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. C

    Calculating the Volumetric Strain for a Rectangular Steel Bar

    Homework Statement A rectangular steel bar has length 250 mm, width 50 mm, and thickness 25 mm. The bar is subjected to a compressive force of 450 kN on the 250 mm x 50 mm face, a tensile force of 450 kN on the 250 mm x 25 mm face, and a tensile force of 45 kN on the 50 mm x 25 mm face...
  2. T

    Finding mass with given stress, strain, and original area

    Homework Statement figure whatever represents an insect caught at the midpoint of a spider-web thread. The thread breaks under a stress of 8.2 x 10^8 N/m^2 and a strain of 2. Initially, it was horizontal and had a length of 2cm and a cross-sectional area of 8 x 10^-12 m^2. As the thread was...
  3. H

    Investigating Wood Expansion & Contraction w/ Strain Gauge

    Hi i have just been given my physics coursework and wondered if anyone had any pointers or tips on how to answer? The question is on the expansion and contraction of wood with changes in temperature and humidity using a strain gauge. We have to explain how we would use lab equipment to...
  4. S

    Investigating Wood Expansion/Contraction with Strain Gauges

    hi I've just been given this piece of coursework which is the latest(2008) version and I am just wondering if I could get any help on this? thnx! :cheesy grin: The manufacturers of wood floors need to know how much the wood expands and contracts with changes in humidity and temperature. One...
  5. Saladsamurai

    Does any one know how to make a stress strain diagram in MS excel?

    Or know of any good tutorials? This is a PAIN to do by hand.
  6. J

    Understanding the Equation for Measuring Strain on a Cantilever Beam

    I have a lab where we used the following equation to theroretically measure the strain on a cantilever beam heald stationary at the left end. Measuring back from the right side its length is L2 and the length from the free (right) end to the point where the strain gagues were was L1 (fixed...
  7. M

    Roark's formulas for stress and strain

    Hi all, i hope that i am in the right forum. As you see in my topic i have a problem with Roark's formula especially for elastic stability of plates and shells. The formula i got a problem with is the following: If you have the book: sixth edition: page 689 table 35 formula 15. or...
  8. D

    Stress and Strain - Materials

    The last question on my homework (always the hardest). Homework Statement A wire of diameter 1.0mm and length 2.3m is made of copper. Young modulus is 1.1 x 10^11. Find: a) The cross-section of the wire in m² b) The strain if the wire is stretched by 0.85mm c) The stress d) The force...
  9. B

    Help An issue with a cantilever tube instrumented with strain gauges.

    I am working on the development of an instrument which can be simply thought of as a cantilever tube. This tube is instrumented with strain gauges to measure the X/Y strains and two sets of rosettes, each consisting of two strain gauges at 45 degree. Note that the X/Y are 3-wire half bridge and...
  10. E

    Comparing Circular vs Rectangular Diaphragm Strain Gage Pressure Transducers

    I am currently trying to learn about pressure transducers. There are two configurations which have been suggested for a particular pressure transducer -- 1) a circular diaphragm strain gage and 2) a rectangular diaphragm strain gage. Each configuration has four strain gages. For 1) there are...
  11. G

    Calculating force required for specific strain

    I have a cantilever with one fixed end and a point force on the other end. The cantilever beam itself is a perfect rectangular prism. We used a strain gage to measure the strain values, so how would I calculate the point force? I know the value for Young's Modulus of the cantilever used. Any...
  12. R

    Understanding Axial Strain Calculations

    Hi all, I have a problem with respect to axial strain.As far as I know the axial strain is calculated by using the formula given below. Strain=(L-Lo)/Lo where Lo : Orginal length and L : current length. However, another formula is written in one of the program manuals I have been...
  13. B

    Solving Strain in a Box on the X-Y Axis: A Homework Problem

    Homework Statement I've got a problem that I can't figure out. It deals with strain. I've got a box, sitting on the x-y axis(like normal x-y axis's are). The box extends 4 inches from the origin in the x direction, and 2 inches up. Going clockwise(starting at origin) the corners are...
  14. L

    Calculate Modulus of Toughness from Stress-Strain Graph

    1. Find modulus of toughness Given Data : Load (kip) 0.00 1.50 4.60 8.00 11.00 11.80 11.80 12.00 16.60 20.00 21.50 19.50 18.50 Elongation 0.0000 0.0005 0.0015 0.0025 0.0035 0.0050 0.0080 0.0200 0.0400 0.1000 0.2800 0.4000 0.4600Lenght= 2 in Diameter= 0.501 in 2. Homework Equations ...
  15. S

    Calculate initial diameter from longitudinal strain and final diameter

    "Calculate the initial diameter of a wire that has been longitudinally strained by 30% and whose final diameter is 0.1cm. Assume no volume change." Now I know that if there is no volume change, v=poisson's ratio= 0.5. Thus the lateral strain would equal 30%*0.5= 15%. But when I plug it...
  16. P

    Understanding Stress Strain Graphs: Exploring Yield Point and Material Behavior

    Just a question. The internet is mixed with this. But in a Stress Strain Graph; after the YIELD POINT, does the material experience more strain for a lesser stress? I.e. does it slightly curve down before going up?
  17. P

    Wanted: Stress and Strain Tutorial

    Looking for a Tutorial on Stress and Strain and couldn't find it >.< Please help:frown:
  18. X

    Some Strain Gauge Theory Help

    First, I am not the greatest at LaTex so if I screw this post up I will go back and try to clarify. I will skip some steps, but get the general gist of everything. Ok, I am following the derivation of the resistive strain gauge equations starting from the basic form of resistance of a wire...
  19. X

    Some questions about strain gauges

    I am trying to figure out a couple questions involving strain gauges. First of all, how is the gauge factor physically determined. Anyone know the process by which a company gets that. I am particularly using a Vishay strain gauge with a GF of 2.035, and indeed in practice most standard...
  20. B

    Failure modes of strain gauges

    I am trying to determine some failure modes of strain gauges and the means of accomplishing some of them. Things like loose leads, debonding, physical damage, thermal effects, doing things that cause saturation. I am looking for ideas of what other failure modes are and ways to accomplish...
  21. B

    Calculate stress, strain & YME

    Appreciate if someone can take the time to check my answers to the following question. If wrong, could you point me in the right direction. A round bar, 800 mm long, CSA 15 mm^2 experiences an applied tensile load of 6 kN and stretches elastically by 3 mm.a) Calculate the tensile stress in the...
  22. M

    Finding Major and Minor Strain from Mohr Circle of Stress

    Hey everyone. Quick question about the Mohr circle. If I have got the major and minor stress from a Mohr Circle of stress how do you go about finding the major and minor strains? Can you just use Young's Modulus equation and value for Young's Modulus or will I need to construct Mohr...
  23. A

    Calculating Bending Moment & Torque from Mohr's Strain Circle

    Hi, desperately need help with this assignment question as its in for 2moro! "At a point on the surface of a shaft with diameter of 100mm, a 45deg rosette strain gauge is positioned with the middle gauge along the axis of the shaft. The gauges measure strains of a= -0.00015, b = 0.0003, c =...
  24. A

    Finding M & T Using Mohr's Strain Circle

    Hi, desperately need help with this assignment question as its in for 2moro! "At a point on the surface of a shaft with diameter of 100mm, a 45deg rosette strain gauge is positioned with the middle gauge along the axis of the shaft. The gauges measure strains of a= -0.00015, b = 0.0003, c =...
  25. A

    Is Strain a scalar quantity?

    Hi, I know that strain is a unit less quantity (Tensile Strain) but whether Strain is a scalar quantity or not? If it is a scalar quantity then why? Regards, Muhammad Rizwan Khalil
  26. R

    Calculating Steel String Length and Frequency for Optimal Guitar Performance

    One type of steel has a density of 7000 kg/m^3 and a breaking stress of 7.30×10^8 Pa. A cylindrical guitar string is to be made out of a quantity of steel with a mass of 3.50 g. What is the length of the longest and thinnest string that can be placed under a tension of 930 N without breaking...
  27. J

    Solve Volumetric Strain | Question 3 on http://img201.imageshack.us/my.php

    Homework Statement How do I solve the following block to find the volumetric strain. Its question 3 on the link http://img201.imageshack.us/my.php?image=file0001pf0.jpg I know that volumetric strain is equal to change in volume EV/ origninal volume(V) Is Ev = Ex + Ey +...
  28. W

    Is Strain Dimensionless According to Dimensional Analysis?

    The quantity "strain" expressed in terms of the fundamental quantities (mass, length, time) is equivelent to? isn't this dimensionless?
  29. S

    Calculating force required for specific strain

    How would I approach the problem of calculating the amount of force necessary to enduce a certain flexural strain on a piece of alumnium? Would I use Young's Modulus and if so how would I use it? Thanks, -scott
  30. S

    How is non-uniaxial strain defined?

    Hello, How is non-uniaxial strain defined? How would Nitinol's 8% maximum strain before failure be defined as in terms of other than stretch? How does one define the 8% in terms of bending the wire? So in other words how much bending of the wire equates to an 8% strain limit? Thanks...
  31. T

    Solve Stress and Strain Qs | Equations, Diagrams, Steps

    Q: A copper wire of diameter d is stretched by a load hanging vertically from its lower end . The strain of the wire is 8.0x10^-4 . What's the strain in another copper wire of the same length but of diamteter 2d ? A: 2x10^-4 Q: A light rod of length L hangs from the lower ends of two...
  32. D

    Strain Gage Research: Seeking Physics-Based Sites

    Hello. I'd like to ask you if you know any links to strain gage research sites. I'm going to design a full bridge gage but I'd like to read something first. I'm not talking about gage-maker sites, such as vishay,omega,hbm,etc. I already read them all. I'm interested in more physics-based...
  33. A

    Strain vs Pressure: What's the Difference?

