9 Conclusions and Future Work
9.3 Implications of the research
1. A detailed FE model of a commercially available motorcycle helmet, with a composite shell, has been developed in LS-DYNA crash code and validated against normal and oblique impact test data. This model, coupled with the head of various human body or dummy FE models, can be used to study different aspects of standards or motorcycle accidents.
2. An analytical model has been proposed for the helmeted headform impact. The solution to this model has revealed the relations between impact inputs, properties of the helmet and impact outputs.
3. The head and neck of the FE model of the Hybrid III dummy provided for LS-DYNA users by LSTC has been validated in impact scenarios where the head is subjected to direct impact loading.
4. The THUMS human body model (2008) has been validated against cadaver experiments with respect to the upper neck forces.
5. In order to test helmets in impact conditions which are more realistic to real world accidents and stringent, it has been proposed to increase the mass of the headform, in the drop test procedure of the UNECE 22.05 standard. For
impacts at points B, R and X this increase is 20%. For vertex impact (point P), the proposed increase is 42%. To avoid helmet designs with stiff liner foams, the mass increases should be together with respectively 9% and 16%
reductions in the acceptance limit of acceleration.
6. An alternative to the above proposal is using two headforms of the same size to test helmets: one with the original mass and one with the increased mass. In this way, there is no need to change the acceptance limit of head acceleration.
7. Modifying the inertia matrix of the headform has been proposed as an economical yet appropriate measure to include the influence of the body on rotational acceleration of the head.
8. The same modifications to the headform mass and moment of inertia mentioned above has been proposed for including the influence of the body on intracranial parameters in helmeted headform drop tests.
9. An FE model of the Hybrid II headform with a deformable rubber skin has been developed in LS-DYNA and validated.
10. The Strasbourg University FE head model has been transferred from Radioss to LS-DYNA and validated against cadaver experiments for skull fracture and intracranial pressures in short duration impacts.
Acknowledgements
The author would like to thank Professor Ugo Galvanetto and Dr Lorenzo Iannucci for their continual supervision, support and guidance through this research.
The work presented in this thesis was completed within the research training network MYMOSA funded by a Marie Curie fellowship of the 6th framework programme of the EU, under contract no. MRTN-CT-2006-035965. The author would like to acknowledge network partners, whose help was essential to complete this work: Dainese S.p.A. (Italy) for providing the AGV-T2 helmet for the tests and its CAD files, TRL (Transport Research Laboratory, UK) for providing the Hybrid III dummy, test facilities and technical assistance to perform the drop tests, LMU (Ludwig-Maximilians University, Germany) for providing the THUMS human body FE model and SU (Strasbourg University, France) for allowing the author to use the SUFEHM.
Particular thanks go to Mr Alessandro Cernicchi from Dainese, Mr Vincent StClair, Mr Brian Hardy, Mr Ian Wickens, Mr Chris Geddis and Mr James Nelson from TRL, Dr Steffen Peldschus, Miss Zahra Asgharpour and Miss Sarah Doerfel from LMU and Professor Remy Willinger and Dr Caroline Deck from SU. The author also thanks Mr Gary Senior, John Cole and Joseph Meggeysi from the Composites Centre of Imperial College London.
I would like to thank my wife for her support during this endeavour and also my parents for their encouragement and advice throughout my life.
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