What is mechanism of fatigue failure?
Fatigue is a failure mechanism that involves the cracking of materials and structural components due to cyclic (or fluctuating) stress. While applied stresses may be tensile, compressive or torsional, crack initiation and propagation are due to the tensile component.
What are the three stages of fatigue failure?
Therefore, it can be said that fatigue failure occurs in three stages – crack initiation; slow, stable crack growth; and rapid fracture.
What does fatigue failure look like?
Fatigue failure occurs based on crack formation and crack propagation. As a crack initiates, it may be hard to notice much change until the crack size reaches a critical limit. A quick analysis of the fracture surface of a fatigue failure will often show features casually referred to as “beach marks”.
Where does fatigue failure occur?
Fatigue failure is when the surface of a material begins to crack or fracture, causing the part to weaken. Typically, the first stage of fatigue failure is crack initiation. Crack initiation occurs once applied stress exceeds tensile strength. The next stage that occurs is crack growth.
What is meant by fatigue failure?
Fatigue failure is the formation and propagation of cracks due to a repetitive or cyclic load. Most fatigue failures are caused by cyclic loads significantly below the loads that would result in yielding of the material. Fatigue cracks can also propagate from existing macroscopic cracks, such as weld defects.
What are the factors that influence fatigue failure?
Fatigue life is influenced by a variety of factors, such as temperature, surface finish, metallurgical microstructure, presence of oxidizing or inert chemicals, residual stresses, scuffing contact (fretting), etc.
What is fatigue failure material?
Fatigue failure is the formation and propagation of cracks due to a repetitive or cyclic load. Most fatigue failures are caused by cyclic loads significantly below the loads that would result in yielding of the material.
What are the main features of the fatigue fracture surface?
The fracture surface presents a characteristic appearance, with the progression marks (sometimes called beach marks) visible with an unaided eye most of the time. The second stage cracks can cover most of the fracture surface, even if not taking most of the load cycles.
What is the nature of fatigue fracture?
Fatigue fracture is the result of repetitive cyclic short-time stress or tensile stress, or deformation well below the tensile or flexural strength of the material (78). Fatigue is thus an important and complex phenomenon as it accounts for 80% of all structural failures (79).
How do you control fatigue failure?
Premature fatigue failure is prevented by careful attention to detail at the design stage to ensure that cyclic stresses are sufficiently low to achieve the required endurance. Stress concentrations should be avoided where possible; a design with smooth ‘flowing’ lines is usually the optimum.
What causes fatigue in material?
Material fatigue is a phenomenon where structures fail when subjected to a cyclic load. This type of structural damage occurs even when the experienced stress range is far below the static material strength. Fatigue is the most common source behind failures of mechanical structures.