Anthropometric Test Device Research Articles

Research on the centre-of-mass adjustment method for the head of an anthropometric test device based on a head impact biomechanics model

Head injury is the primary cause of serious lesions or death in automobile accidents. During crash tests, the mass and centre-of-mass position of the head of anthropometric test devices are crucial factors determining the accuracy of head injury test data. However, owing to the irregular shape as well as complex structure and material composition of the head of dummies, problems such as uneven mass distribution easily occur, resulting in deviations between the actual and designed positions of the centre-of-mass of the head. This study conducted research on head impact biomechanics and the centre-of-mass adjustment method for the head of dummies. Specifically, the biomimetic mechanical equivalent of the head was investigated, and head impact mechanics were analysed. Then, a predictive model was established for head drop mechanical response; the accuracy of this model was verified through head drop experiments. Based on the model, the law of centre-of-mass influence on the mechanical response of the dummy head was investigated, yielding an evaluation method for the different mechanical responses of the head. Using the rotational centre-of-mass measurement method, the mass and centre-of-mass position of the head were obtained. The distributed centre-of-mass adjustment method based on the principle of torque equilibrium was utilized to solve the deviations in the centre-of-mass position, the geometric dimensions of the counterweights and the centre-of-mass itself. Two counterweights were distributed on both sides of the internal cavity wall of the dummy head, resolving the positioning issue of the counterweights in the head cavity. The rationality of the centre-of-mass adjustment results was analysed using the predictive model for head impact mechanical response. The analysis results indicate that the centre-of-mass-adjusted dummy head better aligned with the mechanical response of the head in real collision scenarios, providing a new approach for the adjustment of the centre-of-mass of the head of dummies.

The effects of postural support padding modifications to child restraints for children with disability on crash protection

Objective Many children with physical disabilities need additional postural support when sitting and supplementary padding is used on standards approved child restraints to achieve this when traveling in a motor vehicle. However, the effect of this padding on crash protection for a child is unknown. This study aimed to investigate the effect of additional padding for postural support on crash protection for child occupants in forward facing child restraints. Methods Forty frontal sled tests at 49 km/h were conducted to compare Q1 anthropometric test device (ATD) responses in a forward-facing restraint, with and without additional padding in locations to increase recline of the restraint, and/or support the head, trunk and pelvis. Three padding materials were tested: cloth toweling, soft foam, and expanded polystyrene (EPS). The influence of padding on head excursion, peak 3 ms head acceleration, HIC15, peak 3 ms chest acceleration and chest deflection were analyzed. Results The influence of padding varied depending on the location of use. Padding used under the restraint to increase the recline angle increased head injury metrics. Toweling in multiple locations which included behind the head increased head excursion and chest injury metrics. There was minimal effect on injury risk measures with additional padding to support the sides of the head or the pelvis position. Rigid EPS foam, as recommended in Australian standards and guidelines, had minimal effect on injury metrics when used inside the restraint, as did tightly rolled or folded toweling secured to the restraint at single locations around the body of the child. Conclusions This study does not support the use of postural support padding to increase recline of a forward-facing restraint or padding behind the head. Recommendations in published standards and guidelines to not use foam that is spongy, soft or easily compressed, with preference for secured firm foam or short-term use of tightly rolled or folded toweling under the child restraint cover is supported. This study also highlights the importance of considering the whole context of child occupant protection when using additional padding, particularly the change in the child’s seated position when adding padding in relation to the standard safety features of the restraint.

Translating Cadaveric Injury Risk to Dummy Injury Risk at Iso-energy.

Injury risk assessment based on cadaver data is essential for informing safety standards. The common 'matched-pair' method matches energy-based inputs to translate human response to anthropometric test devices (ATDs). However, this method can result in less conservative human injury risk curves due to intrinsic differences between human and ATDs. Generally, dummies are stiffer than cadavers, so force and displacement cannot be matched simultaneously. Differences in fracture tolerance further influence the dummy risk curve to be less conservative under matched-pair. For example, translating a human lumbar injury risk curve to a dummy of equivalent stiffness using matched-pair resulted in a dummy injury risk over 80% greater than the cadaver at 50% fracture risk. This inevitable increase arises because the dummy continues loading without fracture to attenuate energy beyond the 'matched' cadaver input selected. Human injury response should be translated using an iso-energy approach, as strain energy is well associated with failure in biological tissues. Until cadaver failure, dummy force is related to cadaver force at iso-energy. Beyond cadaver failure, dummy force is related to cadaver force through failure energy. This method does not require perfect cadaver/dummy biofidelity and ensures that energy beyond cadaver failure does not influence the injury risk function.

