Thermal cycling is the repeated heating and cooling of a material or component. Temperature changes cause materials to expand and contract; when different parts respond at different rates, stress can build at joints, seals, and interfaces. Over time, this may cause fatigue, cracking, loosening, or leaks.
In cyber security, thermal cycling matters when assessing the physical reliability of equipment and infrastructure, including servers, sensors, and industrial systems. In a heat-driven refrigerator, for example, repeated temperature changes can challenge pressure-bearing parts and seals that must keep working fluids contained. Defenses include selecting materials rated for operating temperatures, designing for expansion, and testing components over repeated cycles while checking for leaks or damage.