What is Tensile stress: Definition and 33 Discussions

In continuum mechanics, stress is a physical quantity that expresses the internal forces that neighbouring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material. For example, when a solid vertical bar is supporting an overhead weight, each particle in the bar pushes on the particles immediately below it. When a liquid is in a closed container under pressure, each particle gets pushed against by all the surrounding particles. The container walls and the pressure-inducing surface (such as a piston) push against them in (Newtonian) reaction. These macroscopic forces are actually the net result of a very large number of intermolecular forces and collisions between the particles in those molecules. Stress is frequently represented by a lowercase Greek letter sigma (σ).
Strain inside a material may arise by various mechanisms, such as stress as applied by external forces to the bulk material (like gravity) or to its surface (like contact forces, external pressure, or friction). Any strain (deformation) of a solid material generates an internal elastic stress, analogous to the reaction force of a spring, that tends to restore the material to its original non-deformed state. In liquids and gases, only deformations that change the volume generate persistent elastic stress. However, if the deformation changes gradually with time, even in fluids there will usually be some viscous stress, opposing that change. Elastic and viscous stresses are usually combined under the name mechanical stress.

Significant stress may exist even when deformation is negligible or non-existent (a common assumption when modeling the flow of water). Stress may exist in the absence of external forces; such built-in stress is important, for example, in prestressed concrete and tempered glass. Stress may also be imposed on a material without the application of net forces, for example by changes in temperature or chemical composition, or by external electromagnetic fields (as in piezoelectric and magnetostrictive materials).
The relation between mechanical stress, deformation, and the rate of change of deformation can be quite complicated, although a linear approximation may be adequate in practice if the quantities are sufficiently small. Stress that exceeds certain strength limits of the material will result in permanent deformation (such as plastic flow, fracture, cavitation) or even change its crystal structure and chemical composition.
In some branches of engineering, the term stress is occasionally used in a looser sense as a synonym of "internal force". For example, in the analysis of trusses, it may refer to the total traction or compression force acting on a beam, rather than the force divided by the area of its cross-section.

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  1. K

    Need help calculating maximum stress in a bolted assembly

    Trying to calculate the maximum stress that would occur in the attached assembly... The assembly consists of a tube sandwiched between two plates that are bolted down to a larger plate with an M6 bolt. Each of the two plates have a 400N force acting on them which is perpendicular to the axis of...
  2. kyrosboi

    Stress in a spinning flywheel

    I'm wonder how one could calculate the total mega pascals total mega pascals that can be applied to a spinning flywheel before it exceeds its tensile strength example: a cast iron flywheel is spinning at 10,000rpm(Tangential velocity = 104.72) it has a radius of 100mm and a weight of 500g...
  3. S

    Ultimate tensile stress of material

    My answer is A but the answer key is B. I don't understand why B. I would think B is the breaking point. Thanks
  4. weezy

    Measuring Tensile Strength in an alternative way

    So I've been looking at a few material tests and they all start with a rectangular sample of the material, loaded into a machine which extends them by increasing load at a constant rate and measures the strain/stress till the point of material fracture. The yield stress is measured in usually...
  5. Perodamh

    Relationship between thickness, width and length

    1.A rectangular steelbar of length subjected to tensile force of 80kN. Calculate the change in length if the width and thickness are (40 & 25)mm respectively. (E = 207 GN/m2). Homework Equations E= stress/strain stress = F/A; F =80kN strain = dL/L 3. I just want to know what to use for the...
  6. DevonZA

    Tensile stress in perforated steel plate

    Homework Statement Two lengths of steel plate 100mm wide and 15mm thick are riveted together by a single 18mm diameter rivet. If the joint carries a tensile load of 8kN calculate: a) The shear stress in the rivet b) The tensile stress in the perforated plate Homework Equations stress = force...
  7. arpon

    I Isn't the force calculated twice?

