Sistema de baixo custo para nuclea？？o de pré-trincas por fadiga em corpos de prova de tenacidade à fratura

fracture toughness testing becomes a very important parameter for mechanical design and maintenance of parts and structures. this work presents the design and construction of a machine device to perform the pre-crack nucleation on se(b) specimens for fracture toughness testing. employing this device, it is possible to test materials for kic, ctod and jic in a conventional tensile test equipment, assisted by a data acquisition system. the device is based on the concept of loading from an eccentric mechanism, controlling the displacement by means of a marking ring. the main contribution of this work is the low cost technology offered for laboratories, without high priced servo-hydraulic testing machines, giving them autonomy for the execution of fracture toughness tests. the experimental results satisfied the expectation about crack nucleation on se(b) and applied loading control.