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Effective State Awareness Information is Enabling for System Prognosis

Effective State Awareness Information is Enabling for System Prognosis. Mark M. Derriso Advanced Structures Branch Air Vehicles Directorate Air Force Research Laboratory. Workshop on Prognosis of Aircraft and Space Devices, Components, and Systems February 19-20, 2008 – Cincinnati, OH.

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Effective State Awareness Information is Enabling for System Prognosis

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  1. Effective State Awareness Information isEnabling for System Prognosis Mark M. Derriso Advanced Structures Branch Air Vehicles Directorate Air Force Research Laboratory Workshop on Prognosis of Aircraft and Space Devices, Components, and Systems February 19-20, 2008 – Cincinnati, OH

  2. Overview Workshop Topics: • “…In the future, the USAF would like to develop state awareness monitoring capabilities that could enable accurate prediction of the remaining service life and future performance capability of critical components as well as be used to take specific corrective actions to assure mission completion and minimize operating cost and risk.” This is Integrated Systems Health Management!

  3. Determine Ability to Perform Mission Determine Ability to Perform Mission Assess Damage Assess Damage Detect Damage Detect Damage

  4. Critical Components Damage Data Analysis Sub-systems Measurands Multiple 0.02 inch Cracks in fuselage HM Data Structural Health Management Flight Control Actuator Frozen at 20 degrees HM Data Controls Health Management Bearing Spalling HM Data Engine Health Management LRU is Malfunctioning HM Data Electronics Health Management

  5. CL max T max Altitude q max Mach System Performance System Performance Bounds Multiple 0.02 inch Cracks in fuselage Vehicle-Level Health Status Data Analysis Flight Control Actuator Frozen at 20 degrees Bearing Spalling LRU is Malfunctioning

  6. Airframe Design (Device, Component, or System) STRUCTURE MATERIAL Materials Processing Manufacturing Loads, Boundary Conditions, Operational Environment Materials Properties Uncertainty_Total = U_material + U_manufacturing + U_operational UNCERTAINTY associated with each of these areas that propagates through to the system level

  7. Design for Uncertainty • Damage-tolerant design • Damage-tolerant is the property that enables a system to continue operating properly in the event of the failure of (or one or more faults within) some of its components. If its operating quality decreases at all, the decrease is proportional to the severity of the failure • Safe-life design • The Safe-life design technique is employed in critical systems which are either very difficult to repair or may cause severe damage to life and property. These systems are designed to work for years without requirement of any repairs. F-4 F-16

  8. Failure Mode, Effects, & Criticality Analysis (FMECA) • FMECA • The objective of FMECA is to identify the components of products and systems most likely to cause failure, so that these potential failures can then be designed out. • FMECA allows the identification early in the product development process of potential problems or safety hazards which are inherent in a product design.

  9. Closure Spar F-15 Wing Rear Spar Main Spar Front Spar Conduit Hole (hot spot) V&V of Airframe Design Structural Design Problem Areas Identified Airframe Prognosis: No Failures Throughout Design Life Full- Scale Fatigue Testing Inspection Schedule Constructed

  10. Airframe Prognosis • However, requirements changes • Vehicles asked to perform different missions • Vehicles modified to fulfill new purposes • Vehicles asked to serve past original design life • What is the prognosis then? • Vehicle prognosis based on airframe prognosis

  11. Operational Uncertainty • External Loading • maneuvers, gusts, taxi-loads • Internal Loading • bending, torsion, shear • Environmental Conditions • temperature, humidity All are Factors the Effects Fatigue Life

  12. State Awareness • State awareness refers to knowledge regarding the current condition or capability • For airframe subsystems, state awareness is from the diagnostic portions of the structural health monitoring (SHM) system which detect, localize and assess any damage • State awareness allows subsystem prognosis which enables overall system prognosis

  13. Definition of SHM • SHM refers to automated methods for determining adverse changes in the integrity of mechanical systems • SHM system capability is typically broken into the following levels of increasing difficulty: • damage detection • damage localization • damage assessment • life prediction diagnosis prognosis

  14. SHM Development Process

  15. Damage detection sensor Ultrasonic wave propagation model Requirements and knowledge of structural behavior and loads Sensing technology and sensing system design + SHM System Design Maintenance Benefit SHM Development Framework

  16. State Awareness Architecture Based on Col Boyd’s OODA Loop Predictions (physics-based models, trending) The Real World Experience & Knowledge Reasoning Process Data Analysis Measurands Loads, damage, etc.. Current State Information

  17. The ISHM Goal “I don't care about what anything was DESIGNED to do, I care about what it CAN do”.

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