Fig. 4
Charpy impact test especially developed for breaking energy measurements. a Principle of the Charpy impact test: starting from the horizontal position, the pendulum sways, breaks the wood beam and continues its movement. The difference in height between the initial and final positions indicates the total loss of energy ΔE that is dissipated (fracture energy of the sample + friction). m is the mass at the extremity of the pendulum, L is the length of the pendulum and g is the gravitational acceleration. The positions of the pendulum are continuously recorded by an angle position sensor that makes it possible to determine the corresponding heights (hinitial, hfinal, Δh). b Large view and details of the device