    Isn't the force calculated twice here? For example, the force along AB is at first calculated for the resultant force along OB, then for the resultant force along AC. I think the compression and tensile stress should be ##\frac{F}{2a}##.
  8. C

    Tensile Stress: Understanding Its Effects on Materials and Structures

    Homework Statement can someone explain about part b (tensile stress) here? in which way does the stress act? Homework EquationsThe Attempt at a Solution FromW wikipedia, tensile stress refres to the stress to break a rope...How does it related to the case above?
  9. S

    Tensile Stress at Mid-span of Beam

    Hi, I'm struggling with finding the tensile stress at the mid-span of this beam. I've done the previous questions but have no idea how to begin with this one as I've never dealt with this question before. What is the general method? Correct answer is 1.66MPa. Thanks.
  10. A

    Bending of beams: calculation of stresses

    The cross-section of a cost-iron beam is shown in figure below, the loading being in the plane of the web, the upper portion of the section being in compression. If the maximum permissible stresses are 2000 kg/ cm2 in tension and 3000 kg/ cm2 in compression, find the moment of resistance of the...
  11. I

    Tensile Stress Analysis of Bolted Connection

    Determine the tensile stress in the bolted connection shown below for the load F = 210 kN. Using a safety factor of 2, determine whether the plates will fail or not if the yield strength of the plate material is 270 MPa and the thickness of the plate is 12 mm. The nominal diameter of the bolts...
  12. G

    Tensile Stress and shear stress

    Suppose, a mild steel bar is being pulled from both ends.The stress acting on it will be tensile in nature.There is no compressive stress on material in this situation.When the pull exceeds material's yield strength,plastic deformation and strain hardening will occur.If pulling force is...
  13. davidbenari

    Tensile stress, and youngs modulus.

    I'm studying elasticity right now in my chemistry class, and I'm confused as to what exactly tensile stress (and maybe compression stress too ) might mean. It's given in N/m^2. And you're stretching the material. Is the cypher I'm given indicative of what's happening only one side? Indicative...
  14. B

    Maximum tensile stress on rod with eccentric rotating tensile load

    I was solving this paper, but got stuck on this question, and it's been bugging me endlessly. I don't know what I'm missing. Here's the question: A rod of 20 dia is fixed to the ceiling of a roof on one end. A rotor of 50 kg mass is attached to the free end with bearings. The CG of the rotor...
  15. N

    Calculating tensile stress? help please?

    Homework Statement A cable containing 37 strands of 0.0250" diameter steel wire successfully supports 1000 lb load in tension. Calculate tensile stress? Do you think this is a reasonable and safe design stress level?Homework Equations tensile stress = F/A The Attempt at a Solution A = [...
  16. marellasunny

    Glass compressive and tensile stress

    http://www.glassalchemy.com/media/upload/image/stressfig1.gif In the manufacturing of glass(flat glass),the outside cools first followed by the inside.So,this means that the outer surfaces compresses on the hot inner surface.What I don't understand is how the tensile stresses are developed on...
  17. G

    Tensile stress, radius and Young's modulus

    Homework Statement An Aluminum cable of length 3.5m has 15,000 N tensile force acting on it if the wire is only allowed to be stretched by 1mm before it breaks, What must be the radius of the wire if the Young's modulus of Al is 6.9 x 10^10 N/m^2? I am also supposed to find the tensile...
  18. A

    Calculate the tensile stress anpplied at maximum load

    (a) The steel cable to the hoist is 15m in length and has a diameter of 25mm. Its steel has a maximum permissible working stress of 200N/mm2 and a Young’s modulus of elasticity of 210,000N/mm2. The maximum load allowed on the hoist is 75kN. Determine the following:- (i) the cross-sectional...
  19. B

    Finding elongation of bar and maximum tensile stress

    Homework Statement L=52 in A=2.76 in^2 E=10.4*10^6 psi Homework Equations σ=F/A ε=σ/E δ=εLThe Attempt at a Solution 4) σAB = (3P)/A ε=(3P)/(AE) δAB=(3PL)/(6AE) → δAB=(PL)/(2AE) solving for P P=[0.17*2*2.76*(10.4*106)]/52 → P=187680 lb → P=187.7 kip 5) Because AB and CD are in tension i...
  20. P

    Tensile stress given theta and force

    Tensile stress given theta and force (I'm kinda desperate) Homework Statement Aluminum wire is lightweight. You can hang a piece of it nearly horizontally with very little tension. After having done so, you then hang a HEAVY (25 kg) block from the wire. The wire sags to make an angle of 12...
  21. J

    Tensile stress with unequal forces

    I need to find the stress σ (defined as normal force/area, in N/m^2) for the following simple situation. The forces are not equal. I can't wrap my head around what's going on - the whole system should be accelerated, so what's the final force that should be used for calculating the stress?
  22. S

    How do I work out ultimate tensile stress?

