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

Timber design, design of timber in flexural members in terms of extreme fib...

design of timber in flexural members in terms of extreme fibre stress in bending, maximum horizontal shear stress, deflection and bearing stress perpendicular to the grain. the ful

Sucker deck principle for changeable depth bridge decks, Question What is t...

Question What is the sucker deck principle for changeable depth bridge decks ? Answer For a variable depth bridge deck, depth of continuous multi-span bridge deck is greate

Pcc, Specific Gravity & Water Absorption of Fine Aggregate

Specific Gravity & Water Absorption of Fine Aggregate

1, which Subject that wants civil engineers?

which Subject that wants civil engineers?

Define underwater inspection methods - inspection of bridge, Define Underwa...

Define Underwater inspection methods - inspection of bridge? Method for underwater inspection of a bridge depends on type and extent of damage expected, inspection intensity le

Rb slab, #questionshow me picture..

#questionshow me picture..

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