# Strain Definition and 44 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. ### A Does strain affect on-site energy?

I want to study strain effects on the one material which has non-zero on-site energy . Does strain affects on-site energies?
2. ### Formula for the energy of elastic deformation

In every book I checked, the energy (per unit mass) of elastic deformation is derived as follows: ## \int \sigma_1 d \epsilon_1 = \frac{\sigma_1 \epsilon_1}{2} ## and then, authors (e.g. Timoshenko & Goodier) sum up such terms and substitute ##\epsilon ## from generalised Hooke's law i.e. ##...
3. ### Poisson Ratio -- Finding a corresponding analytical solution for the strain

Hi, I ran into problems using the poisson ratio. For a FE simulation I created a simple 2D 1mm x 1mm block, and prescribed a 0.1 mm displacement at the top edge. Furthermore, the bottom edge is constraint in the y-dir, and the left edge in the x-dir. The material parameters are E = 100, and v...
4. ### Biophysics Q: Impact of stiffness (Young's modulus) on stress failure

Hi. I'm a physician trying to understand the micromechanics of lung injury due to overdistension. The basic idea is that overstretching of the plasma membrane of the lung epithelial cell causes "stress failure" --> i.e. plasma membrane rupture --> cell death. The concepts of stress, strain, and...
5. ### Capped pressure vessel - strength and stability

Hi, in mechanics of materials books one may easily find fomulas for stress and strain in thin- and thick-walled cylindrical pressure vessels subjected to internal pressure. However, it is assumed that they are open. So what are the formulas for stress and strain in capped vessels (with flat or...
6. ### I Maximum Strain For Samples of Different Cross-Sectional Areas

I would assume that because the samples are made of the same material they would fail at the same stress and so the same strain. However, the data shows that the sample with a greater cross-sectional area fails at a greater strain, and the two are roughly proportional. Does anyone know what...
7. ### How to decide which component is best in terms of stress and deformation?

Summary: In terms of stress, strain & deformation, what is better for a given component. 1) low stress or high stress 2) less strain or large strain 3) less deformation or large deformation? Some dimensional changes were made in an existing component to study how these changes effect the...
8. ### Find the stretch of a steel wire in a static equilibrium problem.

If I can determine the weight of that heavy object placed on the plank, I will be able to determine the stretch of that wire. But, when using the second condition for static equilibrium (torques of the system equal to 0), I always end up with two unknowns, no matter what point of rotation I...
9. ### Relation between magnetism and material creep

Hello, I am a civil engineer and have been working on concrete creep phenomenon for several years now. After reviewing a large amount of literature on related topics throughout this time, some interesting observations have emerged, and they have formed the idea that the material creep mechanism...
10. ### Thermal Expansion of a Wire Connected To a Rod

Homework Statement Homework Equations ΔL=LαΔT σ=EΔL/L The Attempt at a Solution For part a, I used the coefficient of linear expansion for copper and the change in temperature to find the change in length (0.068%). I thought part b had the same answer. The two are attached, and I would...
11. ### Strain sensing project

Hello, I am a 3rd year EEE student and am working on a project that will go on to form my 3rd year dissertation. I am having trouble formulating a project idea from the guidelines. I was told I should use a strain sensor to form some kind of self sensing smart material that could be used to...
12. ### Creating Mohr's strain circle from a strain rosette

Homework Statement A sample is put in tension and a strain rosette gives the following results: i) Calculate principal strains and poissons ratio using Mohrs strain circle. ii) Calculate principal stresses from principal strains and poissons ratio. Homework Equations Mohr's strain circle γ =...
13. ### Automotive What is the compression force of a ring seated inside a cylinder

Hello. I am finding out how many normal force between ring and cylinder. I try to find around for many hours but get noting. there are 8.2 mm inner diameters than put in 8.6 mm cylinder. The hardness of sealing element is 55 ShA. Contact area is 48.63 mm^2. I have data and drawing in attachment...
14. ### Stress and Strain tensors in cylindrical coordinates

Homework Statement I am following a textbook "Seismic Wave Propagation in Stratiﬁed Media" by Kennet, I was greeted by the fact that he decided to use cylindrical coordinates to compute the Stress and Strain tensor, so given these two relations, that I believed to be constitutive given an...
15. ### Strain produced in a rod after expansion

