What is Stress concentration: Definition and 24 Discussions

A stress concentration (also called a stress raiser or a stress riser) is a location in an object where the stress is significantly greater than the surrounding region. Stress concentrations occur when there are irregularities in the geometry or material of a structural component that cause an interruption to the flow of stress. This arises from such details as holes, grooves, notches and fillets. Stress concentrations may also occur from accidental damage such as nicks and scratches.
The degree of concentration of a discontinuity under typically tensile loads can be expressed as a non-dimensional stress concentration factor



{\displaystyle K_{t}}
, which is the ratio of the highest stress to the nominal far field stress. For a circular hole in an infinite plate,




{\displaystyle K_{t}=3}
. The stress concentration factor should not be confused with the stress intensity factor, which is used to define the effect of a crack on the stresses in the region around a crack tip.For ductile materials, large loads can cause localised plastic deformation or yielding that will typically occur first at a stress concentration allowing a redistribution of stress and enabling the component to continue to carry load. Brittle materials will typically fail at the stress concentration. However, repeated low level loading may cause a fatigue crack to initiate and slowly grow at a stress concentration leading to the failure of even ductile materials. Fatigue cracks always start at stress raisers, so removing such defects increases the fatigue strength.

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  1. Y

    Effects of notch's position along a rod that is in tension

    Say I have a rod with a notch at the very centre and another ro with a notch at the very end. Both rods are identical in length radius materials etc. Who would be impacted by the notch more? And if then both were to support a load at the end of the rod (both in tension), what effects would the...
  2. M

    Mechanical engineering - Stress concentration

    1. In my materials science's exam, I had the following question: What would be the maximum force F to cause failure in a block that has been drilled at two place? See following drawing: (Lame paint skills, I know..) 2. Homework Equations 1) D/W 2) σ = F/S The Attempt at a Solution 1)First...
  3. R

    Stress concentration factor and notch sensitivity in a shaft

    Homework Statement [/B] I can't seem to get the image links to work sorry! Also, I think the question is supposed to say 2.5mm radius notch, not 10mm https://imgur.com/Klxw4gG https://imgur.com/C9d81Rl https://imgur.com/7H421ou Homework Equations [/B] q = Ka - 1 / Kt - 1 M = Fd (σa / σ'e)...
  4. K

    A Fatigue stress concentration factor (Kf)

    Hi, I had been reading about the fatigue stress concentration factor (Kf) which is reduced compared to the geometric stress concentration factor (Kt). The reduction in turn dpends upon the material's sensitivity to notches...
  5. G

    Find Axial Force P: Stress Concentration Homework

    Homework Statement The stress distribution along the section of a bar is shown below. From this distribution, find the approximate axial force P in kip. Homework Equations δavg=P/A A= (.6+.6)(.5) δavg=30ksi[/B]The Attempt at a Solution P=(30ksi)(.6in2)=18kip It says this answer is wrong...
  6. T

    Machine elements stress concentration

    Homework Statement A flat part with constant thickness b is loaded in tension as shown. The height changes from 50 to 87 mm with a radius r = 4.0 mm. Find how much lower a load can be transmitted through the bar if the height increases from 50 to 100 mm and the radius increases from 4.0 to 10...
  7. K

    Understanding Stress Concentration Factor in FEA for Stepped Shafts

    Hi, I want to understand how stress concentration factor or notch factor is considered in FEA method. Lets assume a case of stepped shaft which has got the left end of the shaft fixed with rigid wall and the other end being pulled by an axial load. In the case of conventional calculation...
  8. S

    Shear Pin Stress Concentration V-Notch vs. U shape grooved in bending

    Can someone link a website or attach a picture of a chart distinguishing the differences between the stress risers in a shear pin (round circular shaft) with a V-notch groove versus if it was a rounded groove. I have been looking but can only find charts, tables and graphs for round circular...
  9. K

    Stress Concentration Calculation

    Hi everyone, I wanted to know the stress concentration factor (Kt) for a cantilever beam with a fillet at the root with a point load applied at the end. Can I get the stress concentration factor if this beam is a 3D beam (thickness is comparable to length)? I had a look at Peterson's SCF...
  10. E

