Simple go/no-go test for subcritical damage in body armor panels

The development of a simple test for subcritical damage in body armor panels using pressure‐sensitive dye‐indicator film has been performed and demonstrated effective. Measurements have shown that static indicator levels are accurately reproduced in dynamic loading events. Impacts from hard blunt impactors instrumented with an accelerometer and embedded force transducer were studied. Reliable correlations between the indicator film and instrumented impact force are shown for a range of impact energies. Force and acceleration waveforms with corresponding indicator film results are presented for impact events onto damaged and undamaged panels. We find that panel damage can occur at impact levels far below the National Institute of Justice acceptance test standard

High contrast air-coupled acoustic imaging with zero group velocity Lamb modes

The well known zero in the group velocity of the first-order symmetric (S1) plate wave mode has been exploited in air-coupled ultrasonic imaging to obtain significantly higher sensitivity than can be achieved in conventional air-coupled scanning. At the zero group velocity point at the frequency minimum of the S1mode, a broad range of wavenumbers couple into the first-order symmetric mode at nearly a constant frequency, greatly enhancing transmission at that frequency. Coupled energy remains localized near the coupling point because the group velocity is zero. We excite the mode with a broadband, focussing, air-coupled transducer at the frequency of the zero group velocity point in the S1 mode. By exploiting the efficient coupling at the zero group velocity frequency, we have easily imaged a single layer of Scotch tape attached to a 6.4-mm thick Plexiglas plate and 3.2-mm Teflon inserts in a composite laminate

Nonlinear elastic behavior of sub-critically damaged body armor panel

A simple go/no-go test for body armor panels using pressure-sensitive, dye-indicator film (PSF) has been shown to be statistically effective in revealing subcritical damage to body armor panels. Previous measurements have shown that static indicator levels are accurately reproduced in dynamic loading events. Further impact tests on armor worn by a human resuscitation dummy using instrumented masses with an attached accelerometer and embedded force transducer have been performed and analyzed. New impact tests have shown a reliable correlation between PSF indication (as digitized images) and impact force for a wide range of impactor energies and masses. Numerical evaluation of digital PSF images is presented and correlated with impact parameters. Relationships between impactor mass and energy, and corresponding measured force are shown. We will also report on comparisons between ballistic testing performed on panels damaged under various impact conditions and tests performed on undamaged panels

Preface: Review of Progress in Quantitative Nondestructive Evaluation

The 38 th annual Review of Progress in Quantitative NDE was held at the University of Vermont in Burlington, VT, on July 17-22, 2011. This conference, widely regarded as the most prestigious of NDE research conferences, emphasizes the interface between current research results in the development of new measurement techniques (theory with experimental confirmation) and early engineering applications used to enhance the safety in high technology systems. With an attendance of 350 persons - approximately one half coming from overseas and the other half from U.S. academia, industry, and government - over 320 technical papers were presented in both verbal and poster sessions. As is customary for this meeting, papers in essentially all NDE technologies were presented, ranging from fundamental theoretical analyses to practical applications. Attendees included members of the World Federation of NDE Centers, an organization dedicated to broad cooperation in and harmonization of research and education for NDE. Student papers from the 9th Annual Student Poster Competition were incorporated as a part of the Review and are included in these volumes. The Review was organized by the Center for Nondestructive Evaluation at Iowa State University and sponsored by QNDE Programs with welcome assistance from the Air Force Research Laboratory, the Ames Laboratory (DOE) at Iowa State University, the American Society of Nondestructive Testing (ASNT), the Army Research Laboratory, the Federal Aviation Administration (FAA), the National Aeronautics and Space Administration (NASA), and the National Science Foundation (NSF) Industry/University Cooperative Centers

Human Factors Considerations in the Assessment of Nondestructive Evaluation (NDE) Reliability

The overall performance level for an NDE operation is dependent on the NDE material, equipment, processes (methodology) and human skills applied to the operation. It is important to understand and consider human factors elements and contributions to NDE applications in the improvement of applications, in the design and validation of new applications, in automating portions of task performance, and in the development of modeling tools for the prediction of task performance for existing and new applications

Towards Intelligent Databases

This article is a presentation of the objectives and techniques of deductive databases. The deductive approach to databases aims at extending with intensional definitions other database paradigms that describe applications extensionaUy. We first show how constructive specifications can be expressed with deduction rules, and how normative conditions can be defined using integrity constraints. We outline the principles of bottom-up and top-down query answering procedures and present the techniques used for integrity checking. We then argue that it is often desirable to manage with a database system not only database applications, but also specifications of system components. We present such meta-level specifications and discuss their advantages over conventional approaches

Forward Modeling of Transducer Misalignment Effects in Ultrasonic Leaky Wave Measurements

Ultrasonic measurements performed with a pair of acoustic transducers in pitch-catch mode are of common use in the NDE field. In particular, for nearfield leaky wave (LW) measurements which are directed at precise determination of material properties of layered elastic structure in immersion. In LW measurements, the acoustic transducer beams are aligned at angles so as to phase match to one or several of the structure’s leaky (Rayleigh or Lamb) waves. The amplitude and phase of the scattered acoustic energy collected, and converted to an electrical voltage, by the phase-sensitive receiving transducer depends not only on the properties of the structure but also on the parameters of the transducers used, in particular, their apertures and alignment angles. Transducer alignment issues are especially important for transducers that radiate or receive over a narrow angular range

Wednesday Evening Session XIX ‘Town Meeting on a Working Group in NDE’

The following record of the Wednesday evening problem session at th effort Magruder Inn, Williamsburg was transcribed from audio tapes made during the presentations and discussion

Editorial: Fibrosis and inflammation in tissue pathophysiology

In adult mammals, tissue damage activates a wound healing response with acute inflammation followed by either complete repair (for low-grade damage or in highly regenerative tissues, such as the liver) or replacement fibrosis (for extensive damage or in poorly regenerative tissues, such as the myocardium). Persistent damage and repeated insults sustain continuous activation of repair pathways leading to chronic inflammation, progressive tissue fibrosis and sclerosis. Despite the evolutionary advantage conferred by scarring as a rapid repair mechanism, chronic fibrosis leads to tissue adverse remodeling and impaired function. Persistent low-level inflammation and fibrosis are observed in many pathological conditions (e.g. hypertension, obesity, diabetes, genetic diseases), and lead to further complications including atherosclerosis and ischemic events, organ failure, autoimmune diseases, cancer, aging, and reduced resilience to infectious diseases. Pathological fibrosis plays a major role in a wide range of diseases, accounting for an increasingly large fraction of mortality cases worldwide. While recent advances have unveiled many environmental and genetic causes of fibrotic disorders, a better understanding of both ubiquitous and tissue-specific regulatory pathways and cellular dynamics could help to design new targeted therapies, and to identify the etiology of idiopathic diseases. Within this Research Topic, we invite submission of articles (reviews, original research, or methodology articles) on the pathophysiological role of fibrosis and inflammation in different tissues. Areas to be covered include, but are not limited to: - genetic and environmental causes of persistent low-level inflammation and fibrosis (e.g. autoimmunity, hypertension, obesity, diabetes, genetic diseases, latent infections); - comorbidities including systemic sclerosis, neurological disorders, organ failure (heart, skeletal muscle, kidney, liver, lungs), cancer, and reduced resilience to infectious diseases; - in vivo (animal models) and in vitro (organoids, tissue culture) modelling of fibrotic diseases for the discovery of novel therapeutic targets and potential tissue-specific treatments; - vascular responses to inflammation and inflammation of vascular tissues; - system biology approaches to identify molecular and cellular networks leading to chronic inflammation and fibrosis