A unified energy release rate based model to determine the fracture toughness of ductile metals from unnotched specimens. (January 2019)

• Record Type: Journal Article
• Authors: Zhang, Tairui; Wang, Shang; Wang, Weiqiang
• Is Part Of: International journal of mechanical sciences. Volume 150(2019)
• Page Start: 35
• Page End: 50
• Publication Date: 2019-01
• Subjects: Damage mechanism -- Mode I/II loading -- Unnotched specimens -- Fracture toughness -- Energy release rate; Mechanical engineering -- Periodicals; Génie mécanique -- Périodiques; Mechanical engineering; Maschinenbau; Mechanik; Zeitschrift; Periodicals; 621.05
• DOI: 10.1016/j.ijmecsci.2018.10.022
• Languages: English
• ISSNs: 0020-7403

Abstract

Highlights: The similarities and differences of fracture (damage) mechanisms for notched and unnotched specimens were investigated through stress triaxiality analysis and SEM observations. An energy release rate based model that takes the damage mechanism into consideration was proposed in this study in order to calculate fracture toughness from different unnotched specimen configurations. Experiments on four metals revealed that the new proposed model can provide fracture toughness evaluations with a maximum error less than 10%, and thus is accurate enough for engineering applications. Though the new proposed energy release rate based model was verified through uniaxial tensile, uniaxial compression and spherical indentation tests, it may also be applicable to other specimen configurations. Abstract: Based on stress triaxiality analysis and SEM observations, the similarities and differences of fracture (damage) mechanisms for notched (both Mode I/II loading) and unnotched (uniaxial tension, uniaxial compression and spherical indentation tests) specimens were investigated. The investigations revealed that when the stress triaxiality was similar, the notched and unnotched specimens had a similar fracture (damage) mechanism. Thus, the damage in tensile tests was correlated with Mode I fractures, while the damage in uniaxial compression and spherical indentation tests were correlated with Mode II fractures. Taking the damage mechanism into consideration, a unified energy release rate based model to calculate the fracture toughness was proposed. Compared with previous studies, the energy release rate based model proposed in this study has a clear physical meaning and can be applied to different specimen configurations. Experiments on SA508, SA533, 15CrMoR, and S30408 revealed that the fracture toughness calculated from all three kinds of unnotched specimens using the new proposed energy release rate based model are as reliable as those from conventional compact tension tests. Graphical abstract: