Dummy Kinematics Research Articles

Dummy kinematics in frontal impact, comparison of simulations in Madymo with sled tests

The paper aims to respond to the current requirements regarding the usage of modern virtual analysis tools in accidentology research, presenting the methods of performing the virtual and experimental studies. The main objective of this paper is to determine the movement of the dummy by comparing the kinematic parameters provided by the simulations performed in Madymo with the experimental tests (sled tests). A prototype test device was used to analyse the movement of the dummy in a vehicle cabin at different impact situations of a frontal collision. The experiment was performed for two different cases: with seatbelt and without seatbelt. For the virtual study in Madymo two different setups were prepared in order to obtain the results for both testcases based on a parameterized model. The analysis of the results is performed by comparison, between experimental results and simulation results. Three different phases are taken into consideration in order to make a study of a frontal collision: pre-collision, collision and post-collision.

Influence of retractor and anchor pretensioning on dummy responses in 40 km/h rear sled tests

Objective This study compared dummy kinematics and biomechanical responses with and without retractor pretensioning in a severe rear sled test. It compliments an earlier study with buckle pretensioning. Methods Three rear tests were run at 40 km/h (25 mph) delta V with a lap-shoulder belted Hybrid III 50th male dummy on a 2013-18 Ford Escape driver seat and belt restraint. One test was with the lap-shoulder belts only, a second with retractor and anchor pretensioning and a third with only retractor pretensioning. The head, chest and pelvis were instrumented with triaxial accelerometers. The upper and lower neck, thoracic spine and lumbar spine had transducers measuring triaxial loads and moments. Lap belt load was measured. High-speed video recorded different views of the dummy motion. Dummy kinematics and biomechanical responses were compared to determine the influence of retractor belt pretensioning. Results The dummy kinematics and biomechanical responses were essentially similar with and without retractor or retractor and anchor pretensioning in rear sled tests. There was an initial spike in lap belt load with pretensioning, but it did not result in different dummy head, neck or chest responses. In the tests, the dummy moved rearward away from the shoulder belt. The belts were tightened with the rapid pull on the webbing by pretensioning. The dummy loaded the seat, which yielded rearward restraining its motion. There was no significant effect of pretensioning on the dynamics of the dummy until late in rebound. Conclusions There were no significant differences in dynamics of the Hybrid III with and without retractor or retractor and anchor pretensioning in a 40 km/h (25 mph) rear sled test. Belt pretensioning did not influence biomechanical responses in the rear impact because the seat supported the dummy.

Improving the Chest Protection of Elderly Occupants in Frontal Crashes Using SMART Load Limiters

Objective: To determine whether varying the seat belt load limiter (SBL) according to crash and occupant characteristics could have real-world injury reduction benefits in frontal impacts and, if so, to quantify those benefits.Methods: Real-world UK accident data were used to identify the target population of vehicle occupants and frontal crash scenarios where improved chest protection could be most beneficial. Generic baseline driver and front passenger numerical models using a 50th percentile dummy were developed with MADYMO software. Simulations were performed where the load limiter threshold was varied in selected frontal impact scenarios. For each SBL setting, restraint performance, dummy kinematics, and injury outcome were studied in 5 different frontal impact types. Thoracic injury predictions were converted into injury probability values using Abbreviated Injury Scale (AIS) 2+ age-dependent thoracic risk curves developed and validated based on a methodology proposed by Laituri et al. (2005). Real-world benefit was quantified using the predicted AIS 2+ risk and assuming that an appropriate adaptive system was fitted to all the cars in a real-world sample of recent frontal crashes involving European passenger cars.Results: From the accident data sample the chest was the most frequently injured body region at an AIS 2+ level in frontal impacts (7% of front seat occupants). The proportion of older vehicle front seat occupants (>64 years) with AIS 2+ injury was also greater than the proportion of younger occupants. Additionally, older occupants were more likely to sustain seat belt–induced serious chest injury in low- and moderate-speed frontal crashes. In both front seating positions, the low SBL provided the best chest injury protection, without increasing the risk to other body regions. In severe impacts, the low SBL allowed the driver to move dangerously close to the steering wheel. Compared to the driver side, greater ride-down space on the passenger side gave a higher potential for using the low SBLs. When applying the AIS 2+ risk reduction findings to the weighted accident data sample, the risk of sustaining an AIS 2+ seat belt injury changed to 0.9, 4.9, and 8.1% for young, mid, and older occupants, respectively, from their actual injury risk of 1.3, 7.6, and 13.1%.Conclusions: These results suggest the potential for improving the safety of older occupants with the development of smarter restraint systems. This is an important finding because the number of older users is expected to increase rapidly over the next 20 years. The greatest benefits were seen at lower crash severities. This is also important because most real-world crashes occur at lower speeds.

