cranfield university aj lamb experimental investigation and numerical modelling of composite

270 Pages·2007·11.07 MB·English

by  Andrew Lamb

CRANFIELD UNIVERSITY

A. J. LAMB

EXPERIMENTAL INVESTIGATION AND NUMERICAL
MODELLING OF COMPOSITE-HONEYCOMB MATERIALS
USED IN FORMULA 1 CRASH STRUCTURES

SCHOOL OF APPLIED SCIENCES

PhD THESIS

CRANFIELD UNIVERSITY

SCHOOL OF APPLIED SCIENCES

PhD THESIS

Academic Year 2004-2007

A. J. LAMB

Experimental Investigation and Numerical Modelling of Composite-Honeycomb
Materials used in Formula 1 Crash Structures

Supervisor: Professor A. K. PICKETT

January 2007

This thesis is submitted in partial fulfilment of the requirements for the degree of
Doctor of Philosophy.

© Cranfield University 2007. All rights reserved. No part of this publication can be
reproduced without written permission of the copyright owner.

ABSTRACT
This thesis has investigated composite-honeycomb sandwich materials commonly used
in Formula 1 nosecone structures. Experimental work has investigated their failure
behaviour under static and dynamic crash loading, from which new constitutive failure
laws for implementation in the explicit Finite Element code PAM-CRASHTM have been
proposed.

An investigation using an improved Arcan apparatus has been conducted to establish
the mixed shear-compression properties of the honeycomb. An investigation has also
been performed to establish relationships between in-plane deformation and out-of-
plane compression properties. These relationships have been identified and successfully
implemented into a honeycomb solid element material model available in PAM-
CRASHTM. A further investigation to represent honeycomb using geometrically
accurate shell representation of the honeycomb has also been presented. This model was
shown to reproduce trends observed during testing.

The composite skin material has also been experimentally investigated and presented.
This investigation made use of digital image correlation to examine the onset of intra-
laminar shear failure mechanisms, from which a non-linear damage progression law was
identified. This law was successfully implemented into the Ladevéze damage model in
PAM-CRASHTM for composite material modelling and has been shown to improve the
representation of in-plane shear damage progression and failure.

A series of experimental investigations to examine the energy absorbing properties of
the sandwich have been conducted and presented. These investigations include three
point bend flexural testing and edgewise impact loading. Failure mechanisms in the skin
and core have been identified for each loading case. Experimental findings were used to
assess the capability of PAM-CRASHTM for sandwich material modelling. This
investigation has highlighted deficiencies in the material models when representing the
sandwich, specifically with the existing composite skin and honeycomb models.
Improvements introduced to the core and skin material models have shown some
improvement when representing sandwich structures.
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ACKNOWLEDGEMENTS
I wish to thank my supervisor Professor Anthony Pickett. His guidance has been
invaluable towards to production of this work and success at the 2005 IOM3/SAMPE
student presentation contest in London. I wish him all the best in his new role at ESI
and at Stuttgart.

There are my fellow PhD research colleagues, who have both finished and begun their
working careers, Dr. Gavin Creech and Dr. Michel Fouinneteau who welcomed me into
the group and helped me with many issues encountered during this work. A special
thank you also goes to Jim Hurley, Ben Hopper, Michael May, Mathieu Colin De
Verdiere, Fabien Chaudoye and all those who I have had the pleasure of working with
during this research.

I would also like to thank the assistance of Mark Oxley and those at Honda Racing F1
who provided valuable information and the test samples used throughout this research.
In addition, I wish to thank the EPSRC for funding this research and thus giving me the
opportunity to pursue a PhD.

Finally there are my family and friends, who have provided support and guidance over
the years. Thank you!

