GMAX testing is an impact test that measures the shock attenuation performance of synthetic turf systems. Synthetic turf systems are to perform to the requirements set by the ASTM standard F1936 and the Synthetic Turf Council guidelines. Providing a safe playing surface is a very vital part of concussion safety.

 

The impacting missile contains an accelerometer sensor that measures the magnitude of deceleration (measured in units of gravity or g’s) for the duration of impact. The deceleration measured during impact creates a curve. The peak of that curve is referred to as the “Gmax”. This is the primary value measured with this test. The maximum allowable Gmax as specified in the current ASTM F1936 test specification is 200 g’s.

 

The test procedure involves dropping a 20 pound impacting missile three times at each location from a consistent height of 24 inches. The test is typically performed at 10 locations. The locations are based on the primary sport and the discretion of the tester. The first drop conditions / compacts the loose infill. This value is recorded but not included in the location average. The second and third drops are recorded and averaged for the location average. The location averages are used to determine the field average.