A classic work on leadership for business men and women, government leaders and all persons in positions of authority.

Servant Leadership: A Journey Into the Nature of Legitimate Power and Greatness

J+=j

We provide a review of the alignment literature in IT, addressing questions such as: What have we learned? What is disputed? Who are contributors to the debate? The article is intended to be useful to faculty and graduate students considering conducting research on alignment, instructors preparing lectures, and practitioners seeking to assess the ‘state-of-play’. It is both informational and provocative. Challenges to the value of alignment research, divergent views, and new perspectives on alignment are presented. It is hoped that the article will spark helpful conversation on the merits of continued investigation of IT alignment.

/pdf/it-alignment-what-have-we-learned-nxwe0wokck.pdf

IT alignment: what have we learned?

A hierarchical approach to defining marine heatwaves

Assessment of the integrity of structures containing defects

Fracture and Fatigue Control in Structures: Applications of Fracture Mechanics

This study investigates the applicability of the J-integral test procedure to test short crack specimens in the temperature region below the initiation of ductile tearing where J 1 c cannot be measured. The current J-integral test procedure is restricted to determining the initiation of ductile tearing and requires that no specimen demonstrates brittle cleavage fracture. The J 1 c test specimen is also limited to crack-depth to specimen-width ratios (a/W) between 0.50 and 0.75. In contrast, the crack tip opening displacement (CTOD) test procedure can be used for testing throughout the entire temperature-toughness transition region from brittle to fully ductile behavior. Also, extensive research is being conducted to extend the CTOD test procedure to the testing of short crack specimens (alW ratios of approximately 0.15). The CTOD and J-integral fracture parameters are compared both analytically and experimentally using square (cross-section) three-point bend specimens of A36 steel with a/W ratios of 0.50 (deep crack) and 0.15 (short crack). Three-dimensional elastic-plastic finite element analyses are conducted on both the deep crack and the short crack specimens. The measured J-integral and CTOD results are compared at various levels of linear-elastic and elastic-plastic behavior. Experimental testing is conducted throughout the lower shelf and lower transition regions where stable crack growth does not occur. Very good agreement exists between the analytical and experimental results for both the short crack and deep crack specimens. Results of this study show that both the J-integral and the CTOD fracture parameters work well for testing in the lower shelf and lower transition regions where stable crack growth does not occur. A linear relationship is shown to exist between J-integral and CTOD throughout these regions for both the short and the deep crack specimens. These observations support the consideration to extend the J-integral test procedure into the temperature region of brittle fracture rather than limiting it to J 1 c at the initiation of ductile tearing. Also, analyzing short crack three-point bend specimen (a/W < 0.15) records using the load versus load-line displacement (LLD) record has great potential as an experimental technique. The problems of accurately measuring the CMOD of short crack specimens in the laboratory without affecting the crack tip behavior may be eliminated using the J-integral test procedure.

A Comparison of the J -lntegral and CTOD Parameters for Short Crack Specimen Testing

An investigation was conducted to determine whether correlations could be developed between K sub Ic and CVN test results in the transition-temperature range to assist both the materials engineer and the structural designer. The results showed that various correlations do exist between K sub Ic and CVN test results in the transition-temperature range. Static K sub Ic values were correlated with the energy absorptions determined with slow-bend fatigue-cracked CVN specimens. Empirical correlations also were developed between the results of slow-bend K sub Ic tests and the results of standard CVN impact tests for the transition-temperature region.

Correlations Between K Ic and Charpy V-Notch Test Results in the Transition-Temperature Range

Short crack test specimens (a/W ≪ 0.50) are frequently employed when conventional deep crack specimens are either inappropriate or impossible to obtain, for example, in testing of particular microstructures in weldments and in-service structures containing shallow surface flaws. Values of elastic-plastic fracture toughness, here characterized by the crack tip opening displacement (CTOD), are presented for square (cross-section) three-point bend specimens with a/W ratios of 0.15 and 0.50 throughout the lower-shelf and lower-transition regions. Three dimensional, finite-element analyses are employed to correlate the measured load and crack mouth opening displacement (CMOD) values to the corresponding CTOD values, thus eliminating a major source of experimental difficulty in previous studies of shallow crack specimens. In the lower-transition region, where extensive plasticity (but no ductile crack growth) precedes brittle fracture, critical CTOD values for short crack specimens are significantly larger (factor of 2–3) than the CTOD values for deep crack specimens at identical temperatures. Short crack specimens are shown to exhibit increased toughness at the initiation of ductile tearing and decreased brittle-to-ductile transition temperatures. Numerical analyses for the two a/W ratios reveal large differences in stress fields ahead of the crack tip at identical CTOD levels which verify the experimentally observed differences in critical CTOD values. Correlations of the predicted stresses with measured critical CTOD values demonstrate the limitations of single-parameter fracture mechanics (as currently developed) to characterize the response.

Stanley T. Rolfe

Papers

Fracture and Fatigue Control in Structures: Applications of Fracture Mechanics

A Comparison of the J -lntegral and CTOD Parameters for Short Crack Specimen Testing

Correlations Between K Ic and Charpy V-Notch Test Results in the Transition-Temperature Range

Effects of crack depth on elastic-plastic fracture toughness

Fatigue-crack propagation in high yield-strength steels