    Short Beam Stress Concentration

    Hi there Are anyone familiar with tables of stress concentration factors, or the like for short beams for different span/depth ratios. My beam is technically not a beam, but I would still like to estimate maximum bending stresses related to normal stresses caused by bending moment (sigma =...
  11. L

    Maximum stress and stress concentration factor (SCF)

    Hi guys, have been struggling with this exercise, could anyone give any help? thank you so much!
  12. M

    Stress concentration factors for hollow shafts under pure bending

    Hi everone, I am trying to make a rough estimate of fatigue life of a hollow shaft under pure bending at a particular load level.The hollow shaft has a shoulder fillet. The minuimum outer diameter is 69mm and the maximum outer diameter is 72mm with a transition radius of 6mm.The thickness of the...
  13. U

    Stress concentration factor using combined static loads

    i want to design a machine which is capable of applying all three types of loads that is axial, bending and torsion. Using this application of static loads , I want to measure the stress concentration factor.
  14. R

    How to Combine Stress Concentrations for Multiple Keyways on a Shaft?

    Hello I have done a Soderberg shaft design calculation, taking into account the stress concentration for a keyway. However, I've just noticed that I might need to adapt this for a feather type keyseat, or 2 (parallel, 180deg apart) keyways in the same cross section. I'm sure I read...
  15. C

    Re-arrangement of Stress Concentration Calculation

    Hi i was wondering if anyone could help me by showing me how to re-arrange this equation: a=2b*(c\d)½ i need to make c the formula. Any help would be greatly appreciated. Chris
  16. E

    Solving an Ansys WB Stress Concentration Issue on Stiffener Tip

    Ansys WB, getting non-realistic stress conce. (stiffener tip on pipe column face)?? Hi, I am facing a problem in getting accurate stress in Ansys WB for stiffened base plate supporting pipe column (See attached pics) The problem is that I'm getting very high stress concentration at the tip...
  17. P

    Finding Stress Concentration Factor K for Chamfered Joints

    Hello, I have a rod of two different diameters and I'm trying to find the stress concentration at the chamfer between the two diameters. I understand how to find the stress concentration factor, K, if the joint was a fillet (using r/d and D/d to find K in the appropriate table). However I can't...
  18. R

    Solving Stress Concentration for Elliptical Hole in Square Panel

    Homework Statement Square panel , elliptical hole, uniform pressure p in x direction. calc stress at end of minor axis. pt A L=40in p=10psi a=1in b=0.5 in t=0.2 in Homework Equations i know that stress at end will be max stress multiplied by stress conc. factor. bt i don't know...
  19. C

    What is the purpose of a stress concentration factor?

    Hello, in a recent lecture on introductory engineering, our professor made reference to a stress concentration factor that pops up due to inconsistencies or changes in the shape of a material subject to a load. The introduction he gave referenced a method of stopping cracks by drilling a hole...
  20. Q_Goest

    Stress Concentration, Stepped Shaft

    Most texts have stress concentration factors for a stepped shaft in tension that has a radius where the smaller shaft meets the larger one such as this reference: http://www.pirate4x4.com/tech/billavista/PR-BV60/Materials/7.jpg I'm looking for a reference (perhaps "Peterson's Stress...
  21. A

    Stress Concentration around a circular hole on a flat rectangular plate

    Can anyone help with how to find the analytical solution to problem involving finding the stress concentration around a circular hole in a flat plate. The plate is has tensile load on both sides.
  22. T

    Stress concentration sensitivity definition

    what is the defination for the following:stress concentration sensitivity, fracture load cycle, notch size factor?? pls help thanx
  23. T

    Stress Concentration: Notch Radians & Formula

    does anybody knows what is and how to find notch radians??any formula??
  24. T

    Critical Section Location in Stepped Shaft Under Torque Load

    What are the cases for section 1 and 3?? this is a stress concentration factor of notched or fillet bars problem. From the picture,how can we choose whether it is t=tension,z=compression or b=bending?? http://files.filefront.com//;5410211;;/ and...