The Charpy impact test is one test that measures the resistance of a material to fracture....

The Charpy impact test is one test that measures the resistance of a material to fracture. In this test, the fracture toughness is assessed by measuring the energy required to break a specimen of a given geometry. This is done by releasing a heavy pendulum from rest at an angle θi, and then measuring the maximum swing angle θf reached by the pendulum after the specimen is broken.

Figure P8.28

Consider a test rig in which the striker S (the pendulum’s bob) can be modeled as a uniform disk of mass mS = 19.5 kg and radius rS = 150 mm, and the arm can be modeled as a thin rod of mass mA = 2.5 kg and length LA = 0.8 m. Neglecting friction and noting that the striker and the arm are rigidly connected, determine the fracture energy (i.e., the kinetic energy lost in breaking the specimen) in an experiment where θi = 158° and θf = 43°.