Relationship between strain rate concentration factor and stress concentration factor

• Published in: Theoretical and applied fracture mechanics Vol. 90; pp. 218 - 227
• Main Authors: Noda, Nao-Aki, Shen, Yunong, Takaki, Rei, Akagi, Daichi, Ikeda, Tomohiro, Sano, Yoshikazu, Takase, Yasushi
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.08.2017; Elsevier BV
• Subjects: High speed; High speed tensile test; Impact strength; Impact tests; Notch fracture; Strain concentration; Strain rate; Strain rate concentration factor; Stress concentration; Stress concentration factor; Tensile strength; Stress concentration factor; Strain rate concentration factor; Impact strength; Notch fracture; High speed tensile test
• ISSN: 0167-8442; 1872-7638
• DOI: 10.1016/j.tafmec.2017.05.017

•The strain rate concentration is considered for high speed tensile test.•Izod and Charpy tests do not coincide with the real failure of real products.•The influences of notch geometry and specimen length is studied.•The strain rate concentration factor remains the same in similar specimen geometries.•The strain concentration factor can be estimated from stress concentration factor. In this study, the strain rate concentration is considered for high speed tensile test, which is now being recognized as a standard testing method. To evaluate the impact strength of engineering materials under high impact speed, Izod and Charpy tests are unsuitable since they cannot control the impact speeds and therefore do not coincide with the real failure of real products. For smooth specimens, the strain rate can be determined from the tensile speed u/t and specimen length l as ε̇smooth=u/tl. For notched specimens, however, the strain rate at the notch root ε̇notch should be analyzed accurately. In this study, therefore, the strain rate concentration factor defined as Ktε̇=ε̇notch/ε̇smooth is studied with varying the notch geometry and specimen length. It is found that the strain concentration factor Ktε̇ can be estimated from stress concentration factor Kt∗.