Faculty Advisor or Committee Member

Kristen L. Billiar, Committee Member

Faculty Advisor or Committee Member

Allen H. Hoffman, Advisor




Low velocity impacts to the back are known to cause severe injury to crucial components such as the spine and kidneys. Researchers at Natick Soldier Center want to develop a solution that incorporates protection against low velocity impacts with the ballistic body armor (vest and plate) that is used today. The current ballistic body armor was developed to provide ballistic protection. Ballistic protection is designed to stop the penetration of bullets at velocities exceeding 300 m/s. Techniques to provide low velocity impact protection include reducing transmitted force by elongating collision time. In order to develop back protection for the soldier against low velocity impacts the performance of the ballistic body armor and impact protecting foams was evaluated. Low velocity impact tests were performed based on European standards for back protectors for horse riders (EN 13158) and motorcyclists (EN 1621-2). Performance requirements outlined by the standards and published literature established peak forces of 4 kN and 9 kN transmitted through materials under impact as minimum levels of safety before significant injury occurs. Experiments were conducted at an energy level of 4 J to compare the performance of different materials. Energy levels were then increased until maximum acceptable force transmissions were reached. At 4 J the ballistic materials showed peak transmitted forces between 11.0-16.2 kN. This indicated that the ballistic materials were not an adequate method to provide sufficient back protection. The addition of polyurethane foams to ballistic materials reduced peak force values by a factor of 15. Energy levels of 25 J and 40 J were reached with peak forces of 3.5 kN and 6.6 kN. This research provided a basis for the future development of protective equipment that provides both ballistic and low velocity impact protection.


Worcester Polytechnic Institute

Degree Name



Biomedical Engineering

Project Type


Date Accepted





Low Velocity Impact, Ballistic Materials, Back Protection, Body armor, Back, Wounds and injuries