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

What is load carrying capacity of a pile, Q-  What are loads and forces ta...

Q-  What are loads and forces taken into account for designing a pile and what is load carrying capacity of a pile. Ans. For designing a pile the following loads and force ar

Pattern of load distribution of piles in such agreement, Question For a...

Question For a rigid pile cap with vertical piles at middle and raking piles at the sides, what is pattern of load distribution of piles in such agreement? Answer Becau

Demonstrate the economical design of concrete, Demonstrate the economical d...

Demonstrate the economical design of concrete A safe, serviceable and economical design of concrete structures requires a comprehensive knowledge of the loads expected to be a

Basic things used in road construction, Basic things used in road construct...

Basic things used in road construction: Water Absorption : The quantity of water absorbed by aggregates. Aggregate Impact Value : The percentage by weight of crushed ma

Environmental Question, An activated sludge tank treats 1 MGD from the pri...

An activated sludge tank treats 1 MGD from the primary clarify and has an X of 2200 ppm SS. The water euent is 0.9 MGD. 1.0 MGD of the sludge is recycled back into the tank and has

Statics, Applications of statics

Applications of statics

Advantages of unbonded post-tensioning systems, Advantages of unbonded post...

Advantages of unbonded post-tensioning systems Similarly, some advantages of unbonded post-tensioning systems over bonded post-tensioning ones may be written as under :  (a)

Define limitations of radiography - inspection of bridge, Define Limitation...

Define Limitations of Radiography - Underwater Inspection of Bridge? i. Radiography is a costly and time consuming method, which re- quires extensive safety measures to be adop

Traffic surveys, Traffic Surveys: The following traffic surveys are n...

Traffic Surveys: The following traffic surveys are needed for preparing a good road project: Classified Volume Counts This survey is normally carried out for 7 days,

#title.Mr., What are the Desirable Characteristics of a Pavement in highway...

What are the Desirable Characteristics of a Pavement in highway engineering

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