Abstract
The instant distributions of plastic strain in carbon steel Sharpy Test Pieces during impact have been investigated using the photoelastic coating method and a high speed recording technique. Color photoelastic patterns in the coating film which relate to the difference of plastic principal strain ∈1-∈2 were satisfactorily taken at various stage of impact of the test pieces by a delay-Xenon-micro-flash system with a resolving power of about 2/1, 000, 000sec. The results obtained show that the plastic strain energy absorbed in the test piece is notably localized to and concentrated in the two regions of the contact point of the hammer and the bottom of the notch at which cracks usually originate. The test pieces used were made of 0.25% carbon steel and were shaped according to the Sharpy impact test piece with a U-notch-JIS No. 3.
