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. H

    Question about stress and strain

    Homework Statement The elastic limit for a type of material is 1.6 x 10^8 Pa.Determine the minimum diameter if a wire which is made of this material so that it can support a load of 100N without the stress exceeding the elastic limit. Homework Equations elastic limit=stress...
  2. S

    Stress Strain Curve: Converting Psi and In/In to MPa and mm/mm

    Hi All, I have a stress strain curve, which have strain(in/in) on x-axis and stress in Y axis(Psi). Here I want to conver the curve to stress(MPa) and strain (mm/mm). I know that Psi can be converted by multiplying the digit by 0.00689475729. But in this case I need to change the strain...
  3. R

    Understanding Strain Gauges: Measuring Mechanical Strains in Structures

    I am studying strain gauges at uni and was wondering if you could clarify for me how they may be used to measure mechanical strains in structures like towers, houses etc.. I know that it is possible to use a mechnical gauge that measures the development of a crack (see wiki)but I can't work...
  4. J

    Calculating Compression of Bored Out Steel Column - Stress & Strain

    I have been given a question to recap by my tutor as i find this topic fairly difficult. A steel column is 90cm long and 150mm diameter. If a hole 100mm diameter and 60cm long is bored out, calculate the total compression of the column when carrying a load of 1MN. Take the modulus of...
  5. B

    Young's Modulus (Finding Average Strain)

    Homework Statement A 30kg sledge hammer strikes a steel spike of 2.30 cm diameter while moving at 20.9 cm/s. The hammer rebounds with a speed of 10.0 cm/s after 0.110 s. What is the average strain in the spike during impact? Mass of hammer = 30 kg Radius of Spike = 1.15 cm or 0.0115m...
  6. J

    Solve Torsional Strain Problem: 8.1 & 8.2

    hey everyone I am stuck on a problem and would appreciate any guidance you could give me. here is the question: Much as in exercise 8.1, the end of a .75-in-diameter rod is fixed to an immovable plate. the length of the rod is 18.0-in. A 50-lb weight is attached to a 16.0-in lever at the...
  7. D

    Elasticity,stress, and strain questions

    1. A 3.0-mm2 cross sectional area metal rod is stretched by 0.4 mm when a certain stretching force is applied to it. Another rod of the same length and metal but of a cross sectional of twice as large is stretched by the same amount of force. Calculate the stretching in the second wire. the...
  8. A

    Definition of the Lagrangian finite strain tensor

    The Lagrangian finite strain tensor is defined as: E_{i,j}=\frac{1}{2}\left(\frac{\partial x_k}{\partial X_i}\frac{\partial x_k}{\partial X_j}-\delta _{i,j}\right) Is it in Einstein Notation so that there is a summation symbol missing, i.e. would it be the same thing if one wrote it as...
  9. S

    Calculating Bending Result of Volumetric Strain in a Beam

    I'm working on a problem involving the bending of a beam. The bending is a result of an expansion within the beam, rather than an external load. Basically, there is an expansion in the volume of one side of the beam and a contraction on the other side. I have therefore calculated a...
  10. 8

    Load Displacement to stress strain

    Hello, so here is my problem. Homework Statement I am given tensile data, which is displacement (mm) and load (kgf). also I am given width(mm), thickness(mm), gauge length (mm) and cross-head speed (mm/min). How do i make a stress strain curve from this? The Attempt at a Solution...
  11. E

    Shunt Calibration of a Strain Gauge

    I've recently been researching how to measure strain using strain gauges. I came upon the subject of shunt calibration and hit a mental roadblock. From what I understand, shunt calibration simulates a strain across a strain gauge using a comparatively large resistor placed in parallel with...
  12. R

    Difference in simple shear and rotational strain

    Is simple shear same as rotational strain? or, is it a type of rotational strain?
  13. R

    Calibrating a strain gauge/thermistor?

