Summary of New DARWIN TM Capabilities for Surface Damage Tolerance Assessment and Related Enhancements

Transcription

1 Summary of New DARWIN TM Capabilities for Surface Damage Tolerance Assessment and Related Enhancements Mike Enright, Luc Huyse, Yi-Der Lee, Graham Chell, Craig McClung, Gerald Leverant Southwest Research Institute Harry Millwater University of Texas at San Antonio Simeon Fitch Mustard Seed Software 6th Annual FAA/Air Force/NASA/Navy Workshop on the Application of Probabilistic Methods to Gas Turbine Engines March 18-20, 2003

2 Overview Review of Previous DARWIN TM Enhancements Zone Refinement Importance Sampling Surface Damage Enhancements DARWIN TM User defined stress/temp DARWIN TM 5.0-3D FE capability Additional Enhancements Mission mixing PC/Linux versions, execute analysis code from GUI GUI Report generation, electronic help system 2

3 DARWIN TM Phase II Code Release Summary GUI enhancements, web site distribution of code Improved K solutions, Inspection transition Element subdivision, zone refinement Surface damage, importance sampling enhancements GUI Report generation, electronic help system PC and Linux versions, execute analysis code from GUI Mission mixing, 3D GUI, additional surface damage 3

4 Zone Refinement (3.5 release) 16 Zones 0 Retrieved 2:30 (2:30) 22 Zones 13 Retrieved 1:53 (3:50) 62 Zones 48 Retrieved 6:02 (25:28) 70 Zones 59 Retrieved 5:05 (30:44) 34 Zones 12 Retrieved 7:42 (11:02) 53 Zones 24 Retrieved 10:58(19:29) 73 Zones 68 Retrieved 2:25 (32:09) Risk as percent of initial model Iteration Number Disk failure probability converges from above with zone discretization DARWIN TM 3.5 provides a semi-automated zone refinement strategy for identifying and subdividing high risk zones 4

5 Under Development: Combined Zone Refinement + Optimal Sampling ZONE REFINEMENT OPTIMAL SAMPLING Probability Density Increasing zone refinement Probability Density Increasing number of samples Disk Failure Probability P f Disk Failure Probability P f For a fixed number of disk samples, primary influence of zone refinement is on mean disk failure probability For a fixed number of zones, primary influence of optimal sampling is on COV of disk failure probability 5

6 Preliminary Results for Combined Approach NORMALIZED FAILURE PROBABILITY (Pf / Pf,1) ZONE REFINEMENT ONLY MEAN (NO INSP) COV (NO INSP) MEAN (WITH INSP) COV (WITH INSP) ZONE REFINEMENT ITERATION OPTIMAL SAMPLING ONLY Zone refinement primarily reduces disk failure probability mean Optimal sampling primarily reduces disk failure probability COV 6

7 4.1 Enhancements: Importance Sampling Confidence Bounds Monte Carlo Confidence bounds introduced in 3.5 release. Failure probability COV is dependent on p F and samples N COV 1 p F = Importance Sampling Confidence bounds added in 4.1 code. Failure probability COV depends primarily on samples N COV = p p F p F N F, tot, wo p F N 2.0E-6 1.5E-6 1.0E-6 5.0E-7 2.0E-6 1.5E-6 1.0E-6 5.0E-7 Without inspection With inspection Monte Carlo (10,000 samples) 0.0E Importance Sampling (100 samples) Without inspection With inspection 0.0E

8 DARWIN TM 4.0 Surface Damage Enhancements 8

9 DARWIN TM 4.0 Surface Damage: Zone Definition Feature-based risk methodology Zones are feature based (e.g., bolt hole) Disk risk = sum of individual zone risks Feature multiplier used to account for multiple identical features User inputs zone information: Plate dimensions Stress/temp gradients 9

10 DARWIN TM 4.0 Surface Damage: New K Solutions Surface damage features are modeled as one of the following crack types: Surface crack Surface crack at Hole Corner crack at Hole Weight function solution method used surface surface at hole corner at hole 10

11 DARWIN TM 4.0 Surface Damage: Plate/Gradient Visualization Gradient of selected load step displayed in plate and plot Plate filled with color gradient mapped directly from gradient points. 11

12 DARWIN TM 4.0 Surface Damage Inherent Vs. Surface Damage Common GUI tools are used to define a number of input variables associated with inherent and surface-damage-based defects Fracture model Material properties Inspections POD Curves Probability methods The remaining input variables are treated separately in the GUI: Crack types Defect distribution Stress & temperature Inherent Embedded, surface, corner FAA Advisory Circular 2D finite element model Surface Damage Surface, surface at hole, corner at hole Under development User defined Risk basis Volume Feature 12

