Accuracy of Gmax / HIC Measurements
John I. Dunlop/Hans J. Kolitzus
10-Feb-2002
Round Robin - g-max and HIC
One of the stated aims of the ISSS is the assessment and standardisation of test methods for sports surfaces. To this end we have conducted a round Robin of impact testing equipment and techniques used for soft fall material testing.
Time frame
During the period November 2000 to November 2001 samples were circulated to 6 testing laboratories for impact testing.
Trial Controller: H.J. Kolitzus
Samples
The 2 samples circulated for testing were:
Sample 1 PUR Bound Rubber Fibres (Tile) roughly 61 mm thick
Sample 2 PUR Bound Rubber Fibres (Tile) roughly 41 mm thick
Testing Regime
The laboratories were requested to conduct impact tests on the samples under the following conditions:
Sample temperature - reported ambient after conditioning for at least 24 hr
Base - thick concrete of thickness in excess of 100 mm, with smooth finish
Drop Heights - 4, 5 and 6 feet
Determined values of g-max and HIC for the first drop were to be reported for each of these drop heights for each sample.
Laboratories/Equipment
| Acousto-Scan, Sydney, Australia | 5 kg ISO J head |
| CST, London, England | 10 lb EN1177 hemi head |
| IST, Eschenz, Switzerland | 10 lb EN1177 hemi head |
| Labosport, Le Mans, France | 10 lb EN1177 hemi head |
| North West Testing Laboratory, Seattle, USA | 10 lb EN1177 hemi head |
| USSL, Hopewell, VA, USA | 10 lb EN1177 hemi head |
Two of the laboratories tested the samples twice, once early in the trial and again at the end of the trial (eg. Lab02-2 in 2001 and Lab03-2 in2002) to check on changes to the samples.
Results
The results of the testing (laboratories coded) are summarized in Fig. 1 and 2.
These figures show the deviations from the global average of each of the laboratory's tests.
Comments
The results indicate a remarkable consistency of test results considering the range of laboratories, testing and equipment.
The consistency within each laboratory's results is very high showing a small range of variability. The variations between laboratories indicate systematic differences in their equipment and techniques. However this should be viewed in terms of the general uncertainty of the measurements. Acousto-Scan has calculated the uncertainty of its g-max determination at 4 % and of its HIC at 5 % using the methods outlined in the ISO publication Guide to the Expression of Uncertainty in Measurements, 1993
HJK+JID
Nov 02
New Impact Tester of Sports Hall Wall Padding