Escapement escapement was used for a washstand design in ancient Greece and the Hellenistic world, particularly Ptolemaic Egypt, while liquid-driven escapements were applied to clockworks beginning in Tang dynasty China and culminating during the Song dynasty. However, the fully mechanical escapement in mechanical clocks was first invented in medieval Europe during the 14th century. The importance of the escapement in the history of technology is that it was the key invention that made the all-mechanical clock possible. The invention of the first all-mechanical escapement, the verge escapement, in 13th-century Europe initiated a change in timekeeping methods from continuous processes, such as
Strain energy release rate a straight path, the mode I stress intensity factor (formula_10) is related to the energy release rate (formula_5) by where formula_13 is the Young's modulus and formula_14 for plane stress (as in a thin tensed elastic sheet) and formula_15 for plane strain (as in a thick elastic slab). Therefore, the energy release rate failure criterion may also be expressed as where formula_17 is the mode I fracture toughness. Strain energy release rate The strain energy release rate (or simply energy release rate) is the energy dissipated during fracture per unit of newly created fracture surface area. This quantity is central