    Calibrating a strain gauge/thermistor? Hey guys, Im abit confused on the method of calibrating a strain gauge/thermistor, i know they both use a wheatstone bridge (resistance). At the moment i have gathered this information, Transducers and sensors which produce a change in resistance are...
  14. R

    Calibrating a strain gauge/thermistor

    Homework Statement Hey guys, Im abit confused on the method of calibrating a strain gauge/thermistor, i know they both use a wheatstone bridge (resistance). At the moment i have gathered this information, Transducers and sensors which produce a change in resistance are typically used...
  15. T

    Defining principal strain + direction

    Homework Statement Question: The strain state in a point is defined by the tensor: 0.9 0 0 0 -0.4 0.2 0 0.2 0.6 - Define principal strains and directions in the point - Explain how deforms the element shown in figure 2b (they just drew a cube on 3d axis) - Draw the principal directions...
  16. E

    Does heightening a sofa increase strain in the centre?

    Hi, I was wondering... if by heightening a sofa (150cm in length approx) from floor level by about 20-30 centimeters, would increase, or could potentially increase the strain in the centre of a sofa when people sit on it? I have a long sofa, that was raised and I notice that my sofa is sagging...
  17. M

    Stress and Strain fracture and flow

    Stress and Strain...fracture and flow If a material has a maximum tensile fracture stress of S, and a maximum shear stress of T which causes plastic flow, how will it deform: If T=S and if 3T=S ?? Its not an important question, but I am just curious? I can't get my head...
  18. B

    Strain gauges - converting to parrallel binary word

    Homework Statement I want to convert the output of a strain gauge into an equivalent parellel binary word Homework Equations i need to list the process blocks in correct sequence and starting at the strain gauge The Attempt at a Solution Strain gauge- convert ohms to volts-...
  19. G

    Stress & Strain: Exploring Copper Wire Properties

    http://www.ami.ac.uk/courses/topics/0123_mpm/images/met_mpm_imgb.gif http://i859.photobucket.com/albums/ab152/Greener1011/Untitledpicture.png First off I am sorry about the massive size. The top graph is how a stress strain graph of a metal should look. However i can't seem to think why Mpa...
  20. Saladsamurai

    Wheatstone Bridge Strain Gauge Question

    Homework Statement I recently did a bending lab with a WB Strain Gauge in a bunch of different configurations. One measurement in particular is bothering me. Referring to the figure below, there are four strain gauges, Yellow, Orange, Black and Red mounted to a cantilevered beam with an...
  21. H

    Convert Strain gauge readings to stress

    Hello i am trying to convert the strain gauge readings i took in a lab from an I beam that was subjected to torsion. I am trying to convert the microstrain readings to stress and shear stress. I have the following information the Yield strength of the I beam and the youngs modulus but not the...
  22. B

    Strain gauge data acquisition board?

    Ok, so what I am looking for, as the title suggests, is a strain gauge data acquisition board. Currently, we have been using all sorts of National Instruments stuff to obtain our goals. To this point they have worked fine, but now we need to seriously downsize for a new lab device we are...
  23. A

    Vertical deflection, stress, and strain Help

    The shear modulus of aluminum is 2.4 × 1010 N/m2. An aluminum nail of radius 7.5 × 10–4 m projects 0.035 m horizontally outward from a wall. A man hangs a wet raincoat of weight 25.5 N from the end of the nail. Assuming the wall holds its end of the nail, what is the vertical deflection of...
  24. T

    Engineering problem (uses stress, strain, Young's Modulus)

    Homework Statement 2. As engineers, we wish to use a metal bar as a support arm on a crane. The bar has a Young’s Modulus of 3x106psi . Assuming the rod will need to be 3ft long. Answer the following questions… a)If the crane is designed so that the maximum tensile force on the rod is...
  25. L

    How Do Material Properties Affect Wire Deformation?

    1. A copper wire has length 200cm and radius 0.40mm. A mass of 1.00kg is suspended from the end and allowed to come to rest. The Young modulus of copper is 130Pa. Calculate: a) the stress b) the strain c) the extension d) the elastic energy stored Repeat the calculations for the case of a carbon...
  26. M

    Where Can I Find Affordable Strain Gauges?

