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Diskussionsgruppe COMPOSITES
Composites Structures: Civil Airplanes Applications
Boeing 787 Airbus A350
In black the composite parts
Composites Structures: Automotive & Marine
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Composites Structures: Manufacturing & Civil
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MD NastranMD NastranMD NastranMD Nastran
MD Nastran
• Three major questions come up again and again
• What is it?– How does it differ from MSC.Nastran
• Backward Compatibility– Can I run my existing & legacy MSC.Nastran jobs?– Can I run my existing & legacy MSC.Nastran jobs?– Do I have to learn something new?
• What is the advantage?– What’s the payoff?
747-8 FEM
7
MultiMulti--Discipline / MultiDiscipline / Multi--Scale Optimization (SOL400)Scale Optimization (SOL400)
MD Nastran Architecture
FE Optimization (SOL 200)
Structures /Mechanical
Thermal Dynamics/Aero, …
Adv NLAdv NL(Implicit,(Implicit,Explicit)Explicit)
MBSMBSServiceService
MSC/NASTRAN 1980 thru
19901990 thru
20002000 thru
20052005 thru
2009
Basic Basic NLNL
Nastran FootprintMore than Doubles
45 Years of Pedigree
2010+
Genoa integration NAI Sinda integration nCode integrationContact Algorithm
LS-Dyna
/Mechanical /Aero, …Explicit)Explicit) ServiceServiceNLNL
MD Framework (solver integration, 3MD Framework (solver integration, 3 rdrd party integration, scripting)party integration, scripting)
• The attractiveness of composites lies in their mechanical properties; such as weight, strength, stiffness, corrosion resistance, fatigue life. That is why the analysis of composite structures is imperative for the industries. The main advantage of composites is their flexibility in design. Mechanical properties of the laminate can be altered simply by changing the stacking sequence, fibre lay-up and thickness of each ply which leads to
Introduction to Composites: Technologies
sequence, fibre lay-up and thickness of each ply which leads to optimization in a design process.
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Classical Lamination Theory
Ed Dickerson
• Laminate effective material properties are tailored to meet performance requirements through the use of lamination theory integrated in the MSC.Software products.
• Used to accurately predict laminate properties. These analysis methods
θ= 0º, t=0.0125
θ= 45º, t=0.01
θ= 90º, t=0.01
θ= -45º, t=0.01
θ=0º, t=0.01
θ= -45º, t=0.0125
θ= 90º, t=0.0125
θ= 45º, t=0.0125
Classical Lamination Theory (CLT)
properties. These analysis methods address:
• Stress-strain relationship for membrane and bending response
• Thermal and moisture effects
• Inelastic behavior
• Strength and failure
• Interlaminar stresses
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• First-Ply Failure (FPF)– Linear analysis based on failure theory– Compute failure index or strength ratio
for the ply material– Optimization of ply angle/thickness
First-Ply-Failure Analysis
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Critical Margin of Safety
Access to MD Nastran Advanced Composite Solution
Extensive MD content now
• Progressive Failure Analysis• Adv. Progressive Failure Analysis • Fracture Mechanics and Delamination:
VCCT (Virtual Crack Closure Tecnique)• Delamination: Cohesive Zone Modeling• Delamination: Breaking glued contact• Delamination: Breaking glued contact• 3D Composites• Composites Beam
Progressive Failure Analysis
Ed Dickerson
Progressive Failure Analysis
• The progressive failure analysis is a method developed for predicting the nonlinear response and failure of laminated composite structures from initial loading to final failure.
• Failure is indicated by the failure criteria used.
• When failure occurs, the FEM element stiffness is degraded.
• The material will not heal; the damaged elements keep the degraded properties after unloading.
Progressive Failure Analysis
properties after unloading.
• Investigations of effect of overloads on composite structures• Available for existing criteria: Maximum Strain/Stress, Hill, Tsai-Wu • Available for NEW criteria: Puck, Hashin, Hashin-Tape, Hashin-Fabric
These failure theory are able to predict the failure load and also the mode of failure such as fiber failure and/or matrix failure.
Progressive failure
• How does failure affect the different material moduli ?
• Assume – 1-direction is fiber direction– 2-direction is matrix direction in the plane of the ply– 3-direction is through the ply thickness
• Fiber failure– Reduce E1 and E3
• Matrix failure– Reduce E2, G12, G23 and G31
Progressive Failure Analysis
Adv. Progressive Failure Analysis
Ed Dickerson
Adv. Progressive Failure Analysis
• GENOA is an integrated structural analysis software suite to predict strength, reliability and durability of structural composite components
• The use of material library from Genoa is available in MD Nastran.
Micromechanical Composite Material Definition
Nastran.• Based on constituent properties,
Fiber and Matrix, evaluates the structural and material response including degradation of material properties due to initiation and growth of damage.
• Over 20 Micro Mechanical Failure Criteria Failure Criteria available with MD Nastran Adv. PFA analysis
• It is a fully integrated solution, Genoa material stiffness evaluation is in the increment loop, MD Nastran calls Genoa for each element, damage reflected as modified stiffness.
2D Woven
LaminateComponent
FEMVehicle
Traditional FEM stops here Lamina
3D Fiber
Adv. Progressive Failure Analysis
• At each individual load step, the stresses and strains, obtained through the composite micro-stress analysis, are checked according to distinct failure criteria.
Unit cell at node
Sliced unit cell
Micro-Scale
Traditional FEM stops hereGENOA goes down to micro-scale
Lamina
FEM results carried down to micro scale Reduced properties propagated up to vehicle scale
Takes full advantage of MD Nastran capabilities and Genoa material library
Failure theories for Adv. Progressive Failure Analysis
• Longitudinal tension
• Longitudinal compression
• Transverse tension
• Transverse compression
• Normal tension
• Normal compression
• In-plane shear
• Transverse normal shear
• Fiber micro-buckling
• Tsai-Wu theory
• Hill theory
• Hoffman theory
• Maximum stresses theory
• Maximum strain theory
• First strain invariant failure
theory
• Longitudinal normal shear
• Modified distortion energy
• Inter-ply relative rotation
Honeycomb failure modes recognized
• Inter-ply relative rotation
• Fiber crashing
Wrinkling Crimping Dimpling
Genoa Integration: Modeling composite
materials at constituent LevelFusolage Stiffened Panel Adv. Progressive Failure A nalysis with Micromecanical material definition (Fi ber / Matrix)
Glued Contact between frames and panel
Micromechanical Damage IndexStress Strain
Fracture Mechanics and Delamination
Ed Dickerson
• Delamination is one of the main failure mechanisms in laminated composites• Possible reasons for delamination are:• Manufacturing defects and stress• Gradients near geometric discontinuities (like stiffener terminations and
bolted joints)• Delamination may result in local failure or even a significant loss of the
Delamination Introduction
• Delamination may result in local failure or even a significant loss of the structural integrity
• Three different approach available:
– VCCT– CZM– Breaking glued contact
(Virtual Crack Closure Tecnique)
• The VCCT is the fracture mechanics approach for studying delamination and crack initiation and growth.
• It is used for calculating the energy release rate of single or multiple cracks.
Fracture Mechanics with VCCT
• In linear fracture mechanics, a crack starts to grow when– Total G > Gc
– G is the energy release rate– Gc is the fracture toughness
(Virtual Crack Closure Tecnique)Fracture Mechanics with VCCT
– Gc is the fracture toughness
• VCCT is a methods used to compute the energy release rate.• Energy release rate:
G = Fu/2a
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(Virtual Crack Closure Tecnique)Fracture Mechanics with VCCT
Mode I: Opening
Mode II: Sliding
Mode III: Tearing
VCCT Example:
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• The so-called interface elements can be used to simulate the onset and progress of delamination. The constitutive behavior of these elements is expressed in terms of tractions versus relative displacements between the top and bottom edge/surface of the elements.
• Considering a 3-D interface element, the relative displacement components with respect to the local element system:
Cohesive Zone Modeling (CZM)Delamination:
components with respect to the local element system:
• The interface elements can be modeled between 2D and 3D structural finite elements:
• The effective traction is introduced as a function of the effective opening displacement, and is characterized by an initial reversible response followed by an irreversible response as soon as a critical vc effective opening displacement has been reached. Three standard functions are
Cohesive Zone Modeling (CZM)Delamination:
opening displacement has been reached. Three standard functions are currently available
Cohesive Zone Modeling: examples
DCB
Test Specimen
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Delamination of NASA Test
Specimen
Test Specimen
• Release glued contact when stress criteria is satisfied:
Breaking glued contactDelamination:
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• Use contact normal and tangential stress
• After break, do regular contact with friction and separation
Breaking glued contact: examples
Stringer termination analysis
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Shear Stiffened Panel Analysis
Continuum Elements are required for Composites Modelling:
• When detailed out-of plane stress recovery are needed
• When transverse shear effect are predominant
3D composites
• When accurate interlaminate stresses such near localized region of complex loading or geometry
• When better contact condition are needed
Detailed out-of plane stress recovery3D composites: Examples
Three Point Bending Test
Free-Edge Delamination
Composites Beam
Ed Dickerson
Composites Beam
Composite Beam Using the Variational AsymptoticMethod (VAM)
• Arbitrary beam cross section (ABCS) capability available in MD Nastran, and composite support for an arbitrary beam cross section has been implemented. The variational asymptotic method (VAM) is used to compute the beam properties of an arbitrary cross section.
• The composite beam using VAM provides an alternative to conventional 3-D/2D modeling technique, and permits the use of beam element to model composite beams. The layup of composite beam plies is described model composite beams. The layup of composite beam plies is described on the PCOMP/PCOMPG Bulk Data entries. In addition, the cross section of the composite beam can be expressed conveniently with the CP/OP options of the PBMSECT Bulk Data entry
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• Examples of Composites Beam Bulk Data Entry:
Composite Beam Using the Variational AsymptoticMethod (VAM)
• PBMSECT,32 is a box beam made of composite material. All segments have a common CORE=204 with four plies. Segments from POINTs 2 through 5 have one ply on top, layer=(210,101), and one ply at the bottom, L(2)=(210,103).
• Limitations
• Beam must be straight when used as a composite beam (not curved).
• SOL 200 does not yet support the composite beam.
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• MSC.Software expertise is proven by the collaboration with all main global players in the Composites Material market
• MSC.Software solutions are already succefully applied in any stage of composites products development
• MSC.Software local team is highly experienced in delivering and implementing our solutions to customers
Conclusions:
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implementing our solutions to customers
Largest Autoclave in the World Statistics:Inside working diameter: 30ft. (9.26M)Ouside diameter: 32ft. (9.88M)Inside working length: 76 ft. (23.5M)Overall length: 112 ft. (34.5M)Vessel volume: 82,000 cu.ft.Max temperature: 450FMax pressure: 150 psigVought Aircraft in Charleston, SC
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Ing. Armando MetePreSales EMEAEuropean Composite Material Technical [email protected]
http://www.mscsoftware.com/