to find permanent offset(AC) and I don't know How to find the...
  14. C

    Normal strain of cable through arc

    Homework Statement See attachment Homework Equations eAB=(Lf-Lo)/(Lo) The Attempt at a Solution Ok, this is not for HW. I am preparing for a mechanics of materials class next semester. I don't understand when CB goes through the 0.3 degree arc, they say the height is still 300mm. Shouldn't...
  15. M

    Maximum Bore Diameter for Axial Tensile Load question

    A 25mm diameter solid circular section bar made from given material tested is to be bored axially to produce a cylinder of uniform thickness. If this cylinder is then subjected to an axial tensile load of 75kN, what is the maximum diameter of the bore possible if the stress in the cylinder is...
  16. M

    Elasticity (understanding elasticity from stress strain curve)

    Hello .. I have problem understanding how to decide which material is more elastic based on stress strain curve.. my understanding is as follows 1)if a material has big youngs modulus.. then it is more stiff 2)a material with a big youngs modulus may be or may not be very elastic (elasticity...
  17. N

    Problem involving temp changes in stress and strain topic.

    1. Knowing that a 0.5 mm gap exists when the temperature is 20 degree celsius, Determine the tempature at which the normal stress in the aluminum bar will be equal to -90 MPa,And the corresponding exact length of the aluminum bar. The Attempt at a Solution I am not familiar with this topic...
  18. N

    How Is Normal Strain Derived in Continuum Mechanics?

    http://imgur.com/SnHyP What are the mathematical steps and assumptions to reach the conclusion that length(ab) ≈ dx + ∂u/∂x*dx ? If you consider the the squares of the gradients to be negligible, you still have a square root and multiplication by the constant "2". What other assumptions do...
  19. N

    Derivation of normal strain

    http://imgur.com/SnHyP What are the mathematical steps and assumptions to reach the conclusion that length(ab) ≈ dx + ∂u/∂x*dx ? If you consider the the squares of the gradients to be negligible, you still have a square root and multiplication by the constant "2". What other assumptions do...
  20. S

    Theoretical gage factor for resistive wire strain gages?

    What model correctly predicts the sensitivity of a resisitive wire straing gage to applied strain? This question is motivated by an an old pamphlet found in a used book store, "Theory Of Strain Gage Flight Test Instrumentation" by Eugene Frank, 27 May 1946. The gage factor of a strain gage...
  21. G

    Working out strain and stress of an elastic band (youngs modulus)

    This is regarding youngs elastic modulus I need help as I am trying to figure out the stress and strain of an elastic band when a force has been applied - in youngs modulus. Does anyone know how to go about this?
  22. V

    Trouble understanding stress and strain problems

    Hi everyone, so I'm trying to understand how to use the (Cauchy I think?) stress tensor. The definition I have is that the element \sigma_{\alpha\beta} of the stress tensor σ is the force per unit area in the α direction on a surface that's normal to the β direction. I also have a...
  23. X

    Stress strain laboratory question

    Homework Statement Establish the constitutive relationship for the cantilever beam material, i.e., provide an empirical formula for the relationship σxx=σxx(εxx) and generate a plot of this relationship. What is the cantilever beam material? Homework Equations This is a pure beam bending...
  24. J

    Buy Cable Strain Relief | Mouser, Amazon & Beyond

    Where can I buy strain reliefs? All I could find on Amazon are 6,000 different kinds of RJ-45 booties, which are not what I'm looking for. Mouser is impossible for things like this unless you already know exactly what you are looking for. I quite like the strain relief used on the LeCroy...
  25. Saladsamurai

    Short Beam Bending: Roark's Formulas For Stress and Strain

    Is anyone familiar with the Roark's text that can clarify some terms for me? I am trying to clarify what Roark is referring to in the above mentioned text in the section on short beams (in the 5th edition 7.10 and in the 7th edition 8.10). Throughout the text, he uses the terms "span" and...
  26. P

    Stress and Strain problems help

    Does anyone help me to solve this problem in the attached file? When I solved this problem, I got wrong answers. Attached file is the image file with the problem and answer. (Question No.3) I think I have to find allowable shear stress of Pin A to find the safety factor of this pin...
  27. E

    Strain Gauges for small cylinders

    Hello all, I would like to know if there are strain gauges out there that could be used for small cylinders. To describe the problem/design more thoroughly, I am trying to design (or purchase) a cylinder no bigger than 3mm. When the end of the cylinder is compressed (across the circular...
  28. O

    High temperature fibre optic strain adhesive anyone?

    So I am currently using a high temperature epoxy based strain adhesive on a polyimide coated single mode fibre. This however gives rubbish results in terms of creep at anything above 160 deg C. Does anyone have any experience with this type of problem at all? I know that there are...
  29. X

    Tensile Test Lab Results: Strain Gage Reading

    Hey guys so i did a tensile test lab and got the following results from the strain gage: SecondsElapsed Strain u 0.1 0 1.1 1 2.1 1 3.1 0 4.1 0 5.1 1 6.1 1 7.1 2 8.1 5 9.1 9 10.1 47 11.1 129 12.1 209 13.1 278 14.1 335 15.1 386 16.1 434 17.1 482 18.1 529 19.1 579...
  30. T

    Converting Strain Gage Voltage to Force: A Guide for Scientists

    Hello, I am doing a project where I have 4 strain gages (in a full bridge Wheatstone configuration) and I am continuously recording their output voltages. These strain gages have been installed on an aluminum bar and are recording bending. My question is how to I convert the output voltage...
  31. L

    What are the elements of the strain tensor for a wide beam under bending?

