measurement techniques in advanced materials systems

Measurement Techniques in Advanced Materials SystemsProf. K. PadmanabhanSMBSVIT-VelloreEmail: [email protected]

Bottom up and

Top down Philosophy

ContentsAdvanced Materials SystemsDesign ConsiderationsAdvanced Materials Testing (AMT)- The differenceFracture, Failure and Fractography of AMNDT , FEA and MeasurementsImprovement from feedbackInnovations in AMT, Product testing and DFACase Studies and Conclusions

Advanced Materials SystemsAl-Mg and Mg Alloys and CompositesCarbon, Glass, Kevlar, Zylon fibre reinforced compositesMetal Plastic Composite SystemsCermets and their CompositesCeramic-Polymer CompositesSelf Reinforced Composites ( Carbon/Carbon)Super Alloys and Composites.Hybrids, Super hybrids and Sandwiches

Definition A composite material is a multi-component system with at least a matrix and a reinforcement.The desired properties must be better than at least one of the constituents.The constituents are normally physically separable , with a line of heterogeneity between them, called the interface.

Ford Soybean FRP Car of 1940sPicture shows Henry Ford I trying to break The Soybean with a sledgehammer, rather unsuccessfully. Soybean was made of steel tubular frame and 14 panels containing phenolic resin and natural fibres. It was worlds first car with an FRP body courtesy Ford Motors

General Design RequirementsTensile, Compressive, Shear , Flexure and CreepLoad Control, Position Control and Strain Control.Ductility and Plastic StrainBuckling, Collapsibility and CrushingModularity and FlexibilityCrumple Zones and Crashworthiness Static and Dynamic Fracture EnergyImpact Strength and ToughnessNoise Vibrations and HarshnessFatigue , Hot Wet Fatigue, Acoustic Fatigue, Fatigue after DBTStatics and Dynamics of Structures and AssembliesFailure Mode Interactions, Multiple Causes of FailureMulti Functionality

Design Requirements-MaterialsMaterial IndexMerit IndexStructural IndexShape FactorsMechanically Efficient ShapesSpecific Properties

Material Property Charts: Modulus - Density

*There is another, better, way to display relationships; the bubble-chart or material property chart. It is central to the optimal selection of materials, as will appear in Unit 2. It is shown in this schematic. Here two properties are plotted: Youngs modulus and density. When this is done it is found that each family of materials occupies a particular area of the plot metals near the upper right, foams at the lower left, polymers low central, and so on.

Design Requirements Ashby Maps

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Design Requirements - FRP CompositesSpecific PropertiesFracture ToughnessDynamic Fracture ToughnessDamage ToleranceHygrothermal DurabilityOverall Reliability ( Hot Wet Fatigue) DFM, DFA and DFMAE.Disposability and SafetyRecycleability, Recoverability and ReusePlastics Waste to Fuel Conversion

Micromechanics is where design begins !Design is defined as the complete information required to produce a product or render service - Anonymous

The Fibre-Resin Micro bond

A drop of the cured resin on the fibre surface showing adhesionFibre pullout test through a micro vise design fixture

Micro bond Bundle Pull-out TestRef: K. Padmanabhan , Final project report to the Singapore MIT Alliance ,Singapore, November 2002

Interface Tests Single fibre pullout testSingle fibre push out test, brittle materialsMicro bond single fibre pullout testMultiple fibre pullout test and Micro bond multiple fibre pullout test, Statistically averaged results, More precise, Less difficult, Mesomechanical in nature. Interlaminar shear strength test, ILSS.

