The investigation on dynamic fracture behavour of materials under compressive-shear combined stress waves |
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Authors: | Ma Wei Duan Zhuping |
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Institution: | (1) LNM, Institute of Mechanics, CAS, 100080 Beijing, China |
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Abstract: | In this paper, an improved plate impact experimental technique is presented for studying dynamic fracture mechanism of materials,
under the conditions that the impacting loading is provided by a single pulse and the loading time is in the sub-microsecond
range. The impacting tests are carried out on the pressure-shear gas gun. The loading rate achieved is dK/dt∼108 MPa m1/2s−1. With the elimination of influence of the specimen boundary, the plane strain state of a semi-infinite crack in an infinite
elastic plate is used to simulate the deformation fields of crack tip. The single pulses are obtained by using the “momentum
trap” technique. Therefore, the one-time actions of the single pulse are achieved by eradicating the stress waves reflected
from the specimen boundary or diffracted from the crack surfaces. In the current study, some important phenomena have been
observed. The special loading of the single pulse can bring about material damage around crack tip, and affect the material
behavior, such as kinking and branching of the crack propagation. Failure mode transitions from mode I to mode II crack are
observed under asymmetrical impact conditions. The mechanisms of the dynamic crack propagation are consistent with the damage
failure model.
The project supported by the National Natural Science Foundation of China (No. 19672066 and 18981180-4) and the Key Project
of Chinese Academy of Sciences (No. KJ951-1-20) |
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Keywords: | single pulse compressive-shear combined stress wave pressureshear gas gun |
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