Assessment of finite element human body and ATD models in estimating injury risk in far-side impacts using field-based injury risk

The objective of this study was to assess the ability of finite element human body models (FEHBMs) and Anthropometric Test Device (ATD) models to estimate occupant injury risk by comparing it with field-based injury risk in far-side impacts. The study used the Global Human Body Models Consortium midsize male (M50-OS+B) and small female (F05-OS+B) simplified occupant models with a modular detailed brain, and the ES-2Re and SID-IIs ATD models in the simulated far-side crashes. A design of experiments (DOE) with a total of 252 simulations was conducted by varying lateral ΔV (10-50kph; 5kph increments), the principal direction of force (PDOF 50°, 60°, 65°, 70°, 75°, 80°, 90°), and occupant models. Models were gravity-settled and belted into a simplified vehicle model (SVM) modified for far-side impact simulations. Acceleration pulses and vehicle intrusion profiles used for the DOE were generated by impacting a 2012 Camry vehicle model with a mobile deformable barrier model across the 7 PDOFs and 9 lateral ΔV’s in the DOE for a total of 63 additional simulations. Injury risks were estimated for the head, chest, lower extremity, pelvis (AIS 2+; AIS 3+), and abdomen (AIS 3+) using logistic regression models. Combined AIS 3+ injury risk for each occupant was calculated using AIS 3+ injury risk estimations for the head, chest, abdomen, and lower extremities. The injury risk calculated using computational models was compared with field-based injury risk derived from NASS-CDS by calculating their correlation coefficient. The field-based injury risk was calculated using risk curves that were created based on real-world crash data in a previous study (Hostetler et al., 2020). Occupant age (40 years), seatbelt use (belted occupant), collision deformation classification, lateral ΔV, and PDOF of the crash event were used in these curves to estimate field injury risk. Large differences in the kinematics were observed between HBM and ATD models. ATD models tended to overestimate risk in almost every case whereas HBMs yielded better risk estimates overall. Chest and lower extremity risks were the least correlated with field injury risk estimates. The overall risk of AIS 3+ injury risk was the strongest comparison to the field data-based risk curves. The HBMs were still not able to capture all the variance but future studies can be carried out that are focused on investigating their shortfalls and improving them to estimate injury risk closer to field injury risk in far-side crashes.

Obese Occupant Response in Reclined and Upright Seated Postures in Frontal Impacts.

The American population is getting heavier and automated vehicles will accommodate unconventional postures. While studies replicating mid-size and upright fore-aft seated occupants are numerous, experiments with post-mortem human subjects (PMHS) with obese and reclined occupants are sparse. The objective of this study was to compare the kinematics of the head-neck, torso and pelvis, and document injuries and injury patterns in frontal impacts. Six PMHS with a mean body mass index of 38.2 ± 5.3 kg/m2 were equally divided between upright and reclined groups (seatback: 23°, 45°), restrained by a three-point integrated belt, positioned on a semi-rigid seat, and exposed to low and moderate velocities (15, 32 km/h). Data included belt loads, spinal accelerations, kinematics, and injuries from x-rays, computed tomography, and necropsy. At 15 km/h speed, no significant difference in the occupant kinematics and evidence of orthopedic failure was observed. At 32 km/h speed, the primary difference between the cohorts was significantly larger Z displacements in the reclined occupant at the head (190 ± 32 mm, vs. 105 ± 33 mm p < 0.05) and femur (52 ± 18 mm vs. 30 ± 10 mm, p < 0.05). All the moderate-speed tests produced at least one thorax injury. Rib fractures were scattered around the circumference of the rib-cage in the upright, while they were primarily concentrated on the anterior aspect of the rib-cage in two reclined specimens. Although MAIS was the same in both groups, the reclined specimens had more bi-cortical rib fractures, suggesting the potential for pneumothorax. While not statistical, these results suggest enhanced injuries with reclined obese occupants. These results could serve as a data set for validating the response of restrained obese anthropometric test device (ATDs) and computational human body models.

