Peter Halldin. MIPS AB Stockholm Sweden. Royal Institute of Technology (KTH) Stockholm, Sweden

Transcription

1 Using an advanced FE model of the human head to understand the risk for brain injuries in helmet impact tests - A Presentation of the MIPS approval test Peter Halldin MIPS AB Stockholm Sweden Royal Institute of Technology (KTH) Stockholm, Sweden

2 Outline MIPS AB KTH The KTH FE model of the human head The MIPS approval test method 2

3 MIPS AB 20 Years of research at the Royal Institute of Technology (KTH) and the Karolinska Institute. 58 Brand partners 220 Models with MIPS 25 Employees 6 Patents and more pending Current markets Projected markets Bike, Snow, Motorcycle, Equestrian Team Sport and Military

4 Current MIPS partners

5 MIPS - copying the evolution Multi-directional Impact Protection System 5

6 MIPS II Implementation process In house CAD design Low friction layers (PC) produced in Sweden or China. No change of outer design gram added weight. Already in 220 different helmet models in 4 different helmet segments SLS-modell MIPS layer in place

7 Outline MIPS AB KTH The KTH FE model of the human head The MIPS approval test method 7

8 Research activities at the Division of Neuronic, KTH FFI Pedestrian accident LF Helmet test method PIPER Child modeling HEADS BVFF-Vinnova Accident reconstruction Helmet test method New child neck model MC & ski accident reconstruction Fall injury biomechanics Head injury prediction Head injury prediction New child head& brain model Axonal brain model Neck model validation Elderly Head model Helmet test method

9 Research activities at the Division of Neuronic, KTH FFI Pedestrian accident LF Helmet test method PIPER Child modeling HEADS BVFF-Vinnova Accident reconstruction Helmet test method New child neck model MC & ski accident reconstruction Fall injury biomechanics Head injury prediction Head injury prediction New child head& brain model Axonal brain model Neck model validation Elderly Head model Helmet test method

10 Research activities at the Division of Neuronic, KTH FFI Pedestrian accident LF Helmet test method PIPER Child modeling HEADS BVFF-Vinnova Accident reconstruction Helmet test method New child neck model MC & ski accident reconstruction Fall injury biomechanics Head injury prediction Head injury prediction New child head& brain model Axonal brain model Neck model validation Elderly Head model Helmet test method

11 Outline MIPS AB KTH The KTH FE model of the human head The MIPS approval test method 11

12 The KTH head model Kleiven 2007 o o o o o nodes eight-node brick elements, four-node shell and membrane elements 22 two-node truss elements hexahedral elements represented the brain 12

13 Material properties used in the head model (Kleiven 2007) Mat #77 Ogden rubber Kleiven, S., Predictors for traumatic brain injuries evaluated through accident reconstruction. Proc. 51th Stapp Car Crash Conf., Society of Automotive Engineers Paper , pp

14 Relative motion in the head Kleiven and Hardy, Stapp Car Crash Journal

15 x z Relative Motion in the head Kleiven and Hardy, Stapp Car Crash Journal

16 Radial vs. oblique impact First principle strain distribution in a radial impact First principle strain distribution in an oblique impact Kleiven, Enhanced Safety of Vehicles

17 Reconstruction of MX accident

18 The accident Malmabanan outside Västerås The velocity was ca 50km/h for both riders. The impact was almost perpendicular.

19 Injuries CT images from Akademiska Sjukhuset, Uppsala Hematoma in frontal lobe In addition more than 10 small hematomas of various sizes Hematoma along the tentorium

20 Reconstruction set up (Kleiven 2007)

21 Strain pattern in the brain CT images FEM-simulations Large strains are seen in red Hematoma in the frontal lobe Hematoma in the rear part of the brain (Kleiven 2007)

22 Reconstruction of 58 NFL accidents - Kleiven et al 2007 Courtesy of Biokinetics 2006 Striking player (H1) Struck player (H2) Courtesy of Biokinetics 2006 Courtesy of Biokinetics 2006 (Kleiven 2007)

23 Strain as a predictor of MTBI (Kleiven 2007)

24 Strain as a predictor of MTBI * ** ** ** ** ** ** * P<0.01; ** P<0.001 (Kleiven 2007)

25 Outline MIPS AB KTH The KTH FE model of the human head The MIPS approval test method 25

26 Experimental test methods Current test methods Accident reconstructions New test methods 26

27 The MIPS helmet test lab DYNAmore Nordic Users Forum

28 Test conditions: Three impact points/directions 6.5m/s, 45 degree impact DYNAmore Nordic Users Forum 2016

29 Pass fail criteria 6DOF (3 linear and 3 rotational) accelerations based pass fail criteria BRIC, HIP, PRHIC, GAMBIT Injury risk assessment tool based on one FE model. About 8 existing models in the world. s n c m c t a t a G t 1 ) ( ) ( ) ( DYNAmore Nordic Users Forum 2016

30 Example from MIPS Approval test Experimental tests Original MIPS Global Kinematics Diff %

31 Reduction of strain computed in KTH FE model of human head Yrot Xrot Zrot DYNAmore Nordic Users Forum

32 No MIPS MIPS Test protocoll Ski helmet test standard EN1077 Linear acceleration < 250G Yrot Xrot Zrot Linear acceleration + Angular acceleration Strain reduction > 10% DYNAmore Nordic Users Forum

33 Thank you! DYNAmore Nordic Users Forum