Abstract
This paper aims to investigate experimentally the impact resistance of a cutter bit of the shield tunneling excavation machine. As a metal specimen and a falling weight impact blade, different kinds of hard metal of sintered alloy, two kinds of carbon steel and a cored steel were prepared. Thereafter, several impact tests were executed by use of a new falling weight test method. The critical impact values when the metal specimens are broken at fracture probability 99% in Weibull's distribution of impact fracture stress have been measured. As a result, it is clarified that, for hard metal, the critical impact bending resistance is increased with the increment of the flexural strength and with the decrement of the hardness, the critical impact shear resistance is almost constant for all hard metals, and the critical impact bending resistance becomes almost six times of the critical impact shear resistance.
