Hi SW, I have no particular customer requirement. I just want to find out how my composite material performance under thermal shock condition. I was thinking of plunging the test samples into a chamber set at, say -50C, leave for 5-10 minutes and move them to hot chamber, say 100C, leave for 5-10 minutes and back to -50C and repeating the cycles number of times. These would mean a quite severe heating/cooling rate. Is there a recommended rate of cooling/heating??
One of the most severe tests is dipping in liquid nitrogen. It survives that it will likely pass any test.
The test should be somewhat more severe than the worst case expected exposure to be realistic. There are different thermo-cycles used in different industries. I'm not aware of any standard cycle in aerospace.
Just as important as the cycle is the lay-up of the laminate. Thick plies are far more likely to micro-crack than thinner ones. If I recall, a common lay-up is a 0-90 symmetric, with each ply made from three layers of prepreg, so you have six layers together in the center.