Linear Impactor Testing of Hockey Helmets to Determine the Effects of the MIPS System on Head Response

Report No.:

R13-02 Date:

2013-02-25 Status:

Commerical in Confidence Prepared for:

Daniel Lanner MIPS

Birger Jarlsgatan

SE-114 29 Stockholm

Sweden

Authors:

Michael Wonnacott Ed Fournier

Biokinetics and Associates Ltd.

2470 Don Reid Drive

Ottawa, Ontario, K1H 1E1

Canada

tel: (613) 736-0384

fax: (613) 736-0990 www.biokinetics.com

Biokinetics and Associates Ltd. (2013) Biokinetics accepts responsibility for the technical validity of the contents. Approval or endorsement of the contents or opinions is not implied.

Biokinetics and Associates Ltd. (2013) R13-02/ February 27, 2013 / Page 1

1. Test Objectives

To evaluate the effect of the MIPS system on head kinematic response when implemented in an ice hockey helmet.

2. Test Setup/Method

• The test helmets were fitted to Hybrid III 50th percentile male headform on a flexible neck and impacted with the linear impactor.

• The headform was fitted with two pairs of stockings, to reduce the friction of the vinyl headskin.

• The impact face was angled at 45° about the vertical axis.

• The standard linear impactor impact face was used and comprised of a domed nylon cap with 37mm of VN600 foam backing.

• Each helmet was impacted once to the front boss and once to the side. The impact locations and impact vectors were specified by the client.

• Each impact location was repeated three times. A new helmet, which had not previously been impacted in the same location was used for each repeat impact.

• The Hybrid III headform was instrumented with nine accelerometers from which angular headform accelerations could be computed in addition to the measured linear accelerations.

• The target velocity at impact was nominally 7.00 m/s.

• All test were conducted in ambient conditions (21°C).

• The helmet positioning index was 68 mm from the lower edge of the brow of the helmet to the tip of the nose.

The impact sites are shown in Figure 1 to Figure 3.

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Figure 1: Site 1 (front boss).

Figure 2: Site 1 (front boss) top view.

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Figure 3: Site 2 (side)

The data acquisition parameters are summarized in Table 1 below.

Table 1: Data collection parameters.

Sampling rate (Hz) 10,000

Analogue filter CFC 1000

Digital filter CFC 180

Sample duration (ms) 200

High speed video framing rate (FPS) 1,000

Pre-trigger samples 5%

Accelerometer capacity (G) 2,000

Accelerometer resonance (Hz) 25,000

Amplifier full-scale setting (G) 250

Bias removal The average of 10% of the pre-trigger samples is subtracted from the individual transducer signals prior to secondary calculations

Impact velocity measurement Measured within 2.5 cm of impact. Light gate signal used to trigger the data acquisition.

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3. Results

The results of the linear impactor testing of the ice hockey helmets are presented in Figure 4 to Figure 7. Included are comparisons for the average peak linear acceleration, average peak angular acceleration, the average Severity Index (SI) and the average Head Injury Criterion (HIC 15). Results for each individual test are presented Appendix A.

Figure 4: Results – Average peak linear acceleration.

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Figure 5: Results – Average peak angular acceleration.

Figure 6: Results – Average severity index.

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Figure 7: Results – Average HIC.

4. Conclusions

The two impact orientations tested using the linear impactor produced differing results when adding the MIPS system to a hockey helmet. The impact to the front boss resulted in reductions in the average responses of 12% (rotational acceleration) to 46% (HIC) for the helmet with the MIPS system installed. When impacted at the side site, increases of 2% (rotational acceleration) to 11.5% (SI) were observed when comparing the MIPS equipped helmet to a standard helmet. The statistical significance of the results remains to be determined.

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Biokinetics and Associates Ltd. (2013) R13-02/ February 27, 2013 / Page A-1

Appendix A: Summary of Test Results

Site HelmetVelocity

(m/s)

Peak Linear

Accel. (G)

Peak Angular

Accel. (rad/s2)

SI HIC15 File

1 O1 7.00 37.8 3368 61 49 hl_site1_orig1

1 M1 7.05 33.7 3376 42 34 hl_site1_mips1

1 O2 7.01 39.7 3751 64 50 hl_site1_orig2

1 M2 7.02 29.9 3092 31 24 hl_site1_mips2

1 O3 7.00 39.8 3434 65 51 hl_site1_orig3

1 M3 6.96 27.8 2822 30 23 hl_site1_mips3

2 O1 7.02 31.0 3210 33 28 hl_site2_orig1

2 M1 7 33.5 3446 38 31 hl_site2_mips1

2 O2 7 30.8 3293 32 27 hl_site2_orig2

2 M2 7 34.6 3639 39 33 hl_site2_mips2

2 O3 7 35.6 3761 39 32 hl_site2_orig3

2 M3 6.98 34.2 3404 39 32 hl_site2_mips3