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Halldin, Peter
Publications (8 of 8) Show all publications
Meng, S., Cernicchi, A., Kleiven, S. & Halldin, P. (2019). The biomechanical differences of shock absorption test methods in the US and European helmet standards. International Journal of Crashworthiness, 24(4), 399-412
Open this publication in new window or tab >>The biomechanical differences of shock absorption test methods in the US and European helmet standards
2019 (English)In: International Journal of Crashworthiness, ISSN 1358-8265, E-ISSN 1754-2111, Vol. 24, no 4, p. 399-412Article in journal (Refereed) Published
Abstract [en]

Nowadays crash helmets are tested by dropping a free or unrestrained headform in Europe but a guided or restrained headform in the United States. It remains unclear whether the free fall and the guided fall produce similar impact kinematics that cause head injury. A ?nite element helmet model is developed and compared with experimental tests. The resulting head kinematics from virtual tests are input for a ?nite element head model to compute the brain tissue strain. The guided fall produces higher peak force and linear acceleration than the free fall. Eccentric impact in the free fall test induces angular head motion which directs some of the impact energy into rotational kinetic energy. Consequently, the brain tissue strain in the free fall test is up to 6.3 times more than that in the guided fall. This study recommends a supplemental procedure that records angular head motion in the free fall test.

Place, publisher, year, edition, pages
Taylor & Francis Group, 2019
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-252954 (URN)10.1080/13588265.2018.1464545 (DOI)000468457900004 ()2-s2.0-85046630058 (Scopus ID)
Note

QC 20190802

Available from: 2019-08-02 Created: 2019-08-02 Last updated: 2019-08-02Bibliographically approved
Halldin, P. & Fahlstedt, M. (2018). How sensitive are different headform design parameters in oblique helmeted impacts?. In: Proceedings of International Research Council on Biomechanics of Injury (IRCOBI) Conference: . Paper presented at IRCOBI.
Open this publication in new window or tab >>How sensitive are different headform design parameters in oblique helmeted impacts?
2018 (English)In: Proceedings of International Research Council on Biomechanics of Injury (IRCOBI) Conference, 2018Conference paper, Published paper (Refereed)
National Category
Other Medical Sciences
Identifiers
urn:nbn:se:kth:diva-248779 (URN)2-s2.0-85061102416 (Scopus ID)
Conference
IRCOBI
Note

QC20190418

Available from: 2019-04-10 Created: 2019-04-10 Last updated: 2019-04-18Bibliographically approved
Panzer, M. B., Giudice, J. S., Caudillo, A., Mukherjee, S., Kong, K., Cronin, D. S., . . . Brown, P. (2018). NUMERICAL CROWDSOURCING OF NFL FOOTBALL HELMETS. Paper presented at 3rd Joint Symposium of the International-and-National-Neurotrauma-Societies-and-AANS/CNS-Section on Neurotrauma and Critical Care, AUG 11-16, 2018, Toronto, CANADA. Journal of Neurotrauma, 35(16), A148-A148
Open this publication in new window or tab >>NUMERICAL CROWDSOURCING OF NFL FOOTBALL HELMETS
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2018 (English)In: Journal of Neurotrauma, ISSN 0897-7151, E-ISSN 1557-9042, Vol. 35, no 16, p. A148-A148Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Mary Ann Liebert, 2018
Keywords
Biomechanics, Computational / Modeling, Concussion / mTBI
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:kth:diva-234624 (URN)000441527400400 ()
Conference
3rd Joint Symposium of the International-and-National-Neurotrauma-Societies-and-AANS/CNS-Section on Neurotrauma and Critical Care, AUG 11-16, 2018, Toronto, CANADA
Note

QC 20180913

Available from: 2018-09-13 Created: 2018-09-13 Last updated: 2019-08-20Bibliographically approved
Meng, S., Fahlstedt, M. & Halldin, P. (2018). The effect of impact velocity angle on helmeted head impact severity: A rationale for motorcycle helmet impact test design. In: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI: . Paper presented at 2018 International Research Council on the Biomechanics of Injury, IRCOBI 2018, 12 September 2018 through 14 September 2018 (pp. 454-469). International Research Council on the Biomechanics of Injury
Open this publication in new window or tab >>The effect of impact velocity angle on helmeted head impact severity: A rationale for motorcycle helmet impact test design
2018 (English)In: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI, International Research Council on the Biomechanics of Injury , 2018, p. 454-469Conference paper, Published paper (Refereed)
Abstract [en]

