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Neck injuries in rear impacts: Dummy neck development, dummy evaluation and test condition specifications
Crash Safety Division, Department of Machine and Vehicle Systems, Chalmers University of Technology, Gothenburg, Sweden.ORCID iD: 0000-0001-6868-5673
2001 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The objective of the work underlying this thesis was firstly to develop a neck for a new rear impact dummy, to evaluate the complete dummy and to specify test conditions for a consumer test with attention to AIS 1 neck injuries in rear impacts. In the development of the dummy neck, a mathematical neck model was developed and evaluated. Furthermore, impact severity and seat designs were also investigated.

Rear collisions can result in AIS 1 neck injuries. These injuries, which are becoming more frequent, occur mostly at low changes of velocity (less than 30km/h). Since AIS 1 neck injuries can result in long-term symptoms, it is of major importance to devise protection from these injuries. When testing the safety performance of seats and head restraints, an essential tool is the crash test dummy. However, the standard crash dummy of today, the Hybrid III, has had limitations in its interaction with the seat and head restraint.

The new dummy neck developed was evaluated by using data from crash tests involving volunteers as well as post mortem human subjects. For comparison, the Hybrid III frontal impact dummy was also tested under the same conditions. The new neck was found to have more human-like motion than that of the Hybrid III in low velocity rear tests when compared to both volunteers and post mortem human subjects. This was found to be the case for the head relative to upper torso horizontal and angular displacement. The new dummy neck became a fundamental part of the new, low-velocity rear impact crash dummy, the BioRID. The BioRID was found to have more human-like motion than that of the Hybrid III in low velocity rear impact tests when compared to both volunteers and post mortem human subjects. This result was observed for angular, vertical and horizontal displacement of the upper torso.

The variations in acceleration pulse characteristics in different vehicle models in identical impact conditions was shown to be substantial. A similar delta-V could be generated in a large variety of ways in terms of mean acceleration and acceleration pulse shape in a rear impact. The variation in crash pulse characteristics for the same car model from different real-world crashes of similar delta-Vs was also shown to be significant. This served as a background for the specifications of the test conditions for a proposed consumer test.

Real-world rear impact collisions with crash recorder-equipped vehicles, were reconstructed on a sled reproducing the real-world crash pulse. The results illustrate the risk of sub-optimisation when using only a single test in assessing neck injury protection. Further, five different seat configurations were evaluated in a series of sled tests at four impact severities. Identical vehicle seats were found to perform differently in tests with of different severities. Changing the mean acceleration (from 4.2g to 7.6g) influenced key dummy readings more than changing the delta-V (from 15km/h to 25km/h). Therefore, it should be expected that different real-world rear collisions at similar delta-Vs imply highly differing loading conditions to the occupants. As a consequence, the test conditions for the proposed consumer test program included specifications for several levels of change of velocity and mean acceleration.

The results of this thesis are expected to become important input in the definition of future rear impact test procedures for neck injury risk assessment.

Place, publisher, year, edition, pages
Göteborg: Chalmers University of Technology , 2001. no 1789, p. 58
Series
Doktorsavhandlingar vid Chalmers Tekniska Hogskola, ISSN 0346-718X ; 1789
Keywords [en]
Neck, Injury, Anthropometric dummy, Severity, Impact test, Rear end collision, Seat, Mathematical model, Velocity, Thesis, Optimization, Mathematical neck models, Rear impact tests, Biomechanics
National Category
Applied Mechanics
Research subject
90 Road: Vehicles and vehicle technology, 911 Road: Components of the vehicle
Identifiers
URN: urn:nbn:se:vti:diva-243ISBN: 9172911069 (print)OAI: oai:DiVA.org:vti-243DiVA, id: diva2:659974
Available from: 2013-10-28 Created: 2013-10-28 Last updated: 2025-05-16Bibliographically approved
List of papers
1. A new mathematical neck model for a low-velocity rear-end impact dummy: Evaluation of components influencing head kinematics
Open this publication in new window or tab >>A new mathematical neck model for a low-velocity rear-end impact dummy: Evaluation of components influencing head kinematics
2000 (English)In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 32, no 2, p. 261-269Article in journal (Refereed) Published
Abstract [en]

A mathematical model of a new rear-end impact dummy neck was implemented using MADYMO. The main goal was to design a model with a human-like response of the first extension motion in the crash event. The new dummy neck was modelled as a series of rigid bodies (representing the seven cervical vertebrae and the uppermost thoracic element, T1) connected by pin joints, and supplemented by two muscle substitutes. The joints had non-linear stiffness characteristics and the muscle elements possessed both elastic stiffness and damping properties. The new model was compared with two neck models with the same number of vertebrae, but without muscle substitutes. The properties of the muscle substitutes and the need of these were evaluated by using three different modified neck models. The motion of T1 in the simulations was prescribed using displacement data obtained from volunteer tests. In a sensitivity analysis of the mathematical model the influence of different factors on the head-neck kinematics was evaluated. The neck model was validated against kinematics data from volunteer tests: linear displacement, angular displacement, and acceleration of the head relative to the upper torso at 7 km/h velocity change. The response of the new model was within the corridor of the volunteer tests for the main part of the time history plot. This study showed that a combination of elastic stiffness and damping in the muscle substitutes, together with a non-linear joint stiffness, resulted in a head-neck response similar to human volunteers, and superior to that of other tested neck models.

