Examples of Current Research in “State Awareness” for Digital Models: ICME and NDE Links to Structural Analysis Michael Enright Craig McClung Southwest Research Institute San Antonio, Texas Digital Twin Roadmap Workshop NASA Langley Research Center September 10-11, 2012

Examples of Current Research in “State Awareness” for Digital Models Goal of “State Awareness”: Incorporate relevant digital information about the condition of the material/component into the digital models for calculation of life and reliability Examples: Calculate full-field, location-specific bulk residual stress or microstructure resulting from the manufacturing process, and use the information to inform the fatigue crack growth life and reliability predictions Calculate location-specific Probability-of-Detection (POD) curves and use the information to inform the structural reliability prediction

DARWIN Overview Design Assessment of Reliability With INspection Life Scatter Stress Scatter 3 Copyright 2012 Southwest Research Institute

Integration with Manufacturing Process Simulation Link DEFORM output with DARWIN input  Finite element geometry (nodes and elements)  Finite element stress, temperature, and strain results  Residual stresses at the end of processing / spin test  Location specific microstructure / property data  Tracked location and orientation of material anomalies 4 Copyright 2012 Southwest Research Institute

DARWIN-DEFORM Links Residual Stresses Microstructure Anomaly Tracking and Deformation 5 Copyright 2012 Southwest Research Institute

Effect of Material Processing Residual Stress on FCG Life Stress Life Without Residual StressWith Residual Stress 6 Copyright 2012 Southwest Research Institute

Effect of Material Processing Residual Stress on Risk Life Without Residual StressWith Residual Stress Risk 7 Copyright 2012 Southwest Research Institute

DARWIN-DEFORM Links Residual Stresses Microstructure Anomaly Tracking and Deformation 8 Copyright 2012 Southwest Research Institute

9 Demonstration Example: Influence of Grain Size Scaling on Life & Risk ANSYS ABAQUS DEFORM DARWIN Stress Results Files Grain Size Results File grain size contour service stress contour Copyright 2012 Southwest Research Institute

10 Influence of Grain Size Scaling on Crack Growth Rate grain size contour crack growth rate multiplier C=1.56 x n 2 =3.66 Nominal values: Copyright 2012 Southwest Research Institute

Effect of Location-Specific Grain Size Scaling on FCG Life a=0.01” Without Grain Size ScalingWith Grain Size Scaling a=0.02” 11 Copyright 2012 Southwest Research Institute

Effect of Location-Specific Grain Size Scaling on Risk Life Without Grain Size ScalingWith Grain Size Scaling Risk a=0.01” 12 Copyright 2012 Southwest Research Institute

Overall Vision to Link DEFORM & DARWIN Phase I/II Work Phase II Work Future work Residual Stresses 13 Copyright 2012 Southwest Research Institute

Example: Random Residual Stress Modeling Design of Experiments  Identify values of input variables for response surface construction in DEFORM using Latin Hypercube sampling  Perform deterministic DEFORM runs to determine residual stress values at all nodes within FE model Response Surface Fitting  Determine the residual stress response at selected locations within the FE model in DARWIN using Gaussian Process (GP) model  Determine response along the crack path in DARWIN using GP model combined with Principal Components Analysis Monte Carlo Simulation  Propagate random variables through response surface in DARWIN to determine the random residual stresses along the crack path and influence on life and risk values 14 Design of Experiments Response Surface Monte Carlo Copyright 2012 Southwest Research Institute

Awareness of Existing Cracks: NDE POD Considerations The DARWIN analysis framework permits reduction of risk based on finding cracks during occasional NDE inspections Key random inputs to this calculation are the uncertain time of inspection and the POD curve The POD curve depends on inspection method/calibration and could also vary from location to location 15

Linking DARWIN with MAPOD Model-assisted POD technology (based on the same digital component models) can be used to generate location-specific POD curves for improved reliability analysis 16

Conclusions Some of the fundamental elements of “state awareness” for life and reliability management using digital structural models and advanced commercial software are already under development More work is needed! 17