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System Design Constraints, RAM-T, a Paradigm Shift Vern Fox United Defense LP.

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Presentation on theme: "System Design Constraints, RAM-T, a Paradigm Shift Vern Fox United Defense LP."— Presentation transcript:

1 System Design Constraints, RAM-T, a Paradigm Shift Vern Fox United Defense LP

2 2 Agenda RAM-T Overview Legacy Methods Legacy Results Paradigm Shift: RAM-T Case Implementation

3 3 RAM-T Overview What is RAM-T Reliability - The ability of a system or component to perform its required functions under stated conditions for a specified period of time. Availability – the ability of a product to be ready for use when the customer wants to use it (uptime/uptime+downtime) Maintainability - the relative ease and economy of time and resources with which an item can be retained in, or restored to, a specified condition when maintenance is performed by personnel having specified skill levels, using prescribed procedures and resources at prescribed level of maintenance and repair. Testability – A design characteristic which allows the status (operable, inoperable or degraded) of an item to be determined and the isolation of failures within the item to be performed in a timely manner. System Design Constraints

4 4 Legacy Methods Perform predictions Based on handbook data Based on similar equipment Address SOME RAM-T drivers RAM-T optimized during test Low initial RAM-T High test hours, high $s Legacy Approach AssessmentsSubsystem Int System Int and Test Preliminary DesignDetailed DesignTestFielding Late identification of component RAM-T shortcomings limits corrective action Eliminate some component RAM-T drivers Fix integration issues Update design Eliminate some component RAM-T drivers Fix integration issues Update design

5 5 Legacy Results Of Failed Tests, 75 % Of Systems Failed to Achieve Even Half Of Their Requirement! Of Failed Tests, 75 % Of Systems Failed to Achieve Even Half Of Their Requirement! (Data Oct 01) Only 30% Success

6 6 Paradigm Shift: RAM-T Case Legacy methodologies failing Methodology required for infusing RAM-T into design Criteria Early, influence design during design phase Return on Investment (ROI) Result: Paradigm Shift – RAM-T Case Make case for how RAM-T requirements will be met Combination of analyses and tests o Physics of Failure (PoF) analyses o RAM-T Enhancement Tests (RET) RAM-T Case Management Plan RAM-T Case Report Elevate RAM-T constraint importance

7 7 Paradigm Shift Legacy Approach RAM-T Case Approach Emphasize: Early identification and elimination of RAM-T shortcomings Example: Achieve Higher M i on prototype delivery AssessmentsSubsystem Int System Int and Test Preliminary DesignDetailed DesignTestFielding PoFRETSubsystem Int System Int and Test Early identification and elimination of component level failures Late identification of component RAM-T shortcomings limits corrective action Eliminate some component RAM-T drivers Fix integration issues Update design Eliminate component reliability drivers Update design Eliminate component reliability drivers Update design Fix integration issues Update design Fix integration issues Update design Eliminate some component RAM-T drivers Fix integration issues Update design

8 8 Paradigm Shift: RAM-T Case Make case for meeting RAM-T requirements Documented in RAM-T Case Management Plan A living document, updated throughout the program Plan and supporting data subject to approval RAM-T requirements are clearly understood Methods/activities to be performed to make case Ensure RAM-T is key factor in the design process Ensure RAM-T is of equal weight with other engineering disciplines RAM-T Case Report A living document, updated throughout the program Reasoned, auditable documentation of progressive assurance that RAM-T requirements will be met Audit trail of engineering considerations, trade studies, analyses and assessments

9 9 Paradigm Shift: RAM-T Case A RAM-T Case Program/Plan sample contents Benchmarking RAM-T Requirements Dynamic/static design modeling, simulation, or probabilistic analysis Critical component identification RAM-T Modeling, Optimization and Component/System Testing Environmental stress (operate and storage) Physics-of-Failure (PoF) Structural finite-element stress analysis Fatigue analysis Wear-out/service life analysis Long-term storage (shelf life) assessment Prognostics analysis Fault detection/isolation analysis Built-in Test False alarm rate analysis Availability Analysis On-board Sparing: Supportability analysis RAM-T Block Diagram RAM-T Assessments Analysis Risk assessment & mitigation Diminishing resources/obsolescence plan Pit Stop Engineering

10 10 Paradigm Shift: RAM-T Case RAM-T Case Management Plan Methods/activities to be performed to make case Goal - Robust designs Physics of Failure (PoF) Finite Element Analysis (FEA) Fatigue Analysis Probabilistic Analysis calcePWA Analysis Pit-Stop Engineering RAM-T Enhancement Testing (RET) Highly Accelerated Life Testing (HALT) Accelerated Life Testing (ALT)

11 11 Physics of Failure, -Model the root causes of failure (e.g., fatigue, fracture, corrosion & wear) CAD tools developed - By industry/academia/government - To address specific materials, sites, & architectures Benefits Design-in reliability Eliminate failures prior to test Increased fielded reliability Decreased O&S costs Benefits Design-in reliability Eliminate failures prior to test Increased fielded reliability Decreased O&S costs Stress (e.g., vibration) is propagated from system level to failure site Root-cause failure is cracking of solder joint Engineering-Based Reliability

12 12 Software Tools Solid ModelingDynamic Simulation Finite Element Modeling Fatigue Analysis Thermal Fluid Analysis Electronic Circuit Card and IC Toolkits

13 13 CalcePWA Circuit Card Tool CalcePWA Circuit Card Tool PoF-Based ESS Accelerated Life Testing on critical board or IC failure mechanisms Accelerated Life Testing on critical board or IC failure mechanisms Thermal Conditions Enclosure Design Vibration/Shock Environment Physics of Failure to Evaluate Electronics Computational Fluid Dynamics Model Computational Fluid Dynamics Model Circuit Card Design Determine if electronics are acceptable based on analysis Determine if circuit card or enclosure can be redesigned to eliminate failure mechanism Determine if electronics are acceptable based on analysis Determine if circuit card or enclosure can be redesigned to eliminate failure mechanism