Frontal-oblique impact sled tests of a rearward-facing child restraint system with and without a support leg

ObjectiveTo quantify the head and neck injury metrics of an anthropometric test device (ATD) in a rearward-facing child restraint system (CRS), with and without a support leg, in frontal-oblique impacts. MethodsSled tests using the Federal Motor Vehicle Safety Standards (FMVSS) 213 frontal crash pulse (48 km/h, 23 g) were performed with a simulated Consumer Reports test buck, which comprised a test bench that mimics the rear outboard vehicle seat of a sport utility vehicle (SUV). The test bench was rigidised to increase durability for repeated testing and the seat springs and cushion were replaced every five tests. A force plate was mounted to the floor of the test buck directly in front of the test bench to measure support leg peak reaction force. The test buck was rotated 30° and 60° relative to the longitudinal axis of the sled deck to represent frontal-oblique impacts. The door surrogate from the FMVSS 213a side impact test was rigidly attached to the sled deck adjacent to the test bench. The 18-month-old Q-Series (Q1.5) ATD was seated in a rearward-facing infant CRS, which was attached to the test bench with either rigid lower anchors or a three-point seatbelt. The rearward-facing infant CRS was tested with and without a support leg. Conductive foil was attached to the upper edge of the door panel and a strip of conductive foil was attached to the top of the ATD head so that a voltage signal quantified contact with the door panel. A new CRS was used for each test. A repeat test was performed for each condition for a total of 16 tests. Data sourcesResultant linear head acceleration 3 ms clip; head injury criterion 15 ms (HIC15); peak neck tensile force; peak neck flexion moment; potential difference between the ATD head and the door panel; support leg peak reaction force. ResultsThe presence of a support leg significantly reduced head injury metrics (p < 0.001) and peak neck tensile force (p = 0.004) compared to tests without a support leg. Rigid lower anchors were associated with significant reductions in head injury metrics and peak neck flexion moment (p < 0.001) compared to tests that attached the CRS with the seatbelt. The 60° frontal-oblique tests had significantly elevated head injury metrics (p < 0.01) compared to the 30° frontal-oblique tests. No ATD head contact with the door was observed for 30° frontal-oblique tests. The ATD head contacted the door panel in the 60° frontal-oblique tests when the CRS was tested without the support leg. Average support leg peak reaction forces ranged from 2167 to 4160 N. The 30° frontal-oblique sled tests had significantly higher support leg peak reaction forces (p < 0.001) compared to the 60° frontal-oblique sled tests. ConclusionsThe findings of the current study add to the growing body of evidence regarding the protective benefits of CRS models with a support leg and rigid lower anchors.

Assessment of the sensitivity of thoracic injury criteria to subject-specific characteristics using human body models.

Introduction: Chest deformation has been proposed as the best predictor of thoracic injury risk in frontal impacts. Finite Element Human Body Models (FE-HBM) can enhance the results obtained in physical crash tests with Anthropometric Test Devices (ATD) since they can be exposed to omnidirectional impacts and their geometry can be modified to reflect specific population groups. This study aims to assess the sensitivity of two thoracic injury risk criteria (PC Score and Cmax) to several personalization techniques of FE-HBMs. Methods: Three 30° nearside oblique sled tests were reproduced using the SAFER HBM v8 and three personalization techniques were applied to this model to evaluate the influence on the risk of thoracic injuries. First, the overall mass of the model was adjusted to represent the weight of the subjects. Second, the model anthropometry and mass were modified to represent the characteristics of the post-mortem human subjects (PMHS). Finally, the spine alignment of the model was adapted to the PMHS posture at t = 0ms, to conform to the angles between spinal landmarks measured in the PMHS. The following two metrics were used to predict three or more fractured ribs (AIS3+) of the SAFER HBM v8 and the effect of personalization techniques: the maximum posterior displacement of any studied chest point (Cmax), and the sum of the upper and lower deformation of selected rib points (PC score). Results: Despite having led to statistically significant differences in the probability of AIS3+ calculations, the mass-scaled and morphed version provided, in general, lower values for injury risk than the baseline model and the postured version being the latter, which exhibited the better approximation to the PMHS tests in terms of probability of injury. Additionally, this study found that the prediction of AIS3+ chest injuries based on PC Score resulted in higher probability values than the prediction based on Cmax for the loading conditions and personalization techniques analyzed within this study. Discussion: This study could demonstrate that the personalization techniques do not lead to linear trends when they are used in combination. Furthermore, the results included here suggest that these two criteria will result in significantly different predictions if the chest is loaded more asymmetrically.

