simulation driven development of composite structures

SIMULATION DRIVEN DEVELOPMENT OF COMPOSITE STRUCTURES Mikael Lauth Senior Engineering Analyst, FEM EDR & Medeso AB 2012-06-07

ANSYS Composite Prepost

Efficient pre- and postprocessor for analysis of structures made of composite materials

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Summary

• Dedicated to allow for easy and efficient definition and modification of layered-composite structures as well as their specific post-processing • Dedicated to provide leading-edge technology in pre- and post processing of layered composite structures • Integrates with Mechanical Simulation as well as with Mechanical APDL • Provides failure assessment as well as manufacturing information such as draping and plybooks.

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Composites

• Composite materials are made of at least two distinct materials with different material parameters for each phase • Fiber reinforced composites (FRC) are composites where one material component (fiber) is used as a reinforcing material for the matrix • Composites have a wide range of usage: sports, civil engineering, automotive & aerospace industry, shipbuilding, cables, consumer goods…

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Basics

Fibers- Bonded or embedded reinforcing fibers that are usually responsible for the anisotropy of the composite.

Matrix- A homogeneous base material that forms the bulk of a composite material layer.

T

L Lamina- A composite material in sheet form usually referred to as a layer or ply. The material properties of a layer is usually determined through an equivalent homogenization (smearing) process.

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Laminate- A stack of lamina joined together in arbitrary directions, referred to as a composite lay-up.

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Basics laminating

• wet-in-wet - hand-lay-up - sprayed-lay-up • filament winding • pultrusion • resin transfer molding

lamina

layer 4 o 4 = 0

laminate

layer 3 3 = -  layer 2 2 = +  layer 1 o 1 = 90

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[90o / + / -  / 0o] laminate

angle-ply laminate ± stacking sequence

cross-ply laminate  = 0o / 90o

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Tools neded for analysis

• An accurate representation of the structure in its environment: geometry, mesh, loads & boundary conditions • An accurate representation of the composites : material behavior, ply definitions, orientations of the fibers… • A numerically accurate solver • A wide array of tools to investigate and understand the results and estimate the risks of failure • Links to the manufacturing process (draping, plybooks) • All of this in a user-friendly environment!

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ANSYS ACP

The ANSYS Composite Prep/Post Advantage

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Model representation

• User of the ANSYS Composite Prep/ Post benefit from all the advantages of the ANSYS solutions: • Direct CAD imports from all major CAD products • Import of standard geometry formats (STEP, Parasolid…) • Geometry cleaning • Best-in class meshing capabilities for surface and solid models – with linear or quadratic elements

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Model representation

• Meshing information as well as loads and boundary conditions are transferred to ANSYS Composite PrepPost

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Laminate modelling

• A hierarchical data description of materials, stackups and laminates Base information: Engineering data and material limits

Add thickness, pricing and draping information

Fabrics Stack fabrics, add pricing and draping information

Stackups Define final laminate product

Laminates

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Definition of fiber direction

• A key element of the definition of composite materials is the proper orientation of the fibers • ANSYS Composite PrepPost uses a concept of oriented element-sets: • user can define material application direction and material 0°direction • One or several coordinate systems assigned to an oriented element-set • no need for ply-subdivision • Cartesian, cylindrical and spherical systems are supported

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Definition of fiber direction

• ANSYS Composite PrepPost uses a concept of oriented element-sets: • user can use lines or edged of the geometry to specify fiber direction • no need for ply-subdivision • Cartesian, cylindrical and spherical systems are supported

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Defining laminate areas

• Laminates and associated orientations are defined on zones (element groups) • Zones can be applied a predefined laminate • Additional Laminates can be constructed by progressive stacking on zones • Support for layer drop-off

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Visualization of stacking

• Stacking sequences and composite thicknesses can be displayed on arbitrary sections or on the entire model

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Creating solid model based on shell model

• Easy generation of solid model based on shell model (suitable for thick laminate analysis)

Shell model

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Extruded solid

Snap to geometry

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Computing the solution

• The ANSYS Composite Prep/Post uses the ANSYS Mechanical solutions to compute the base solution of the model. • All advantages of our core solutions are therefore available: • Support of the latest element generation: linear and quadratic shells, linear and quadratic solids • Layered element formulation • Isotropic, orthotropic and anisotropic material models • Fast and accurate solver • Multiple time steps support

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General postprocessing

• Basic quantities like displacement, stress and strain. • Arbitrarily configurable envelope contour failure plot

• Overlay Text-plots for easy identification of the relevant failure-modes and critical layer • Sensor to calculate mass, area etc. for complete model or selected areas or group of elements. • Generate superposition load cases based on initial load cases

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Failure analysis

• ANSYS Composite PrepPost provides a unique set of failure criteria to analyze the product: • From simple criteria (max stress) to stateof-the art analysis (Puck, Hashin, Cuntze) • Interlaminar shear, normal stresses for shells • Through thickness failure for shells • Combination of failure criteria provides failure envelope • 3D implementation of main criteria (Tsai-Hill, Hashin, Puck etc.) • Ability to create user-defined criteria

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Failure analysis

• Results can be displayed as: • Most critical failure criteria • Critical layer • Reserve, inversed reserve factors and safety margin (based on stress limits)

• Standard results (stresses….) per layer • Sampling elements

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Draping & flatwrap

Draping

• ANSYS Composite PrepPost provides draping functionality to analyze for drapability as well as for calculation of the fiber-angle correction

• Further ANSYS Composite

Flat-wrap

PrepPost can also provide the flat-wrap of plies with their distortion

• Flatwrap boundaries export to STEP or IGES format 2012-06-07

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Plybook generation

• A set of plies or all plies are selected for ply-book generation.

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Additional capabilities

• Python scripting capabilities provide full automation for the setup of the composite models as well as reusing data generated previously.

• ANSYS Composite PrepPost can update the model definition upon design changes without the need to redefine the entire model through a simple update of the input mesh.

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Development process

• ANSYS Composite Prepost is the high end tool in calculating composite structures and is suited to study lay ups with hundreds of layers • Without engaging ANSYS Composite Prepost it is possible to set up layered section in Workbench Simulation to perform concept studies to find out: • Overall thickness • Major fiber orientation for individual layers • Material selection

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Development process

• In the example shown of a flat plate, simply supported and subject to an offset load at half length. • The lay up is a sandwich construction with a core and 8 layers of glass fiber • The governing output is total deflection • How does the fiber angles closest to the core influence the deflection?

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Development process

• ANSYS WorkBench Environment can with a few mouse clicks set up a sensitivity study (what if study) to investigate the variation of the output parameter due to a variation of an input parameter.

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Development process

• Next step is to go further using DesignExplorer that is a tool for performing: • Design of Experiments (DOE) studies on multiple input parameters

• Goal Driven Optimization to find the best design proposal • Design for Six Sigma to account for scatter in input data and obtain a probability of how well the result fulfills the design requirements

• Get knowledge of how much each input parameter influence the output parameter. Which parameters are important and which who have less influence on the output parameters.

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ESAComp

FE-export/import

• ESAComp analyses can be used with the design tools for the preliminary design of laminated structures. • Laminate lay-ups and the related properties specified in ESAComp can be exported into FE software using the FE export interface. • After FE analysis, designers can import results to ESAComp using the FE import interface. This allows laminate level post processing and further improvement of the structure. Analysis Tools

• • • • •

Fiber/matrix micromechanics Plies and laminates Plates and stiffened panels Beams and columns Bonded joints and mechanical joints

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The End

END OF PRESENTATION Thank you for listening

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