La fatiga de los materiales - Concepto- Grupo GIE

Understanding Material Fatigue

What is Material Fatigue?

• Material fatigue occurs when a piece is subjected to repeated cycles of loading and unloading over time. This phenomenon is more common than one might think, as seen in everyday actions like opening car doors or refrigerator doors.

Mechanism of Fatigue

• Each cycle of load and unload creates small fissures in the material at specific points, which grow with each subsequent loading cycle. The greater the applied load, the fewer cycles the material can withstand before failure.

Impact of Load on Lifespan

• The concept of treating materials carefully to prolong their lifespan is closely related to fatigue. Reducing the load applied to materials can significantly increase their fatigue life.

Fatigue Curve Analysis

• One commonly used tool in studying fatigue is the fatigue curve, which plots applied load against the number of cycles a piece can endure. For example, under a certain load, a piece may withstand 1,000 cycles; reducing that load by half could allow it to endure up to 1 million cycles.

• This relationship between applied load and cycle endurance is not linear but exponential. A slight reduction in load can lead to a substantial increase in fatigue life.

Failure Process Due to Fatigue

• When loads are sufficiently high, micro-cracks form within the material. These cracks grow faster with higher loads and slower with lower loads. As these cracks develop, they leave behind marks known as "fatigue beaches," resembling water marks on sand at a beach—indicative of ongoing damage within the material.