Multiple Fibre Pullout

Ref: K. Padmanabhan , Toyobo Confidentiality Report, 2002.Ref: C. Y. Yue and K. Padmanabhan , Composites B, 30(1999) p205. Micro bond Matrix slab

Modelling and AnalysisCarbon Fibre and Zylon Fibre /epoxy Matrix Embedded Composite Systems

Cylindrical Assemblage Model Matrix Pull Out Through a Micro vise Micromechanicsle

Interfacial Parameters Interfacial shear strength,Interfacial frictional stress, fFibre/matrix coefficient of friction, Matrix shrinkage pressure, PoPressure due to Poisson expansion, paContact pressureInterfacial wear

Non-linear Quasistatic AnalysisSurface to surface contactCAM is anisotropic and matrix is isotropicOnly failure and post failure conditions were considered due to relevance and precision Model has dihedral symmetry

Solid 8 noded brick 185 element Hex swept volumes

Results of ANSYS Analysis37 MPa Zylon/epoxy shear stress at CAM interface

FEM Analysis Results Carbon/epoxy shear stress at CAM interface

Nano Structuring of Kevlar

Kevlar Fibre Nano Structuring

Kevlar Fibre Nano Structuring

10 Min Methanol And water Washing

XPS of Treated Kevlar Surfaces

SEM of Treated Kevlar Surfaces

Kevlar Fibre/ Epoxy Composites- Interfacial Results

Static mechanical propertiesTensile propertiesIn accordance with ASTM D3039 standardSpecimen preparation, adhesive bonding at the end gripsRecommended cross head speed of 0.02 cm/minStrain gaging, rosette strain gaging.0 and 90 (fibre direction) tests for E11and E22.. Similarly for major and minor poissons ratios .

Tensile Specimen

Tensile propertiesOff axis tensile tests for extensional stress and in plane shear stress evaluation. Statistical conceptsNormal and weibull distribution, location parameter and weibull shape parameter.Probability of failure and probability of survival.Longitudinal splitting, transverse cracking, angled cracking.

Off axis Tensile Test

Weibull Statistics

Failure and Survival

Tensile stress vs strain curves

Tensile Failures

Tensile PropertiesUni directional, cross plyModulus and strength in angle ply composites vs angle of fibre or fibre orientation.Multi directional laminates and tensile failure, symmetric , asymmetric etc.The concept of first ply failure (FPF)Transverse cracking in multi directional laminates, damage development.

Tension vs Fibre orientation

Tensile properties of Cross ply

Multi-directional laminates

Angle ply laminates

Tensile cracking

Tensile PropertiesTensile properties of woven fabric composites.Transverse microcracking in woven fabric compositesLaminates with holes, effect of stacking sequenceSheet moulding ( Crazing, transverse cracking, fibre matrix shear failure ) and interply hybrid composites.

Laminates with a hole

Interply hybrid composites

Compressive propertiesCelanese test rigIITRI test rigSandwich edge wise compression testComparisonsBuckling and microbuckling of composites and fibres.Types of failures

Celanese Standard

IITRI Test Rig

Sandwich Compression Test

Micro buckling and Design Micro buckling can be prevented by choosing higher fibre diameter, higher fibre elastic modulus and high interfacial bond strength between fibre and matrixBoron fibres are the best for design against micro buckling

CompressibilityThe compressive strength of single fibers is very difficult to measure and is usually inferred from the behavior of composites including the fibers. Euler buckling is one possible mode of compressive failure: it occurs when a fiber under compression becomes unstable against lateral movement of its central region.

Flexural Properties

Asymmetric Hybridization

In-plane shear

Iosipescu shear test

Rail shear test

In-plane shear properties

Interlaminar shear

ILSS of Kevlar/Epoxy Composites

Creep Comparison

Fatigue

Flexural Fatigue

ILSS Fatigue

Torsional Fatigue

Damage in Fatigue

Strain Controlled Fatigue Test

Impact Test

Impact Properties

Drop Weight Impact

Drop Weight Impact Properties

Instrumented Impact

Impact Energy in Izod

Drop Weight Impact Energy

Charpy Impact Energy

Impact vs. Fibre Content

Residual Strength After Impact

Compression After Impact

Pin Bearing Strength

Composite Joints

Adhesively bonded joints

Single lap joints

Standard lap shear specimens

Common Failure Modes

Hygrothermal Behaviour Fibre reinforced plastics are known for environmental attacks that reduce their function.Mechanical properties degrade over time !Moisture plays havoc at elevated temperatures, in the presence of voids, defects and in low Tg plastics .Diffusion and osmotic pressure are the driving mechanisms for hygrothermal attackEvaluation methods and surface preservation Important in marine, biomedical, aeronautical, electronic and automobile applications

