Basic Fatigue & S-N Diagrams Video Lecture | Design of Machine Elements - Mechanical Engineering

Ans. Fatigue in mechanical engineering refers to the phenomenon of structural failure that occurs when a material is subjected to repeated loading and unloading, leading to the weakening and eventual fracture of the material. It is a common concern in engineering design, as it can significantly reduce the lifespan and reliability of components or structures.

Ans. Fatigue failure is different from other types of failures, such as static or impact failure, because it occurs over a period of time under cyclic loading. Unlike static failure, which is caused by a single high-stress event, fatigue failure is the result of repeated stress cycles that lead to the accumulation of damage and eventual failure. It is often characterized by a gradual propagation of cracks, which can be difficult to detect.

Ans. An S-N diagram, also known as a stress-life diagram or fatigue curve, is a graphical representation of the relationship between the applied stress amplitude (S) and the number of cycles to failure (N) of a material. The S-N diagram helps engineers understand the fatigue behavior of a material by providing information on its endurance limit, fatigue strength, and the number of stress cycles it can withstand before failure.

Ans. An S-N diagram is useful in mechanical design as it allows engineers to assess the fatigue strength and durability of materials under cyclic loading conditions. By analyzing the S-N diagram, engineers can determine the safe operating stress levels for a given number of stress cycles, which helps in designing components and structures with sufficient fatigue life. The S-N diagram also aids in material selection, as it provides a basis for comparing the fatigue performance of different materials.

Ans. Fatigue failure can be prevented in mechanical engineering by employing various design and engineering practices. Some preventive measures include: - Conducting thorough fatigue analysis during the design phase to identify potential high-stress areas and determine appropriate material selection. - Implementing proper surface treatments, such as shot peening or nitriding, to improve the material's fatigue resistance. - Incorporating design features like fillets and smooth transitions to reduce stress concentration and promote stress distribution. - Regularly inspecting and maintaining components to detect and repair any cracks or damage before they propagate further. - Applying load control techniques, such as load balancing or stress relief, to minimize cyclic loading and prevent excessive stress accumulation.