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TABLE OF CONTENTS
1 Introduction...........................................................................................................1
1.1 Aims and Objectives.........................................................................................2
2 Literature Review..................................................................................................5
2.1 Formula 1 Structures and Crash Testing..........................................................5
2.1.1 A Brief History of Motorsport Safety and Materials................................6
2.1.2 BAR-Honda 006 Frontal Impact Structure...............................................7
2.1.3 Design of a New Nosecone....................................................................11
2.2 Composite-Honeycomb Sandwich Materials.................................................12
2.2.1 Honeycomb Materials............................................................................12
2.2.2 Composite Materials...............................................................................26
2.2.3 Sandwich Structures...............................................................................40
2.3 Finite Element Analysis.................................................................................47
2.3.1 FE in Automotive Applications..............................................................48
2.3.2 Honeycomb Modelling...........................................................................48
2.3.3 Composite Modelling.............................................................................52
2.3.4 Composite Sandwich Modelling............................................................57
2.4 Summary of Literature Review......................................................................59
3 FE Modelling of Composite-Honeycomb Materials...........................................62
3.1 Honeycomb Core Modelling Requirements...................................................65
3.2 Composite Laminate Skins.............................................................................67
3.3 Sandwich Structure.........................................................................................69
3.3.1 Mode-I Crack Propagation.....................................................................69
3.3.2 Sandwich Flexural Properties.................................................................73
3.3.3 Wedge Impact Testing............................................................................73
3.4 Nosecone Representation...............................................................................76
3.5 Section Summary............................................................................................76
4 Experimental Procedures and Results.................................................................78
4.1 Digital Image Correlation...............................................................................78
4.1.1 Benefits of Digital Image Correlation....................................................80
4.2 Test Samples...................................................................................................82
4.3 Honeycomb Experimental Testing.................................................................82
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4.3.1 Principal Direction Compressive Properties...........................................83
4.3.2 Pre-Crushing In-Plane effect on Out-of-Plane Properties......................89
4.3.3 Testing Procedure and Results for the Multi-axial Loading of
Honeycomb Material............................................................................................102
4.4 Composites Sample Testing.........................................................................111
4.4.1 Tensile Properties of the Composite in the Fibre Direction.................112
4.4.2 In-Plane Shear and Cyclic Shear Loading............................................115
4.4.3 Compressive Loading...........................................................................121
4.5 Composite Sandwich Structure....................................................................124
4.5.1 Flatwise Loading Test..........................................................................124
4.5.2 Cracked Sandwich Beam Testing.........................................................128
4.5.3 Three-Point Bend Flexural Testing......................................................135
4.5.4 Axial and Oblique In-Plane Sandwich Loading...................................139
4.6 Section Summary..........................................................................................154
5 Computational Modelling of Sandwich Materials............................................157
5.1 Honeycomb Modelling.................................................................................157
5.1.1 Macro-Scale Modelling........................................................................158
5.1.2 Meso-Scale Modelling Investigation....................................................167
5.2 Laminate Modelling.....................................................................................177
5.3 Sandwich Modelling.....................................................................................181
5.3.1 ‘T’ Direction Sandwich Loading..........................................................181
5.3.2 Crack Propagation Modelling...............................................................182
5.3.3 Three-Point Bending Modelling...........................................................184
5.3.4 Impact Wedge Modelling.....................................................................191
5.4 Considerations towards Nosecone Modelling..............................................198
5.5 Section Summary..........................................................................................203
6 Discussion..........................................................................................................206
6.1 Honeycomb Experimental and Numerical Investigation.............................206
6.1.1 Experimental Limitations of Honeycomb Testing...............................207
6.1.2 Limitations of the Investigated Honeycomb Modelling.......................211
6.2 Composite Material Testing and Numerical Modelling Investigation.........215
6.2.1 Experimental Investigation of the Woven Composite Material...........215
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6.2.2 Composite Numerical Limitations.......................................................217
6.3 Sandwich Structure Testing and Numerical Modelling Investigation..........218
6.3.1 Experimental Investigation of the Sandwich Structure........................218
6.3.2 Limitations of Investigated Numerical Sandwich Modelling...............223
6.4 Current and Future Crashworthiness Modelling of Sandwich Structures....224
7 Conclusions.......................................................................................................226
8 Future Research.................................................................................................231
8.1.1 Addressing Investigation Limitations...................................................231
8.1.2 Further Crashworthiness Evaluation....................................................231
8.1.3 Extended Material Investigation...........................................................232
9 References.........................................................................................................233
10 Appendices.............................................................................................................i

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TABLE OF FIGURES
Figure 2-1: McLaren MP4/1, the first truly composite F1 car [5]....................................7
Figure 2-2: High performance yet safety conscious design in action [7].........................7
Figure 2-3: 2004 BAR-Honda Formula 1 race car [8].....................................................8
Figure 2-4: Variations in collapse modes of square frusta subjected to a frontal loading
(a) Mode-1 (b) Mode-2 (c) Mode-3 and (d) Mode-4 [10]................................................9
Figure 2-5: Variation in Mode-1 type failure (a) Mode-1a (b) Mode-1b [11].................9
Figure 2-6: Summary of forces and failure mechanisms in the progressive crush zone
[12].................................................................................................................................10
Figure 2-7: Simplified design process for a new frontal impact structure.....................11
Figure 2-8: Core types (a) honeycomb (b) open-cell foam (c) closed-cell foam [17]....12
Figure 2-9: Varieties of honeycomb (a) aluminium hexagonal (b) paper-phenolic resin
(Nomex) (c) ceramic square (d) ceramic triangular [17]................................................13
Figure 2-10: Principal directions of honeycomb material [18] and cell geometry.........13
Figure 2-11: Definition of in- and out-of-plane loading.................................................14
Figure 2-12: ASTM C365-03 compression testing apparatus [19]................................15
Figure 2-13: ‘T’ direction compressive load profile [20]...............................................15
Figure 2-14: Arcan apparatus in (a) pinned and (b) clamped configuration [23]...........16
Figure 2-15: Mohr and Doyoyo modified Arcan apparatus [24]....................................17
Figure 2-16: Arcan apparatus schematic for large honeycomb samples [25]................18
Figure 2-17: Peak and plateau loading profiles of honeycomb dependent on loading
direction [25]..................................................................................................................18
Figure 2-18: Apparatus for combined shear-compression testing by Hong et al. [28]..19
Figure 2-19: Description of in-plane orientation angle [28]...........................................19
Figure 2-20: Elastic deformation, (A) ‘W’ compression, (B) ‘L’ compression [17].....20
Figure 2-21: Example of the variation between in-plane compression properties
depending on sample size [45].......................................................................................21
Figure 2-22: Comparison between theoretical size dependency influence on peak
crushing strength and foam compression results [100]..................................................22
Figure 2-23: Deformed honeycomb due to out-of-plane compression loading [30]......22
Figure 2-24: Alexander's model: Folding of thin walls in a cylinder [31].....................23
Figure 2-25: McFarland model: ‘T’ direction crushing mechanism [32].......................23
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