Evolution of QNDE\u27s core interdisciplinary science and engineering base

Nondestructive testing (NDT) for flaws in materials and structures has undergone an evolutionary change over the past 50 years. In the U.S. it has moved from a testing strategy (NDT) with a zero defects requirement to a test and evaluate technology (NDE) based upon damage tolerant design considerations. Here it is assumed that the part will always contain defects but those greater than a critical size, specified by fracture mechanics, will be removed by inspection thereby resetting the part’s service clock. In this talk, events will be identified that were critical in promoting this paradigm shift and in moving on to quantitative NDE (QNDE). A number of major research programs were also initiated to upgrade NDT to meet the new requirements; principal attention in this talk will be given to research highlights initiated in the first of these programs, the DARPA∕AFML Interdisciplinary Program for Quantitative Flaw Definition that was established 35 years ago. Its purpose was threefold: to develop a new core science∕people base for inspection technology that could meet the new requirements, to set the stage for new field—adaptable engineering tools, and to initiate the current continuing series of quantitative NDE (QNDE) meetings. Advances initiated in this program and pursued by many over the years have resulted in a scientific core structure for quantitative NDE (QNDE) based on a linkage of fundamental models of the various measurement processes that are involved in any inspection and∕or technology. These models and their linkage will be discussed and the core structure defined. A new and powerful set of engineering tools—i.e. simulation programs for UT, X‐ray, and EC technologies ‐has also been developed using these models. Applications of these tools will be highlighted and their role in other advanced programs including Structural Health Monitoring and Condition‐Based Maintenance will be noted. Finally, a discussion of visions of future opportunities and directions for QNDE will be given

Nonlinear acoustics and honeycomb materials

The scope of research activity that Bruce Thompson embraced was very large. In this talk three different research topics that the author shared with Bruce are reviewed. They represent Bruce\u27s introduction to NDE and include nonlinear acoustics, nondestructive measurements of adhesive bond strengths in honeycomb panels, and studies of flexural wave dispersion in honeycomb materials. In the first of these, four harmonics of a 30 Mhz finite amplitude wave were measured for both fused silica and aluminum single crystals with varying lengths and amounts of cold work using a capacity microphone with heterodyne receiver with a flat frequency response from 30 to 250 Mhz. The results for fused silica with no dislocation structure could be described by a model due to Fubini, originally developed for gases, that depends upon only the second and third order elastic constants and not the fourth and higher order constants. The same was not true for the aluminum with dislocation structures. These results raised some questions about models for harmonic generation in materials with dislocations. In the second topic, experiments were made to determine the adhesive bond strengths of honeycomb panels using the vibrational response of the panels (Chladni figures). The results showed that both the damping characteristics of panel vibrations as a whole and velocity of propagation of elastic waves that travel along the surface and sample the bondline can be correlated with destructively determined bond strengths. Finally, the phase velocity of flexural waves traveling along a 1-inch honeycomb sandwich panel was determined from 170 Hz to 50 Khz, ranging from 2.2×104 cm/sec at the low end to 1.18×105 cm/sec at 40 Khz. The dispersion arises from the finite thickness of the panel and agreed with the results of continuum models for the honeycomb. Above 40 Khz, this was not the case. The paper concludes with a tribute to Bruce for his many wonderful contributions and lessons beyond his technical legacy for all of us

Preface

This report contains the edited transcripts of the Review of Progress in Quantitative NDE held at Cornell University, June 14-17, 1977. The Review was sponsored by the Advanced Research Projects Agency and the Air Force Materials Laboratory as a part of and at the conclusion of the third year of work on the Interdisciplinary Program for Quantitative Flaw Definition, Contract No. F33615-74-C-5180. Arrangements for the Review were made by the Science Center, Rockwell International, host organization for the Interdisciplinary Program, and the Materials Science Center at Cornell University, Prof. H. H. Johnson, Director

Preface

This report contains the edited transcripts of the Review of Progress in Quantitative NDE held at Cornell University, June 14-17, 1977. The Review was sponsored by the Advanced Research Projects Agency and the Air Force Materials Laboratory as a part of and at the conclusion of the third year of work on the Interdisciplinary Program for Quantitative Flaw Definition, Contract No. F33615-74-C-5180. Arrangements for the Review were made by the Science Center, Rockwell International, host organization for the Interdisciplinary Program, and the Materials Science Center at Cornell University, Prof. H. H. Johnson, Director

Preface

This report contains the edited transcripts of the Review of Progress in Quantitative NDE held at the Scripps Institution of Oceanography, July 17-21, 1978. The Review was sponsored by the Advanced Research Projects Agency and the Air Force Materials Laboratory as a part of the Interdisciplinary Program for Quantitative Flaw Definition, Contract No. F33615-74-C-5180. Arrangements for the Review were made by the Science Center, Rockwell International, host organization for the Interdisciplinary Program, and the Scripps Institution of Oceanography, Dr. William A. Nierenberg, Director

Introductory Remarks

I\u27m Don Thompson, Director of the Structural Materials Department at the Rockwell International Science Center and Program Manager for the ARPA/ AFML program. It\u27s a pleasure to welcome you to our annual ARPA/AFML Review of Progress in Nondestructive Evaluation. It is the first time that this meeting has not been held at the Science Center; we are very pleased with the courtesies and hospitalities that the people at Asilomar have shown us. This has been a busy summer for meetings in NDE. The schedule started with a meeting at the Bureau of Standards in April followed by an ASTM meeting in Florida on NDE; a special ARPA session was held in La Jolla in July and a meeting was held at Sagamore last week which was arranged by the AMMRC people;this review is to be followed by an internal DoD meeting on NDE and an international meeting in Cannes, France next week. Despite all these, we have a good crowd for which we\u27re very pleased

Program Description and Purpose

I\u27d like to spend a few minutes to give a brief overview of the ARPA/AFML research program in NDE. The objectives of the program are as follows: To pursue advanced research in quantitati ve techniques for NDE To establish a focal point for NDE research To establish communication between the research community and the NOE user To promote the image of ND

Introductory Remarks

I\u27m Don Thompson, Director of the Structural Materials Department at the Rockwell International Science Center and Program Manager for the ARPA/ AFML program. It\u27s a pleasure to welcome you to our annual ARPA/AFML Review of Progress in Nondestructive Evaluation. It is the first time that this meeting has not been held at the Science Center; we are very pleased with the courtesies and hospitalities that the people at Asilomar have shown us. This has been a busy summer for meetings in NDE. The schedule started with a meeting at the Bureau of Standards in April followed by an ASTM meeting in Florida on NDE; a special ARPA session was held in La Jolla in July and a meeting was held at Sagamore last week which was arranged by the AMMRC people;this review is to be followed by an internal DoD meeting on NDE and an international meeting in Cannes, France next week. Despite all these, we have a good crowd for which we\u27re very pleased

Preface

Several years ago (1969), the National Materials Advisory Board recommended the initiation of an interdisciplinary research effort in nondestructive evaluation. Their recommendation was based upon an assessment of future needs of both the Department of Defense and the nation as a whole..