Thermal shock is a type of rapidly transient mechanical load. By definition, it is a mechanical load caused by a rapid change of temperature of a certain point. It can be also extended to the case of a thermal gradient, which makes different parts of an object expand by different amounts. This differential expansion can be more directly understood in terms of strain, than in terms of stress, as it is shown in the following. At some point, this stress can exceed the tensile strength of the material, causing a crack to form. If nothing stops this crack from propagating through the material, it will cause the object's structure to fail.
- Reducing the thermal gradient seen by the object, by changing its temperature more slowly or increasing the material's thermal conductivity
- Reducing the material's coefficient of thermal expansion
- Increasing its strength
- Introducing built-in compressive stress, as for example in tempered glass
- Decreasing its Young's modulus
- Increasing its toughness, by crack tip blunting (i.e., plasticity or phase transformation) or crack deflection