Analysis of the spinal 3D motion of postmortem human surrogates in nearside oblique impacts

Objective: The objective of this study is to analyze the 6 degrees of freedom (DOF) motion of the spine using the finite helical axis (FHA) in three postmortem human surrogates (PMHS) sled tests. Methods: The sled test configurations corresponded to a 30° nearside oblique impact at 35 km/h. Two different restraint system versions (RSv) were used. RSv1 was used for PMHS A and B while RSv2 was used for PMHS C. The 6 DOF motion of the head and three selected vertebrae have been analyzed using the FHA which describes the 3 D motion of a rigid body between two instants of time as a rotation about and a translation along a unit vector. A minimal amount of rotation is necessary to the FHA calculation, thus the FHA components have been calculated based on a pre-defined interval of 8° of rotation. Results: The analysis of the FHA components demonstrated right lateral bending until around 100 ms, when the rebound phase was reached and the head and the lower spine undergoes left lateral bending. The three PMHS exhibited, in general, flexion movement of the whole body and torsion to the right side of the occupant. This general motion can be associated to the effect of the seatbelt acting as a fulcrum of the rotational movement of the bony landmarks. The interaction of the PMHS with the retention system can be noted by analyzing the time in which the head and the upper spine initiated the rotation and the sudden changes of rotational direction of the three PMHS’s head. Conclusions: The rotational analyses have shown to be more sensitive to experimental events than the trajectory analyses for the studied physical tests. Additionally, the results presented in the present study contributes to the analysis of the body kinematics during an oblique impact and adds new experimental data for Human Body Models (HBM) and Anthropometric Test Devices (ATD) benchmarking.

Size and age of fatal drivers by crash type, vehicle type and gender

Objective: The objective of this study was to determine the physical characteristics of fatal drivers in motor vehicle crashes with focus on rear impacts. Methods: 1998 to 2020 FARS data was analyzed for height, weight, and age of fatal drivers. The data was queried by gender, crash type and vehicle type. Results: The average fatal driver weighed 80.4 kg, was 173.4 cm tall, and was 43 years old. Females were 16.0 kg lighter and 14.2 cm shorter than males on average. The height was 151.2 cm for the 5th percentile female, 177.0 cm for the 50th male and 188.9 cm for the 95th male. The weight of fatal drivers increased linearly with calendar year. The increase rate was greater in females than in males. About 3% of fatal drivers were involved in rear crashes, 39.9% in frontal crashes and 36.8% in rollovers. The average fatal driver was 172.5 cm tall and weighed 81.0 kg in rear impacts. They were similar in height and weight to the overall sample. The average fatal driver in rear impacts was 46 years old, 3 years older than the overall average. Pickup truck drivers weighed 85.4 kg and were 176.8 cm tall on average. They were heavier and taller than passenger car drivers on average, which were 78.0 kg and 172.2 cm. Fatally injured minivan drivers were 10 years older than fatally injured passenger car drivers on average. The findings are compared with ATDs (anthropometric test devices) used in sled and crash testing. Conclusion: The average weight of fatal drivers increased with calendar year. The average size of fatal drivers was similar by crash types. Fatal drivers were older in rear impacts.

The effect of Rear-End collisions on triaxial acceleration to occupant cervical and lumbar Spines: An analysis of IIHS data