Homework Statement A rod of length ##L_o## is kept on a friction-less surface. The coefficient of linear expansion for the material of the rod is ##\alpha##. The the temperature of the rod is increased by ##\Delta T## the strain developed in the rod will be? Homework Equations  \Delta L=...
16. ### Simple strain gauge in rectifier, last part of the problem

Homework Statement Homework Equations The Attempt at a Solution I do not understand this last part: Is this needed? The divide by two is the voltage divider, correct?
17. ### Relationship of viscoelasticity, creep and strain

Can someone explain the terms viscoelasticity, creep and strain and their relationship to each other? Especially the difference between creep and strain. Any help would be greatly appreciated, thank you!
18. ### B What is a good physical reference for microstrain?

I can say that the distance between my knuckle and my finger joint is 1~ inch, that a baseball weighs ~1 lb, and ~60 joules is the feeling of dropping a bowling ball on your foot. I'd like to understand strain in this way, can anyone offer a common place reference? Also, I know strain is...
19. ### Calculate tension and strain of wire

Homework Statement A load of 1150 kg is suspended as shown in the figure. The angle θ1 = 57° and the angle θ2 = 36°. (a) Calculate the tension in all three wires (that is, the magnitude of the tension force exerted by each of these wires): Tension in left wire Tension in right wire Tension in...
20. ### B A statistical definition of Young's Modulus?

Young's Modulus is usually defined as the intrinsic property of a material indicating it's stiffness, or it's ability to resist deformation. Though, it is measured in Pa, meaning it should have some statistical description. Spring constant, for example, can be define as the stiffness of an item...
21. ### Traction/ Compression stress and strain exercise

Hello everyone, could you help me with this exercise? I am stuck, and I can't find anything on the internet that solves this. Your help is very much appreciated :) 1. Homework Statement Circular steel bar, clamped at extremities. Two parts: A(ab)=800mm² A(bc)=400mm² L(ab)=...
22. ### Deriving Strain in Cantilever Beam with Known Deflection

I am trying to derive the strain at the base of a cantilever beam with a known deflection. I know the bending stress is equal to Mc/I, so the strain is Mc/IE, where c is the distance from the neutral axis. For a point load ,P, the strain would then be PL/IE. Since the deflection is known I...
23. ### Is a latex balloon's maximum strain independent of thickness?

Is latex balloon maximum strain independent of latex thickness? I have been in search of a latex balloon that is relatively small when deflated and very large when fully inflated. Standard balloons that reach the desired inflated dimensions are much larger deflated than I would like...
24. ### I Finding Maximum Strain

Hello, I am trying to establish what the moment of inertia is for this cantilever beam as well as the maximum strain. General formals preferred. Thank you
25. ### Strain of a Cantilever beam

Hi, Well i have a system with a excited (in y axis) cantilever beam. I struggling to obtain a expression that gives the strain based on the dislocation y. I know that the displacement of the beam is given by: Ya=PL^3/(3EI) but how i make a correlation between this and the strain of the...
26. ### Calculating stress and strains for beam of applied force

Homework Statement If I consider a force, which is applied to both ends of a rectangular beam to its cross section with dimensions w (width) and h (height) and I know the length of the beam is l and the force is parallel, how can I calculate the stress? Also, what if the force were parallel to...
27. ### Work done up to fracture

Good day everyone! i have a problem dealing with the fracture analysis. We all know that the work done per unit volume is equal to the area under the curve of stress-strain curve or we can express it in terms of integral form, and if we're looking at necking point stress can be express in this...
28. ### Critical Buckling loads-how to plot?

Homework Statement Hi all, I am an architect so engineering is not my strong point. for these equations I am unsure how to correctly determine the mode of failure and plot a graph. Any help would be greatly appreciated. Also the attached files have the formulas written and question written...
29. ### Displacement gradient same as strain?

