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- Törnvall, Fredrik, 1975
(författare)
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A New Shoulder for the THOR Dummy Intended for Oblique Collisions
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Offset and oblique frontal car collisions represent a type of crash in which severe and fatal injuries frequently occur. This indicates the importance of having protective systems in vehicles for these types of collisions. Evaluation of such protective systems requires access to crash test dummies that accurately replicate the human body kinematics. The objectives of this research are to develop and evaluate a new shoulder that is anticipated to facilitate the development of safety systems for cars involved in offset and oblique frontal collisions.First, the performance of current frontal impact dummies in oblique impact situations was investigated. Tests were carried out in far-side (away from the shoulder belt anchor) and near-side (towards the shoulder belt anchor) collisions. The Hybrid III dummy did not show human-like head kinematics. The THOR dummy showed human-like head kinematics, but slipped out of the shoulder belt more easily than a post mortem human subject (PMHS) in the 45° far-side collisions. It was found that the THOR shoulder may not be adequately biofidelic.Next, five volunteers and a THOR dummy were tested in a rig where both arms were statically loaded in three directions, forward, diagonally forward-upwards and upwards, while the sternum was supported. The displacement between the right shoulder and the sternum was estimated by means of photo analysis. The THOR dummy was observed to be stiffer and to allow a smaller shoulder range-of-motion then the volunteers. Three belted PMHSs and a THOR dummy were then tested in 0° full-frontal tests, in 45° far-side tests and in 30° near-side tests to study the shoulder and belt-to-shoulder interaction. High-speed video recorded the motions of the test subjects. For the 45° far-side impact, it was concluded that the PMHSs did not slip out of the shoulder belt as easily as the THOR NT did. Further analysis revealed that the geometrical properties of the shoulder bones may be important for the interaction with the shoulder belt in oblique impacts. The response of the human shoulder complex may also influence the head kinematics and thereby head-to-door interaction in oblique near-side collisions.A new mechanical shoulder prototype was developed for the THOR NT dummy, the THOR SD-1NT. Its design was based on results from the volunteer and the first PMHS study. The shoulder design, SD-1, was intended to have bony surface landmarks and a range-of-motion similar to that of a human, to enable improved belt-to-shoulder interaction during a collision. To resemble the human shoulder stiffness during anterior motion, the SD-1 was designed to have a linearly increasing resistance. The THOR SD-1NT was evaluated against the second PMHS study. It is believed that the geometrical properties and bony landmarks of the SD-1 are in accordance with the human anatomy, and that they provide a human-like belt-to-shoulder interaction, especially during oblique impacts. However, the SD-1 needs further tuning, especially the shoulder range-of-motion. Therefore, a second prototype of the shoulder design, SD-2, was built.
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| 2. |
- Törnvall, Fredrik, 1975, et al.
(författare)
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A New THOR Shoulder Design: A Comparison with Volunteers, the Hybrid III and THOR NT
- 2007
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Ingår i: Traffic Injury Prevention. - 1538-957X .- 1538-9588. ; 8:3, s. 211-222
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Tidskriftsartikel (refereegranskat)abstract
- Objective Since the shoulders are rarely seriously injured in frontal or oblique collisions, they have been given low priority in the development of frontal impact crash test dummies. The shoulder complex geometry and its kinematics are of vital importance for the overall dummy kinematics. The shoulder complex also influences the risk of the safety belt slipping off the shoulder in oblique forward collisions. The first aim of this study was to develop a new 50th percentile male THOR shoulder design while the second was to compare the new shoulder, mounted on a THOR NT dummy, with volunteer, THOR NT and Hybrid III range-of-motion and stiffness data. The third aim was to test the repeatability of the new shoulder during dynamic testing and to see how the design behaves with respect to belt slippage in a 45° far-side collision.Methods The new 50th percentile THOR shoulder design was developed with the aid of a shell model of the seated University of Michigan Transportation Research Institute (UMTRI) 50th percentile male with coordinates for joints and bony landmarks (Schneider et al., 1983). The new shoulder design has human-like bony landmarks for the acromion and coracoid processes. The clavicle curvature and length are also made similar to that of a male human, as is the range-of-motion in the anterior-posterior, superior-inferior and medial-lateral directions. The new shoulder design was manufactured and tested under the same conditions that Törnvall et al. (2005b) used to compare the shoulder range-of-motion for the volunteers, Hybrid III and THOR Alpha. The new design was also tested in two dynamic test configurations: the first was a 0° full-frontal test and the second was a 45° far-side test. The dummy tests were conducted with an R-16 seat with a three-point belt, the ΔV was 27.0 ±0.5 km/h and the maximum peak acceleration was approximately 14.6 ±0.5 g for each test.Results A new shoulder design with geometry close to that of humans was developed to be retrofitted to the THOR NT dummy. The results showed that the range-of-motion for the new shoulder complex during static loading was larger by at least a factor of three, for the maximum load (200 N/arm), than that of either the Hybrid III or the THOR NT; this means it was more similar to the volunteers’ range-of-motion. It was observed that the THOR NT with the new shoulder did not slide out of the shoulder-belt during a far-side collision. The performance of the new shoulder was reasonably repeatable and stable during both the static tests and the sled tests.Conclusions A new shoulder for the THOR NT has been designed and developed, and data from static range-of-motion tests and sled tests indicate that the new shoulder complex has the potential to function in a more human-like manner on the THOR dummy.