Structural Design Strategies for Improved Small Overlap Crashworthiness Performance.

In 2012, the Insurance Institute for Highway Safety (IIHS) began a 64 km/h small overlap frontal crash test consumer information test program. Thirteen automakers already have redesigned models to improve test performance. One or more distinct strategies are evident in these redesigns: reinforcement of the occupant compartment, use of energy-absorbing fender structures, and the addition of engagement structures to induce vehicle lateral translation. Each strategy influences vehicle kinematics, posing additional challenges for the restraint systems. The objective of this two-part study was to examine how vehicles were modified to improve small overlap test performance and then to examine how these modifications affect dummy response and restraint system performance. Among eight models tested before and after design changes, occupant compartment intrusion reductions ranged from 6 cm to 45 cm, with the highest reductions observed in models with the largest number of modifications. All redesigns included additional occupant compartment reinforcement, one-third added structures to engage the barrier, and two modified a shotgun load path. Designs with engagement structures produced greater glance-off from the barrier and exhibited lower delta Vs but experienced more lateral outboard motion of the dummy. Designs with heavy reinforcement of the occupant compartment had higher vehicle accelerations and delta V. In three cases, these apparent trade-offs were not well addressed by concurrent changes in restraint systems and resulted in increased injury risk compared with the original tests. Among the 36 models tested after design changes, the extent of design changes correlated to structural performance. Half of the vehicles with the lowest intrusion levels incorporated aspects of all three design strategies. Vehicle kinematics and dummy and restraint system characteristics were similar to those observed in the before/after pairs. Different combinations of structural improvement strategies for improving small overlap test performance were found to be effective in reducing occupant compartment intrusion and improving dummy kinematics in the IIHS small overlap test with modest weight increase.

Comparison of the THOR and Hybrid III Responses in Oblique Impacts

NHTSA has been investigating a new test mode in which a research moving deformable barrier (RMDB) impacts a stationary vehicle at 90.1 kph, a 15 degree angle, and a 35% vehicle overlap. The test utilizes the THOR NT with modification kit (THOR) dummy positioned in both the driver and passenger seats. This paper compares the behavior of the THOR and Hybrid III dummies during this oblique research test mode. A series of four full vehicle oblique impact crash tests were performed. Two tests were equipped with THOR dummies and two tests were equipped with Hybrid III dummies. All dummies represent 50th percentile males and were positioned in the vehicle according to the FMVSS208 procedure. The Hybrid III dummies were instrumented with the Nine Accelerometer Package (NAP) to calculate brain injury criteria (BrIC) as well as THOR-Lx lower legs. Injury responses were recorded for each dummy during the event. High speed cameras were used to capture vehicle and dummy kinematics. The vehicle restraint devices and their associated deployment times remained the same for each test. Post test analysis investigated each dummy injury response, kinematics, and vehicle structural performance. The results of the current study show that during an oblique impact, where significant lateral motion of the vehicle is observed, there are differences between the THOR and Hybrid III dummies. Language: en

Influence of a Combo Side Airbag on the Risk for Basilar Skull Fracture in a Far-Side Occupant