13 DARWIN TM 5.0 Surface Damage Enhancements 13

14 DARWIN TM 5.0 Surface Damage Enhancements Initial 3D GUI for surface damage nearly complete Provides capability to extract stresses from 3D finite element models for use in surface damage analysis Currently limited to 8 node brick elements Additional K solutions for surface damage Offcenter surface crack at offset hole Corner crack at offset hole Through crack at offset hole Can be used in conjunction with 3D GUI DARWIN TM 5.0 Alpha - scheduled for release mid April

15 5.0 3D GUI: Strategy For Surface Damage Import 3D model into GUI GUI provides zoom, pan, and 3D dynamic rotation capability Select surface crack location and propagation plane User selects a surface node GUI locates node and associated principal stress plane GUI computes stresses and temperatures in principal stress plane and translates to a 2D cross section Specify zone properties User rotates plate in 2D cross section to define gradient direction User selects a crack type from surface damage library User selects remaining properties using existing GUI tools 15

16 5.0 3D GUI: Strategy For Surface Damage User selects: Surface Damage analysis mode, 3D geometry mode User imports 3D model geometry 16

17 5.0 3D GUI: Select Surface Crack Location and Propagation Plane Load 3D Model Compute Slice User selects a surface node GUI locates node and associated principal stress plane User adjusts cutting plane orientation as necessary GUI computes stresses and temperatures in cutting plane and translates to a 2D cross section (2D slice) 17

18 5.0 3D GUI: Summary: Surface Crack Location and Propagation Plane 18

19 5.0 3D GUI: Specify Zone Properties User rotates plate in 2D cross section to define gradient direction User selects a crack type from surface damage library User selects remaining properties using existing GUI tools 19

20 Additional DARWIN TM Enhancements 20

21 Mission Mixing (DARWIN TM 5.0) Stress Input Format Developed several formats for importing stress & temperature data for multiple missions: Accepts data from multiple finite element results (UOF) files Added new stress and temperature scaling factors can be applied to some or all of the load steps Introduced zone groups can define specific regions to apply scaling factors or regression results from OEM-specific tools 21

22 Mission Mixing (DARWIN TM 5.0) Load Definition Load cases in UOF may be individually selected Click Button on Mission Editor Select Load Case File (UOF) Pick Load Cases to Include Checked load cases added 22

23 Mission stack defines order of missions Mission Mixing (DARWIN TM 5.0) Mission Stack Definition 23

24 DARWIN TM Enhancements: Computation Speed Improvements Streamlined SIESTA code Now read stresses directly into memory SIESTA still used externally to convert finite element stresses Improved Stress Processing Speed Reduced memory footprint of entire code Reduced disk I/O increases stress processing speed by a factor of 5 Problem 1 Problem 2 Problem 3 DARWIN input file SIESTA GUI Analysis DARWIN h hrs ANSYS file neutral stress file h 40 DARWIN output file DARWIN Ratio

25 DARWIN TM Enhancements: User-Defined Defect Aspect Ratio User can specify the initial flaw dimensions (a, c) for deterministic crack growth computations Existing GUI tools can be used to visualize the influence of initial aspect ratio on crack growth behavior 25

26 DARWIN TM Enhancements: PC and Linux Versions PC and Linux Versions Verified for Windows 95, NT 4.0, 2000, and XP Verified for Linux Suse 8.0 Capability to execute risk assessment code from the GUI Available on all supported computer platforms SUN, HP, SGI, PC, Linux 26

27 DARWIN TM Enhancements: Standard Report Generation Standard report generation is included in 4.1 release Standard report format approved by TRMD Steering Committee GUI automatically creates report in html format Can be edited by user Includes additional plotting features for detailed components 27

28 DARWIN TM Enhancements: On-Line Help System F1-Screen sensitive Help Cross-linked pages Index available Full Text Search Capability Future Goal: Port theory manual to a Web page format. This will be cross-linked, indexed and be full-text searchable. 28

29 Summary Enhancements in current release - DARWIN TM 4.2 Zone Refinement Importance Sampling Surface Damage new K solutions User defined stress/temp PC/Linux versions Execute analysis code from GUI GUI Report generation, electronic help system Enhancements in upcoming release - DARWIN TM 5.0 (April 2003) Surface Damage new K solutions 3D capability Mission mixing 29