Mechanical Theory
An analytical discipline investigates the initiation and propagation of cracks at the scale of microns within crystalline or polycrystalline materials. Application of micro fracture mechanics allows engineers to predict the lifespan of brittle components like silicon beams or ceramic thin films. It focuses on the energy required to create new surfaces at a crack tip.
Stress Intensity
Localized defects or surface roughness act as nodes where the applied load is concentrated. Within the domain of micro fracture mechanics, the stress intensity factor defines the state of the material near the crack front. Testing involves the use of nano-indentation or micro-cantilever bending to observe the growth of a notch.
These trials are conducted inside an electron microscope to provide real-time visualization of the atomic bond breaking. Precision in these measurements is required because even a sub-micron flaw can lead to catastrophic failure in a high-stress environment.
Grain Boundary
Discontinuities in the crystal lattice hinder or accelerate the movement of a crack depending on their orientation.
Fatigue Life
Cyclic loading causes the gradual degradation of the material even when the stress is below the yield point. Designers use micro fracture mechanics to set the safety margins for resonators that vibrate billions of times during their service life.
