Define the following and give examples in your answer:i. Fatigue failureii. Creep

i. Fatigue Failure: Fatigue failure is a type of failure that occurs in materials after repeated loading and unloading. It is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. The nominal maximum stress values are less than the material's ultimate tensile stress limit, and as such, the failure occurs due to the stress being applied repeatedly over time.

For example, consider a metal rod that is repeatedly bent back and forth. Even though the force applied each time may not be enough to break the rod, over time, small cracks can begin to form at the stress points. These cracks grow with each bend until the rod eventually breaks. This is an example of fatigue failure.

ii. Creep: Creep, in materials science, is the tendency of a solid material to move slowly or deform permanently under the influence of persistent mechanical stresses. It occurs as a result of long term exposure to high levels of stress that are still below the yield or ultimate strength of the material.

For example, consider a metal beam supporting a heavy load. Over time, the beam may begin to bend under the weight. This bending is not due to an immediate failure of the material, but rather a slow deformation over time. This is an example of creep.