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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. Chapter 4 Robust Design 9.0

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-2 9.0 New Features Background of Robust Design What is Robust Design, DFSS, ? Design for Quality Robust Design in Engineering Analysis Illustration Example Sources of Uncertainty Effects of Uncertainty Compare Deterministic and Probabilistic Approach Enabling Technologies Demonstration Overview of Application Example Demo Questions Robust Design Overview

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-3 9.0 New Features Background of Robust Design What is Robust Design, DFSS, etc.? Uncertainty Analysis Quantify the effect of uncertainties on the performance of a product (mean value, standard deviation, etc.) Reliability Analysis Quantify the reliability (failure probability, defects per million) Robust Design or Design For Six Sigma (DFSS) Optimize the design such that it is insensitive to unavoidable uncertainties (e.g. material,loads,) Reliability-based Optimization Optimize the design such that reliability is maximized or failure probability (defects per million) is minimized Robust Design is often synonymous to Design for Six Sigma or Reliability-based Optimization

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-4 9.0 New Features Background of Robust Design Design for Quality Six Sigma Quality = Only 3.4 out of 1000000 parts fail Six Sigma Quality is inherently a probabilistic statement LSL = Lower Specification Limit USL = Upper Specification Limit P.S.: Gaussian distribution is not realistic, but does convey the idea correctly

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-5 9.0 New Features Background of Robust Design Design for Quality quality Six Sigma = Optimize manufacturing processes such that they automatically produce parts conforming with six sigma quality qualityquality Design For Six Sigma = Optimize the design such that the parts conform with six sigma quality, i.e. quality and reliability are explicit optimization goals Design for Six Sigma: Achieve Designed-In quality as opposed to letting customers find out about quality problems Make informed decision that are critical to quality early in the development process

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-6 9.0 New Features FROM: Reactive Quality Management Extensive Design Rework Assess Performance by build-test-build-test- Fix performance/quality problems after manufacturing Quality is Tested-In TO: Predictive Quality Management Controlled Design Parameters Estimate likelihood/rate of performance problems in design & development Address quality problems in design & development Designed for robust performance and quality Quality is Designed-In Background of Robust Design Design for Quality Robust Design is a Paradigm Shift

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-7 9.0 New Features Purpose of Robust Design InputInput ANSYSANSYS OutputOutput Material Properties Geometry Boundary Conditions Deformation Stresses / Strains Fatigue, Creep,... Its a reality that input parameters are subjected to scatter => automatically the output parameters are uncertain as well!! Background of Robust Design Robust Design in Engineering Analysis

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-8 9.0 New Features Questions answered with Robust Design: How large is the scatter of the output parameters? What is the probability that output parameters do not fulfill design criteria (failure probability defects per million)? How much does the scatter of the input parameters contribute to the scatter of the output (sensitivities critical-to-quality)? Background of Robust Design Robust Design in Engineering AnalysisANSYSDesignXplorerANSYSDesignXplorer Purpose of Robust Design

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-9 9.0 New Features PropertySD/Mean % Metallic materiales, yield15 Carbon fiber composites, rupture17 Metallic shells, buckling strength14 Junction by screws, rivet, welding8 Bond insert, axial load12 Honeycomb, tension16 Honeycomb, shear, compression10 Honeycomb, face wrinkling8 Launch vehicle, thrust5 Transient loads50 Thermal loads7.5 Deployment shock10 Acoustic loads40 Vibration loads20 Source: Klein, Schueller et.al. Probabilistic Approach to Structural Factors of Safety in Aerospace. Proc. CNES Spacecraft Structures and Mechanical Testing Conf., Paris 1994 Background of Robust Design Sources of Uncertainty

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-10 9.0 New Features CFD FEMCAD FEM Geometry Materials, Bound.- Cond., Loads,... Materials, Bound.- Cond.,... Materials, Bound.- Cond., Loads,... LCF Materials 0.1-10% 5-50% 5-100% 30-60% ??% 5-100% Thermal Analysis Structural Analysis Background of Robust Design Effects of Uncertainty

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-11 9.0 New Features Influence of Youngs Modulus and Thermal Expansion Coefficient on thermal stresses: thermal = E T Deterministic Approach: Mean = E Mean Mean T Mean = typically used results Probabilistic Approach: Probability that ( thermal >= 105% Mean ) ( thermal >= 110% Mean ) E scatters 5% 16% (~1 out of 6) 2.3% (~1 out of 40) E and scatter 5% 25% (~1 out of 4) 8% (~1 out of 12) E, & T scatter 5% 28% (~1 out of 4) 13% (~1 out of 8) Background of Robust Design Effects of Uncertainty

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-12 9.0 New Features Turbine What-If Analysis Series Background of Robust Design Compare Deterministic/Probabilistic

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-13 9.0 New Features Background of Robust Design Enabling Technology: Parameterization Robust Design for all parameters including CAD

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-14 9.0 New Features Background of Robust Design Enabling Technology: Parameterization Robust Design Supports APDL Parameters

