Verge escapement in mechanical clocks. In the sixteenth century alternative escapements started to appear, but the verge remained the most used escapement for 350 years until mid-17th century advances in mechanics, resulted in the adoption of the pendulum, and later the anchor escapement. Since clocks were valuable, after the invention of the pendulum many verge clocks were rebuilt to use this more accurate timekeeping technology, so very few of the early "verge and foliot" clocks have survived unaltered to the present day. How accurate the first verge and foliot clocks were is debatable, with estimates of one to two hours error per
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