08 Material Failure and Durability Free Online FlashCards

What is fracture?

Fracture is the separation of a material into pieces.

What is fatigue failure?

Fatigue is damage caused by repeated or fluctuating loading. Cracks can grow over many cycles, even when peak stress is below yield strength.

What is creep?

Creep is time-dependent deformation under sustained stress. It is especially important at elevated temperatures, though polymers can creep at ordinary service temperatures.

How does abrasive wear occur?

Abrasive wear occurs when hard particles or rough asperities cut or plow a surface.

What is galvanic corrosion, and how can it be prevented?

Galvanic corrosion can occur between dissimilar metals. Electrical isolation of those metals is one prevention measure.

How does a failure mode differ from a failure cause?

A failure mode describes what happened, such as fracture; a cause explains why it happened, such as cyclic overload, an unsuitable environment, or a defect.

How do ductile and brittle fracture differ?

Ductile fracture often involves substantial plastic deformation before separation; brittle fracture can propagate with little visible deformation.

What does fracture toughness measure?

Fracture toughness is a material’s ability to resist crack growth.

What is corrosion fatigue?

Corrosion can accelerate fatigue damage; this combined mechanism is called corrosion fatigue.

Why is static strength alone insufficient to establish fatigue life?

A single static-strength value does not establish fatigue life. Designers use cyclic-load data and account for the service environment.

What are the three typical stages of a creep curve?

A typical creep curve progresses from a decreasing creep rate to a near-steady rate, then to accelerating deformation that may end in rupture.

How does adhesive wear occur?

Adhesive wear involves local bonding and shearing between contacting surfaces, transferring or detaching material.