Keywords
Neck, Moving, Simulation, Dummy neck, Low-velocity, Mathematical model, Rear-end collision, Soft tissue neck injuries
National Category
Vehicle and Aerospace Engineering
Research subject
Road: Vehicles and vehicle technology, Road: Components of the vehicle
Identifiers
urn:nbn:se:vti:diva-246 (URN)10.1016/S0001-4575(99)00085-8 (DOI)000085209300014 ()
Available from: 2013-10-28 Created: 2013-10-28 Last updated: 2025-05-16Bibliographically approved
2. Design and validation of the neck for a rear impact dummy (BioRID I)
Open this publication in new window or tab >>Design and validation of the neck for a rear impact dummy (BioRID I)
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2002 (English)In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 3, no 2, p. 167-174Article in journal (Refereed) Published
Abstract [en]

To assess the protective performance of seats and head restraints, occupant models able to mimic the motion of a human in a crash are needed. Hence, a new mechanical dummy neck for low-velocity rear collision tests was developed. The dummy neck consists of seven cervical elements connected by pin joints. The stiffness properties of the neck were represented by rubber blocks mounted between each pair of vertebrae, as well as by muscle substitutes between the head and the first thoracic vertebra (T1). The muscle substitutes consist of cables connected to a unit containing springs and a damper. The neck was validated against volunteer test data (Δv of 7 km/h) and compared with the kinematics of the Hybrid III dummy. The new neck was tested as a part of a new dummy (BioRID) that produced a human-like motion of the T1. The kinematics of the new neck was within the corridor of the volunteers, during the major part of the first 250 ms of the crash event, for both displacement of the head relative to T1 and for the acceleration of the head. This applies to both duration and peak values. When compared with the new neck, the Hybrid III showed an earlier decrease of the horizontal acceleration of the head, less maximum horizontal displacement, and an earlier increase of the rearward angular displacement of the head relative to T1.

Keywords
Anthopometric dummy, Neck, Design, Head restraint, Acceleration, Device, Human, Human experiment, Kinematics, Normal human, Protective equipment, Rigidity, Traffic accident, Velocity, Whiplash injury
National Category
Vehicle and Aerospace Engineering
Research subject
Road: Traffic safety and accidents, Road: Personal injuries
Identifiers
urn:nbn:se:vti:diva-241 (URN)10.1080/15389580211995 (DOI)
Available from: 2013-10-28 Created: 2013-10-28 Last updated: 2025-05-16Bibliographically approved
3. Validation of the BioRID P3 Against Volunteer and PMHS Test Data and Comparison to the Hybrid III in Low-Velocity Rear-End Impacts
Open this publication in new window or tab >>Validation of the BioRID P3 Against Volunteer and PMHS Test Data and Comparison to the Hybrid III in Low-Velocity Rear-End Impacts
1999 (English)In: 43rd Annual Proceedings - Association for The Advancement of Automotive Medicine, Association for The Advancement of Automotive Medicine , 1999, p. 367-381Conference paper, Published paper (Other academic)
Abstract [en]

The aim of the study was to validate the BioRID P3, an improvement of the BioRID I, in regular car seats against rear-end impact volunteer test data and compared it to PMHS data collected previously. The performance of the BioRID P3 was also compared to the performance of a Hybrid III equipped with a TRID neck. The volunteer tests were performed at a change of velocity (Δv) of 10 km/h and a maximum acceleration of 3.5 g. The PMHS (Post Mortem Human Subject) tests were run at Δv of 10 and 15 km/h. The BioRID P3 acceleration and displacement data correlated well with the volunteer and PMHS data. Comparison of the head and chest horizontal displacement and the horizontal neck forces data showed differences between the dummies. 

Place, publisher, year, edition, pages
Association for The Advancement of Automotive Medicine, 1999
Series
Annual proceedings - Association for the Advancement of Automotive Medicine, ISSN 1540-0360
National Category
Vehicle and Aerospace Engineering
Identifiers
urn:nbn:se:vti:diva-22038 (URN)
Conference
AAAM 43th Annual Conference, Barcelona, Spain, September 20-21, 1999.
Available from: 2025-05-16 Created: 2025-05-16 Last updated: 2025-05-16Bibliographically approved
4. Evaluation of the BioRID P3 and the hybrid III in pendulum impacts to the back: A comparison with human subject test data
Open this publication in new window or tab >>Evaluation of the BioRID P3 and the hybrid III in pendulum impacts to the back: A comparison with human subject test data
2002 (English)In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 3, no 2, p. 159-166Article in journal (Refereed) Published
Abstract [en]

Crash test dummies able to mimic the motion of a human are needed to assess the protective performance of seats and head restraints in crash tests. This study evaluates both a newly developed dummy for rear impacts (BioRID P3) and the Hybrid III dummy by means of a recently available set of human subject data. The study also meets the need for validation of the BioRID P3 at a higher impact severity than that previously achieved. The BioRID P3 and the Hybrid III were evaluated by means of pendulum impacts to the back and compared with data from previously run cadaver tests. Seated dummies were struck with a pendulum with a mass of 23 kg and an impact velocity of 4.6 m/s at the level of the 6th thoracic vertebra. The results showed that peak values and temporal responses of the BioRID P3 was closer to that of the corridor of the cadavers than the Hybrid III in terms of horizontal, vertical, and angular displacement of the head and of the head relative to T1.

