NASA Technical Reports Server (NTRS) 20150023568: X-56A MUTT: Aeroservoelastic Modeling PDF
Preview NASA Technical Reports Server (NTRS) 20150023568: X-56A MUTT: Aeroservoelastic Modeling
X-56A MUTT Aeroservoelastic Modeling X-56A Aeroservoelastic Modeling 1 Background X-56 MUTT 2 Center Bodies 1 Stiff Wing Set 3 Flexible Wing Sets 1 Ground Control Station • With Simulation and SIL Capabilities 28 Ft Span 480 lb GTOW 150 Knots 10,000 ft 2 X-56 Modeling Overview • Nonlinear Piloted • Linear NDoF Models v7.030 Simulation – High order – Currently only rigid body – Accurate model of aeroelastic dynamics dynamics • Limited to stiff wing – Usage – High fidelity • Control law design • Nonlinear aerodynamics, • Control law analysis freeplay, etc. • Design of programed test – Usage inputs • Aircrew training • Failure modes and effects testing • Yaw control 3 NDoF Model Development • Stiff Wing • Flex Wing – Development of the modeling – Prediction of body freedom methodology flutter • Identical approaches used for – Demonstration of flutter both wing sets suppression • Only differences is finite element parameters – V&V of modeling methodology • Validation of stiff wing models is validation of flex wing models • Calibration of rigid body parameters directly applicable to flex wings – Refinement of model requirements Spiral Development Model (Boehm) 4 Modeling and Simulation SYSTEM & ANALYSIS FRAMEWORK 5 Modeling Approach • Linear NDoF Models 𝑥 𝐴𝑠 𝐶𝑟 𝐶𝑒 0 𝐷𝑠𝑐 𝑥 0 𝑠 𝑠 0 𝐴 𝐴 𝐷 𝐵 0 𝑥 𝑟𝑟 𝑟𝑒 𝑟 𝑟𝑐 𝑥 – 260 Total States 𝑓𝑑 = 0 𝐴 𝐴 𝐷 𝐵 𝑓𝑑 + 0 𝑢 𝑥 𝑒𝑟 𝑒𝑒 𝑒 𝑒𝑐 𝑥 𝜉 0 𝐸 𝐸 𝑅 𝐸 𝜉 0 • 6 Rigid Body Modes 𝑟 𝑒 𝑐 𝑥 𝑥 𝑎𝑐𝑡 𝑎𝑐𝑡 0 0 0 0 𝐴 𝐵 • 30 Elastic Modes 𝑎𝑐𝑡 𝑎𝑐𝑡 – 2 states each Variable Description • 108 Aerodynamic Lag States 𝑥 Sensor States 𝑠 • 44 Sensor States 𝑥 Rigid Body (Flight Dynamic) States 𝑓𝑑 • 36 Actuator States 𝑥 Elastic (Structural) States 𝜉 – Models at discrete flight 𝑥 Actuator States 𝑎𝑐𝑡 conditions Nonzero Elements of the A Matrix • Airspeed 0 • Fuel Weight 50 – Updated with data from nonlinear simulation 100 • Sensor Dynamics and Noise 150 • Tuned wind tunnel 200 aerodynamic data • Weight and Balance 250 0 50 100 150 200 250 nz = 15068 6 Modeling Architecture (N2 Chart) Mass Properties Model Structural Dynamics Model Aero Model Sensor Model Actuator Model Engine Model NDoF Model & Simulation 7 Detailed N2 Chart Rigid Body Inertial CONM2 Mass Properties Matrix ASSIGN FEM DOE FEM FEM Modal Ground Model Mass and Testing Tuning Stiffness Wind MATLAB Tunnel Paneling MKAEROZ AIC MKAEROZ Spline SPLINE1 MDAO Model GAF MATLAB Tuning State RFA Space Sensor Transfer Models Function Actuator Transfer Models Function Engine Transfer Model Function State LPV Space System Models Control VMC Inputs Feedback Simulation – Non-inertial coordinate system – Used for aerodynamic loads – Non-inertial coordinate system – Nonlinear simulation equations of motion – Inertial coordinate system – Used in structural model – ZAERO’s aerodynamic model – X & Z flipped from earth fixed coordinates – Structural dynamics orthogonal to rigid body dynamics – Inertial coordinate system – Flat earth 9 Modeling and Simulation NDOF MODEL SUBSYSTEMS 10
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