Research On The Dynamic Fracture Characteristics Of 40Cr And 30CrMnSiNi2A Material Under High Strain Rate

With the fast development of industry, more and more metallic materials are being used in the fields of aviation, spaceflight, ship, transportation and national defence. Generally speaking, these materials undergo load of impact inevitably in their service period. And there are always flaws and small cracks in metallic materials. The fracture characteristics of materials under a dynamic load are much different from those under a static load, and the fracture toughness is relied on the loading rate or strain rate. Therefore, it is of great importance to uncover and research the fracture characteristics of metallic materials under high strain rate for ensuring the safety of metallic structures in their service period.In this paper, the fracture characteristics of two common high strength metallic materials, 40Cr and 30CrMnSiNi2A, under the stain rate of 2000(1/s) are studied with Experiment-Numerical method and self-designed project. Kâ… d and Kâ…¡ of them are obtained.The work done in this paper includes the following contents:1. Finite element analysis of the two materials under high strain rate Mode I, Mode II and mixed-mode load is completed. Different kinds of specimens and the test project are designed according to the results above.2. The two materials are tested under static tension load, from which the Yang's module and the yield stress are obtained. The two materials are also tested under dynamic compress load, and the yield stresses under the strain rate of 2000 1/s are measured.3. Dynamic fracture tests of the two materials are done under three kind of load modes, which are dynamic fracture test Mode I with Hopkinson pressure bar, dynamic fracture test Mode â…¡ with Hopkinson pressure bar and dynamic fracture test Mode I with Hopkinson tension bar. The finite element analysis of the 40Cr material under the two kind of load modes mentioned above and the 30CrMnSiNi2A material under the first are completed and Kâ… d and Kâ…¡d of the two materials under different test modes are obtained.4. The dynamic fracture toughnesses obtained from different test modes of each material are compared. The dynamic fracture toughnesses of the two materials got from the same test mode are also compared.