2008 international ansys conference...tailored design of composite structures: add-on layers with...

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2008 International ANSYS Conference

Lay-Up Evaluation of Composite Tubes

Paulo Roberto Rocha Aguiar Guilherme Pinto GuimarãesCentro Tecnológico do Exército – CTExBrazilian Army Technological Center


Outline

• Introduction • Objectives• Prototypes Modeling• Test Configurations and Finite Element Models • Simulations Results • Conclusions


1 – Introduction

• Brazilian Army Technological Center (CTEx) – Guaratiba / Rio de Janeiro

• Major adoption of composite materials in aerospace. defense. off-shore andother industries

• Use of composite materials: High strength / Low weight• Composite tubes applications in defence: Light weapons• Prototypes production and testing


IntroductionComposite Materials

• Two or more different materials– Materials present different physical properties– New composite material: homogeneous in macroscopic scale

• Constitution of FIBER REINFORCED composite materials: – Matrices– Reinforcement materials

• Particles or fibers

• Fiber reinforced composite materials: different strengths in directions aligned with fibers and transversely to it.

• Several constitutive relations: – Orthotropic behavior– Transversely isotropic behavior



• Fiber reinforced laminated tubular structures production:– Filament winding process

• Layered composite tubes: Stacking of several long-fibersreinforced layers– Total number of layers – Total tube thickness (Sum of individual layer´s thickness)– Layer material (Matrix and fibers)– Winding angle

• Tailored design of composite structures: Add-on layerswith different fibers directions – To form a Laminate

• Overview of strength requirements to withstand serviceloads: Internal blast pressures and tractions

• Axial-torsional coupling behaviour of laminates



• Prototype production overview: Third-party production company– First prototype tests (ORIGINAL lay-up purposed) – New lay-up configurations: Improve strengths to in-service loads and

production winding times and costs

• Winding directions 1 and 2: Radial and Longitudinal • Traction real tests to analyze longitudinal strengths• New lay-up (Remodeled) consider different winding angles for several

layers• Same total thickness for every lay-up configuration


2 – Objectives

• Finite element modeling of composite tubes: Technicalsupport to prototypes design

• Virtual testing to several lay-up configurations and loadingscenarios

• Virtual representation of real testing scenarios• Objectives of this presentation

– Represent real traction test on tube prototype-1 (Partial length)

– Represent and compare blast and traction tests on tube prototype-2 (Total tube length) – Comparison of two lay-up configurations: • (Original) lay-up configuration• (Remodeled) lay-up configuration


• Filament winding capabilities: – Tube longitudinal direction winding (Direction-1)– Tube transverse direction winding (Direction-2)

• Prototype tube finite element model: SHELL99 • Tube made of fiber reinforced laminate composite materials• Two different test scenarios: TEST-1 and TEST-2 configurations

3 – Prototype Modeling

• ANSYS/Multiphysics 7.0 Help System –SHELL99 finite element


Prototype ModelingMaterial Models

• Orthotropic and/or Transversely Isotropic material models• Failure criteria for individual layers• Material data required for every single layer

(Fiber reinforced composite layer): – Layer density– Fiber longitudinal elasticity modulus– Fiber transverse elasticity modulus– Layer shear modulus– Layer poisson’s ratio– Traction strength limits (Longitudinal and transverse)– Compression strength limits (Longitudinal and transverse)– Shear strength limit– Max deformation data in traction (Longitudinal and transverse)– Max shear deformation (Longitudinal and transverse)


• TEST-1 configurations: – Failure criteria: Maximum stress– Boundary condition: Fixation of one of tube’s edges– Load: Static analysis – Longitudinal traction applied in tube’s free edge

• Thermal effects not considered• TEST-1 finite element model

– Boundary conditions and mesh discretization

4 – Test Configurations andFinite Element Models

Colors show different real constant sets – Wall thickness and lay-up configurations


4 – Test Configurations andFinite Element Models

• TEST-2 configurations: – Failure criteria: Maximum stress– Boundary condition: Fixation in two regions– Load: Transient dynamic – Internal pressure and longitudinal internal

traction• Thermal effects not considered• TEST-2 finite element model

– Boundary conditions and mesh discretization

Colors show different real constant sets – Wall thickness and lay-up configurations


Test Configurations and FE Models Test-2 Loading Configurations

• Two lay-up configurations considered in both tests: – Original lay-up– Remodelled lay-up

• Transient dynamic loading data: Load Step

Time (ms)

Time Inc. (ms)

Tube Length

(%)

Internal Pressure

(%)

Internal Traction

(%)1 1.00 1.00 34 91 59 2 1.25 0.25 36 98 63 3 1.45 0.20 39 100 70 4 1.70 0.25 43 97 83 5 1.95 0.25 47 93 100 6 2.50 0.55 60 28 86 7 3.00 0.50 74 13 77 8 3.50 0.50 87 7 71 9 3.90 0.40 100 4 68


5 – Simulation Results

• TEST-1 configurations output data: – Selected layers to be shown: 1 – 4 – 5 – 11 – 24 – Longitudinal displacements – Fiber longitudinal direction stress (S1)– Fiber transverse direction stress (S2)– Comparison between ORIGINAL and REMODELLED lay-ups

• TEST-2 configurations output data: – Same selected layers as TEST-1– Load Step vs. Stresses (S1/S2) graphics – Including strength limits – Longitudinal displacements and S1 stress results to compare

ORIGINAL and REMODELLED lay-up configurations for layers 1 – 5 – 11 – 24, for load steps 1 – 3 – 5


Simulation ResultsTEST-1 Configurations

• Original – Remodelled lay-ups: Longitudinal displacements (mm)

• Original – Remodelled lay-ups: S1 (Pa) – Layer 1



S1 Results (Pa) – Layer1 Over load steps

S1 Results (Pa) – Layer 4 Over load steps



S1 Results (Pa) – Layer5 Over load steps




• Original – Remodelled lay-ups: Longitudinal displacements (mm) – Load Step 1

• Original – Remodelled lay-ups: Longitudinal displacements (mm) – Load Step 3



• Original / Remodelled S1 results (Pa) – Layer 1 / L.S. 1



5 – Conclusions

• Successful modeling of fibrous laminates in ANSYS • Powerful capabilities in post-processing the results

– Transient results from structure analysis for specified layer vs. load step

• Results show failures in some layers, as expected from the original lay-up

• Results also show improvements in structural performance with remodeled lay-up

• Prototype production time with remodeled lay-up reduced by ~3 hours – Gains of time and costs

• Test firings with both lay-ups show overall tube thickness successfully survive


Acknowledgements and Institution´s Contacts

• Marcelo Soares Brisola / André Luiz Tenório Rezende / Othon Sampaio dos Santos – CTEx

• Ricardo Damian / Marcus Reis – ESSS

• CTEx: Centro Tecnológico do Exército – Av. das Américas 28705 Guaratiba – Rio de Janeiro/RJ –Brazil. ZIP 23020.470 www.ctex.eb.br

• Brazilian Army web-site: www.exercito.gov.br• Paulo Aguiar: [email protected]• Guilherme Guimarães: [email protected]• Phones: +55(21) 24106272 / 24106287

THANKS FOR ATTENTION

2008 international ansys conference...tailored design of composite structures: add-on layers with...

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