The impact velocity angle determined by the normal and tangential velocity has been shown to be an important description of head impact conditions but can vary in real-world accidents. The objective of this paper was to investigate the effect of impact velocity angle on helmeted head impact severity indicated by the brain tissue strain. The human body model coupled with a validated motorcycle helmet model was propelled at a constant resultant velocity but varying angle relative to a rigid surface. Different body angles, impact directions and helmet designs have also been incorporated in the simulation matrix (n=300). The results show an influence of impact velocity angle on brain tissue strain response. By aggregating all simulation cases into different impact velocity angle groups, i.e., 15, 30, 45, 60 and 75 degrees, a 30- or 45-degree angle group give the highest median and inter-quartile range of the peak brain tissue strain. Comparisons of strain pattern and its peak value between individual cases give consistent results. The brain tissue strain is less sensitive to the body angle than to the velocity angle. The study suggests that UN/ECE 22.05 can be improved by increasing the current 'oblique' angle, i.e. 15 degrees inclined to vertical axis, to a level that can produce sufficient normal velocity component and hence angular head motion. This study also underline the importance of understanding post-impact head kinematics, and the need for further evaluation of human body models.

Place, publisher, year, edition, pages
International Research Council on the Biomechanics of Injury, 2018
Keywords
finite element method, Head impact conditions, Impact severity, Motorcycle helmet, Test method
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:kth:diva-246506 (URN)2-s2.0-85061089583 (Scopus ID)
Conference
2018 International Research Council on the Biomechanics of Injury, IRCOBI 2018, 12 September 2018 through 14 September 2018
Note

QC 20190329

Available from: 2019-03-29 Created: 2019-03-29 Last updated: 2019-03-29Bibliographically approved
Deck, C., Bourdet, N., Halldin, P., DeBruyne, G. & Willinger, R. (2017). Protection capability of bicycle helmets under oblique impact assessed with two separate brain FE models. In: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI: . Paper presented at 2017 International Research Council on the Biomechanics of Injury Conference, IRCOBI 2017, 13 September 2017 through 15 September 2017 (pp. 190-200). International Research Council on the Biomechanics of Injury
Open this publication in new window or tab >>Protection capability of bicycle helmets under oblique impact assessed with two separate brain FE models
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2017 (English)In: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI, International Research Council on the Biomechanics of Injury , 2017, p. 190-200Conference paper, Published paper (Refereed)
Abstract [en]

The present study proposes a bicycle helmet evaluation under oblique impact based on a coupled experimental versus numerical test method using two separate brain FE models. For each of the 17 helmet types three oblique impacts have been conducted and the 6D headform acceleration curves have been considered as the initial conditions of the brain injury risk assessment based on the FE simulation. The study gives a new insight into helmet protection capability under oblique loading and shows that adequate protection is offered by most of the helmets when impacts leading to rotation around X and Y are concerned. However when impact leads to rotation around Z axis the protection is critical for nearly all helmets. The study considers two separate brain FE models for the assessment of brain injury risk and thus permits a comparative analysis of brain FE modeling. When impact induces rotation around X and Y axis the computed results are comparable. However when rotation around Z axis are concerned significant differences are observed which demonstrate that further efforts are needed in the domain of model based brain injury criteria harmonization. 

Place, publisher, year, edition, pages
International Research Council on the Biomechanics of Injury, 2017
Keywords
Bicycle helmets, Head injury criteria, Oblique impact brain FEM, Test method, Bicycles, Finite element method, Numerical methods, Risk assessment, Rotation, Safety devices, Separation, Acceleration curve, Bicycle helmet, Comparative analysis, Head injury criterion, Initial conditions, Oblique impact, Protection capabilities, Accident prevention
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:kth:diva-246941 (URN)2-s2.0-85057593803 (Scopus ID)
Conference
2017 International Research Council on the Biomechanics of Injury Conference, IRCOBI 2017, 13 September 2017 through 15 September 2017
Note

QC 20190619

Available from: 2019-06-19 Created: 2019-06-19 Last updated: 2019-06-19Bibliographically approved
Alvarez, V., Halldin, P. & Kleiven, S. (2014). The Influence of Neck Muscle Tonus and Posture on Brain Tissue Strain in Pedestrian Head Impacts. Paper presented at 10 November 2014 through 12 November 2014. 58th SAE Stapp Car Crash Conference, STAPP 2014, 58
Open this publication in new window or tab >>The Influence of Neck Muscle Tonus and Posture on Brain Tissue Strain in Pedestrian Head Impacts
2014 (English)In: 58th SAE Stapp Car Crash Conference, STAPP 2014, Vol. 58Article in journal (Refereed) Published
Abstract [en]

