Temperature Effects

Temperature Effects Mechanical characteristics of most materials are greatly influenced by the operating temperature. Stress-strain diagrams are obtained at specific temperatures. High temperature reduces material stiffness and strength, while low temperature increases material stiffness and strength. Almost all materials creep over time if exposed to elevated temperatures under applied load. At "low" temperatures, ductile materials behave like brittle materials, whereas at "high" temperatures, brittle materials behave more like ductile materials.

Historical Perspective:

Although at low temperatures the strength and stiffness of most materials increase, they tend to shrink in size and become rather brittle. This was the root cause of the O-ring failure on one of the space shuttle solid rocket boosters during the launch of Challenger on January 28, 1986. The low temperature (36 °F) that morning caused the O-ring material to contract. When the solid rocket boosters ignited, an O-ring in the right SRB did not expand to prevent the seepage of hot gases. This resulted in a hot gas plume from the failed joint, which impinged directly on the External Tank, burning through it, eventually causing structural failure and ignition of the External Tank's hydrogen and oxygen. This was responsible for the explosion which destroyed the Challenger. Corrective measures were taken after the investigation of the accident to change the design of the O-ring seals to one which is not as sensitive to temperature, as well as new launch procedures to ensure greater safety.