Rear-end impacts are the most frequent type of the more than seven million motor vehicle collisions (MVCs) occurring annually in the United States. The cervical and lumbar spine are the most commonly injured sites as a result of rear-end collisions. The direction and magnitude of accelerations and forces to the spine are considered primary indicators of injury. Yet, there is a dearth of research regarding the relation and quantification of vehicle to occupant accelerations, as well as triaxial acceleration components (and thus, forces) to occupant spines in rear-end impacts. Therefore, the current study utilizes the Insurance Institute of Highway Safety (IIHS) test database to examine the relative relations between vehicle and occupant accelerations, as well as between component accelerations experienced at the cervical and lumbar spines in rear-end collisions. Anthropometric test device (ATD) head and pelvis accelerometer data from IIHS sled testing are used as representative measures of acceleration experienced at the cervical and lumbar spine, respectively. Peak resultant acceleration is calculated at the head and pelvis, and peak directional components (x, y, and z) of acceleration are compared to resultants. This analysis revealed significantly higher occupant head than sled (2.17 ± 0.4 × Sled; p < 0.001) and pelvis than sled (1.24 ± 0.27 × Sled; p < 0.001) accelerations. There were also significant differences across triaxial acceleration components relative to resultant at the head (x = 0.99 ± 0.02, y = 0.11 ± 0.05, z = 0.34 ± 0.06; p < 0.001 for all comparisons) and pelvis (x = 0.94 ± 0.06, y = 0.12 ± 0.14, z = 0.35 ± 0.08; p < 0.001 for all comparisons). A secondary analysis examining differences in occupant dynamics by seat designs across vehicle type revealed significant differences only between the pelvis z component accelerations in the passenger vehicle and SUV groups (passenger vehicle:SUV = 1.07, p < 0.001). Due to the uniform nature of IIHS sled testing protocols, this analysis reflects similarities in seat properties rather than between vehicle types. These results may provide a simplistic approach to quantify the magnitude of directional accelerations and forces to occupant spines in rear-end collisions.

Arc-Length Re-Parametrization and Signal Registration to Determine a Characteristic Average and Statistical Response Corridors of Biomechanical Data

A characteristic average and biofidelity response corridors are commonly used to represent the average behaviour and variability of biomechanical signal data for analysis and comparison to surrogates such as anthropometric test devices and computational models. However, existing methods for computing the characteristic average and corresponding response corridors of experimental data are often customized to specific types or shapes of signal and therefore limited in general applicability. In addition, simple methods such as point-wise averaging can distort or misrepresent important features if signals are not well aligned and highly correlated. In this study, an improved method of computing the characteristic average and response corridors of a set of experimental signals is presented based on arc-length re-parameterization and signal registration. The proposed arc-length corridor method was applied to three literature datasets demonstrating a range of characteristics common to biomechanical data, such as monotonic increasing force-displacement responses with variability, oscillatory acceleration-time signals, and hysteretic load-unload data. The proposed method addresses two challenges in assessing experimental data: arc-length re-parameterization enables the assessment of complex-shaped signals, including hysteretic load-unload data, while signal registration aligned signal features such as peaks and valleys to prevent distortion when determining the characteristic average response. The arc-length corridor method was shown to compute the characteristic average and response corridors for a wide range of biomechanical data, while providing a consistent statistical framework to characterize variability in the data. The arc-length corridor method is provided to the community in the freely available and open-source software package, ARCGen.

Motorcyclist injuries: Analysis of German in-depth crash data to identify priorities for injury assessment and prevention

Globally there are more than 350,000 PTW fatalities each year. Safety concepts to protect Powered Two-Wheeler (PTW) riders exist and are being developed further, but they need appropriate procedures and test tools (Anthropometric Test Devices (ATDs) for physical testing and Human Body Models (HBMs) for virtual testing) to direct and promote those developments. To aid further development of the tools, we aim to rank the frequency of specific injuries arising from the prevalent impact types, discuss how current ATDs and HBMs are equipped to assess these injuries, and suggest what further development should be prioritized.We analyzed a sample of injured riders from the German In-depth Accident Study (GIDAS) according to the Abbreviated Injury Scale (AIS) 2015 classification, using severity thresholds of at-least-moderate (AIS2+) and at-least-serious (AIS3+). PTW rider injuries were ranked by frequency for all crashes and also for sub-samples of specific impact types (impact with passenger cars, ground, and roadside furniture).The most frequent AIS3+ injuries were: femur fracture (17%), rib cage fracture (13%), lung injury (9%), tibia fracture (7%), and cerebrum injury (7%). In all impacts together and as for impacts with the road surface, injuries to the thorax were most frequent. In impacts with cars and road furniture, thorax injuries were also frequent, but outranked by lower extremity injuries. Considering both AIS2+ and AIS3+ injuries, the priorities for PTW rider safety interventions are: fracture of the rib cage, femur fracture, tibia fracture, radius fracture, cerebrum injury, and cerebral concussion.The ATD currently used most frequently, the Hybrid III, is unlikely to provide adequate rib fracture injury assessments, but HBMs are promising in this area. Rib injury assessment may also reasonably predict other injuries that were correlated or in proximity to rib fractures: clavicle, lung, and upper abdomen organ injury. Lower extremity, upper extremity, and head injuries are likely addressable to some extent with current ATDs while HBMs hold the promise of more detailed and mechanism-specific injury assessments. Both ATDs and HBMs need more validation for use in the PTW environment.