Pedestrians are one of the least protected groups in urban traffic and frequently suffer fatal head injuries. An important boundary condition for the head is the cervical spine, and it has previously been demonstrated that neck muscle activation is important for head kinematics during inertial loading. It has also been shown in a recent numerical study that a tensed neck musculature also has some influence on head kinematics during a pedestrian impact situation. The aim of this study was to analyze the influence on head kinematics and injury metrics during the isolated time of head impact by comparing a pedestrian with relaxed neck and a pedestrian with increased tonus. The human body Finite Element model THUMS Version 1.4 was connected to head and neck models developed at KTH and used in pedestrian-to-vehicle impact simulations with a generalized hood, so that the head would impact a surface with an identical impact response in all simulations. In order to isolate the influence of muscle tonus, the model was activated shortly before head impact so the head would have the same initial position prior to impact among different tonus. A symmetric and asymmetric muscle activation scheme that used high level of activation was used in order to create two extremes to investigate. It was found that for the muscle tones used in this study, the influence on the strain in the brain was very minor, in general about 1-14% change. A relatively large increase was observed in a secondary peak in maximum strains in only one of the simulated cases. 

Place, publisher, year, edition, pages
SAE International, 2014
Keywords
Brain tissue strain, Finite element method, Muscle tonus, Pedestrian accidents, Accidents, Brain, Chemical activation, Kinematics, Muscle, Strain, Brain tissue, Impact response, Inertial loadings, Maximum strains, Muscle activation, Neck muscle activation, Pedestrian impact
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:kth:diva-246646 (URN)10.4271/2014-22-0003 (DOI)2-s2.0-85059470111 (Scopus ID)
Conference
10 November 2014 through 12 November 2014
Note

QC 20190618

Available from: 2019-06-18 Created: 2019-06-18 Last updated: 2019-06-18Bibliographically approved
Halldin, P., Lanner, D., Coomber, R. & Kleiven, S. (2013). Evaluation of blunt impact protection in a military helmet designed to offer blunt & ballistic impact protection.. In: Proceedings of the 1st International Conference on Helmet Performance and Design: . Paper presented at 1st International Conference on Helmet Performance and Design. , Article ID HPD-2013-6.
Open this publication in new window or tab >>Evaluation of blunt impact protection in a military helmet designed to offer blunt & ballistic impact protection.
2013 (English)In: Proceedings of the 1st International Conference on Helmet Performance and Design, 2013, article id HPD-2013-6Conference paper, Published paper (Refereed)
Abstract [en]

This paper describes both a numerical and an experimental approach to measuring the ballistic and blunt impact protection offered by military helmets. The primary purpose of military helmets is to protect users from ballistic impact but modern military helmets protect users from blunt force as well. Altering ballistic shell stiffness, lining the shell with material of different density, even separating the liner from the shell so that they can move independently all affect the transfer of stress to the head and the resulting strain experienced by the brain. The results of this study suggest that there is potential for a helmet that protects the user from both blunt and ballistic impact and can be further improved by implementing an energy absorbing sliding layer, such as the MIPS system, between the shell and the liner to mitigate the effect of oblique impacts.

National Category
Applied Mechanics
Research subject
Medical Technology
Identifiers
urn:nbn:se:kth:diva-241069 (URN)
Conference
1st International Conference on Helmet Performance and Design
Note

QC 20190109

Available from: 2019-01-08 Created: 2019-01-08 Last updated: 2019-01-09Bibliographically approved
Halldin, P. & Kleiven, S. (2013). The development of next generation test standards for helmets.. In: The development of next generation test standards for helmets.: . Paper presented at 1st International Conference on Helmet Performance and Design. , 1, Article ID HPD-2013-1.
Open this publication in new window or tab >>The development of next generation test standards for helmets.
2013 (English)In: The development of next generation test standards for helmets., 2013, Vol. 1, article id HPD-2013-1Conference paper, Published paper (Refereed)
Abstract [en]

Injury statistics show that accidents with a head impact often happen with an angle to the impacting object. An angled impact will result in a rotation of the head if the friction is high enough. It is also known that the head is more sensitive to rotation than pure linear motion of the head. CEN has initiated the work to design a new helmet test oblique or angled impact test method a helmet test method that can measure the rotational energy absorption in a helmet during an angled impact. This paper presents a short summary of possibilities and limitations on how to build a helmet test method that can measure the rotational energy absorption in a helmet during an angled impact.

National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-241068 (URN)
Conference
1st International Conference on Helmet Performance and Design
Note

QC 20190109

Available from: 2019-01-08 Created: 2019-01-08 Last updated: 2019-01-09Bibliographically approved
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