Objective: The impact force to the head and neck were measured in sled tests with and without inflation of a combo airbag for a far-side occupant to determine the risk for basilar skull fracture.Methods: Sled tests were run at 24 and 32 km/h (15 and 20 mph) with and without inflation of a combo side airbag to analyze the effect of cross-car diving into the side interior. The matched tests involved one pair at 24 km/h and another at 32 km/h. The 24 km/h pair involved a lap–shoulder-belted 5th percentile female Hybrid III and the series at 32 km/h involved an unbelted 5th percentile Hybrid III. The dummy was ballasted to 69.5 kg (153 lb) and laid on the right side. The dummy was positioned 30.5 cm (12″) from the far-side interior to ensure the full sled delta V occurred before head impact. The buck consisted of a 2001 Ford Taurus. The combo thorax–head side airbag was stored in the seatback. The airbag was triggered about 120 ms before the head impact. The head, chest, and pelvis were instrumented with triaxial accelerometers and the upper and lower neck, thoracic spine, and lumbar spine had transducers measuring triaxial loads and moments. High-speed video recorded different views of the dummy motion. Dummy kinematics and biomechanical responses were compared to study the influence of inflating the side airbag on the head and neck.Results: The top of the head impacted the far side. The force of impact was similar with and without the airbag as the head compressed the airbag and loaded the vehicle interior trim behind the airbag. The peak force on the head was primarily from neck load as torso augmentation occurred. For the 24 km/h (15 mph) tests, the peak force was 4.7 kN (1055 lb) without and 4.8 kN (1088 lb) with the airbag and there was over 2.67 kN (600 lb) of lap belt load. The peak head acceleration was 93 g without and 72 g with the airbag. For the 32 km/h (20 mph) tests, the force on the head was 15.3 kN (3433 lb) without and 15.2 kN (3406 lb) with the airbag, although the instrumentation saturated. The peak head acceleration was 236 g without and 262 g with the airbag.Conclusion: The airbag reduced head acceleration in the belted test but did not influence the diving forces from torso augmentation through the neck of the far-side occupant. The side airbag did not reduce the risk for basilar skull fracture due to high neck compression loads in either the belted or unbelted tests.

Assessment of a dummy model in crash simulations using rating methods

With fast development in high performance computer area and modeling techniques, design of injury countermeasures based on numerical simulations could make the process more cost-efficient. To reduce the risks and uncertainties associated with the use of predictive models for design decision making, an increased attention should be paid to the validation process of human dummy models. The main goal of this study was to assess a numerical THOR dummy model in frontal crash environment using kinetic and kinematic test data and various validation metrics. A THOR-NT dummy positioned on a rigid planar seat and restrained by a standard 3-point shoulder and lap belt system was subjected to two frontal crash sled tests with “initial velocity 40 km/h”. In the numerical analysis, the dummy model was positioned in a test setup model using the same procedure employed in testing. The dynamic and kinematic data of dummy model were compared with corresponding test data using validation metrics implemented in two rating systems. The overall dummy kinematics, the 3D displacement time histories of certain dummy body regions, and the interaction forces of dummy with the sled and the belt obtained in simulation were in reasonable agreement with the corresponding test data. Generally, the rating scores showed to be sensitive to the validation metrics and to the weighting factors used in the assessment process. The current average score of THOR model positioned it in the “fair-to-acceptable” range, which would recommend it for use in impact simulations. The results of this study and the validation methodology may be used for further refinement of the current THOR model, in setting up future dummy tests, the assessment of other human dummy models, and the improvement of model rating methods.

Comparison of Dummy Kinematics and Injury Response between WorldSID and ES-2 in Side Impact

A new highly biofidelic side impact dummy, the WorldSID 50th percentile male, has been developed under the supervision of the International Organization for Standardization in order to harmonize a number of existing side impact dummies in one single dummy. Momentum is growing for using the WorldSID in safety tests in the EU and the US. In the present study, two Euro-NCAP pole side impact tests were conducted to compare ES-2 and WorldSID responses in a midsize SUV with respective seating positions as stipulated in the Euro-NCAP test conditions and fitted with the same side airbag. It was found that, compared with ES-2, the chest, abdomen and pelvis accelerations of WorldSID are more sensitive to variation in the applied external load transmitted by the deployed side airbag and door intrusion. Language: en