    I need to find several cheap strain gauges. I was able to find some at Mouser for several hundred dollars, but that is way too much. I wasn't able to find any at all at digikey or several other suppliers whom I've never heard of. Do cheap strain gauges even exist?
  27. S

    Understanding the Strain Tensor Component: Physical Meaning of d'_{ijk}E_{k}

    There's this equation e_{ij} = \alpha_{ij}\DeltaT + d'_{ijk}E_{k} + Q'_{ijk}H_{k} + s_{ijkl} Sigma_{kl}, which is the strain tensor I'm asking about. All I want to know is what the component d'_{ijk}E_{k} is called and what its physical meaning is. Thanks in advance
  28. M

    Stress vs. Strain and finding the permanent set of bar

    Homework Statement I am told a cirular bar of magnesium alloy is 750 mm long. The bar is loaded in tension to an elongation of 6 mm and then the load is removed. I am given this Stress vs. Strain graph which I can't put up here since its in my book. But Stress is on the y- axis and strain is...
  29. V

    Know of any online stores that sell strain gauges?

    I've just been given a quote on some strain gauges I'm after and the adhesive but I've got a 4-6 week wait from this supplier and I want somewhere else to compare against price wise. If I can get them sooner rather than later it would be cool too. Any suggestions? My searches in Australia...
  30. V

    Minimum microstrains that a wheatstone bridge or strain gauges will pick up?

    I'm wanting to measure the torque output of a cyclist by measuring the shear force induced in the crank arms. I've done some calculations for the minimum amount of strain that I'll want to pick up and it is around 6e-6 m/m. I'll be using a full wheatstone bridge with a constant voltage...
  31. D

    Strain, thermal strain and agle of twist

    the cylindrical beam is attached to 2 walls and a torsion of Mo is applied 30cm from one end, the system is warmed ΔT, if point B is found at the coordinates (a,b) before deformation where will it be after the deformation? (a',b') i found the reactions using equilibruim and the fact that...
  32. 5

    Calculating Nominal strain at which Necking Occurs

    Homework Statement Given two wires of gauge length 100mm and 200mm They are loaded to fracture in tension The 100mm sample extends by 15mm The 200mm sample extends by 25mm. I need to use this information to calculate the nominal strain at which necking commences in the wires Homework...
  33. P

    Strain Energy - Displacement

    Someone please help to solve this its urgent.. Homework Statement Homework Equations The Attempt at a Solution At A-B There is No load so dM/dP= 0 and dU/dP= 0 At B-C M = -px - wx.x/2 dM/dP= -x dU/dP = Wx^4/8EI At C-D M = -Wb + Px dM/dP = x dM/dP = -Wbx^2/ 2EI When i...
  34. P

    How to Calculate Strain Energy for a Beam?

    Any one can help me solving this pleasezzzz http://i49.tinypic.com/2vkm2r8.jpg" My attempt At A-B There is No load so dM/dP= 0 and dU/dP= 0 At B-C M = -px - wx.x/2 dM/dP= -x dU/dP = Wx^4/8EI At C-D M = -Wb + Px dM/dP = x dM/dP = -Wbx^2/ 2EI When i include all vaues...
  35. M

    How Do I Correctly Calculate and Plot Stress-Strain for a Physics Test?

    I need to draw a stress and strain graph. New to physics, so would like to know if i am on the right line and require a bit of help for the last few questions These are the values I have: Diameter - 10.02mm Original Length - 50mm Extension -10mm Diameter After Test - 6.76mm Max Load -...
  36. A

    How to find strain in simple cantilever beam

    Hello to everyone, my question is how to find strain in rectangular cantilever beam applying point load at some point. I am not getting formulas for that..Please save me from this. Its very urgent for me.
  37. T

    Principal Stress and Strain on a Fracture

    Homework Statement Find the expressions for principal stresses in both plane strain and plane stress conditions sigma(x) = (K/(sqrt(2*pi*r)))*cos(theta/2)*(1-sin(theta/2)*sin(3*theta/2)) sigma(y) = (K/(sqrt(2*pi*r)))*cos(theta/2)*(1+sin(theta/2)*sin(3*theta/2)) T(xy) =...
  38. D

    Stress Strain Diagram: Find Constants E, K, n, and α

    given the following points of the stress strain graph and knowing that the stages are defined linear σ=Eε uniform plastic σ=Kδ2 necking σ=αδ where ε is an elastic strain and δ plastic strain find the values of the constants E K n α using the given data i plotted σ(ε) and got the...
  39. T

    A2 Practical Project. Stress, Strain and.. I with the set up.