Dynamic frontal crash performance of old and used child restraint systems

Objective To examine the effect of age on the dynamic performance of child restraint systems in frontal crashes. Methods A sample of used (3-269 months from manufacture) and newly purchased child restraints were subjected to frontal crash simulations of more than 56 km/h and peak deceleration approximately 33 g on a deceleration sled. Restraints were monitored for evidence of damage before and after each impact. Anthropometric test device (ATD) head and chest responses and peak head excursions were recorded for rearward facing restraints using the Q1 ATD and for forward facing restraints and booster seats using the Q6 ATD. The influence of restraint age on peak 3 ms head acceleration, HIC15, head excursion, peak 3 ms chest acceleration and restraint damage were analyzed. Results In all impacts, the ATD remained within the restraint and secured to the test bench demonstrating the crash protection offered by the old and used restraints. There was no apparent relationship between ATD responses and restraint age for any restraint type. Older forward facing restraint systems had a very modest increase in forward head excursion (R2 = 0.59, p = 0.001) of 0.27 mm for each month of age (95% CI, 0.13 mm − 0.42 mm). This equates to a 0.7% increase in the minimum measured excursion per year of restraint age. There was also a small increased likelihood of critical damage to the restraints in the simulated crashes per month of restraint age (OR 1.031, 95% CI 1.010-1.069). Conclusions Overall, degradation in restraint dynamic performance in older restraints, including some that are much older than the currently recommended 10-year lifetime, is minimal. However newer restraints may provide better protection due to marginal improvements in restraint design over time. Furthermore, the results of this study confirm previous recommendations that restraints should not be re-used after crash involvement.

The Requisite for Motorcycle Personal Protective Clothing: Malaysia's Perspective

&#x0D; &#x0D; &#x0D; Nearly 1.3 million people are killed and up to 50 million people are injured on the world's roads every year. Approximately 30% of road deaths involve motorcyclists especially in the ASEAN region. In Malaysia, the number of motorcycle accidents is consistently increasing in parallel with the rising number of registered motorcycles. Motorcyclists are categorized under vulnerable road users (VRUs) due to their disadvantages in terms of safety. It is believed that personal protection equipment (PPE) is able to mitigate and minimize motorcyclist injuries resulted from road crashes. The most basic PPE for motorcyclist is the helmet which is made mandatory in many Southeast Asia countries due to its effectiveness in reducing head injuries. Other than that, protective clothing is also vital to protect human body parts from trauma. This study attempts to explore the effectiveness of motorcycle protective clothing performance available in Malaysia. Selected motorcycle protective clothing was tested using anthropometric test device, calibration equipment and instrument. In addition, a market survey was conducted to explore and examine the types and trends of motorcycle protective clothing available. This study finds that motorcycle protective clothing with protector i.e. padding and airbag can provide potentially reduced neck and chest injury in contrast with those with no protection. Furthermore, the result reveals that 55% of the protective clothing available is made of synthetic material. The overall results provide significant information that is useful in the development of countermeasures to improve motorcyclists' safety.&#x0D; &#x0D; &#x0D;

Developing a Custom Anthropometric Test Device for Experimental Evaluation of Blast Mitigation Seats

The use of improvised explosive devices against moving vehicles has been on the rise recently. Their explosions induce devastating effects on vehicle occupants. Blast mitigation seats are used as a counter measure to reduce such harmful effects. This paper presents the scientific work for evaluating the efficacy of blast mitigation seats. The work involves designing and building a custom anthropometric test device (ATD) and a drop tower test facility that is used to simulate the drop of a vehicle from heights up to 10 m. The ATD was equipped with two accelerometers; at the neck and at the pelvis. For validation, a multibody dynamics model was developed to simulate the drop test and the results were compared with ones from experiments. An overall root mean square error of 1.28 g was achieved. The test facility was then used to measure the performance of a blast mitigation seat. The results showed that blast mitigation seats reduced peak accelerations on the pelvis and neck areas by 92% and 87% respectively and this translates into moving predicted injuries from fatal to moderate.

