Abstract: A heating and cooling apparatus capable of cyclic heating and cooling of a test specimen undergoing fatigue testing. Cryogenic fluid is passed through a block 10 clamped to the specimen 11 to cool the block and the specimen. Heating cartridges 13 penetrate the block 10 to heat the block and the specimen 11 to very hot temperatures. Control apparatus 36 and 46 is provided to alternately activate the cooling and heating modes to effect cyclic heating and cooling between very hot and very cold temperatures. The block 10 is constructed of minimal mass to facilitate the rapid temperature change thereof.

Abstract: An indicator for recording the load at which a fatigue specimen breaks during the last cycle of a fatigue test. A load cell is attached to the specimen which is alternately subjected to tension and compression loads. The output of the load cell which is proportional to the load on the specimen is applied to the input of a peak detector. Each time that the specimen is subjected to a compression load, means are provided for appyling a positive voltage to the reset of the peak detector to reset it. Hence, during the last cycle of the tension load the peak detector measures the maximum load on the specimen. Means are also provided for disconnecting the load cell from the peak detector when there is a failure in the specimen.