Griffith criterion

The Griffith criterion explains how and when a crack in a material will grow. It states that a crack will expand if the energy released from the stress around it exceeds the energy needed to create new surfaces as the crack splits further. Essentially, it's a balance between the stored elastic energy that can drive crack growth and the energy required to form new crack surfaces. When the conditions favor crack extension, the crack propagates, leading to potential failure of the material. This helps engineers predict failure and design more durable materials.