Direct J-R Curve Analysis: A Guide to the Methodology

Abstract

A direct method for evaluating J-R curves from load displacement data is proposed. This method eliminates a need for automatic crack length monitoring equipment. The method uses the geometric normalization suggested by Ernst for deeply cracked bend specimens to develop calibration curves which relate load, displacement, and crack length. Given two of these parameters, the third can be determined from the calibration curves. These curves are developed by assuming a functional form with unknown constants and evaluating the unknowns at calibration points in the test. This method was previously proposed using a power law functional form. In this paper a more general functional form is proposed which combines a power law and straight line. The method is studied for a variety of materials and specimen sizes. From the results a recommendation is made on how to generally apply the method.

Análisis Geomorfológico de la Erupción Volcánica de Jacomar, Fuerteventura (Islas Canarias Orientales)

“…Este constituye una pequeña emisión volcánica, de carácter reciente (Pleistoceno Superior u Holoceno). No obstante, no existen estudios específicos ni cronológicos sobre el mismo, aparte de los datos aportados por la cartografía geológica de la zona (Balcells et al, 1990) o algún trabajo bibliográfico específico (Ortega González y Romero Martín, 1992;Dóniz-Páez, 2009).…”

A new method for determining the accurate J‐R curves of steels

“…6 NM directly uses the monotonic load versus load-line displacement (LLD) or load versus crack mouth opening displacement (CMOD) record, known as P-V curve, to establish the J-R curve for the specimen without the unloading-reloading process. [7][8][9][10][11] In the NM, a calibration function needs to be established to determine the instantaneous crack length corresponding to the load and displacement test data. Various forms of calibration functions have been developed.…”

“…In the NM, a calibration function needs to be established to determine the instantaneous crack length corresponding to the load and displacement test data. Various forms of calibration functions have been developed 6,7,10,12 . The calibration function adopted in the current standard ASTM E1820‐18 Annex 15 1 is the four‐parameter LMNO (or a b c d ) function 1,12 .…”

“…With this regard, the NM was developed by Herrera and Landes 6 . NM directly uses the monotonic load versus load‐line displacement (LLD) or load versus crack mouth opening displacement (CMOD) record, known as P‐V curve, to establish the J ‐R curve for the specimen without the unloading–reloading process 7–11 …”

“…Various forms of calibration functions have been developed. 6,7,10,12 The calibration function adopted in the current standard ASTM E1820-18 Annex 15 1 is the four-parameter LMNO (or a b c d) function. 1,12 NM has since been applied to different materials, including steels, [12][13][14] alloys 15 and polymers, [16][17][18][19][20] and structures.…”