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The nonprofit U.S. Medicine Institute for Health Studies on March 6,2003, gathered decisionmakers from government and the private sector to examine the need for a national surveillance system and how such a system might best be developed, given current, often disparate, attempts at various levels of disease detection. Opinions presented at this forum ranged from assertions that "we have a long way to go" in developing a national system to reassurances that a national surveillance system in fact exists in the form of the current process for reportable diseases overseen by the Centers for Disease Control and Prevention. The prevailing view, however, was that disease surveillance, to be useful, must be real-time, must be automatic and must be standards- based and undoubtedly will rely on DNA sequencing chips that can screen for a vast array of organisms There was hopefulness that the focus on bioterrorism will infuse neglected public health systems with new resources, yet caution that placing too much emphasis on bioterrorism could prove counterproductive in the long run, in that funding likely would dry up should no incident occur within the next several years., The original document contains color images. All DTIC reproductions will be in black and white.

The general goal of this project is to contribute to the development of advanced hybrid yarns for woven fabric body armor and general dynamic applications. Blending stiff low elongation-to-break (LE) fibers with compliant high elongation-to-brake (HE) fibers improves the overall strength of a blended yarn. Interfacial slip between fibers is thought to play an important role in this process. The specific objective of this work is to perform experiments on fiber-to-fiber interfacial slip behavior in fibrous assemblies. Various hybrid yarns were simulated (experimentally) by helically wrapping HE fibers over a LE core fiber at different helix angles. The strength characteristics of these blended yarns were tested in tension. In particular a novel experimental procedure is developed to measure the slip of the core fiber after the first brake occurs. The tests are carried out to show the existence of multiple breaks. The strength of the hybrid yarns is compared with the strength of a single yarn.

A micro-mechanical unit-cell model was developed for 2/2-twill woven fabric composites. A multi-scale bi-directional micro/macro-mechanical analysis technique was applied to the model in an effort to estimate effective material properties of 2/2-twill composites and decompose the effective stresses (strains) of the woven fabric composite into the stresses (strains) of the lows. When this unit-cell model is incorporated into the multi-scale analysis by combining with previously developed modules, the residual strength and stiffness of a laminated structure made of 2/2-twill woven fabric composites can be predicted along with damage progression in the structure. Damage is described at the basic material units of the composite structure, the fibers and matrix. The unit-cell model and the multi-scale analysis were validated by comparing their predicted results to available data in open literature and data obtained from a finite element models., The original document contains color images.

A review of recent developments and state of the art in damage, fatigue and particularly, high-temperature fatigue of ceramic matrix composites is presented. Both laminated, as well as woven configurations are considered, while whisker and particle-reinforced materials are not covered in this review. Based on a detailed discussion of the mechanisms of failure, the problems that have to be addressed for a successful implementation of ceramic matrix composites in design are outlined.

This report includes two projects that were funded under Center of Excellence for Materials Research. In case of Thermomechanics of Fiber-Reinforced Composites, a new apparatus to perform multiaxial thermomechanical tests on small samples has been developed. This report includes our design process, that is, the theoretical ideas and developments that motivated the overall design, the preliminary tests that verified some early hypotheses, the various design alternatives that were considered, and details on the final system that was assembled. In the second project entitled 'High Strain-Rate Behavior and Damage Measurements in Glass-Reinforced Plastics', experimental results are reported over a wide range of strain-rate and in test samples of three orientations. Elastic constants and strengths in two orientations in direction of woven fibers and one perpendicular direction, are reported along with failure mechanisms during quasi-static and impact loading of this material.

The general emphasis for 1994 would be on increased software development, testing of subelements and design calculations. For these purposes, the constitutive law coding and development would be coordinated by Nick Aravas, and implemented in ABAQUS. The initial implementation would be the elastic/plastic model for MMCs with interface debonding developed in 1993 (Leckie). This would be extended in 1994 to include creep and some aspects of thermomechanical cycling. The code would be used for design calculations concerned with MMC rotors, actuators and vanes (Leckie). A plan is being formulated to collaborate with Pratt and Whitney to acquire MMC sub-elements representative of these components during 1994. Experimental tests on these subelements would be capable of providing a direct validation of the code capabilities.

The damage to carbon-carbon composites created by projectile impacts has been characterized for a range of test conditions and for several weave constructions and processing variables. A number of subsurface damage modes have been identified (on sectioned specimens) in the vicinity of the crater produced by particulate impingement. In addition, studies are underway to determine the modes of failure which occurred in the material ejected from the crater. Preliminary analyses of the primary subsurface damage modes have been undertaken to define the approach that would elucidate the microstructural dependence of the impact damage.

