A More Basic Approach to the Analysis of Multiple-Specimen R-Curves for Determination of Jc

Abstract

Multiple specimen J-R curves were developed for groups of 25.4-mm-thick (1T) compact specimens with different a/W values and depth of side grooving. The purpose of this investigation was to determine Jc (J at the onset of crack extension) for each group. Judicious selection of points on the load versus load-line deflection record at which to unload and heat-tint specimens permitted direct observation of approximate onset of crack extension. It was found that the present recommended procedure for determining Jc from multiple-specimen R-curves, which is being considered for standardization, consistently yielded nonconservative Jc-values. A more basic approach to analyzing multiple-specimen R-curves is presented, applied, and discussed. This analysis determined Jc-values that closely corresponded to actual observed onset of crack extension.

Physical Laboratory Automation in Synthetic Biology

“…NGS sequencing has become pervasive in synthetic biology across subdisciplines such as DNA nanotechnology, metabolic engineering of cellular systems (genomics/transcriptomics), and medical applications such as diagnostics and disease therapies. The technology has rapidly evolved in recent years as throughput has dramatically increased and the price per base has fallen faster than Moore’s law . However, while the sequencing process itself is automated, the upstream library preparation protocols prior to sample loading are substantial bottlenecks imposing limitations on throughput.…”

A Study of the J-Integral Method Using Polycarbonate.

“…[7][8] ' 10, [14][15][16][17][18][19][20][21][22][23][24] An ASTM standard is being developed for the measurement of the J-integral at the initiation of crack growth. …”

On the fitting and extrapolation of J‐resistance data derived through the linear normalization technique

“…9 In the present work, both power-law and logarithmic fits have been applied, in conjunction with the linear fitting method, to a broad range of elastic±plastic fracture resistance ( J±Da) data, which were obtained 10 simultaneously through the traditional unloading elastic compliance technique ( UEC) and the more recent Reese & Schwalbe's linear normalization (LN) method. Other methods used to some extent to fit J±R curves include polynomial and linear fits.…”

“…Other methods used to some extent to fit J±R curves include polynomial and linear fits. 9 In the present work, both power-law and logarithmic fits have been applied, in conjunction with the linear fitting method, to a broad range of elastic±plastic fracture resistance ( J±Da) data, which were obtained 10 simultaneously through the traditional unloading elastic compliance technique ( UEC) and the more recent Reese & Schwalbe's linear normalization (LN) method. The results have been evaluated in terms of the effects of the fitting method in two J-criteria of the nuclear industry ± namely, the crack growth initiation J ( J i, 6 ) and the Paris & Johnson's J 50 11 for a healthy conservative assessment of ductile instability in cracked bodies.…”