    Hey guys! I'm really stuck and would be grateful for any help. I'm a postgraduate researcher, though not a physicist so this may be a relatively simple problem for some of you (I hope!). I use a program called Bluehill which is coupled with an Instron machine. The instron is a mechanical...
  23. P

    Finding flexural compressive stress and tensile stress

    How would I use a shear force diagram and a bending moment diagram to find the maximum flexural compressive stress and the maximum flexural tensile stress? I am assuming the peaks at the bending moment diagram is the maximum tensile and compressive stresses? Am I correct? Also, is it...
  24. I

    Problem about tensile stress during thermal contraction

    Hi I am trying to solve this problem. I will present my solution though I couldn't get the tension right. At 40 Celsius , there is no tension in the wire. When the wires are cooled , they contract and the tension increases. But the tensile stress, which is force per unit area, will remain...
  25. R

    Calculating Tensile Stress in a 40mm Rod with 200 KN Load | Formulas & Solutions

    Homework Statement Calculate the tensile stress in a rod 40 mm in diameter with a load 200 KN ? Homework Equations pi*r^2 The Attempt at a Solution 3.14 * (20*20) = 1256 mm^2 200 * 1000 = 200 000 N 200 000 / 1256 = 159.24 N/mm^2 Tensile stress = 159.24 N/mm^2...
  26. P

    Finding Normal Compressive & Tensile Stress: a Example

    Homework Statement [PLAIN]http://img12.imageshack.us/img12/6109/17007711.jpg The attempt at a solution For part (a), I can only find a normal compressive stress. It is as follows: \sigma_{c} = \frac{F}{A} \sigma_{c} = \frac{100*9.81}{\pi(0.013)^{2}} \sigma_{c} = 1847704 Pa...
  27. O

    Calculate Tensile Stress with Strain Gauge

    A strain gauge has a unstrained resistance of 120 ohms, gauge factor of 2.0 is connected to steel girder so it experieces tensile stress. If strained resistance of gauge is 120.13 ohm. How do i calculate the tensile stress value? I have looked all over the internet for equations relating but...
  28. O

    Calculating Tensile Stress Using a Strain Gauge

    A strain gauge has a unstrained resistance of 120 ohms, gauge factor of 2.0 is connected to steel girder so it experieces tensile stress. If strained resistance of gauge is 120.13 ohm. How do i calculate the tensile stress value?
  29. G

    Ultimate tensile stress of rubber?

    Homework Statement How would you define the ultimate tensile stress of rubber? Homework Equations If I had a force/extension graph of rubber, what point in the graph would show me the value of the ultimate tensile stress?? The Attempt at a Solution Is it the same thing as ultimate...
  30. B

    Formula for the tensile stress on a spinning ring

    I'm having a problem finding and equation that will give me the tensile stress acting on a spinning ring, like the rim of a flywheel, that is trying to "pull itself apart". The ring has no spokes or disc, but is just a ring spinning on its axis. I need to know how fast the ring can spin...
  31. L

    Determining Tensile Stress on Pressurized Sphere Skin

    how to determine the tensile stress placed on the skin of a pressurized sphere
  32. H

    What is the Tensile Stress, Strain, and Young's Modulus of a Stretched Wire?

    Homework Statement A load of 172 kg is supported by a wire of length 2.07m and cross-sectional area .143cm^2. The wire is stretched by 0.149 cm. Find tensile stress, strain, and Young's modulus. Homework Equations stress= F/A strain= ∆L/L E= stress/strain The Attempt at a...
  33. N

    Axially Loaded Member and Tensile Stress oh so lost

    Homework Statement "The axial load for a given test sample carries 1590 N. Calculate tensile stress at sections (1) and (2) assuming the sample thickness is 5mm. (Rectangular cross section). http://img208.imageshack.us/img208/121/tensilestressby1.th.jpg Homework Equations normal...