Head injury is the most severe injury caused by motorcycling, bicycling, snowsports and equestrian activities, and it is the leading cause of death within these activities. Linear acceleration has been used extensively to determine head injury risk, but it has been found that brain injury is actually influenced by angular kinematics. This is ignored by current injury criteria and product certification tests. To date, there is no consensus in terms of head injury due to angular kinematics and this represents a significant gap.
The project
The HEADS project (Head projection: a European network for Advanced Designs in Safety), an Innovation Training Network funded under the European Commission’s Marie Sklodowska-Curie Programme, aims to fill this gap. This project will reach a new level of understanding of head injury and how head injury should be prevented, with directly applicable results to European industry.
To achieve this, there are six partners, three industry and three academic, across five countries, who are already involved in EU COST Actions and CEN, ASTM and ISO Standards activities in working towards new helmet standards incorporating oblique impacts: KU Leuven, Belgium; KTH-Stockholm; University College Dublin (lead partner); Charles Owen, UK; AGV, Italy; and Lazer Sport, Belgium.
This Training Network will train 13 ESRs in key competencies, enabling them to perform world-class research and become leaders in this field, paving the way to future academic-industry collaborations. The scientific and training objectives of this network are:
1) To develop new understanding of head impact injury and injury thresholds for rotational kinematics
2) To design new helmet standards test methods (for motorcycle, snowsports, bicycle and equestrian activities) that recognise the importance of head rotational kinematics in head injury
3) To train an elite cohort of ESRs in the multidisciplinary field of head impact protection, who have a unique blend of commercial and industrial market awareness
The science
The scientific goal of HEADS is to improve the understanding of head impact injury and to design new helmet standard test methods that recognise the influence of rotational kinematics. This will lead to improved helmets and a reduction in the severity of injuries and the numbers of fatalities. This objective will be achieved through a combination of computational simulations of real-life accidents, experimental and computational investigation of injury thresholds, and design of new helmet certification tests.
The programme is structured around 13 individual research projects (IRPs; PhD projects), one for each ESR within three main research topics: accident reconstruction and simulation, head model refinement, and helmet certification improvements.
Accident reconstruction and refinement
Accurate accident reconstructions will allow us to generate more realistic injury thresholds, which can be applied to future helmet standards as well as a design target when designing helmets for a particular activity. In order to improve helmet design and protection for a specific activity, detailed knowledge is required on:
- Mechanical input in accidents associated with different activities;
- Injury-specific tolerance criteria; and
- Relative risk of injuries.
There remains a scarcity of data on the ranges of mechanical variables at impact, despite the fact that this data is essential in determining appropriate levels of protection. Four IRPs will focus on determining the mechanical variables at impact associated with different accident types:
- Equestrian
- Bicycle
- Motorcycle and snowsports activities
- Plus the accurate simulation of skull fracture in accident reconstruction.
The four ESRs will work closely together and their results will lead directly into Work Package 2: Head Model refinement (detailed below) to establish realistic helmet standards failure criteria.
This research will involve the collection and analysis of technical accident data from the national road and sports authorities (including police reports, accident details and statistics, damaged helmets, clinical data from relevant hospital records, and related European COST Actions, including TU1101, which involves KTH, UCD, KUL and LS). This data collection will be done with regard to subsequent computer reconstructions using Madymo, Abaqus and Ansys software.
Head model refinement
An advantage of the FE method in biomechanics is the ability to model the anatomy precisely, to identify the kinematics of body parts such as the head and neck and the stresses and strains in tissue despite the complexity of the brain, which is made of multiple substructures marked by different mechanical properties. Establishing a strong correlation between real life brain injury patterns and finite element (FE) head model output would be a significant advancement in the state of the art.
There is a major knowledge gap in designing safety helmets and setting pass/fail thresholds for helmet testing due to the lack of adequate head injury criteria and head injury prediction models. The KTH finite element head model and the UCDBTM have been developed independently of each other during substantial and detailed research in the past 10-15 years.
The aim is to refine these state-of-the-art head models through:
- Development of realistic skin model for head model refinement;
- Introduction of bridging veins into head models;
- Development of a FE head model specifically for the active ageing;
- Morphological and functional thresholds for neuronal damage in head models;
- Brain tissue experiments for determining head injury thresholds.
Helmet certification
It is widely agreed that there is a need to develop new test methods for helmets including an oblique impact test. Within the European Committee for Standardisation (CEN) TC158 (Head Protection), work has begun on designing a new test method for helmets in general and HEADS project partners KTH are leading. HEADS aims to develop appropriate tests for product certification considering issues of rotational acceleration for:
- Equestrian helmets
- Cycling helmets
- Motorcycling and snowsports helmets
A final project will seek to improve new helmet development by investigating novel energy absorbing materials for helmet liner applications.
The first three ESRs above will be industry-based, with the last ESR based at UCD. Given that each activity is exposed to different risks, different test specifications and design requirements are necessary for the different helmet types. The intersectoral R&D experience of the universities and industry partners is essential.
All of the academic and industry partners provide leadership nationally within their own countries in developing helmet test standards; HEADS will provide a transnational approach that is more ambitious and comprehensive than is currently possible within one single EU country.