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| 3. |
- Törnvall, Fredrik, 1975, et al.
(författare)
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A New THOR Shoulder Design: Its Range-of-Motion in Comparison with Volunteers, the Hybrid III and THOR NT
- 2006
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Ingår i: International IRCOBI Conference on the Biomechanics of Impact. ; , s. 409-412
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Konferensbidrag (refereegranskat)abstract
- There is a need for dummies that mimic crash victims kinematics in oblique and offset frontal collisions. Improved seatbelt-to-dummy interaction in crash testing is also desirable. Hence, a new THOR shoulder was developed and evaluated in comparison with volunteers, the Hybrid III and THOR NT shoulder range-of-motion. The new shoulder has human-like bony landmarks, clavicle curvature and length, and joints. The evaluation showed that the range-of-motion for the static loading of the new shoulder was similar to that of the volunteers. This was not so for the Hybrid III and THOR NT. The data indicates that the new shoulder design can provide more human-like shoulder motions in a crash test.
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| 4. |
- Törnvall, Fredrik, 1975, et al.
(författare)
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Comparison of Shoulder Range-of-Motion and Stiffness between Volunteers, Hybrid III and THOR Alpha in Static Frontal Impact Loading
- 2005
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Ingår i: International Journal of Crashworthiness. - : Informa UK Limited. - 1358-8265 .- 1754-2111. ; 10:2, s. 151-160
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to compare the shoulder range-of-motion and stiffness between volunteers and 50th percentile dummies in static loading conditions simulating frontal collisions. Five volunteers a Hybrid III and a THOR Alpha were positioned in a test rig where both arms were statically loaded in the forward-upward direction at 90°, 135° and 170° angles while the sternum was supported. The distances between right shoulders and sternums were estimated by means of photo analysis. The photo analysis showed that the volunteers’ range-of-motion was at least three times larger for the maximum load (200 N/arm) than those of the Hybrid III and the THOR Alpha. The results indicate that the biofidelity of the dummies used today in full-frontal, oblique and offset frontal collisions may be improved by redesigned shoulder complexes. The dummies would then better predict the human kinematics and the loading of the chest by various restraint systems.
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| 5. |
- Törnvall, Fredrik, 1975, et al.
(författare)
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EVALUATION OF DUMMY SHOULDER KINEMATICS IN OBLIQUE FRONTAL COLLISIONS
- 2008
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Ingår i: IRCOBI. - 9783033015807 ; , s. 195-210
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Konferensbidrag (refereegranskat)abstract
- The present study evaluates shoulder kinematics of the Hybrid III and THOR NT, with the firstversion of a new shoulder design (SD-1), in 45° far-side, full frontal and 30° near-side collisions. Intotal eleven dummy tests were conducted in the three collision angles, while film and instrument datawere generated and compared with those of PMHS data from Törnvall (2008). For the 45° far-sideimpact, the THOR SD-1NT dummy retained the shoulder belt on the shoulder during on-loading, as didthe PMHSs, whereas the THOR NT did not. In the 30° near-side impact,
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| 6. |
- Törnvall, Fredrik, 1975, et al.
(författare)
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Frontal Impact Dummy Kinematics in Oblique Frontal Collisions: Evaluation against Post Mortem Human Subject Test Data
- 2005
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Ingår i: Traffic Injury Prevention. - 1538-957X .- 1538-9588. ; 6:4, s. 340-350
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Tidskriftsartikel (refereegranskat)abstract
- Objective Today, a predominant percentage of vehicles involved in car crashes are exposed to oblique or frontal offset collisions. The aim of this study is to evaluate the 50th percentile male Hybrid III, THOR 99 and THOR Alpha dummies by comparing them with the corresponding kinematics of post mortem human subjects (PMHS) in this type of collision.Methods The PMHS data include results from oblique frontal collision tests. They include sled tests with near-side and far-side belt geometries at 15°, 30° and 45° angles. The test subjects were restrained with a three-point lap-shoulder belt and the ?V was 30 km/h.Results The results from the Hybrid III and THOR 99 tests showed that, in most of the test, the head trajectories were an average of approximately 0.1 m shorter than those from equivalent PMHS. The Hybrid III and THOR 99 far-side belt geometry tests showed that the belt remained in place longer on the shoulder of the Hybrid III than on the THOR 99 and the THOR Alpha. This was probably due to a stiffer lumbar spine in the Hybrid III and to a large groove in the steel of the superior surface of the Hybrid III shoulder structure. The THOR 99 escaped from the shoulder belt about 40 - 50 ms earlier than the THOR Alpha. The results from the THOR Alpha tests show that the head trajectory accorded fairly well with the PMHS data, as long as the shoulder belt did not slip off the shoulder. Although the THOR Alpha shoulder escaped the shoulder belt in the 45° far-side belt geometry, the PMHS did not. This may be due to the THOR Alpha shoulder design, with approximately 0.05 m smaller superior and medial shoulder range-of-motion, in combination with a relatively soft lumbar spine.Conclusions The THOR Alpha provides head trajectories similar to those of the PMHS under these loading conditions, provided the shoulder belt remains in position on the shoulder. When the shoulder belt slipped off the dummy shoulder, the head kinematics was altered. The shoulder range-of-motion may be a contributing factor to the overall kinematics of an occupant in oblique frontal impact situations where the occupant moves in a trajectory at an angle from that of the longitudinal direction of the car.
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