Dynamics of the process of the impact testing of specimens in concentrated bending. Report 1

1.	The flexibility of the contact-zone/block system is determined experimentally from impact tests. In the case when high loading rates are used and massive specimens are tested, plastic deformations develop in the contact zone; this leads to effective values on the low side.
2.	The duration and total amplitude of the resultant KI-t and P-t curves for supportfree tests are determined primarily by the flexibility of the specimen, while their character (the number of peaks, and their amplitude) is determined by the ratios of the flexibilities of specimen and block.
3.	A method of calculating KI for a support-free impact loading is theoretically substantiated and experimentally confirmed.
4.	During the impact testing of specimens on supports, separation of the specimen from the supports occurs at the initial time, i.e., these tests are actually support-free at the initial time. The moment of repeated contact between the specimen and the supports of the impact-testing machine corresponds approximately to time required for the force to reach the local minium.

Institute of Strength Problems, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Problemy Prochnosti, No. 5, pp. 25–29, May, 1989.