Second-row occupant responses with and without intrusion in rear sled and crash tests

Purpose Intrusion of the occupant compartment increases the risks for severe injury and death. This study analyzes rear sled and crash tests with an instrumented second-row Hybrid III 5th percentile anthropometric test device (ATD) to assess occupant kinematics and biomechanical responses with and without intrusion of the second-row seatback. Methods Three sled tests and four crash tests were conducted with a 1993 Ford Taurus and a belted 5th female ATD seated behind a belted 50th male ATD on the right-side of the vehicle. The sled tests were conducted at 25, 33 and 40 km/h and involved no intrusion. The first crash test was conducted with a passenger car striking the vehicle at 80 km/h with full centerline overlap. The second to fourth crash tests were with a Sport Utility Vehicle (SUV) striking with a 50% overlap. Tests 2 and 3 were at 51 km/h and test 4, at 80 km/h impact speed. A large wooden speaker box was placed in the trunk of the Taurus in tests 3 and 4. Second-row intrusion was measured at the right-rear outboard package shelf retractor. Results The sled tests without intrusion had occupant responses below injury assessment reference values (IARVs). The right second-row ATD moved rearward relative to the interior, compressing the rear seatback until it rebounded forward. Occupant compartment intrusion of 12–77 cm in the crash tests pushed the ATD forward, increasing head and chest acceleration. The head, neck and chest biomechanical responses were below IARVs in crash tests 1 to 3 with minimal intrusion (≤ 25 cm). Most of the biomechanical responses were above IARVs for the right second-row ATD in test 4 with higher intrusion. The HIC increased with intrusion. Head acceleration was more than 2.5-times greater in test 3 than in test 2, highlighting the importance of cargo in rear crashes. Test 4 had 2.4-times more energy than test 3 and up to 7.7 times greater biomechanical responses with 77 cm of intrusion. Conclusions The crash tests show that intrusion increases occupant responses in the right second-row seat and pushes the occupant forward in rear impacts. The sled tests without intrusion had relatively low biomechanical responses. Intrusion was influenced by the crash energy and cargo.

A Shoulder Injury Criterion for the EuroSID-2re Applicable in a Large Loading Condition Spectrum of the Military Domain.

The EuroSID-2re (ES-2re) is an Anthropometric Test Device (ATD) from the automotive domain designed for lateral impact. Since the 2000's, it has also been used by NATO armies to assess the risk of injury to armored vehicles occupants submitted to an Improvised Explosive Device (IED) attack. The resulting loading conditions from an explosion can vary a lot in term of impact velocity and duration. They range from high velocity impacts (~28 m/s), characterized by a short duration (~10 ms) corresponding to cases where the panel deforms under an explosion, to low velocity impacts (~4 m/s), ch aracterized by a long duration (~50 ms) similar to the automotive domain. The goal of the study is to develop a shoulder injury criterion for the EuroSID- 2re that is relevant over the whole loading conditions spectrum of the military domain. For that purpose, thirty-three laboratory ES-2re tests are conducted to replicate four PMHS shoulder impactor test series from the literature. Each test series corresponds to a different loading condition in term of impact velocity and duration: [28 m/s, 3 ms], [14 m/s, 9 ms], [7 m/s, 30 ms], [4 m/s, 50 ms]. The injury result (AIS 2015 scale) of each PMHS test is paired with the shoulder sensor force response signal of the corresponding ES-2re test, resulting in a sample of 75 paired-data. The proposed injury criterion resulting from the sample analysis is the straightened peak force Fs, which is an estimate of the peak of the external force applied to the shoulder. This criterion combines two metrics from the response signal of the shoulder force sensor Y-axis of the ES-2re ATD: the initial slope (S) and the peak (Fmax). The threshold value for a given injury risk depends on the duration of the impact: it is higher for the shorter duration. Thus, a third metric should be extracted from the ES-2re shoulder load cell: the duration of the force T. The present study proposes three force-duration threshold curves Fs=f(T) for low, medium, and high risks of shoulder AI2+ injury.

