Engineering topics
Publications and source records attributed to Gardner, M. R..
Portable ultrasonic scanner moves transducer at constant pressure. Spring-loaded holder moves ultrasonic transducer over test sample at constant pressure. Setup used to determine rate of debond taking place in glued materials subjected to fatigue loading. Holder designed as portable field unit adapted to fatigue machine that transmits data while specimen tested.
A heating and cooling apparatus capable of cyclic heating and cooling of a test specimen undergoing fatigue testing is discussed. Cryogenic fluid is passed through a block clamped to the speciment to cool the block and the specimen. Heating cartridges penetrate the block to heat the block and the specimen to very hot temperaures. Control apparatus is provided to alternatively activate the cooling and heating modes to effect cyclic heating and cooling between very hot and very cold temperatures. The block is constructed of minimal mass to facilitate the rapid temperature changes.
Identical blocks of aluminum, held against front and back of specimen, each contain electrical heaters, liquid nitrogen cavity with input and exhaust tubes, and thermocouple. Thermocouples are connected to control unit, which adjusts specimen temperature during fatigue tests over range of 850 degrees F.
Critical degenerateness in large linear systems represented by coefficient matrices of differential equations