Moisture Absorption

Maximum Moisture Content

Variation of Tg with Moisture

ASTM STP D 5229 M RuleThe MOT( Maximum Operating Temperature) of the material, device/component should be at least 25 Celsius lower than the lowest Tg (normally wet) of the material attained after hygrothermal equillibration. All the polymeric materials and their composites must satisfy this rule in order to qualify for certification for reliability and durability.

Failures and Multiple Causes In nature, most of the real environment failures are due to multiple causes. As enough standard procedures are available for failures due to a single cause, the obvious move is to develop the understanding as well as standard procedures for failures due to multiple causes.An understanding of these failures leads to a better fracture control that aids superior designs with advanced composite materials

MacromechanicsTransversely isotropic composite needs 5 independent elastic constants for efficient modelling (UD/00 )Layered orthotropic composite needs 9 independent elastic constants for efficient modelling

3 D Braided Structures3 D braided ,knitted, stitched and fibre preform structures have enabled easy manufacturing of net shape FRPs. The modelling and performance analysis of such structures poses challenges

Mechanical TestingRef: K. Padmanabhan and Kishore , ` Failure behaviour of carbon/epoxy composites in pin ended buckling and bending tests, Composites, Vol:26,No: 3, 1995, p201.

Bolted and Bonded Composite JointsJoint testing of a composite lug

Fracture Mechanics TestingMixed mode testing of compositematerials is a recent trend as causes are multiple during failure in real conditions Fracture mechanics tests to evaluate fracture toughness and strain energy release rates have found quite a few standards in ASTM

Sandwich Core MaterialsFoamHoneycomb

Types of FoamsThermoset, thermoplastic, elastomeric, ceramic, rock wool, metallic.Rigid, semi rigid, flexible.Filled and unfilledPoissons ratio variationsAuxetic, syntactic ..

Closed pore rigid foam

Open pore rigid foam

Sandwich Showing Core and Skin Core Interfacial Failure

Tensile faceCore failure Ref: ASTM C 393/C393M-06, ASTM D7249/ D 7249 M-06, ASTM D7250/ D7250M-06

Advances in Sandwich CompositesDevelop fracture mechanics test methods for sandwich compositesFocus on facesheet core delaminationBoth Mode I and Mode II

Suitable for ASTM standardizationRef: Dan Adams, Department of Mechanical Engg , Department of Mechanical EngineeringUniversity of Utah, Salt Lake City, UT, USA

Ductile Brittle Transition And Fatigue

The Titanic .... And Tragedy

Liberty Ships : The first all-welded pre-fabricated cargo shipsmass produced in the United States. 2,751 Liberty Ships were built between 1941 and 1945. Only two now remain afloat.Many of the remaining were destroyed by cracking of the type shown.

Ductile-to-Brittle TransitionFCC materials do not show DBT

Good for cryogenic applicationsStainless steel (austenite: fcc) containers for Liq O2 rocket fuelmild steel not good (: bcc)Fine grain size give lower transition temperatureHigh strain rate increase the transition temperature

4. Notches increase the transition temperature

Charpy Impact Testductilebrittle

Design Requirements Plot temperature vs. absorbed energyDraw a curve through the pointsDBTT is mean of upper and lower shelf energy

Ductile-to-Brittle Transitiony (bcc)TTDBTTy (fcc)Tffy < fductilebrittley > f

SEM Principles

FE Gun

Electron Beam

Beam Interaction with Specimen

SEM Column

SEM of Space Shuttle Tile

SEM of a PU Foam

Glass/Epoxy Sheared Sample

Ultrasonic Techniques

Ultrasonic MethodsA non destructive techniqueHigh frequency waves are usedFlaw, blowhole, defect, delamination detectionSound velocity and attenuation are different in different materialsReflection at flaw interfacesPartial reflection at some interfaces like inclusions.