새로운 미국 측면 신차안전도평가 결과에 대한 통계적 분석

New USNCAP has been carried out by NHTSA including front and side crash from MY2011. In this paper, test results for USNCAP Side crash were reviewed by statistical analysis. This review focused on side crash test results to investigate the effect of changes from new USNCAP side crash test protocol among 30 passenger cars. These results were summarized as followings. Total number of 5 star vehicles on the front seat dummy (16 vehicles, 53.3%) was slightly smaller than the rear seat's (17 vehicles, 56.7%) in MDB test. For the ES-2re dummy, chest injury, ie maximum rib deflection contributed to 66% in the mean value of <TEX>$P_{joint}$</TEX>. Pelvis injury was highly dependent upon performance up to 87% in the SID-IIs dummy cited on the rear seat in average <TEX>$P_{joint}$</TEX>. For Pole test, pelvis injury made contribution to the average performance to 83%. For standard deviation, it showed the largest value in the same body region as the mean value for each dummy. Overall front seat performance showed 14 vehicles, 44.6% with 5 star vehicles less than each MDB or Pole test result. This result showed that performances in MDB test were different pattern to Pole test on driver position. Number of 5star vehicles for overall side NCAP performance are 18 passenger cars (60%). Curtain airbag and driver thorax airbag were equipped in all test vehicles. One vehicle is equipped with thorax airbag in the rear seat. Results from two side tests considered as reliability problem, ie the cause for large standard deviation in side crash test. Consequently, the countermeasure for new USNCAP side crash test is essential to design the effective side structures for side collision and to control well dummy kinematics with curtain and thorax airbag in order to reduce chest and pelvis injuries.

Rebound After Rear Impacts

Objective: A number of field accident studies have found that rebound is a source for occupant injury after rear impacts. Sled tests were run to investigate occupant kinematics and rebound, including head velocity and displacement with 3 different seats, 2 conventional seat designs, and 1 all belts to seat (ABTS). Methods: Nine rear-end sled tests were run with a belted 50th Hybrid III dummy on a Taurus, Mustang, or Sebring ABTS seat in nominally 16.5, 24.1, and 32.5 km/h rear-end delta Vs. There was no sled braking after the rear acceleration to study rebound from the seat. Dummy kinematics were analyzed from high-speed video and biomechanical responses from triaxial head and chest accelerations, triaxial upper and lower neck loads and moments, and seat belt loads. Peak responses were tabulated during seat back rotation rearward and rebound forward. Ratios of biomechanical and kinematic responses were determined comparing ABTS to conventional seat responses for each delta V. Student's t-test was used to determine significant differences between the ratios of ABTS to conventional seat responses. Results: The rebound velocity of the head varied from 2.9 to 6.8 m/s with respect to the sled. Overall, it was 69 ± 22 percent higher than the sled delta V. It was greatest with ABTS in the highest severity test where seat back yielding absorbed energy and reduced rebound in the conventional seats. The time to maximum forward excursion was significantly shorter with ABTS compared to the conventional seats with a ratio of 0.54 ± 0.34 (t = 6.13, df = 5, P < .001). Conclusions: ABTS seats remain more upright in rear-end crashes and transfer greater load to the occupant during rebound than conventional seats that yield rearward and absorb energy in higher severity crashes. Rebound occurs earlier and at higher velocities with ABTS. This displaces the occupant toward the front interior. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.

2011년 모델에 대한 정면 미국신차안전도평가 결과에 대한 통계적 분석

New car assessment program (NCAP) originated from USNCAP in 1979 has been implemented in several countries or markets, for instance USA, Europe, Korea, Japan, China and Australia. NCAP has contributed greatly to reduce accidental tolls. But recently, NCAP performance has no distinction between cars because manufacturer have been continuously developed to improve NCAP performance. Therefore, NHTSA announced new USNCAP protocol becoming effective from MY2011. NHTSA had carried out many NCAP tests based on the new test protocol and announced these test results. In this paper, USNCAP test results were reviewed by statistical method. This review was focused on passenger cars and frontal crash test results in order to investigate effect of changes in new NCAP protocol. There are two key changes, one is sited female dummy in passenger position, the other is enlarged to 4 scoring body regions in each dummy. Results of this review were summarized as followings. Performance in Passenger (12.5%) is lower than Driver's (50%) for number of 5 star vehicle. Neck injury criterion is dominant to NCAP star rating for both dummies in the mean sense. For standard deviation, chest deflection is showed largest value in driver dummy but neck injury criterion is showed for passenger's. DKAB and PKAB were equipped 28.1% and 6.2%, respectively. Consequently, the countermeasure for new USNCAP frontal crash test is essential to control well dummy kinematics with some safety features including KAB to reduce neck injuries.