    For my A2 practical project I am using a stress gauage on a 'rule' shape of plastic and adding diffrent weights to see the changein stress and strain. As another varible I will be changing the temperture of the plastic to see how this effects its stress and strain. I'm looking for help...
  40. D

    Stress, strain and deflections due to temperature change

    in the following problem i know that ΔT=120 now the maximum deflection is 0.5mm so i looked for the total deflection had there been no restrictions ΔL(aluminium)=300*(23e-6*120)= 0.8280 ΔL(st steel)=250*(18e-6*120)= 0.5400 this is clearly more than the maximum deflection of 0.5-...
  41. T

    What are the Stress and Strain in each rod?

    Homework Statement A copper rod of 2 meters is joined to a steel rod with length (ls) and with cross sectional area of 1.0cm2 and 2.0cm2 respectively the compound rod is subjected to an equal and opposite force of 3x104N. Find: a) The length of the steel rod if the elongation of the steel...
  42. S

    Stress and Strain/ Hooke's Law Question

    Homework Statement A 50 kg traffic light is suspended above an intersection by a continuous steel cable. The cable has a diameter of 1.0 cm, and the light is depressed 12 degrees below the horizontal. What is the percentage increase in the length of the cable due to the mass of the traffic...
  43. D

    State of stress, strain and hookes law

    in the following question i am asked to find the state of stress given the state of strain. http://lh6.ggpht.com/_H4Iz7SmBrbk/SwBtHnG3qkI/AAAAAAAAB9M/rFS_orHMbGo/Capture.JPG i went about solving this using hookes law \sigmaxx=E[(1-v)\epsilonxx + v(\epsilonyy+\epsilonzz)]/[(1+v)1-2v)] using...
  44. D

    Stress and strain. young modulus

    in the following question, how do i find the changle in AB, the change in AD and the change in AC? http://lh4.ggpht.com/_H4Iz7SmBrbk/Sv_hYT83rYI/AAAAAAAAB8s/7l5YRXMxVfQ/s912/Capture.JP what i have done is used the following \sigmaxx=E*\epsilonxx \deltaAB=\epsilonAB*AB since AB is on the x...
  45. C

    Best Adhesive for Strain Gage on Steel | 10% Strain

    Hi, Can anyone recommend a good adhesive to glue a strain gage to steel? Ideally it would be something readily available at a hardware store or something like that. The expected strain will be approx. 10%... hopefully less, but possibly slightly more. Thanks!
  46. I

    Solid State: Mean Square Lattice Strain

    Homework Statement Okay, this is from Kittel's Introduction to Solid State Physics (8th ed.) and it's driving me crazy. The problem is: In the Debye approximation, consider \langle (\tfrac{\partial R}{\partial x})^2 \rangle =\tfrac{1}{2}\Sigma K^2u^2_0 as the mean square strain, and show...
  47. J

    Measuring Strain on a circular tube.

    If I wanted to determine the principle stresses on the surface of a circular tube could I use a 45deg planar rectangular rosette to measure the strains \epsilonx, \epsilony and \gammaxy? I only ask because on a flat surface the gauges could be oriented along the x-axis, the y-axis and 45 deg...
  48. R

    Find Force Needed to Lengthen Beam w/ Length, Y Modulus, Area

    If I know only the length of the beam, the young's modulus, and the cross sectional area, is there an equation that I can use to determine what amount of force would be required to lengthen a beam by a specified amount? The force is being applied to the beam axially.
  49. T

    Strain Gauge Placement on Cylinder

    1. Problem Statement: I am trying to measure the radial (#s 3-6) and hoop (#s 1, 2, 7, 8) strain (and from that, stress) present in an aluminum cylinder. I am trying to use a standard full wheatstone bridge setup, but am having trouble settling on a setup that would give me an accurate...
  50. C

    Structures and Materials problem - stress and strain

    Homework Statement A 4000 kg car traveling at 160 km/h crashes into a concrete post. If all the kinetic energy of the car is used to crush the low alloy steel at the front of the car, how many kg of steel will be crushed before the car stops? Properties of low alloy steel from a table of...
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