Hi, is displacement gradient du/dx same as strain? i though it would be until someone made a comment that they are not the same thing and now I am confused.
30. ### Effective Strain of Frictionless Punch on Deep Plate

I'm trying to figure out the effective strain of a frictionless punch on a deep plate. For simplicity's sake let's say it's in plane strain. Don't quite know where to start. Closest thing I can think of is the strain from a bulge test, but that involves a thin sheet. Looked at some indentor...
31. ### Graphing stress-strain plots on excel

1. I'm given time (s), extension (mm), tensile stress (mPa), and tensile strain (%) in a table. I'm supposed to graph it on excel, but my graphs don't look at all like a stress-strain graph. 2. I think it's probably because I'm using tensile stress or strain? Or is it an excel error I'm doing...
32. ### How could change the energy band gap(E-K) using the strain?

Hi! I'm sung dae with tensile strain, energy band structure could be changed. bang gap decrease with compressive strain, energy band structure could be changed. bang gap increase but I'm not sure why it could be changed .. Is there someone who explain in detail ? thanks. have a nice day! :)
33. ### Stress due to compression of 3D object

Good day, I am trying to calculate the stress along the yy-direction for a 3D object compressed in the zz direction (perpendicular to it). The width of the object (in the yy direction) is constant, and the object can only deform along the xx direction. All stresses except for sigma_zz (known)...
34. ### How to plot stress-strain curve?

Can we plot stress-strain curve if we only have yield strength, tensile strength, and elongation data? For example if i have: Yield strength = 300 MPa Tensile Strength = 600 MPa Elongation = 50% How to plot the stress-strain curve? Thanks
35. ### High strain rate testing using the SHPB -- Help please

I am a part C mechanical engineering student and require some advice for my individual project, which is based on the high strain-rate testing of a particular glass filled composite material using a split-Hopkinson pressure bar (SHPB) experiment. I gathered the results on a SHPB test rig and...
36. ### Converting stress-strain curve to shear stress-shear strain

Homework Statement For a crystalline metal material - Elastic modulus E - Poisson ratio v - A table with test data of stresses vs. total strains, from a monotonic uniaxial tension test, which generates a stress-strain curve. How would you use this data to find the corresponding pure shear...
37. ### The strain of a dog-bone specimen

Homework Statement A dog-bone specimen made by aluminum alloy is used for tensile testing by a force of 4000N via two steel pins. The dimension of the specimen is shown in the following picture; the thickness of specimen and the length of pins are 4mm and 8mm, respectively. The mechanical...
38. ### Direction of max shear strain

Homework Statement Hi Everyone, I am going to be doing an experiment soon using strain gauges on a beam and I will have to, among other things, calculate the direction of the maximum shear strain with respect to the axis of the beam. I am trying to find the correct equation to use. Homework...
39. ### Hysteresis in helical coils springs

Hi, Do helical springs have hysteresis. Say I do an exercise of plotting deformation Vs load curve of a helical spring, one way will be starting from load zero and increasing till the spring achieves solid length. The other way will be loading the spring till solid length and measuring...
40. ### Stresses and Strains

Homework Statement A 45 degree strain rosette is fixed to a short rectangular section pillar. The gauge reads εa =72x10^6, εb=100x10^6, εc=-240x10^-6. What are the values of W and F? The cross section area is 600mm2 and is made out of steel which E=207GN/m2 and v=0.3. The maximum shear stress...
41. ### Poisson's ratio for a rigid rod

I have a conceptual misunderstanding it seems. Poisson's ratio is the ratio of elastic strain deformation of the transverse and longitudinal components. That being said, if I were to induce thermal stress (heating up) to a rod by keeping its ends (longitudinal component) rigid, would there be a...
42. ### Prove Poisson's Ratio is .5 for Small Strains

Homework Statement Poisson's ratio v is the negative ratio of the transverse strain to the axial strain. For an incompressible (density doesn't change), homogeneous (everything is the same molecule), isotropic (it doesn't matter which direction you pull or push on it, it will act the same way)...
43. ### Anisotropic Modulus of elasticity and Poisson's ratio

Hi, I have some experimental data and I am interested to use this data to calculated modulus of elasticiy (young's modulus) and Poisson's ratio. The material for which the data is given in an anisotropic material, therefore I need to calculate modulus of elasticity and poisson's ration is x,y...
44. ### Stress and Strain Coursework Question

I am struggling with a question in my coursework, and would appreciate some guidance. The question is: The component shown in Fig 1 is made from a material with the following properties and is subjected to a compressive force of 5kN. Material Properties : Young’s Modulus of Elasticity – 200...