Influence of Belt Pretensioning on Dummy Responses in 40 km/h Rear-Impact Sled Tests

Objective: This study compares dummy kinematics and biomechanical responses with and without belt pretensioning in matched rear sled tests. Methods: Two rear-impact sled tests were run at 40 km/h (25 mph) rear delta V with a lap–shoulder-belted Hybrid III 50th percentile male dummy on Ford F-150 driver seats. One test was with the standard lap–shoulder belts and the other with a buckle pretensioner activated at 20 ms. The head, chest, and pelvis were instrumented with triaxial accelerometers. The upper and lower neck, thoracic spine, and lumbar spine had transducers measuring triaxial loads and moments. Lap and shoulder belt loads were measured. High-speed video recorded different views of the dummy motion. Dummy kinematics and biomechanical responses were compared to study the influence of belt pretensioning. Results: The dummy kinematics and biomechanical responses were essentially similar with and without belt pretensioning in the rear-impact sled tests. There were higher belt loads with pretensioning, but they did not result in different dummy lumbar loads or pelvic, chest, and head accelerations. In a rear impact, the dummy moves rearward away from the belts that wrap around the chest and pelvis. The occupant loads the seat, which yields rearward restraining dummy motion. Though pretensioning caused a transient increase in belt load, it was of short duration and there was no sustained effect on occupant dynamics until late in rebound. Conclusions: The matched tests showed no difference in occupant restraint with and without buckle pretensioning in 40 km/h (25 mph) rear-impact sled tests. Belt pretensioning did not influence occupant responses in these rear impacts because the seat supported the occupant.

Influence of standing or seated pelvis on dummy responses in rear impacts

ObjectiveThere is a question whether the standing or seated pelvis should be used in Hybrid III dummy evaluations of seats and belt restraint systems in severe rear impacts. This study compares the standing and seated Hybrid III pelvis in matched rear sled tests. MethodsSixteen sled tests were found at 10, 16 and 24km/h rear delta V in Ford's archives where matched tests were run with the standing and seated pelvis in a belted Hybrid III dummy. Two new tests were conducted at 40km/h rear delta V to extend the severity range. The head, chest and pelvis were instrumented with triaxial accelerometers and the upper and lower neck, thoracic spine and lumbar spine had transducers measuring triaxial loads and moments. Belt Loads were measured. High-speed video recorded different views of the dummy motion. Dummy kinematics and biomechanical responses were compared for all of the data with the two different Hybrid III pelvic designs. ResultsIn the 40km/h sled tests, the dummy motion and excursion were essentially similar with the standing and seated pelvis. The similarities included the lap belt interaction with the pelvis and the leg movement upward flexing the hip joint. Overall, similar biomechanic and kinematic responses were found, including the pelvic acceleration, spinal forces and moments. For the lower speed tests at 10, 16 and 24km/h, the motion sequence was also similar with the two different pelvises, including the upward movement of the legs as the seat was loaded and rebound kinematics. The biomechanical responses were similar. The seated pelvis involves only a small portion of the upper leg molded into the vinyl skin of the pelvis and does not limit leg rotation at the hip joint. Furthermore, lap belt loads were minimal during the rearward movement of the dummy. ConclusionsThe matched testing showed no significant difference in occupant kinematics or biomechanical responses between the standing and seated pelvis in rear sled tests. The Hybrid III dummy with the seated pelvis is suitable for FMVSS 301 and other testing of seats and belt restraint systems in severe rear impacts.