Ultrasonic inspection Reflection from interfacesTime of transit of sound waves.Attenuation of sound waves in a materialRange of 0.1 to 25 MHzThey are mechanical vibrationsAlso detect bond characteristics, grain size, corrosion, thickness, elastic constants.

Basic EquipmentAn electronic signal generator produces bursts of alternating voltageA transducer that emits ultrasonic waves when bursts of alternating voltages are appliedA couplant to transfer energy to test pieceA couplant to transfer output of acoustic energy from the test piece to the transducerThe transducers can be separate or one ( Sending and Receiving ) Signal amplifierOutput recorder like chart, scope, TFT etc..Timer for control of various components of systems

Wave PropagationLongitudinal Waves ( Compression, Rarefaction)Transverse Waves ( Shear Waves )Surface Waves ( Raleigh Waves )Plate Waves or Lamb WavesTwo types of Lamb Waves: dilational or symmetric, Asymmetrical or bending

Variables in InspectionThe frequency chosen depending on flaw sizes and detection requirementsAcoustic Impedance ( % reflected and not transmitted), attenuation.Angle of incidence, critical angle, mode conversion and Snells lawTwo critical angles due to mode conversionBeam intensity , scattering, energy absorption due to heating.Diffraction of sound waves, beam spreading and beam diameter.

Inspection MethodsPulse- Echo Method, continuous through transmission scanning.A Scan- display of amplitude vs time, quantitative display of signal amplitudes and time of flight data.B Scan-time of flight again, relative depth of flaws, size, location over line on test pieceC Scan-Signal amplitudes over an area of the test pieces, quantitative, plan view of the test piece , indication of flaw depth.

FEA as an NDT Numerical method used for solving problems that cannot be solved analytically (e.g., due to complicated geometry, different materials)Well suited to computersOriginally applied to problems in solid mechanicsOther application areas include heat transfer, fluid flow, electromagnetism

Analytical -> exact solutionNumerical -> approximate solution

Finite Element Method PhasesPreprocessing

GeometryModelling analysis typeMaterial propertiesMeshBoundary conditionsSolution

Solve linear or nonlinear algebraic equations simultaneously to obtain nodal results (displacements, temperatures etc.)Postprocessing

Obtain other results (stresses, heat fluxes)

Composites in ProsthodonticsTooth is a functionally gradedcomposite material with enameland dentin. In the third maxillary molar the occlusal stress can be 2-3 MPa.The masticatory heavy chewing stress will be around 193 MPa.A composite restorative must with stand this with an FOS and with constant hygrothermal attack.

Multi Scale Composites for DentistryBis GMA, UDMA, Methacrylic Esters contain glassy particles that are mostly less than 1 micron in sizeEsters and acrylates/ceramic filler (barium alumina silica glass, glassy microfillers, 0.1 to 10 microns size) restorative composites.Multi scale composites are also useful as luting cements, crown and bridge materials and cements and veneer materials.

Wear Data for RestorativesAesthetics, Shade, ReliabilityMost of the composites show a logarithmic wear rate, linear wear rate is unwelcome !Wear of less than 200 microns in 10 years is acceptable.Wear volume will be 0.5 to 0.8 cu. mm per annum, enamel vs restoratives.Coeff of Friction is ~ 0.1 to 0.35.

Case Study : Vibration of Composite PlatesVibration studies in composites are important as the composites are increasingly being used in automotive, aerospace and wind energy applications.The combined effect of vibrations and fatigue can degrade a composite further that is already hygrothermal in affinity.The different modes of vibrations are discussed here.

ANSYS MODE SHAPE FOR CARBON FIBRE/EPOXY COMPOSITE(a) First mode shape(b) second mode shape(c) Third mode shape(d) Fourth mode shape

ANSYS MODE SHAPE FOR GLASS FIBRE/EPOXY COMPOSITE(a) First mode shape(b) second mode shape(c) Third mode shape(d) Fourth mode shape

ANSYS MODE SHAPE FOR GLASS/POLYPROPYLENE COMPOSITE(a) First mode shape(b) second mode shape(c) Third mode shape(d) Fourth mode shape

Case Study : Stabilizer Bars for Four Wheelers

Anti-roll stabilizer bars for four wheelers. Fatigue lifeof the stabilizer bars was estimated for qualification.

Deflection Plot for Stabilizer Bar

Equivalent Stresses for Bar

Deflection Plot for Stabilizer Tube

Equivalent Stresses for Tube

Case Study : LCA GeneratorThe study deals with modeling, analysis and performance evaluation of 5kW DC generator assembly. The complete solid model of the generator with its accessories was modelled using Pro-Engineer. This paper deals with the structural analysis of the DC generator casing to find stress and deflection in the generator casing due to load factor of 9g to which it is designed. The effect of vibration of generator casing and hollow shaft with mounting are investigated through detailed finite element analysis. The bending and torsional natural frequencies of the hollow shaft are estimated to find the critical speeds. Torsional frequency of the hollow shaft is estimated by considering the mass moment of inertias of the rotating masses. For critical speed analysis of the hollow shaft, it is considered as simply supported beam with the required masses and inertias. Then the influence of the critical speeds due to the casing stiffness is found out analyzing the casing with the shaft together.

Model of LCA Generator

Cross-section of the Model

Total Deflection at 9g Maximum deflection of the generator will be 4.761 microns, with-in limits !

Von Mises Stresses at 9g

A stress of about 6.756 MPa is much lesser than the Yield Stress of the material

Mode Shape of Generator Shaft

Mode shape corresponding to the flexural critical speed (54,972 rpm) (using solid element TET10 approximation)

Composites in Microelectronic PackagingThe BOM includes Copper lead frame,Gold wires for bonding, Silver epoxy for die attach, Silicon die and Epoxy mould composite with Phenolics, Fusedsilica powder and Carbon black powderas the encapsulant materials.

Thermal Structural Results Displacement Vector sumVon mises stressStress intensityXY Shear stress

Thermal Shock Test (JESD22 A106B)Purpose of this test is to determine the resistance of the part to sudden exposures of extreme changes in temperature and alternate exposures to these extremes as well as its ability to withstand cyclical stresses Here the IC packages are baked in an oven for 125C/24 Hrs and the temperature is spiked to 260C for lead free product and 240C for leaded product for 5 to 10 minutes.If the baking temperature is higher than the glass transition temperature at this extreme heat the package tends to delaminate or fail. This failure or delamination can be viewed using SAM (Scanning Acoustic Microscopy)

Non Destructive EvaluationUltrasonic C-Scan NDT can do depth profiling of composites delamination and damage profilingScanning acoustic microscope can sense delaminations of micron dimensions ( shown as red areas) in TQLMP IC packages. FEA techniques are also NDE techniques.

SAM (Scanning Acoustic Microscopy) PhotographsSAM picture for 24L TQLMP before preconditioning, No Plasma* cleaning

SAM Picture for 24L TQLMP after preconditioning, No Plasma* Cleaning

Red areas show delaminations in IC Packages

SAM Picture of 24L TQLMP after preconditioning, with Plasma* cleaning

SAM picture of 64L TQLMP Baked at 150C for 24hrs.

Design For Assembly

Defects in Assembly

Human Errors

Typical composite product defects

Minimizing Defects

A Bamboo Bicycle

Composites in Wind Energywww.suzlon.com , www.ge.com Vestas RRB

Composites in Storage Corrosion and weathering free thermoset and thermoplastic matrix glass fibre reinforced composite storage tanks, pressure vessels and containers are cheaper and more durable than conventional containers

Biomedical Compositess75X106 cyles of heart beat 78 x 106 cycles of heart beat over 25 years

Composites in Dentistry

Acrylics, Acrylic esters, Bis-GMA, PMMA derivatives, Ceramic filled compositesCan you make out the difference ?Ref: K. Padmanabhan , Programme overview, NIST ceramics machining consortium, I th Chapter, Gaithersburg, USA, October 8-9, 1998.

Composites in Automobiles Italian automobile with carbon fibre composite chassis

All Composite Engines

Aluminium Composite Engine Composite Engine Manifold

All composite AircraftsIndian Hansa-All composite aircraftVTOL AircraftRef: B.K. Parida, RMVGK Rao and K. Padmanabhan , Proceedings of the third joint National Aerospace Laboratories- Chinese Aircraft Establishment workshop on composites, April 22-24, Bangalore, India, 1996, p9. & NAL website

Composites - Sports & LeisureCarbon fibre-nylon matrix rigid foam tennis racquetComposite Yatch

Composites in Defense

A Bulletproof Vest A missile material case

Composites in SpaceAll aluminium alloy and carbon composites

Science is TrueDont be mislead by facts ! -Murphys Law

BibliographyP,K. Mallick, Fibre reinforced composites, Marcel and Dekker Inc., New York .Derek Hull and T.W. Clyne, ` An Introduction to composite materials, Cambridge solid state science series, 1996.E.J. Barbero, `Introduction to composite materials design, Taylor and Francis ,MI.J.K. Kim and Y.W. Mai, `Engineered interfaces in fibre reinforced composites , Elsevier, 1998. www.wikipedia.orgRao Tummala, Microsystems Packaging,McgrawHill.

BibliographySanjay K Mazumdar, Composites Manufacturing, CRC Press, 2002.Geoffrey Pritchard, Reinforced Plastics Durability, Woodhead publishing,Cambridge, England, 1999.Skinners Science of Dental Materials , R.W. Phillips, A Prism India ed, 1994.ASTM Standards Handbooks Vols: 08.01,08.02 and 08.03, PA, USA. www.astm.orgANSYS v.14 Analysis Manuals, 2014.Rayner M Mayer, Design with Reinforced Plastics, Design Council, London.

BibliographyK. Padmanabhan, S.Subeesh, K. Balaguru and T. Karthik , ` 3D Modelling and Failure Analyses of IC packages, in ANSYS Users Conference CD, 6 & 7 November 2008, Bangalore. K. Padmanabhan, S.Subeesh, K. Balaguru and T. Karthik , ` An Analyses of Reliability and Hygrothermal Effects in IC packages, in ANSYS Users Conference CD, 6 & 7 November 2008, Bangalore. BEST PAPER AWARD K. Padmanabhan, D. Sanjay and S Subeesh,` Design and electro-hygrothermo-mechanical reliability analyses of a leadless quad IC package, in the

BibliographyASTM D3039, Standard test method for tensile properties of polymer matrix composite materials, Annual book of ASTM standards, Philadelphia. ASTM D790-03, Standard test method for flexural properties of unreinforced and electrical Insulating Materials, Annual book of ASTM standards. Philadelphia.ASTM D256, Standard test methods for determining the Izod pendulum impact resistance of plastics, Annual book of ASTM standards, Philadelphia.

. Thirukkural Athikaaram 36 Mei Unarthal -355

*There is another, better, way to display relationships; the bubble-chart or material property chart. It is central to the optimal selection of materials, as will appear in Unit 2. It is shown in this schematic. Here two properties are plotted: Youngs modulus and density. When this is done it is found that each family of materials occupies a particular area of the plot metals near the upper right, foams at the lower left, polymers low central, and so on. *

Analytical -> exact solutionNumerical -> approximate solution