A comparison of anti-whiplash seats during low/moderate speed rear-end collisions

Objectives: The Insurance Institute for Highway Safety (IIHS) rates automotive seats as good, acceptable, marginal, and poor on their abilities to prevent whiplash injuries during rear-end collisions. The goal of this study was to compare the performance of some good- and poor-rated seats at speed changes below 16 km/h where some whiplash injuries occur.Methods: A BioRID II anthropometric test device (ATD) underwent rear-end collisions from 2 to 14 km/h while seated on one of two Volvo Whiplash Prevention seats (WHIPS), a Saab Active Head Restraint seat (SAHR), or a General Motors High Retention seat (GMHR). The WHIPS and SAHR seats were rated good whereas the GMHR seat was rated poor by the IIHS. The ATD’s kinematics, kinetics and three neck injury criteria were evaluated across the range of collision severities.Results: Most of the head and torso kinematics, kinetics and injury criteria exhibited graded responses with increasing collision severities. Only head extension angle remained relatively similar across all speed changes. Differences between the good- and poor-rated seats were most apparent in the upper neck loads and moments, and head retraction for speed changes greater than 6 km/h.Conclusions: The relatively similar occupant responses across all seats could explain the marginal reductions in whiplash injury risk between good- and poor-rated seats in field studies. Further research into the design of anti-whiplash devices is required to better understand the link between occupant response and injury, and to better mitigate the risk of whiplash injuries during rear-end collisions.

Comparison of three-point belt fit between humans and Hybrid-III anthropometric test devices in a driver mockup

Objective: The Hybrid-III anthropometric test devices (ATDs) are widely used by the automotive industry to evaluate restraint system performance in standardized vehicle crash tests. The relationship between the belt fit measured for people in driving posture and the belt fit obtained with ATDs has not been reported in the literature. The present study compares lap and shoulder belt fit data from ATDs and to a statistical estimate for drivers using age, stature, and BMI.Methods: The lap and shoulder belt fits were measured for small-female and midsize-male Hybrid-III ATDs in a laboratory mockup of a midsize sedan. A range of lower and upper belt anchorage locations were used. The ATD belt fit data were compared with predictions from a regression model developed by data from 97 men and women measured in the same driving package conditions. Humans were free to position the belt comfortably, even if the position was not optimal.Results: The measurements of the ATD belt fit were obtained and compared to the regression estimate for a driver using age, stature, and BMI as predictors. For the small female, the ATD’s lap belt was placed 46 mm further forward and 12 mm lower relative to the pelvis than the regression model estimates for a driver’s lap belt placement. For the midsize male, the lap portion of the belt was placed 13 mm more rearward and 33 mm lower on the physical ATD than the regression model estimates for a similarly sized driver. The shoulder belt was placed an average of 66 mm more inboard and 11 mm more outboard on the small-female and midsize-male physical ATDs, respectively, compared with regression model estimates for drivers.Conclusions: Differences in the lap and shoulder belt fits were quantified between the physical ATDs and regression predictions for similarly sized humans in driving postures. The consequences of these differences should be investigated to help increase understanding of the relationship between belt fit and belt performance.

Frontal crash seat belt restraint effectiveness and comfort accessories used by older occupants

Objective: Around a quarter of older occupants use some type of comfort or orthopedic aftermarket accessory on the vehicle seat while traveling in a vehicle. The aim of this study was to investigate the effect of comfort accessories on the performance of the seat belt restraint system in a frontal crash in terms of potential injury implications for older occupants.Methods: Eight frontal sled tests (43 km/h, 32 g) were carried out on a deceleration sled fitted with a three-point lap-sash seat belt and a front passenger seat from a common Australian passenger car for each test. A 5th percentile Hybrid III anthropometric test device (ATD) was positioned in the seat and measurements were recorded for head center of gravity acceleration, chest acceleration, neck forces and moments and sternal deflection. Tests were carried out in a baseline condition and with seven comfort accessories. Each comfort accessory was inserted between the ATD and vehicle seat as it is intended to be used, with the ATD otherwise positioned as close as possible to the baseline test position.Results: Initial distance between the seat belt anchor and ATD hip was associated with a statistically significant decrease in Head Injury Criterion and increase in sternal deflection. Submarining was related to the ATD torso recline angle and angle of the lap belt from the seat belt anchor.Conclusions: Accessories placed between the seat back and the lumbar region of an occupant have the potential to increase the risk of submarining due to a change in posture and should be avoided if such a change in posture when seated with an accessory is excessive. Sitting on seat cushions resulted in the greatest increase in seat belt anchor to hip distances and hence largest increase in sternal deflection. Given the fragility, frailty and particular importance of chest injuries among older vehicle occupants, further investigation is needed to determine whether these changes in ATD sternal deflection observed with seat cushion use results in injury threshold limits being exceeded and whether pretensioners and load limiters would ameliorate these effects without causing other negative changes in occupant response or kinematics.