Define fatigue - materials, Civil Engineering

Assignment Help:

Define Fatigue - Materials

The normative view of the stress/strain is found in the example of the paper clip wire experiment. Take a paper clip wire and try to break it by pulling on it by hand. You are unable to break it because you need to exceed the ultimate stress of the material. Bend a paper clip between your fingers and the following is observed: when the wire rebounds to its original shape the proportional/elastic limit is observed; bend it farther to a point where the wire is permanently deformed, the yield point is observed; and, when the wire is bent one way then the other a few times, the wire breaks easily. The phenomenon is known as fatigue.

1968_Define fatigue - materials.png

All materials have microcracks. The cracks are not critical and are averaged as ultimate strength for the bulk material in a tension test. However, when the material is subjected to cyclic loading, the microcracks can grow until some of the cracks reach critical length, at which time the material breaks. The stress value at cyclic loading is significantly lower than ultimate stress of the material. Failure due to cyclic loading at stress levels significantly lower than the static ultimate stress is called fatigue. All engineered systems account for fatigue failure. At low levels of stress the failure may occur at millions or billions of cycles. Endurance tests determine the cyclic loadings and fatigue strength.

 


Related Discussions:- Define fatigue - materials

Lorentz transfarmation, explain the concept of time dilation on the basis ...

explain the concept of time dilation on the basis of lorentz transfarmation equations

Torsion, what is torsional moment of resistance

what is torsional moment of resistance

Use Structural Analysis in Engineering, As per Australian Standard AS 1170,...

As per Australian Standard AS 1170, what are the different types of loads that can be encountered by structures which need to be taken into account for their design?

Doors, About Doors,windows&vendilators

About Doors,windows&vendilators

Wooden truss, which truss is suitable for 19*22m span on which mangalore ti...

which truss is suitable for 19*22m span on which mangalore tiles can be placed or shud steel truss be preferred for such span and which 1 is more profitable in rural desiggn...

Show elastomeric bearings, 1. Elastomeric bearings must not be placed one b...

1. Elastomeric bearings must not be placed one behind the other along the longitudinal axis of the girder on a single line of support under any circumstances. 2. Bearings of dif

Define the frame column analysis, Define the Frame Column Analysis 1. B...

Define the Frame Column Analysis 1. Based on if a column section is a braced frame or unbraced frame. 2. Braced frame-indicates buckling mode shape does not involve tr

Retaioning walls, what are the uses of retaining wall?!

what are the uses of retaining wall?!

Major dissimilarity between standpipe, Question What is major dissimila...

Question What is major dissimilarity between standpipe, standpipe piezometer and piezometer ? Answer Standpipe usually contains plastic pipes with punctured holes at

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd