Meeting New Challenges: Advanced Materials Aid the Army's ...

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Design ToolsFunctionModelingViabilityStudiesApproximateAnalysisGeometricModelingSimulationOptimizationMethodsCost ModelingComponentModelingFinite ElementAnalysisMarket NeedConceptEmbodimentDetailProductMaterialSelectionAll Materials(low precisiondata)Subset ofMaterials(higher dataprecision)One Material(best availabledata precision)Figure 2. Materials Selection Process in the Various Stagesof Design[5].The utilization of advanced materials in the early designstages (Figure 2) of the acquisition cycle has always been problematic.To minimize risk, design engineers typically utilizecommercial, off-the-shelf materials rather than advanced materialswith limited property data. From a materials perspective,this results in fielded systems being obsolete almost from theday they roll off the production line. Figure 3 illustrates this ongoingproblem for materials. As seen in the figure, it often takes20-30 years to mature a material to the point of widespreadcommercialization or use in engineering systems.THE ARMY’S PROCESS FOR MATERIALS DEVELOPMENTIt is useful for people who are not routinely exposed to advancedmaterials to have working definitions of various aspects of thefield: in particular, the relationship between materials science,materials engineering and materials technology.• Materials Science – the creation of new materials and theunderstanding of the relation of material characteristics(unique signature = chemistry, microstructure, defects) toproperties.Property = f (c, M, PD)Any material is a population of identifiable constituents (c)in a certain physical array (M) with certain, almost unavoidabledefects (PD).• Materials Engineering – the processing/manufacturing ofmaterials with controlled properties and geometries forcertain performance. Materials Figures of Merit (FOM) arecritical links here as they define a quantitative relationshipbetween combinations of properties to desired performance.Performance = f (property 1, property 2, property x, …)• Materials Technology – the successful or highly likelyapplication of materials science and materials engineeringknowledge to the improvement, development and enabling/inventionof useful products and systems.Materials scientists and engineers often work in collaborationwith other engineers (mechanical, electrical, aeronautical,civil etc.) in refining or developing engineering systems.This involves a range of activities from selection of the bestavailable material to optimizing existing materials or creatingnew ones with the desired properties. The process of generatingadvanced materials technology incorporates the synthesis,processing, characterization, properties, performance and predictivemodeling of materials; as well as manufacturing,including miniaturization technologies; and nondestructivetesting technologies to reduce the time, risk, and cost ofacquiring materials. In addition to these activities, materialsscientists and engineers work on processing and manufacturingtechnology to reduce costs and improve the reproduciblequality of existing materials. This usually involves materialcharacterization (determination of the unique signature) byYears-5 or more010 20Discovery of• Concept• Material• MethodDemonstration of Feasibility(Possible Application)1) Synthesis2) Processing3) Characterization4) Property EvaluationPrototype• Scale-up• Data Bases: Materials/Properties• Design• Nomenclature Uniformity• NDT Characterization• StandardizationIncorporation inSystemFailure Due To:• No Performance Improvement• No Cost Improvement• Lack of Reproducibility/Reliability• Lack of Design Data BaseNew Technologyor RediscoveryEmergingTechnologyMaturingTechnologySuccessfulApplicationFigure 3. Materials Technology Evolution[6].The AMPTIAC Quarterly, Volume 8, Number 4 9
Flow Chart for Materials Research and DevelopmentCrystallography1. Synthesis2. Crystal Structure3. Crystal Chemistry4. Compositional VariationsSingle CrystalCharacterization1. Mechanical2. Electromagnetic3. Physical/Chemical4. Optical5. DefectsExistingMaterialCompositional1. Inclusions2. Grain Boundary3. Phases4. HomogeneityCharacterizationProcessing1. Standard2. NewMicrostructural1. Texture2. Void - Cracks3. Grain Sizes4. Defects5. Fracture SurfacesGeneralized Needs1. Present or Potential Use2. Present Material Limitations3. Required Properties:Actual or Predicted4. Estimated Cost EffectivenessMaterial Conceptualization1. Single Crystal2. Particulate Dispersion3. Polycrystalline – Single Phase4. Amorphous MaterialConstituent ComponentSelection and Fabrication1. Phase Equilibria2. Compatibility:Physical and