Plasticity and Fracture Behaviors of Marine Structural Steel, Part I: Theoretical Backgrounds of Strain Hardening and Rate Hardening

doi:2011.25.2.134

J. Ocean Eng. Technol. > Volume 25(2); 2011 > Article

J. Ocean Eng. Technol. 2011;25(2):134-144.
DOI: https://doi.org/10.5574/KSOE.2011.25.2.134

Choung Joon-Mo,Shim Chun-Sik,Kim Kyung-Su

Dep't of Naval Architecture and Ocean Engineering Inha University,Dep't of Naval Architecture and Marine Engineering Mokpo National University,Dep't of Naval Architecture and Ocean Engineering Inha University

조선 해양 구조물용 강재의 소성 및 파단 특성 I: 변형률 경화 및 변형률 속도 경화의 이론적 배경

정준모,심천식,김경수

인하대학교 조선해양공학과,국립목포대학교 조선공학과,인하대학교 조선해양공학과

Keywords: Plasticity, Strain hardening, Strain rate hardening, Fracture, True stress

핵심용어: 소성, 변형률 경화, 변형률 속도 경화, 파단, 진응력

Abstract

In this paper, the global study trends for material behaviors are investigated regarding the static and dynamic hardenings and final fractures of marine structural steels. In particular, after reviewing all of the papers published at the 4th and 5th ICCGS (International Conference on Collision and Grounding of Ship), the used hardening and fracture properties are summarized, explicitly presenting the material properties. Although some studies have attempted to employ new plasticity and fracture models, it is obvious that most still employed an ideal hardening rule such as perfect plastic or linear hardening and a simple shear fracture criterion with an assumed value of failure strain. HSE (2001) presented pioneering study results regarding the temperature dependency of material strain hardening at various levels of temperature, but did not show strain rate hardening at intermediate or high strain rate ranges. Nemat-Nasser and Guo (2003) carried out fully coupled tests for DH-36 steel: strain hardening, strain rate hardening, and temperature hardening and softening at multiple steps of strain rates and temperatures. The main goal of this paper is to provide the theoretical backgroundfor strain and strain rate hardening. In addition, it presents the procedure and methodology needed to derive the material constants for the static hardening constitutive equations of Ludwik, Hollomon, Swift, and Ramberg-Osgood and for the dynamic hardening constitutive equations of power from Cowper-Symonds and Johnson-Cook.