The Development Of Test Protocols For Padded Clothing In Rugby Union Using Human Tissue Impact Surrogates

Padded clothing (shoulder padding) is worn in Rugby Union to allow players to
protect themselves. A performance specification for padded clothing has been set
out by World Rugby™, with the intention that padding only protects against Cuts and
Abrasions [1]. This performance specification is set out in Regulation 12 (padded
clothing) [2]. This limits its density (45 + 15 kg·m-3), thickness (10 + 2 mm) and impact
attenuation performance (acceleration > 150 g for a 14.7 J impact). Regulation 12 was
critiqued and areas for improvement were identified.

A literature review was conducted, covering injury and protection in Rugby Union,
injury modes, anatomy of the human shoulder, organic tissue properties and human
tissue simulants. It was identified that padded clothing’s ability to prevent Cut and
Abrasion injuries have yet to be quantitatively assessed. This was crucial in improving
the Regulation 12 test protocols.

To address this problem, a multi-faceted investigation was performed. To start with,
assessments were made of rugby players’ external and internal shoulder anatomies
using 3D and ultrasound scanning techniques. From this, geometries of rugby players’
shoulders were found. The material properties of organic tissues were also assessed,
with the focus being on the tissue’s compressive response to load. The reason for
this work was to aid the fabrication of a human shoulder surrogate.
Both a simplified and anatomical human shoulder surrogate were fabricated using
human tissue simulants, as well as 3D printing and moulding techniques. A bespoke
muscle simulant was developed with similar compressive properties to organic
muscle tissue.

Both the simplified and anatomical surrogates were integrated into various impact
testing procedures. Padded clothing was tested for its force attenuative properties,
its ability to prevent blunt force Cut and Abrasion injuries, and its ability to prevent
stud-induced injuries. The results from this have led to informed recommendations
3 being made for the improved assessment of padded clothing in Rugby Union and
therefore an improved Regulation 12.

The research conducted in this thesis was the first to quantitatively assess padded
rugby clothing’s ability to protect from specific injuries. As well as fabricate a human
shoulder surrogate for the assessment of sports padding. The testing protocols
developed in this thesis can be easily adapted for the assessment of protection or
padding in other collision sports or even in other industries like ballistics or
automotive.