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-15 9.0 New Features Background of Robust Design Enabling Technology: Parameterization Robust Design Supports ParaMesh Parameters ParaMesh for Geometric Type of Parameterization For Legacy Models or Models with Signifiant FEA Abstraction such that CAD update is problematic Example Ansys Input File: ! File inp_parabatch.inp value=0 /syp,parabatch.exe,'testpb.rsx','testpb.cdb','location',%value%,'testpb_mod.cdb' /inp,testpb_mod,cdb ! Input the modified geometry /solu Solve! Solve it fini /post1 set,first *get,ndepright,node,232,u,z ! Get results *get,ndepleft,node,2,u,z depdiff=ndepleft-ndepright fini Paramesh dbInitial mesh Parameter name Parameter value Output mesh Import Output mesh

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-16 9.0 New Features Background of Robust Design Enabling Technology: DesignXplorer DesignXplorer manages the parameters and the uncertainties

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-17 9.0 New Features CAD GeometryFEM Mesh FEM Boundary Conditions Robust Design Demonstration Overview of Application Example

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-18 9.0 New Features Results for Maximum Principal Stress Pressure SideSuction Side Peak Value s Tang. Leaning Axial Leaning Dove Tail Width Material Density (Gaussian) Fillet Radius (Lognormal) Mass Design Variables and Uncertainties Imbalance: ( p s ) 2 Avg.Stress: 0.5( p + s ) Peak Value p Robust Design Demonstration Overview of Application Example

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-19 9.0 New Features Robust Design Demonstration Robust Design Demonstration Demonstration

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. DesignXplorer Family 9.0

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-21 9.0 New Features DX Family 9.0 New Features DesignXplorer Family (DesignXplorer and DesignXplorer VT) GUI Structure Robust Design - Parameterize DFSS Results New Robust Design View Optimize DFSS Results New Trade-Off Study Genetic Algorithm for Sample Generation Variational Technology (DesignXplorer VT) Support of Discrete Variables in Workbench RSX File Viewing Additional Contact Support 2D Analysis

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-22 9.0 New Features DX Family 9.0 New Features GUI Structure DFSS Charts Page Measures of robustness CDF Plot Y-Axis can be scaled as Gaussian, Log-Normal, Weibull, Exponential

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-23 9.0 New Features Separate DFSS Table Page Statistics Available Customize Tables (add, delete) Sigma-Level in Tables DX Family 9.0 New Features GUI Structure

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-24 9.0 New Features New Robust Design View New DFSS Parameters showing up in Parameter View DX Family 9.0 New Features Parameterize DFSS Results

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-25 9.0 New Features DX Family 9.0 New Features Optimize DFSS results 1) 2) 2) Design Variables: Useable for Robust Design Optimization 1) Random Variables: Uncontrollable used to obtain DFSS results

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-26 9.0 New Features Same optimization functionality as for GDS DX Family 9.0 New Features Optimize DFSS results

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-27 9.0 New Features DX Family 9.0 New Features Trade-Off Studies Mouse-Over Results Pareto Front for Conflicting Goals, Tradeoffs Occur Here Both 2D and 3D Tradeoff Plots are available

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-28 9.0 New Features Mouse- Over Results Pareto Front for Conflicting Goals Infeasible Points in Pareto Front InfeasibleFeasible DX Family 9.0 New Features Trade-Off Studies

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-29 9.0 New Features Choice of Basic (Screening), which is pseudo-random sampling method typically done first, or Advanced (Genetic) Algorithm which is typically done second DX Family 9.0 New Features Genetic Algorithm Sample Generation

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-30 9.0 New Features Advanced sample options DX Family 9.0 New Features Genetic Algorithm Sample Generation

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-31 9.0 New Features Advanced Sample Screening Sample DX Family 9.0 New Features Genetic Algorithm Sample Generation

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-32 9.0 New Features Variational Technology is much faster than DOE for discrete parameters DesignXplorer VT 9.0 Support of Discrete Variables in Workbench

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-33 9.0 New Features Efficient multi- objective Boolean optimizer based on Bayesian sampling faster optimization of discrete parameters Boolean scatter chart representing the solution points of all the parameter combinations of the selected parameters. DesignXplorer VT 9.0 Support of Discrete Variables in Workbench

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-34 9.0 New Features Allows user to view Variational Technology results from a variety of sources including DesignXplorer VT (of course) ANSYS using VT ParaMesh 3 rd Party Variational Technology Applications DesignXplorer VT 9.0 RSX File Viewing Hoover model solved with VT with the ANSYS Environment

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-35 9.0 New Features DesignXplorer VT 9.0 Support for Face-to-Edge Contact

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-36 9.0 New Features DesignXplorer VT 9.0 Support for Edge-to-Edge Contact

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-37 9.0 New Features DesignXplorer VT 9.0 2D Analysis Allows Variational Technology analysis of 2D Simulation studies to include: Axisymmetric Plane Strain Plane Stress

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ANSYS, Inc. Proprietary 2004 ANSYS, Inc. October 1, 2004 Inventory #002156 4-38 9.0 New Features DesignXplorer and DesignXplorer VT Thank you! Questions? Additional Questions: Ray Browell (724) 514-3070 ray.browell@ansys.com Additional Information: http://www.ansys.com/