Keywords
Anthropometric dummy, Comparative study, Whiplash injury, Rear end collision, Cervical Vertebrae
National Category
Vehicle and Aerospace Engineering
Research subject
Road: Traffic safety and accidents, Road: Personal injuries
Identifiers
urn:nbn:se:vti:diva-242 (URN)10.1080/15389580211994 (DOI)
Available from: 2013-10-28 Created: 2013-10-28 Last updated: 2025-05-16Bibliographically approved
5. Acceleration pulses and crash severity in low velocity rear impacts: real world data and barrier tests
Open this publication in new window or tab >>Acceleration pulses and crash severity in low velocity rear impacts: real world data and barrier tests
Show others...
2001 (English)In: 17th International Technical Conference on the Enhanced Safety of Vehicles: Proceedings Booklet, U.S. Department of Transportation - National Highway Traffic Safety Administration , 2001, article id 216Conference paper, Published paper (Other academic)
Abstract [en]

Dummy responses in a crash test can vary depending not only on the change of velocity but also on how the impact was generated. Literature reporting how acceleration pulses can vary in cars impacted in different configurations is limited. The aim of this study was to collect and categorise different acceleration pulses in 3 different types of rear collision. The acceleration pulse resulting from a solid, 1000 kg, mobile barrier test at 40% overlap and an impact velocity of 15 km/h was studied for 33 different cars. Seven cars were impacted at 100% overlap at higher impact velocities using the same mobile barrier. Acceleration pulses from two different car types in real-world collisions producing a similar change of velocity were also analysed.

The results from the barrier tests show that a similar change of velocity can be generated by a large variety of pulse shapes in low velocity rear impacts. The results from real-world collisions showed that a similar change of velocity was generated in different ways both in terms of peak and mean acceleration. The results of this study highlight the importance of knowing the acceleration pulse both when evaluating the severity of a real world crash and when designing test methods for evaluating vehicle safety performance in low velocity rear-end impacts, particularly in respect of soft tissue neck injuries. 

Place, publisher, year, edition, pages
U.S. Department of Transportation - National Highway Traffic Safety Administration, 2001
National Category
Vehicle and Aerospace Engineering
Identifiers
urn:nbn:se:vti:diva-22039 (URN)
Conference
17th International Technical Conference on the Enhanced Safety of Vehicles, Amsterdam, Netherlands, June 4-7, 2001.
Funder
Swedish Transport Administration
Available from: 2025-05-16 Created: 2025-05-16 Last updated: 2025-05-16Bibliographically approved
6. Dynamic performances of different seat designs for low to medium velocity rear impact.
Open this publication in new window or tab >>Dynamic performances of different seat designs for low to medium velocity rear impact.
Show others...
2001 (English)In: 45th Annual Proceedings: Association for the Advancement of Automotive Medicine, Association for the Advancement of Automotive Medicine , 2001, Vol. 45, p. 187-201Conference paper, Published paper (Refereed)
Abstract [en]

There is good evidence that seat design and impact severities in terms of delta-V and acceleration plays a role in AIS 1 neck injury outcomes in the event of a rear impact. This study evaluates a number of current production seats to assess the AIS 1 neck injury protection potential at different impact severities. Five different seat designs were exposed to four different impact severities in a sled simulating a rear impact. The same delta-V produced with different peak accelerations generated very different dummy responses. Head restraint position influenced the angular and horizontal displacement of the head relative to torso and the time of head to head restraint contact. The lowest motion of the head relative to the torso was found in the two anti-whiplash seats tested. The results of the study can be used for the design of future vehicle seats and anti-whiplash systems.

Place, publisher, year, edition, pages
Association for the Advancement of Automotive Medicine, 2001
Series
Annual proceedings Association for the Advancement of Automotive Medicine, ISSN 0892-6484 ; 45
Keywords
Seat, Design, Rear end collision, Neck, Acceleration, Car, Equipment design, Human, Injury scale, Traffic accident, Whiplash injury, Abbreviated injury scale, Acceleration, Accidents, Traffic, Automobiles, Equipment design, Humans, Whiplash Injuries
National Category
Vehicle and Aerospace Engineering
Research subject
Road: Vehicles and vehicle technology, Road: Components of the vehicle
Identifiers
urn:nbn:se:vti:diva-244 (URN)12214349 (PubMedID)
Conference
45th Annual AAAM Conference, 24-26 September, Texas
Available from: 2013-10-28 Created: 2013-10-28 Last updated: 2025-05-16Bibliographically approved

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