Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

4 m Drop Tower with Instrumented Impactor

The Security Technologies Group has a 4-m-tall drop tower that can be configured for a wide variety of impact and impact-related testing.  This drop tower is designed to allow an impactor to be dropped in free-fall while maintaining the impactor alignment to the test article and providing a repeatable impact location on the test article.  The impactor can be easily switched to allow a wide variety of testing to be conducted, including blunted shapes, to characterize the energy dissipation capacity of impact mitigating materials, or engineered knives or spikes, to assess the level of protection provided by stab resistant body armor.

NIST has developed instrumented versions of standard impactors, which allow the accelerations of the impactor and the forces it transmits to the test articles to be recorded.  Combined with a laser break-beam system that allows the speed of the impactor to be measured just prior to impact, and a high-speed video system that can monitor speeds and deformations throughout an impact event, this instrumentation allows researchers to gain a better understanding of how test articles respond during impact.  The instrumented impactor also allows researchers to study the consistency and repeatability of standard impact tests in order to improve the test methods. 

NIST 4 m Drop Tower
Drop Tower and Instrumented Impactor Configured for Material Impact Testing.

Related Projects

Impact Mitigating Materials

Head Health Challenge III

Materials and Systems for Protection Against Penetrating and Blunt Force Phenomena


Maximum drop height: 4 m

Maximum impact speed: 8.5 m/s

Typical peak impact energy: 120 J

Created November 17, 2017, Updated November 15, 2019