Damage and Optimization Models for Analysis and Design of Discontinuous Fiber Composite Structures :
Damage and Optimization Models for Analysis and Design of Discontinuous Fiber Composite Structures 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:
Damage and Optimization Models for Analysis and Design of Discontinuous Fiber Composite Structures :
Damage and Optimization Models for Analysis and Design of Discontinuous Fiber Composite Structures Optimal Control Theory Approach to Short-Fiber Composites Fiber volume fractions Fiber aspect ratios Fiber orientation parameter
Current State of the Art in Design and Optimization of Discontinuous Fiber Composites:
Current State of the Art in Design and Optimization of Discontinuous 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
Vision on Future Directions:
Vision on Future Directions Design andamp; optimization methods should be reliable to effectively assist processing andamp; 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 andamp; manufacturing can rely on efficient design andamp; optimization methods rather than on trial-and-error approaches
Reduce the number of experimental tests and trial moldings Process modeling Structural modeling Manufacturing
Perceived Gaps:
Perceived 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 andamp; manufacturing
Research Thrusts:
Research 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 defects
Continuum 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