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Reliability Evaluation
Published in Richard C. Fries, Handbook of Medical Device Design, 2019
The thermal shock test assures the device will withstand the stresses of alternate exposure to hot and cold temperatures. After the functional checkout, the device is turned OFF and placed in a thermal shock chamber with one chamber set at -20° Centigrade, the second chamber set at +55° Centigrade and the transition time between chambers set at less than five minutes. The minimum time spent at each temperature is one hour. The device should be cycled through a minimum of five cycles of temperature extremes. The unit is functionally tested after the temperature exposure.
Time, Temperature, and Environmental Effects on Properties
Published in David W. Richerson, William E. Lee, Modern Ceramic Engineering, 2018
David W. Richerson, William E. Lee
Thermal shock refers to the thermal stresses that occur in a component as a result of exposure to a temperature difference between the surface and interior or between various regions of the component. Thermal shock failure is often accompanied by a loud cracking noise. A good everyday example of this is when you add a room-temperature can of pop to a glass containing ice cubes, which crack loudly when thermally shocked by the warmer liquid. For shapes such as an infinite slab, a long cylinder (solid or hollow), and a sphere (solid or hollow), the peak stress typically occurs at the surface during cooling according to the equation
Influence of lithium carbonate and superplasticizer as admixtures on low calcium dialuminate cement castable submitted to thermal shock
Published in Journal of Asian Ceramic Societies, 2021
Arlin Bruno Tchamba, George Elambo Nkeng, Nangah Che Randy, Marcel Guidana, Ngouloure N M Zenabou, Yannick Tchedele Langollo, Daniel Ducho, Thomas A. Bier
Refractory concrete as structural material for high-temperature application has received significant attention during the last decade [4]. Ultra-high Performance Concrete (UHPC) requires an optimized granulometry for packing density, a very low water/cement ratio (below 0.25) and compressive strength higher than 150 MPa. During a rapid temperature change of a material, there occurs transient temperature distribution which induce thermal stress, resulting to thermal shock. The stress intensity is related to the difference in temperature between an ascending thermal shock and a descending one. The descending temperature is more destructive to brittle materials and tensile stress is generated on the surface. This circumstance may be sufficient to activate preexisting micro-cracks and to lead to body damage or fracture [8,9].