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American Society for Testing and Materials

https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1048&context=usnavyresearch

Review of fracture toughness (G, K, J, CTOD, CTOA) testing and standardization

The fracture of bulk metallic glasses

The properties of poly(tetrafluoroethylene) (PTFE) in tension

The mechanical properties of poly(ether-ether-ketone) (PEEK) with emphasis on the large compressive strain response

Application of two parameter elastic-plastic fracture mechanics to analysis of structures

The upper shelf fracture toughness and tearing resistance of two structural steels, HY-100 and ASTM A533, Gr. B, were determined over a wide range of applied constraint. The constraint conditions were varied by changes in specimen geometry and loading mode. Bend specimens with shallow and deep cracks, compact specimens, and single and double edge notched tension specimens were used in this study. A rotation correction was developed for the single edge notch tension specimen which greatly improved the behavior of the J-R curves determined using this specimen. The experimental results were used to investigate the applicability of the Q and T stress parameters to the correlation of upper shelf initiation toughness, J{sub Ic}, and tearing resistance, T{sub mat}. The J-Q and J-T stress loci, and corresponding plots of material tearing resistance plotted against Q and T, were developed and compared with the expectations of the O`Dowd and Shih and the Betegon and Hancock analyses. The principle conclusions of this work are that J{sub Ic} does not appear to be dependent on T stress or Q while the material tearing resistance, T{sub mat}, is dependent on T stress and Q, with the tearing modulus increasing as constraint decreases.

Effects of constraint on upper shelf fracture toughness

J–Resistance curve testing of HY80 steel using SE(B) specimens and normalization method

Fracture resistance of ductile materials is often characterized by a J-R curve, and measured using the fracture toughness testing standard ASTM E1820 (Standard Test Method for Measurement of Fracture Toughness) The recommended elastic unloading compliance method or resistance curve test method requires simultaneous measurements of applied load (P), load-line displacement (LLD), and crack-mouth opening displacement (CMOD) from a single test for the single-edge notched bend [SE(B)] specimen The P-CMOD record is used to determine crack extension, and the P-LLD record in conjunction with the crack extension is used to calculate the J-integral However, it is well known that while highly accurate CMOD measurements can be made, the measurement of LLD is less accurate and more difficult because of transducer mounting difficulties, specimen load point indentions and load train deflections, or a combination thereof Extensive finite element analyses showed that the LLD-based J equation may give inaccurate results for a shallow-cracked SE(B) specimen because its geometry factor η may depend on the strain hardening exponent In contrast for the same geometry, the CMOD-based η factor is insensitive to the hardening exponent, and thus a CMOD-based J equation could be more accurate to be used in the determination of J-R curves Based on the energy principle, this paper proposes a CMOD-based J equation for a growing crack using an incremental function similar to the present ASTM E1820-06 formulation that is applicable to the J calculations for a J-R curve testing The proposed CMOD-based J formulation contains two geometry factors, ie, CMOD-based η and γ, and can consider the crack growth correction The solutions of four geometry factors are presented for the SE(B) specimens with a wide range of crack length The proposed formulation is then applied to determine J-R curves for HY80 steel using the load-CMOD record for SE(B) specimens, and the results are compared with those using the traditional LLD-based formulation The comparison shows close agreement between these two formulations It is recommended that the proposed formulation be used in ASTM E1820 to determine more accurate J-R curves and reduce test costs as well

James A. Joyce

Papers

Review of fracture toughness (G, K, J, CTOD, CTOA) testing and standardization

Application of two parameter elastic-plastic fracture mechanics to analysis of structures

Effects of constraint on upper shelf fracture toughness

J–Resistance curve testing of HY80 steel using SE(B) specimens and normalization method

Experimental Estimation of J-R Curves from Load-CMOD Record for SE(B) Specimens