damage and optimization models for analysis and design of discontinuous fiber composite structures...
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Damage and Optimization Models for Analysis Damage and Optimization Models for Analysis and Design of Discontinuous Fiber Composite and Design of Discontinuous Fiber Composite
StructuresStructures
Damage and Optimization Models for Analysis Damage and Optimization Models for Analysis and Design of Discontinuous Fiber Composite and Design of Discontinuous Fiber Composite
StructuresStructures
Ba Nghiep Nguyen
Acknowledgements: PNNL’s Computational Science Engineering Initiative –
Korolev Vladimir, Brian Tucker (contributors)
NSF/DOE/APC Workshop: Future of Modeling in Composites Molding Processes (Design &
Optimization Session), June 9-10, 2004, Arlington, Virginia
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Damage and Optimization Models for Analysis and Design of Damage and Optimization Models for Analysis and Design of Discontinuous Fiber Composite StructuresDiscontinuous Fiber Composite Structures
Damage and Optimization Models for Analysis and Design of Damage and Optimization Models for Analysis and Design of Discontinuous Fiber Composite StructuresDiscontinuous Fiber Composite Structures
Acoustic emission techniques to identify damage
Model validation
Damage & failure analyses
- Fibers, matrix - Fiber/matrix interfaces - Microcracks
Continuum
Homogenization
Microscale
Composite representative volume element
Mesoscale
Macroscale
Composite structure
Constitutive relations Evolution laws Finite element analysis
A multiscale mechanistic approach to damage based on micromechanical and continuum damage mechanics descriptions
An optimization approach using the optimal control theory accounting for the composite microstructure
An experimental procedure for acquiring acoustic emission signals to identify damage
PNNL has developed:
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Damage and Optimization Models for Analysis and Damage and Optimization Models for Analysis and
Design of Discontinuous Fiber Composite StructuresDesign of Discontinuous Fiber Composite Structures Damage and Optimization Models for Analysis and Damage and Optimization Models for Analysis and
Design of Discontinuous Fiber Composite StructuresDesign of Discontinuous Fiber Composite Structures
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Optimal Control Theory Approach to Short-Fiber Composites
Fiber volume fractions Fiber aspect ratios Fiber orientation parameter
Optimization of fiber orientation distributionfor the plate under tensile loading. The orientationsare planar with density: e)(
λOptimizer
Using sequential linear programming Determines optimum
Finite Element Analysis Resolution of direct &
adjoint equations Stress/strain computation
Micromechanics Stiffness calculation Derivative of stiffness
Derivative Calculator Lagrange Functional Stationarity conditions
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Current State of the Art in Design and Optimization of Current State of the Art in Design and Optimization of Discontinuous Fiber CompositesDiscontinuous Fiber Composites
Current State of the Art in Design and Optimization of Current State of the Art in Design and Optimization of Discontinuous Fiber CompositesDiscontinuous Fiber Composites
Elastic analysis-based design Micromechanical models rely on material database (fiber volume fraction, aspect
ratio, orientation distribution, etc.) to predict effective properties Process modeling to predict fiber orientation Control of process and microstructural parameters to improve composite stiffness Elastic finite element analysis of the as-formed composite structure
Nonlinear analysis based design: Phenomenological models rely on material database and testing of specimens Nonlinear micromechanical models derived from the self-consistent and Mori-
Tanaka frameworks (e.g. elastic-plastic, damage, creep) PNNL damage models using a multiscale mechanistic approach ORNL micromechanical models
Formal optimization methods Only at the beginning Duvaut et al. (2000). “Optimization of Fiber Reinforced Composites,” Composite
Structures, 48, 83-89 PNNL optimization model using the optimal control theory
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Vision on Future DirectionsVision on Future DirectionsVision on Future DirectionsVision on Future Directions
Design & optimization methods should be reliable to effectively assist processing & manufacturing of composite components and parts Development of new process and constitutive models accounting for the
constituents’ characteristics and properties, and their interaction with each other Interface between process modeling and structural modeling to create and
design a composite part through simulations Processing & manufacturing can rely on efficient design & optimization methods
rather than on trial-and-error approaches Reduce the number of experimental tests and trial moldings
Process modeling Structural modeling Manufacturing
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Perceived GapsPerceived GapsPerceived GapsPerceived Gaps
Where we are now Micromechanical models predict
elastic properties and some nonlinear responses
Process models provide qualitative predictions of fiber orientations in injection molding
Phenomenological constitutive models exist in commercial FE codes for structural analyses
Limited interface between process and structural modeling
Analysis and design are still based on intensive material database obtained through experiments
Initiation of multiscale mechanistic models based on micromechanics and continuum mechanics
Where we should be… Accurate micromechanical models
accounting for concentrated fiber volume fractions
Accurate process models for short- and long-fiber thermoplastic injection molding
Constitutive physics-based models for predicting durability and time-dependent behavior
Interface between process and structural modeling for linear and nonlinear analyses
Optimization methods accounting for process, design and loading variables and constraints
Analysis and design should rely on reliable physics-based models to assist processing & manufacturing
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Research ThrustsResearch ThrustsResearch ThrustsResearch Thrusts
Micromechanics Process micromechanics: Effects of fiber content, length on the
rheology and fiber orientation Micromechanics of materials: Homogenization accounts for interaction
between constituents and defectsContinuum mechanics: Need of constitutive models for Fatigue Time dependent behaviors (creep, relaxation,..) Impact Moisture
Optimization models accounting for nonlinear behaviors Minimization of damage Improvement of durability (fatigue, creep)
Multi-scale modeling From a microstructural to a continuum model