Development and validation of pedestrian sedan bucks using finite-element simulations: a numerical investigation of the influence of vehicle automatic braking on the kinematics of the pedestrian involved in vehicle collisions

Previous vehicle-to-pedestrian impact simulations and experiments using pedestrian dummies and cadavers have shown that factors such as vehicle shape, pedestrian anthropometry and pre-impact conditions influence pedestrian kinematics and injury mechanisms. Generic pedestrian bucks, which approximate the geometrical and stiffness properties of current vehicles, would be useful in studying the influence of vehicle front-end structures on pedestrian kinematics and loading. This study explores the design of pedestrian bucks, intended to represent the basic vehicle front-end structures, consisting of five components: lower stiffener, bumper, hood leading edge and grille, hood and windshield. The deformable parts of the bucks were designed using types of currently manufactured materials, which allow fabricating the bucks in the future. The geometry of pedestrian bucks was approximated according to the contour cross-sections of two sedan vehicles used in previous pedestrian dummy and cadaver impact tests. Other cross-sectional dimensions and the stiffness of the buck components were determined by parameter identification using finite-element (FE) simulations of each sedan model. In the absence of a validated FE model of human, the FE model of the POLAR II pedestrian dummy was used to validate a mid-size sedan (MS) pedestrian buck. A good correlation of the pedestrian dummy kinematics and contact forces obtained in dummy–MS pedestrian buck with the corresponding data from dummy–MS vehicle simulation was achieved. A parametric study using the POLAR II FE model and different buck models – an MS buck and a large-size sedan (LS) buck – were run to study the influence of an automatic braking system for reducing the pedestrian injuries. The vehicle braking conditions showed reductions in the relative velocity of the head to the vehicle and increases in the time of head impact and in the wrap-around-distances (WAD) to primary head contact. The head impact velocity showed a greater sensitivity to the different buck shapes (e.g. LS buck versus MS buck) than to the braking deceleration. The buck FE models developed in this study are expected to be used in sensitivity and optimisation studies for the development of new pedestrian protection systems.

A study of the pedestrian impact kinematics using finite element dummy models: the corridors and dimensional analysis scaling of upper-body trajectories

Pedestrian–vehicle impact experiments using cadavers have shown that factors such as vehicle shape and pedestrian anthropometry can influence pedestrian kinematics and injury mechanisms. Although a parametric study examining these factors could elucidate the complex relationships that govern pedestrian kinematics, it would be impractical with cadaver tests because of the relative expense involved in performing numerous experiments on subjects with varying anthropometry. On the other hand, finite element modelling represents a more feasible approach because numerous experiments can be conducted for a fraction of the expense. The current study examined the relationship between pedestrian anthropometry and front shape of a mid-size sedan using a PAM-CRASH model of the 50th-percentile male (50th M) Polar-II pedestrian dummy extensively validated against experimental data. To evaluate the influence of pedestrian anthropometry on response kinematics, scaled dummy models were developed on the basis of the weight and height of the 5th-percentile female (5th F), 50th-percentile female (50th F) and 95th-percentile male (95th M). Simulations of the 5th F, 50th F, 50th M, and 95th M Polar-II finite element models struck at 40 km/h by a mid-size sedan were used to generate trajectories of the head, upper thorax, mid-thorax and pelvis. In an effort to assess the validity of scaling techniques when interpreting trajectory data from vehicle–pedestrian crashes, the trajectories of the 5th F, 50th F and 95th M model were scaled to the 50th M and compared with those generated by the 50th M model. The results demonstrated non-linear behaviour of dummy kinematics that could not be accounted for with traditional dimensional analysis scaling techniques.

A New THOR Shoulder Design: A Comparison with Volunteers, the Hybrid III, and THOR NT

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 Δ V 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. Conclusion. 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.

Reconstruction of Crashes Involving Injured Child Occupants: The Risk of Serious Injuries Associated with Sub-Optimal Restraint Use May Be Reduced by Better Controlling Occupant Kinematics

