3. Sheep-pendulum shock tests

3.1 The benefits of sheep-pendulum shock testing

Instinctively, to break a piece of metal, we hit it with a hammer. This intuitive action is well justified, as the high-speed deformation caused by impact increases yield strength and, correlatively, resistance to plastic instability, deformation at fracture, and a reduction in cleavage stress for cubic-centered or hexagonal metals. Impact loading therefore increases brittleness. At the end of the 19th century, in response to steam boiler blowouts, engineers set out to develop impact fracture tests. When a mass falls from a given height, a calibrated shock is exerted on a test specimen, but when this produces failure, no indication is given of the energy consumed. Comparative tests are then required, for example at different temperatures....