2018 ncode User Group Meeting North America February 28 March 1

Transcription

1 2018 ncode User Group Meeting North America February 28 March 1

2 An In depth look at the differences Between the Duty Cycle and the Aerospectrum Loading Types Ben Madsen Aerospectrum Spectrum Order Aerospectrum Sequential Order Duty Cycle Time History Compressed

3 Intro to General Atomics 3 General Atomics Systems Integration, LLC (GA SI), an affiliate of General Atomics, is a provider of military and commercial engineering services. GA SI is a leading edge expert in systems integration technologies, reliability improvements, and controls system design17 years Improving Military Aircraft for 17 years Landing Systems Failure Investigation Load Development Redesign Testing (flight, qualification, certification) Maintenance and Flight Services GrayEagle, MQ 1, MQ 9 UAVs Ben Madsen Analysis Supervisor Testing (validation, correlation) Analysis (FEA & Fatigue Analysis)

4 Finite Element based Fatigue Analysis 4 ANALYSIS /TEST FE Damage Modeling LOADS STRESS HISTORIES LIFE SN Plot of : Z-Specimen Database : nmats 600 Mean Type : R-ratio Stress type: RANGE Stress 400 Stress Units: MPa UTS: E value: e E4 1E5 1E6 1E7 Cycles

5 FEA Unit Loading 5 Unit Load 1 L 1 =1 L 2 =1 C 1 C 2 C 1 x C 2 x Unit Stress x Real Load L 1 Over Time 1 + Unit Stress x Real Load L 2 Over Time = C = FE Stress tensor for Unit Load Cases Stress from time signal at element (L 1 direction)

6 Superposition and Time Histories 6 L 1 L 1 A Stress time signal at element L 2 L 2 Stress for combined loads calculated by FE point by point

7 Load Providers 7 Load Providers A load provider provides loading information that allows the analysis engines to use the FE analysis results to calculate the fluctuating stresses (or strains) required for fatigue analysis The chosen load provider assemble FE results sets into stress histories Constant amplitude Time Step Time Series Duty Cycle (including Aerospecturm) All approaches will give the same overall answer for life How load data is described and input Detailed event data output Options can change life result Time history compression Sequencing Event processing

8 Duty Cycle 8 Duty Cycle A Duty Cycle load provider allows a time history to be constructed from sequences and repeats of the other load providers Each duty cycle consists of an event and a repeat count Mix and match load providers Many structures see more than a single loading event Allow multiple events sequenced into an overall total life history Channel mapping can differ from event to event Can provide additional detailed output about events Provides different combination methods to balance between efficiency and accuracy Event Processing Time history compression Sequential sequencing Nested (duty cycles within duty cycles) Two types; standard time based (.dcy) and aerospectrum

9 Duty Cycle Time Series 9 Time Series load provider provides the information that an analysis engine needs to create a stress or strain history by scaling and linear superposition of FE results. Static superposition combination Time Series can be measured values from testing Long time histories may have solution time and disk space requirements Allows for time history compression defined % threshold of cycles are removed

10 Duty Cycle Aerospectrum 10 Utilizes load & spectrum file Allows for defined sequenced load events in time history Allows for detailed damage output Detailed damage report down to individual events Detailed damage report down to maneuver (example: taxiing) Multicolumn filter & manipulation (glyphs) can be used to consolidate reports Event type flights can rearrange flight sequences to maximize the flight mix Maximize cycles across flights (may produce max conservative damage if susceptible to sequence) Loads file L1 & L2 List of Events Pushback 100, 20 Taxi 40, 10 Left turn 0, 30 Right turn 0, 30 Take off 40, 0 Landing A 150, 20 Landing B 200, 30 Braking 100, 20 Spectrum file Flight Definition Example Flight, 1, 3 BackAway, 1, Pushback, Left turn, Taxi, Right turn Taxiing, 10, Taxi, Left turn, Taxi, Right turn, Taxi TakeOff, 1, Take off Landing, 1, Landing A Braking, 2, Braking Taxiing, 5, Taxi, Left turn, Taxi, Right turn, Taxi

11 Event Output Post processing damage by event (e.g. aircraft braking event) 11

12 Flight Output 12 Post processing damage by flight (e.g. multiple aircraft events: landing, braking, taxi, etc.)

13 Flight Output 13 Post processing damage by flight

14 Example 14 Duty Cycle Time Series vs. Aerospectrum (see ncode example demonstration)

15 Ben Madsen General Atomics si.com