Aeroelastic analysis

You can perform an aeroelastic analysis in Pre/Post using the Simcenter Nastran SOL 144 Static Aeroelastic Response and SOL 145 Aeroelastic Flutter solution sequences:

• Use SOL 144 Static Aeroelastic Response to perform the following types of static aeroelastic analysis:Trim load analysis of rigid and flexible aircraftStability and control derivative analysisControl effectiveness (control reversal) analysisStatic aeroelastic instability (divergence) analysis

• Use SOL 145 Aeroelastic Flutter to perform aeroelastic flutter analysis.

An aeroelastic analysis model consists of the following features:

• A structural modelThe structural stiffness, mass, and damping matrices are generated from the structural model. You can use any structural finite elements, except axisymmetric elements, to construct the structural model.

• Aerodynamic panelsThe aerodynamic surfaces are meshed with aerodynamic panels. The aerodynamic influence coefficient matrices are generated from the aerodynamic panels and bodies.Use the Aero Panel command to create a mesh of CAERO1 elements over aerodynamic lifting surfaces such as wings and ailerons.Use the Aero Body command to create a mesh of CAERO2 elements over aerodynamic slender bodies and interference elements such as fuselages and external tanks.

• A structural/aerodynamic interfaceThe structural mesh and aerodynamic panel mesh are independent of one another. Splines are used to interpolate between the meshes. Use the Aero Spline command to create:Surface splines (SPLINE1 bulk entries in Simcenter Nastran) that relate the structural deflections to the aerodynamic surface deflections.Linear splines (SPLINE2 bulk entries in Simcenter Nastran) that relate the structural deflections to the aerodynamic deflections along an axis.Simcenter Nastran uses the SPLINE1 or SPLINE2 bulk entry to generate a transformation matrix that transfers the aerodynamic forces and moments at aerodynamic boxes to the structural nodes.For more information on splines, see Spline options.

Although Simcenter Nastran supports subsonic and supersonic lifting theories, at present, Pre/Post supports subsonic flow only. The subsonic theory is the Doublet-Lattice method, which can account for interference among multiple aerodynamic surfaces.

Constructing the FE model

When you perform an aeroelastic analysis, you construct the FE representation of the structure as you would any other structural analysis.

In the FEM file, you mesh the aerodynamic lifting surfaces with aero panels (CAERO1 bulk entries in Simcenter Nastran). You do this with the Aero Panel command.

With the Aero Panel command, you also specify the following:

• The leading edge of the aerodynamic surfaces

• The chord at the root and tip of the aerodynamic surfaces

• The mesh density

• The flow directionThe flow direction is the positive X-direction of the coordinate system that you specify in the Aero Panel dialog box.

When you create the mesh of aero panels, Pre/Post creates an aero panel collector that appears in the Simulation Navigator. Unlike mesh collectors for the structural mesh that contain physical properties such as elastic modulus, Poisson's ratio, and so on, the aero panel collector is simply a dummy collector that you can ignore.

For more information on meshing aero panels, see Creating aerodynamic panel meshes.

In the FEM file, you can also mesh aerodynamic slender bodies and interference elements with aero panels (CAERO2 bulk entries in Simcenter Nastran). You do this with the Aero Body command.

With the Aero Body command, you also specify the following:

• The starting point (leading point) of the aerodynamic body and the length of the aerodynamic body in the flow direction

• The mesh density

• The flow directionThe flow direction is the positive X-direction of the coordinate system that you specify in the Aero Body dialog box. This coordinate system is unique and it is used by both the aero bodies and aero panels.

When you create the mesh of aero bodies, Pre/Post creates an aero body collector that appears in the Simulation Navigator. Unlike mesh collectors for the structural mesh that contain physical properties such as elastic modulus, Poisson's ratio, and so on, the aero body collector is simply a dummy collector that you can ignore.

For more information on meshing aero bodies, see Creating aerodynamic body meshes.

In the Simulation file, you create the simulation objects, modeling objects, and constraints that are required for the specific type of aeroelastic analysis.

For information on the simulation objects, modeling objects, and constraints that are required for divergence or trim analysis, see Static aeroelastic response analysis (SOL 144).

For information on the simulation objects, modeling objects, and constraints that are required for flutter analysis, see Aeroelastic flutter analysis (SOL 145).

Contact and glue

Contact and glue are currently not supported in Pre/Post for Simcenter Nastran SOL 144 or 145.

Mapping of Simcenter Nastran bulk entries to the Pre/Post user interface

The following table maps aeroelastic-specific Simcenter Nastran bulk entries to Pre/Post commands.

Task	Pre/Post command	Simcenter Nastran bulk entry
Define links between control surfaces, standard trim variables, and user-defined trim variables for aeroelastic trim analysis	Trim Variables Manager	AELINK
Define the flow direction	Aero Panel Aero Body	AERO
Define standard and user-defined static trim variables for aeroelastic trim analysis	Trim Variables Manager	AESTAT
Define aerodynamic panel	Aero Panel	CAERO1
Define aerodynamic body	Aero Body	CAERO2
Define a matrix of correction factors that adjusts the force and moment so that they agree with experimental data for incidence changes	Aero Element Correction Factor	DMI (WTFACT)DMI (WKK)
Define the interpolation between the structural and aerodynamic models	Aero Spline	SPLINE1 (for surface splines)SPLINE2 (for linear splines)
Define the Mach number, dynamic pressure, trim analysis type, and constrained values for the trim variables in aeroelastic trim analysis	Trim Variables Manager	TRIM

The following table maps aeroelastic-specific Simcenter Nastran bulk entries to Pre/Post modeling objects.

Task	Pre/Post modeling object	Simcenter Nastran bulk entry
Define reference chord length and reference density, and, if applicable, symmetry for aeroelastic flutter analysis	Aerodynamic Parameters	AERO
Define reference chord length, reference span, reference wing area, and, if applicable, symmetry for static aeroelastic analysis	Aerodynamic Static Parameters	AEROS
Specify the Mach numbers and the number of divergence roots for divergence analysis	Aerodynamic Divergence Data	DIVERG
Define the aerodynamic conditions such as density ratios, Mach numbers, and reduced frequencies at which to perform an aeroelastic flutter analysis	Aerodynamic Physical Data	FLFACT
Define the aerodynamic pressure altitudes at which to perform an aeroelastic flutter analysis	Aerodynamic Pressure Altitudes	FLFACT
Define the aerodynamic velocities at which to perform an aeroelastic flutter analysis	Aerodynamic Velocity Data	FLFACT
Define the flutter analysis method and related data, and select the aerodynamic conditions at which to perform the aeroelastic flutter analysis	Aerodynamic Flutter Data	FLUTTER
Define a table of Mach numbers and reduced frequencies at which the generalized aerodynamic forces are computed explicitly for aeroelastic flutter analysis	Aerodynamic Matrix - Mach Numbers and Reduced Frequency Table	MKAERO1

Where do I find it?

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partSimcenter Nastran as the specified solverStructural as the specified analysis type
Command Finder	Solution

Learn more

Creating aerodynamic panel meshes

Creating aerodynamic body meshes

Spline options

Quick links

Command reference

Pre/Post video examples

Bulk Entry Descriptions

Simcenter 3D tutorials

Browse Simcenter 3D help by product area

Aeroelastic analysis, Simcenter 3D 2021.1 Series

© 2020 Siemens

window.mainLanguage="en_US"

window.delivId=""

window.projectId=""

MathJax.Hub.Config({ TeX: { extensions: ["autoload-all.js"] }, tex2jax: { displayMath: [ ] }, "SVG": { scale: 125 } });