Objective. To determine whether injuries to sub-optimally restrained child occupants in real-world crashes were likely to be preventable by alternative restraint usage practices and to assess the usefulness of crash reconstruction for exploring injury mechanisms in child occupants. Methods. Real-world crashes in which child occupants sustained significant injuries were reconstructed on a laboratory crash sled using the Hybrid III family of child dummies. Alternative restraint scenarios and cases in which children were not seriously injured were also simulated to compare dummy kinematics and dynamic responses in optimal restraint configurations. Results. Restraint misuse was associated with greater motion of the dummy torso and head during crashes, often allowing contact between the child and the vehicle interior, resulting in injury. Poor pre-crash posture for a child inappropriately restrained in an adult belt appeared to worsen the geometry of the sash (shoulder) belt, resulting in a cervical injury due to direct interaction with the belt. Dynamic dummy data did not appear to discriminate between injury and non-injury cases. Conclusions. Dummy kinematics suggest that injuries in which inappropriate use and misuse were a factor were less likely if the most appropriate restraint was used correctly. Adequately controlling the head and upper body of the child occupant was seen to prevent undesirable interactions with the vehicle interior and restraint system, which were associated with injury in the real world. Neck forces and moments and injury criteria calculated from these did not predict injury reliably.

A Comparison of Volunteers and Dummy Upper Torso Kinematics with and Without Shoulder Belt Slack in a Low Speed Side/Pre-Roll Environment

Objective. The objective of this study was to compare the occupant and dummy kinematics in a low-speed lateral environment with and without shoulder belt slack. Methods. A buck of a small European car was mounted on a side impact sled. The parameters evaluated were pulses, sitting location, and belt slack. A total of 24 tests were carried out. Three 50th-percentile male volunteers and one Hybrid III 50th-percentile male were tested. The pulses consisted of Pulse 1:+/- 0.7 g's pulse and Pulse 2: a -0.9 g pulse to simulate low-speed pre-roll/side events. Both pulses had a duration of 500 msec. Results. The peak lateral head excursion was higher in the far-side occupants than in the near-side occupants. Furthermore, for the far-side volunteers, lateral head displacements were lower in the no-slack condition than in the slack condition, at 388 ± 64 mm and 455 ± 84 mm respectively for Pulse 1 and at 138 ± 2 mm and 207 ± 70 mm for Pulse 2. The timing required to reach peak lateral displacement was higher in Pulse 1 than in Pulse 2. In comparison to the volunteers, the Hybrid III dummy lateral motion was lower. The peak lateral displacement in Pulse 1 was 231 mm with slack and 194 mm without and 98 mm and 107 mm for Pulse 2, respectively. Conclusions. The results obtained in this study indicate that removing seatbelt slack would be more beneficial for far-sided occupants than near-sided. They also point to the lack of biofidelity of the Hybrid III dummy in low g lateral pulses.

The relationship of seat backrest angle and neck injury in low-velocity rear impacts

Car-rear-impact-induced cervical spine injuries present a serious burden on society and, in response, seats offering enhanced protection have been introduced. Seats are evaluated for neck protection performance but only at one specific backrest angle, whereas in the real world this varies greatly owing to the variation in occupant physique. Changing the backrest angle modifies the seat geometry and thereby the nature of its interaction with the occupant. Low-velocity rear-impact tests on a BioRID II anthropomorphic test dummy (ATD) have shown that changes in backrest angle have a significant proportionate effect on dummy kinematics. A close correlation was found between changes in backrest angle and the responses of neck injury predictors such as lower neck loading and lower neck shear but not for the neck injury criterion NICmax. Torso ramping was evident, however, with negligible effect in low-velocity impacts. The backrest angle ranged from 20° to 30° whereas the BioRID II spine was adapted to a range from 20° to 26.5°. Nevertheless, in general, instrumentation outputs correlated well, indicating that this ATD could be used for evaluating seats over a 20–30° range rather than solely at 25° as required by current approval test specifications.

前面衝突時の乗員傷害値の最適化(J18-1 解析・設計の高度化・最適化(1),J18 解析・設計の高度化・最適化)

To secure occupant safety is one of the most important factors in vehicle design. To evaluate occupant safety, the injury indexes of dummies are defined by regulations. Dummy kinematics is so complicated: that many vehicle parameters affect the injury indexes. Balancing the characteristics of the restraint systems is a multi-objective, multi-parameter optimization. Generally the injury indexes show linearity in relation to the parameters of the restraint systems. However, a discontinuous boundary exists in which airbag bottoming out causes a peaky reaction force. This paper proposes a DOE (Design of Experiment)-based optimization method that eliminates this discontinuity and provides a high-fidelity response surface model An optimized result obtained with the response surface model was certified by simulation.