    If I have a wide beam, parallel to the x axis, with its COM at the origin, then I want it to curve about the y axis, what would the elements of the strain tensor be? I have come to the conlusion that the beam would, for example,contract above x-axis and expand below it. But I don't know how...
  32. F

    Compound Bar Stress and Strain Analysis

    Question The compound bar is composed of Aluminium surrounded by High Density Polyethylene Al= E = 69x10^9 Pa Al= r = 0.035 m HDPE= E = 0.8x10^9 Pa HDPE= r = 0.055 m The compound bar has a load of 75000N applied evenly to each of its ends. Part 1. Find the change in...
  33. H

    Deformation Analysis: When to Use Plane Strain vs 3D?

    Hi all, I have a question regarding deformation analysis. For materials with non-zero Poisson's ration, when is it justified to use plane strain analysis rather than three-dimensional? Perhaps one case is when we are going to analyze a thin sheet. Are there other cases too? Thanks, Hassan
  34. C

    Deflection using strain gages?

    Hi Guys, I'm wanting to measure deflection in an injection mould tool. I'm planning on using strain gages to measure the strain in the tool under injection pressure. Is there a way I can use these strain readings to calculate the deflection in the plates? Thankyou for any help. :)
  35. S

    Strain and stress related to young modulus

    Homework Statement A three-legged stool has one leg of aluminium (E = 7 x 1010 Pa), one copper (E = 11 x 1010 Pa) and one of steel (E = 20 x 1010) Pa. The legs have the same dimensions. If the load on the stool is at the exact center, a. Which leg is under the greatest stress? Explain why b...
  36. S

    Strain Gauge Bonding: Permanent & Chemical Options

    I have a few strain gauges that are going onto the suspension of a race bike. I've never installed these things before. While I have found a lot of information on installing them, I am having a hard time finding many adhesive and chemical options. It seems a lot of them are non-permanent, or...
  37. R

    Purchasing Torsional Strain Gauges

    Does anyone know where I can purchase a torsional strain gauge? Website? Company? Thanks
  38. S

    Axial stress rate vs axial strain rate

    Homework Statement I have a Mohr-Coulomb plasticity model with isotropic hardening on the cohesion c(k). The angle of internal friction is constant. k=sqrt((2/3)*(de)'Q*de), where de is the time derivative of the plastic strain. Q is diag[1,1,1,0.5,0.5,0.5]. It is a triaxial test assuming...
  39. W

    Stress and strain, maximum applied force before permanent deformation/breakage

    Compute the maximum longitudinal force that may be supported by a bone before breaking, given that the compressive stress at which bone breaks is 2.00e8 N/m^2. Treat the bone as a solid cylinder of radius 1.55 cm. The attempt at a solution I tried using the equation Max Torque = pi/4 * (r^3) *...
  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. X

    Strain Gauge Angle Homework question.

    [a]1. Homework Statement [/b] I thought it would be easier to post a picture since this way the drawing can be seen. I'm having a hard time deciding what angles to use with the relevant equations, see below. Homework Equations I know that: Ex' =...
  43. E

    Maximum Strain of Steel in Space Elevator Design | Physics Homework Help

    Homework Statement Alright, so I have this final project in physics which was due yesterday and I'm turning it in late because i have a problem with understanding one thing. so the project it about space elevators and the teacher asked me to make calculations about what is the maximum height...
  44. F

    Understanding the strain energy function invariant term

    Hi, Dear all, Facing problem to understand strain energy function invariant terms A typical strain energy function consist of strain invariant can be defined as followed W(I1,I4)=C0+C1(I1-3)(I4-1)+C2(I1-3)^2+C3(I1-4)^2+C4(I1-3)+C5(I4-1), I1 and I4 are so called invariants of Green's strain...
  45. W

    Observation of gravitational wave strain.

    Hello, I have a question or two about gravitational waves. My current job is basically to measure atomic strains using x-ray diffraction. I have managed to reduce the error in measurement low enough to reveal an annual sine wave in my data for a sample which should not contain any strain. I...
  46. F

    What type of tensor describes strain in a cubic object?

    dear all, as a newbie in solid mechanics modelling, i always come across these few terms, Cauchy-Green strain tensor Green Lagrange strain tensor isochoric Cauchy green strain tensor. Consider a cubic, when we move the top face, while fixing the bottom face, we will able to see the...
  47. P

    Plastic strain depens on loading path

    Hi there, My teacher gave me a homework, but this Theory of Plasticity is new and difficult to me. He has calculated the strain according to path (1), now I have to do with the path (2) and (3). This is what he did with path (1): ε11=∫(1/E)dσ11 +...
  48. P

    Project Using Strain Gage and/or Accelerometer

    Hey guys, new here, been trying to come up for a project idea using a strain gage and/or an accelerometer. Thought maybe you all might have some cool ideas of things to do! No required theme, other than those listed below: • Must utilize computerized data acquisition National...
  49. S

    No strain rate dependency- then?

    i, I'm attaching a file which have the stress strain curves of same material at quasi static and high strain rates. See materials on page 1 and page 2. Both are same materials. The curve on page 1 is obtained at quasi static strain rate and the curve on page 2 is obtained at high...
  50. S

    Material tests at quasi static and high strain rates

    Hi, I'm attaching a file which have the stress strain curves of same material at quasi static and high strain rates. See materials on page 1 and page 2. Both are same materials. The curve on page 1 is obtained at quasi static strain rate and the curve on page 2 is obtained at high...
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