A virtual human body model (HBM), developed for vehicle crash simulations, was used to conduct a pilot study of dangerous accidents that occur in equestrian sports. It was performed to illustrate the potential that the explicit finite element (FE) HBMs have to improve rider safety and to assess the protective capacity of the safety vest. Four different questions were addressed:
1. When a rider is trampled by a horse, how does the risk of injury vary with chest impact location?
2. Does a safety-vest provide protection if the rider is kicked by a horse and does the protection vary with the violence of the hoof impact?
3. Can a safety-vest provide any benefit when the rider is hit by the horse after a rotational fall?
4. How does the risk for thoracic injuries vary when the rider falls off the back of a horse at different angles?
The HBM was the Total Human Model for Safety AM50 version 3.0 (Toyota Motor Corporation, Japan), improved for thorax injury predictability in a previous automotive project. The FE code was LS-DYNA (Livermore Software Technology Corporation, USA). Models of a generic safety vest, a horse impactor and a hoof were developed as part of this project. The risk of thorax injury was evaluated with stresses and strains measured for each rib, and the chest deformation criteria Dmax and DcTHOR.
The following results were obtained for each question:
1. The risk of injury was higher for hoof impacts close to the sternum compared to more lateral locations that had up to 25% less risk. Hence, this knowledge could be used to optimize novel safety-vest designs with HBM simulations.
2. Yes, the safety-vest provided protection against horse kicks, and it varied with the violence of the kick. Therefore, if the range of impact energy that occurs in real-world accidents is known, HBM simulations can be used to optimize the vest material properties.
3. No, the safety-vest did not provide any benefit when the horse lands on top of the rider. This conclusion suggests that safety measures should focus on preventing this type of accident, rather than designing personal protection for the rider.
4. When the rider falls with the head first, the number of predicted rib fractures increases compared to flat falls. However, the model predicts rib fractures for all of the falls simulated from a height of 1.5 meters for a rider without a safety vest.
To conclude, FE HBMs have the potential to improve equestrian safety and further studies on equestrian safety-vests designs are warranted.
Biträdande professor vid Chalmers, Mekanik och maritima vetenskaper, Fordonssäkerhet, Personskadeprevention
Finansierar Chalmers deltagande under 2015–2016