14 14 Examples: ICEPAK, FLOWMAX, University of Maryland CalceCFD Inputs Exterior ambient air temperature Initial temperature Fan properties Power dissipated for each CCA Outputs Interior air velocity Interior air temperature CCA edge temperature Outputs from CFD analysis used as boundary conditions for CCA thermal modeling Computational Fluid Dynamics (CFD) Modeling

15 15 Reports and documentation Toolbox Architecture & environment modeling Thermal analysis Vibration analysis Failure assessment & sensitivity analysis UMD CalcePWA Software Tool

16 16 Radar Ground Station Analysis showed commercial circuit card OK Identified weak link in design & verified Validated with testing Tri-Service Radio $27M Cost Avoidance Air Force analysis showed commercial ICs OK Army Helicopter Tracked Vehicle Identified potential thermal & vibration problems Air & Ground System Electronics Circuit card & thermal box-level analyses Identified problems & ensured reliable expansion of capability Missile System $50M Savings Analysis on Plastic Ball Grid Array IC package $1.2M Saved Increased Reliability Evaluate New Technology Design Changes Recommended Electronics Circuit Card Success Stories

17 17 List of Critical Nodes Dynamics Analysis FE Model System Model FEA Fatigue Life Assessment Reliability Based Design Optimization DRAW Pro/E DADS NASTRAN Dynamic Load Analysis Solid Modeling Component Stress Analysis Reliability Analysis Fatigue Analysis Using Dynamic Simulation & FEA Terrain Model

18 18 CAD: Pro/Engineer, AUTOCAD, I-deas, Solidworks, Used for design and manufacture Used to develop Finite Element Analysis & Dynamic Analysis models Three-Dimensional CAD Solid Models

19 19 Examples: NASTRAN, ANSYS, ABACUS, Pro/Mechanica, I-deas Calculates vibration modes Calculates stress and strain Input into fatigue analysis Used for structural stress evaluation Finite Element Analysis (FEA) Models Mode 1 Mode 2

20 20 Examples: DADS & ADAMS Multi-body approach Use input from solid model & FEA model Experimental data used for model inputs of tire, shock absorbers & suspension Determines force/ acceleration time history at all locations on trailer Vehicle traversing simulated terrain profile Flexible-Body Dynamic Analysis Model Input into FEA & fatigue analyses

21 21 Fatigue Analysis Software Examples: nCode, LMS, University of Iowa DRAW Edits & characterizes strain time histories Rainflow counting & mean stress correction of strain cycles Estimates plastic strain based on elastic stress or strain calculations Calculates fatigue life based on measured (strain gauge) or FEA strain time histories

22 22 Trailer Physics-of-Failure Project White represents low fatigue life Fatigue life estimates of drawbar consistent with failure data Enlargement of Critical Region Life (Blocks) Critical Point Benefits: Early identification of failure modes Better test planning and design Improved maintenance procedures

23 23 Paradigm Shift: RAM-T Case Pit-Stop Engineering User/Maintainer hardware interface as a key design parameter Develop Standards of Excellence Defines the critical parameters Examples 37 pounds maximum for an electrical assembly. Spares on board to provide on board failure recovery. Placement of electronics should be on exterior man accessible surfaces, no buried electronics. No cables in places where they cannot be accessed. Use common connectors throughout. Etc. Visualization for decision making

24 24 Paradigm Shift: RAM-T Case

25 25 Paradigm Shift: RAM-T Case

26 26 Paradigm Shift: RAM-T Case

27 27 Paradigm Shift: RAM-T Case Reliability Enhancement Testing (RET) Testing focused on Reliability improvement Objective Find failure modes Eliminate failure modes Mitigate those not able to eliminate Period of performance Once hardware is available Methodologies Use up the life of the product Normal use (years) Accelerated life test (weeks or months) Highly accelerated life test (days)

28 28 Paradigm Shift: RAM-T Case Load Levels Upper Destruct Limit Upper Operating Limit Upper Design Limit Upper Specification Limit Lower Specification Limit Lower Design Limit Lower Operating Limit Lower Destruct Limit Nominal Upper Design Margin Lower Design Margin Upper Destruct Margin Lower Destruct Margin Upper Operating Margin Lower Operating Margin

29 29 Paradigm Shift: RAM-T Case Environmental Stress Chamber with Unit Under Test (UUT) Powered-up and Functioning under load Test Equipment Providing real-time status of UUT performance

30 30 Implementation Embrace the philosophy Determine critical items Put together multi-disciplined team Reliability Improvement Working Group (RIWG) Determine RAM-T Case methodologies Document in Action Plan

31 31 Implementation Reliability Improvement Working Groups Integrated, collaborative team composed of design, specialty, and test personnel to develop Action Plans for critical components to improve the reliability early in the design process. Action Plans cover proactive reliability tasks such as design reviews, load/stress surveys, failure mode analysis, physics of failure, probabilistic analysis, and reliability enhancement testing. Forum for discussing Action Plans with and receiving input from reliability improvement experts from customer, OPM, AMSAA, AEC, and other government and industry organizations.

32 32 Implementation Risk Mitigation & Proactive Reliability Tasks Note: Planned through March 2004 unless otherwise indicated Note (1): Planned by PDR

33 33 Implementation Emerging Findings, Physics of Failure, FEA Recoil Seal The gaps show that the whole surface area is not being used to seal.

34 34 RIWG Projected Costs Emerging Findings, RET Rammer Chain Housing Material Material Sample Result: Influenced material selection Significant parameters: Wear and heat buildup


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