This paper deals with the continuing study of the effects of instrumentation installation design parameters upon the ablative performance of carbon-carbon nosetips as observed in ground tests conducted during the past 18 months at the Air Force Flight Dynamic Laboratory (AFFDL) 50 MW Arc Jet Test Facility. Some of the parameters studied in Phase II were: the differences in the structure of the various carbon-carbons; the clearance between an instrumentation rod and the hole in which it is installed; carbonization of the bonding material; charring out of the bonding agent; and, further study of multiple source assemblies mounted into the nosetip. In general, the Phase II results have shown that even the subtlest, and assumed harmless, change in an instrumentation installation parameter produced very large and sometimes unexpected (and undesired) effects on carbon-carbon nosetip ablation performance. (Author), Presented at the Instrumentation Society of America Aerospace Symposium Thermal Measurements Session (20th).

Joints in glass fibre/epoxy (GFRP) and 'Kevlar' fibre/epoxy (KFRP) laminates show similar characteristics to those in carbon fibre/epoxy (CFRP) but with differences brought about by the low elastic modulus of glass of fibres, and the low compressive strength of 'Kevlar' fibres. The current paper presents data for GFRP laminates manufactured manufactured from layers of unidirectional fibre prepreg, and for KFRP laminates manufactured from layers of balanced, bi-directional, woven fabric prepreg. Comparative data for CFRPeek is also given. As far as GFRP is concerned, tests on single-hole joints show that the effects of width, end distance, hole size, bolt clamping pressure and stacking sequence are similar to those in CFRP. In general, strength levels for GFRP are about 20% below tose for CFRP. The best lay-up is judged to be 0/ + or - 45, with 60% of the plies at + or - . A stronger inter-delaminate rather than showing in-plane shear or tensile cracking. Due to the nature of the prepreg the range of possible lay-ups for KFRP is restricted; only 0/90, + or - are tested. Bearing strengths are generally in the range 500-600 MN/m2, i.e. 25-30% below GFRP. Overall behaviour is found to be similar to other FRP although the ultimate failure mode is almost invariably tensile. There is evidence that the inherent compressive characteristics of 'Kevlar' fibre contribute to the low bearing strength. Surprisingly, although ver large hole distortions are seen at failure there is very little evidence of resin cracking. (SDW), This article is from 'Behaviour and Analysis of Mechanically Fastened Joints in Composite Structures', AD-A199 171, p15-1 - 15-9.

Although flywheels, such as the potter's wheel can be dated back several thousand years, there has been a great resurgence of interest recently in the flywheel as an energy storage mechanism. The reasons are both economic and technological -- economic because the growing costs and potential scarcity of energy have increased the importance of energy storage as a conservation measure, and technological because improvements in materials and mechanics make flywheel energy storage more and more attractive. The United State Energy Research and Development Administration in its Office of Conservation is responsible for research and development promoting energy storage systems in the national interest. To this end a gathering of leaders in flywheel technology from industry, government and universities was conceived. Thus, the Energy Research and Development Administration and the Lawrence Livermore Laboratory sponsored the 1975 Flywheel Technology Symposium at Lawrence Hall of Science, Berkeley, California, November 10-12, 1975. The Symposium was designed as a forum where these leaders of flywheel technology and research could exchange information and ideas on advances, potential applications, and research needs of the flywheel technology. The symposium was also designed to provide a seminar at which interested people could update their understanding of flywheels. (MM)

A limited study was made to characterize the effects of parametric variations in construction on the mechanical performance of various parachute items made from polybenzimidazole (PBI) yarns. The results indicate that most of the specifications originally written for nylon parachute components can be met with PBI if suitable modifications are made in construction to allow for the lower tenacity of PBI yarn. Strength translation efficiencies are good enough to permit prediction of breaking loads of structures with reasonable accuracy on the basis of one pound per 100 deniers of yarn used. Sufficient amounts of each required end item were made to permit complete laboratory characterization including testing at ambient, 350 F, 450 F, 700 F, 900 F, and 1000 F after exposures ranging from 0 to 200 hours. Only the threads and one fabric were tested over the specified range when it became apparent that finish modifications would be required before reliable results could be obtained from high temperature testing. An investigation was made of the high temperature resistance of available candidate finishes and finish components applied to PBI fabric and yarn by various methods. While no satisfactory material was found, some leads were developed which may be useful in further studies. The testing done on the threads and lightweight fabric showed that PBI yarn structures retain about 40% of their original strength after exposure at 700 F for two hours, even with an unsatisfactory finish., See also AD-488 533

Al texturizar el hilo, éste adquiere una mayor voluminosidad, así como una gran fuerza elástica. Por ello es muy adecuada para determinadas aplicaciones textiles., Peer Reviewed