    What's the difference between strain & pressure? The formulas look the same...
  34. A

    Stress, Strain - Axial loading (axial forces)

    Hello everyone I study mechanics of materials, curently stress and strain. I don't understand how to figure out those axial forces in specific fields of mechanic construction. Picture 1 - Construction 1: http://img.photobucket.com/albums/v309/Andreii/P9150003.jpg" Picture 2 - Construction...
  35. T

    Difference between force-elongation and stress - strain diagram?

    what is the difference between force-elongation and stress - strain diagram?? pls show some example such as diagrams for future reference thanx
  36. N

    LED Lights for Desk: College Student's Guide to Eye Strain Relief

    Hello. Does anyone here use and LED light for their desk? I am a college student and spend a lot of time at my desk reading. I get pretty bad eye strain from reading so much. I am thinking about getting one of these LED lamps. Also, does anyone use any other type of lamp that is better...
  37. A

    Young's Modulus and the strain on a sphere due to a uniform pressure

    If I have thin shell like a beach ball inflated with air how would I calculate the change in radius and resistance there of due to the pressure inside the sphere? I have calculated the strain on the sphere to be Pr/2h where P=pressure r=radius h= thickness by cutting the sphere in half and...
  38. D

    How Much Weight Can an 8mm Diameter Steel Bar Safely Support?

    The Ultimate tensile strength of steel is 470MPa. Assuming a factor of safety of 5 the maximum working load an 8.00mm diameter round steel bar should support against gravity is?
  39. S

    How can the electric polarization be induced the strain gradient?

    How can the electric polarization be induced by the strain gradient? It is said in some papers the strain gradient can induce electric polarization in solid materials. Why can it happen? Who can explain this phenomenon to me?
  40. J

    Materials Science Ballistics: Investigating Strain and Recrystalization

    I have been given kind of a bonus question that requires a little thinking and I wanted to ask if I am going in the right direction with my thinking as I am new to Materials Science. Given: Ballistics test in which a high velocity projectile is fired at a block of material. Isotropic. Does...
  41. C

    Distributed Strain Sensing with FO Bragg Gratings

    Not really something I would expect most people to know so I will keep it out of the Homework help section (it is not homework) I am working on distributed strain sensing with fibre optic Bragg gratings for aircraft. For those that don't know, FO Bragg gratings are a periodic variation in...
  42. Cyrus

    Strain: Result of Suddenly Applied Load

    This kind of had me puzzled for the last week. If you apply a tensile stress on a body, it will elongate, and get a little bit thinner. The amount of stretch will be a function of the stresses. But then I started wondering, "Well, if that’s the case, then it will stretch and get a little...
  43. tandoorichicken

    Statics: Axial Load and Strain

    My statics text says the following: The relationship between axial stress and strain can be represented by the equation \sigma = E\epsilon "At higher levels of stress, the following nonlinear equation may be a better fit to describe the correlation between axial stress and strain: \sigma...
  44. K

    Strain Energy: Potential Power in Stretching

    why is strain energy (i.e. the work done in stretching a wire) regarded as a form of potential energy? ehm i don't really know how to explain this. anyone help?
  45. ZapperZ

    Antibacterial-resistant strain

    Humm.. I actually have a biology question. I don't normally troll around in this part of PF, so I don't know if it has been asked before. There have been advice to not use antibacterial soaps, and reducing the frequency of use of antibiotics. The reason for this is the report on the more...
  46. I

    Calculating Acceleration & Force of Strain Thread

    J must count acceleration of each weight and the force of strain thread. Here is a picture:
  47. N

    Need a clie on how to build a Laboratory scale using strain gages

    Need a help on how to go about building a Laboratory scale using strain gages I need to build a scale with a working range of 2 to 200 gm, an accuracy of at least 2 gm, footprint of no more that 16 in sq, and use no more that 6 strain gages. I believe I need to set up the strain gages in...
  48. S

    Strain rate effects on steel strength

    I was wondering exactly how yield and tensile strength increases with increasing levels of strain rate for a typical steel grade? I understand dislocations are generated during straining (work hardening), but what happens at higher strain rates which increases the strength?
  49. S

    Effects of Rotation on Strain in a Disk

    If a hollow disk of say radius R is heated which causes it to expand a bit and a solid disk of radius slightly greater than R is fixed inside it after which both cool down, the solid disk will be in compression and the hollow disk in tension right? Now if this disk is rotated at a some speed...
  50. Tsu

    News On Capitol Hill, Military Warns of Being under Strain

    http://www.latimes.com/news/nationworld/iraq/la-fg-troops18nov18,0,6045845,print.story Getting ready for the draft?
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