In materials science, fracture toughness is a property which describes the ability of a material containing a crack to resist fracture, and is one of the most important properties of any material for many design applications. The linear-elastic fracture toughness of a material is determined from the stress intensity factor at which a thin crack in the material begins to grow. It is denoted KIc and has the units of or . Plastic-elastic fracture toughness is denoted by JIc, with the unit of J/cm2 or lbf-in/in2, and is a measurement of the energy required to grow a thin crack.
The subscript Ic denotes mode I crack opening under a normal tensile stress perpendicular to the crack, since the material can be made deep enough to stand shear (mode II) or tear (mode III).
Fracture toughness is a quantitative way of expressing a material's resistance to brittle fracture when a crack is present. If a material has much fracture toughness it will probably undergo ductile fracture. Brittle fracture is very characteristic of materials with less fracture toughness.
Fracture mechanics, which leads to the concept of fracture toughness, was broadly based on the work of A. A. Griffith who, among other things, studied the behavior of cracks in brittle materials.
A related concept is the work of fracture which is directly proportional to, where is the Young's modulus of the material. Note that, in SI units, is given in J/m2.
Read more about Fracture Toughness: Example Values, Crack Growth As A Stability Problem, Transformation Toughening, Conjoint Action, Stress-corrosion Cracking (SCC)
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