Summary:
Focus: Digital Twins for complex physical systems
Computational challenges:
Example: injecting resin into mold to create parts
Flow: rate depends on pressure non-linearly
Solids
Scale mixing
High range of reynolds numbers
High gradient (changing quickly over space)
Multiphysics at multiple scale
Different physical processes coupled at microscopic scale
Data-physics driven multiscape approach for high-pressure resin transfer molding
Molding parts of large devices (cars) quickly and reliably
We have a mold
Inject resin into the mold at high pressure
Cure the resin
Model: Navier-Stokes fluid flow
Single-phase saturated flow model
Two-scale composite
Non-linear relation between average velocity and pressure gradient
Non-linear map from micro-scale finite volumes to macro-scale mold’s behavior
Unique solution: given pressure gradient one can uniquely determine average velocity and instantaneous permeability
Thus, can train a neural surrogate of these two bi-variate relationships (99.9% accuracy after 5 minutes training)
3-scale model
Microscale representative volume: porous medium
Mesoscale representative volume: fluid, with history dependence
Macroscale
Fit a neural surrogate to this 3-scale model with high accuracy (different nets for the scales)
Reduced Order Homogenization for component analysis
We have a solid that has been cured curing manufacturing
Transformation field analysis
Fine-scale train can be computed from the coarse scale strain
Small changes in volume/strain induces a deviation in shape
Need to compute the eigen-strains:
independent types of macro deformations and how they affect the micro-state
Eigen-strains need to be discretized
Inference of eigen-strains
Trained a Recurrent neural network (GRU) on high-fidelity model of the micro behavior
Several runs of high-fidelity model produces the history of the process, which simplifies the training process
Bayesian inference uses neural network model to optimize
Produces a high-quality model with good values of free parameters
Coupled Chemo-Thermo-Mechanical Multiscale model for predicting effects of manufacturing on the product
Interactions among:
Temperature-induced crystallization
Thermal strains
Effective material properties
Multi-scale approach makes it possible to predict defects in micro-structure (prior work could only predict for macro-structure)
Was used to model impacts on car bodies, which enables GM to use lighter materials
Summary:
Data-driven physics multi-scale model can approximate Navier Stokes well
Multi-phase and multi-scale modeling is needed to account for all the phenomena with resins
Prediction: integrated multi-scale analysis tools for digital twins will become practically used in 5-7 years
Observations:
In using data-driven models, start with simple approaches
Few parameters
Phenomenological
Data-driven approximations work best when solutions are unique
When the model is history-dependent the training challenge is much larger
Good use-case: model reduction
Analytic and data driven models need to be validated using experimental data in similar