Question

Write a literature review on

• the catastrophic effect of failure and fatigue on structure

Dont just copy paste from net please

Answer 1

Structural failure can be defined as the process in which a structural fail to fulfil the desired purpose for desired amount of period, for which it was constructed. Failures in structure can be because of many reasons like:

1. Technical defects
2. Construction defects

Technical defects are the defects which arises due to defective design and analysis process like underestimation of actual loading condition that the structure will encountered in its designed life period.

Major form of structure failures are as follows:

1. Shear failures:Shear failure in a structure basically occurs when the structure lacks the sufficient thickness for the induced force.
2. Flexural failures:Flexural failures occur when the structure fails due to induced bending. The section modulus structure is not sufficient enough to hold against the induced load.
3. Buckling failures: Buckling failures mostly occurs in vertical and diagonal members of the structures. Failures generally occurs in the members having high slenderness ratio when the buckling force exceeds the critical buckling force that a member can bear.
4. Tensile failures: Tensile failure occurs when the structure is subjected to the excessive tensile force and the member strength is not sufficient enough to resist the induced tensile force. “Necking” of structure occurs where the structural cross section decreases continuously and member fails after yielding.
5. Corrosive failures: Structural fails due continuous decrement in thickness due to excessive corrosive environment.
6. Fatigue failures: Fatigue failures occurs due to action of small amount of forces acting for large number of cycle.

Fatigue failures in structure are initiated in four different stages:

1. Crack initiation at the stress concentration points
2. Crack growth at the stress concentration points
3. Crack propagation after the crack growth
4. Final rupture

Fatigue failures are of two types:

1. HCF (High cycle fatigue): This mode of fatigue failure occurs when large amount of cycle (millions) are required to reach the threshold or predefined failure criterion (rupture).
2. LCF (Low cycle fatigue): This mode of fatigue failure requires smaller amount (thousand) of cycle to reach the threshold or predefined failure criterion (rupture).

The above-mentioned mode of failures can cause catastrophic damage to both human beings and wealth management associated with it. The most famous example of fatigue failure is airline crash of De Havilland Comet in 1954.

Construction defects:

Construction defect are mainly caused due to following effects:

1. Poor communication among various professionals involved in the supervision and execution of works like fabricator and erectors.
2. Bad workmanship and untrained professional
3. Unethical professionalship or usage of degraded material during fabrication or construction.