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

Reverse and direct circulation drill drilling in piling, Q. Reverse and dir...

Q. Reverse and direct circulation drill drilling in piling? For reverse circulation drilling and direct circulation drilling, major difference in drilling method is connected t

The regulations and specification that followed for compacti, what are The ...

what are The regulations and specification that followed for compaction works for earth dam in Oman.

Main dissimilarity among cement plaster and cement render, Question Wha...

Question What is main dissimilarity among cement plaster , cement render and cement screed ? Under what state each of above can be used? Answer Purpose of plaster

Elimination of formwork with reasons, Question For a l ong slender structur...

Question For a l ong slender structure similar to beams, propping is compulsory after elimination of formwork with reasons? Answer After concreting, time at which arresting of

Explain hot weather patrolling, Q. Explain Hot weather Patrolling ? Hot...

Q. Explain Hot weather Patrolling ? Hot weather Patrolling is done for LWR and CWR tracks when the rail temperature reaches td + 20 0 C and above and td + 14 0 C for Central

Structure, what is the different between axial force and shear force?

what is the different between axial force and shear force?

The covers of electrical machines are made of what materials, The covers of...

The covers of electrical machines are made of what materials ? Answer: It is made of  soft magnetic materials.

Determine the major and minor principal effective stresses, The stresses ac...

The stresses acting on the plane of maximum shearing stress by a given point in sand are as follows: total normal stress = 250 kN/m 2 ; pore-water pressure = 88.5 kN/ m 2 ; shearin

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