Chemical3. Powder PreparationScaleupOptimization LoopMechanical1. Strength2. Stiffness3. Hardness4. Impact Strength5. Fracture Energy6. Friction7. CompressiveStrengthEngineering PropertiesThermal1. Conductivity2. Expansion3. Specific Heat4. ShockStrengthCharacterization1. Optical2. X-Ray3. Trace Analysis4. Grain Size, etc.Actual orSimulatedUtilizationTestsE/M-Optical1. Conductivity2. Mag. Suscep.3. Dielectric K4. Loss Tangent5. TemperatureDependence6. VIS - IR - UVTransmissionFigure 4. Conventional Materials Research and DevelopmentFlowchart[7].non-destructive or destructive means and materialstesting/evaluation of the desired electrical, mechanical ordurability requirements, including property design allowablesused by design engineers. (See for example, MIL-Handbook-17, a composites materials handbook for organic matrix,metal matrix and ceramic matrix composites.) Of course,there are always the underlying competing goals of performance,cost, production capacity and strategic availability, asmodified by environmental and safety issues, which may haveto be traded off to achieve the desired performance withinbudgetary constraints. All of these issues should be taken intoaccount during the research, development, design and acquisitioncycle.New materials technology emerges from a systematicresearch and development strategy. Basic (6.1) and appliedresearch (6.2) agendas typically can be determined in two ways:• Strategic (technical) opportunities – knowledge driven• Strategic objectives – application pulledArmor Materials by Design is an example of a basic researchStrategic Research Objective (SRO) that the Army uses to helpguide the basic research agenda; it is an application pull, strategicallyfocused process. This Armor Materials by Design SROis not how to design components (systems) with existing materials,but rather how to select and design materials for verydemanding passive armor applications. Conventional materialsresearch and development typically follows a more sequentialprocess as illustrated in Figure 4.Passing the Torch:Materials EngineersTurn YoungAmericanson to ScienceScientists, engineers, and technologists form a very small segment of our national workforce – onlyabout five percent. The National Science Foundation (NSF) reports in “Science and EngineeringIndicators 2004” that while Americans express strong support for science and technology (S&T),they are not very well informed about these subjects.[1] For instance, in the US and Europe, mostadults pick up information about S&T primarily from watching television; the print media are adistant second. In addition, most Americans (two-thirds in the 2001 NSF survey) do not clearlyunderstand the scientific process. Knowing how ideas are investigated and analyzed – a sure sign ofscientific literacy – is important.A recent Building Engineering and Science Talent (BEST) publication entitled “The QuietCrisis: Falling Short in Producing American Scientific and Technical Talent” reports that aquarter of the current science and engineering workforce, whose research and innovationgenerated the economic boom in the 1990s, is more than 50 years old and will retire by theend of this decade.[2]Because it is essential to keep a minimum number of scientists & engineersin the workforce and to have a reasonably educated and interested population withregard to scientific issues, the US Army has been engaged in a number of programs designedto encourage young students to consider science as a possibility for their future.Most Army S&T labs have outreach programs at the local level. These programs range fromjudging at science fairs to participating in career day at schools to going out to classrooms towork with kids in hands-on science activities. Two of the local programs at Aberdeen ProvingGround (APG) are the Kids & Chemistry Program and the Science-in-the-Library program.These programs involve materials scientists and engineers from the Army Research Laboratoryand Edgewood Chemical Biological Center. In the Kids & Chemistry Program, Army volunteersgo into local schools and perform hands-on science experiments (e.g. Jiggle Jelly, What’sIn a Color? and The Cool Blue Light). In Science/Chemistry-in-the-Library Program, Army volunteersgo into libraries and schools in Baltimore City, Howard, Cecil and Harford County, Maryland,and New Castle County Delaware and work with kids doing hands-on experiments ranging from“Monster Snot!” (the Science of Slime – Polymers) to “It’s Gross and We Ate It!” (Food Chemistry)10The AMPTIAC Quarterly, Volume 8, Number 4
Page 3: James W. McCauleyWeapons and Materi
Page 8 and 9: Thermal Conductivity (W m -1 K -1 )

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