Kristian Holmqvist

Comparison of Shoulder Range-of-Motion and Stiffness Between Volunteers, Hybrid III and THOR Alpha In Static Frontal Impact Loading

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.

Heavy vehicle frontal sled crash test analysis - chest deflection response in the Hybrid III dummy

The aim of this study was to analyse the Hybrid III dummy chest loading in heavy vehicle frontal crashes. In total, eight truck front-to-trailer-type sled tests were performed. The Hybrid III, in driver position, was equipped with the chest deflection sensor system RibEye and its standard potentiometer sensor was compared with the RibEye deflection data. The chest impact point was established by using Fuji film impression, as well as from video data. Chest-to-steering wheel rim contact occurred in all tests. Differences in chest loading were found between the Hybrid III dummy reference test and the load case identified in this study, predominantly impact velocity, direction, distribution and location of loading. The steering wheel rim contact is the major contributor to chest deflection. The chest deformation consists of anterior/posterior compression and upward deflection of the sternal plate. The Hybrid III standard chest deflection sensor is not reliable in this load case due to the modes of sternal displacement and the single-point measurement location. Combining the RibEye system with global dummy kinematic data and accurate contact detection is required to fully assess chest deflection. New biomechanical data are needed to adapt the injury risk assessment to the identified load case.

Evaluation of finite element human body models in lateral padded pendulum impacts to the shoulder

Lateral impacts are of great concern for occupant safety. In order to design side protective systems, it is of importance that the timing of the body and the head should be well predicted. Today, experimental and numerical Anthropometric Test Devices (ATDs) are used as human substitutes to predict the human kinematics. As a complement to the ATDs, numerical Human Body Models (HBMs) are used as research tools. The objective of this study is to compare the loading and kinematics of the shoulder complex in three different HBMs with published biological experiments. This study also compares the models with each other and with two numerical ATDs. The results indicate that no HBM can be used for detailed prediction of the kinematics of the human shoulder complex. However, in the presented statistical analysis, all HBMs show a better overall correlation to experiments compared to the numerical ATDs.

Improving Hybrid III Injury Assessment in Steering Wheel Rim to Chest Impacts Using Responses from Finite Element Hybrid III and Human Body Model

Objective: The main aim of this study was to improve the quality of injury risk assessments in steering wheel rim to chest impacts when using the Hybrid III crash test dummy in frontal heavy goods vehicle (HGV) collision tests. Correction factors for chest injury criteria were calculated as the model chest injury parameter ratios between finite element (FE) Hybrid III, evaluated in relevant load cases, and the Total Human Model for Safety (THUMS). This is proposed to be used to compensate Hybrid III measurements in crash tests where steering wheel rim to chest impacts occur. Methods: The study was conducted in an FE environment using an FE-Hybrid III model and the THUMS. Two impactor shapes were used, a circular hub and a long, thin horizontal bar. Chest impacts at velocities ranging from 3.0 to 6.0 m/s were simulated at 3 impact height levels. A ratio between FE-Hybrid III and THUMS chest injury parameters, maximum chest compression C max, and maximum viscous criterion VC max, were calculated for the different chest impact conditions to form a set of correction factors. The definition of the correction factor is based on the assumption that the response from a circular hub impact to the middle of the chest is well characterized and that injury risk measures are independent of impact height. The current limits for these chest injury criteria were used as a basis to develop correction factors that compensate for the limitations in biofidelity of the Hybrid III in steering wheel rim to chest impacts. Results: The hub and bar impactors produced considerably higher C max and VC max responses in the THUMS compared to the FE-Hybrid III. The correction factor for the responses of the FE-Hybrid III showed that the criteria responses for the bar impactor were consistently overestimated. Ratios based on Hybrid III and THUMS responses provided correction factors for the Hybrid III responses ranging from 0.84 to 0.93. These factors can be used to estimate C max and VC max values when the Hybrid III is used in crash tests for which steering wheel rim to chest interaction occurs. Conclusions: For the FE-Hybrid III, bar impacts caused higher chest deflection compared to hub impacts, although the contrary results were obtained with the more humanlike THUMS. Correction factors were developed that can be used to correct the Hybrid III chest responses. Higher injury criteria capping limits for steering wheel impacts are acceptable. Supplemental materials are available for this article. Go to the publishers online edition of Traffic Injury Prevention to view the supplemental file.

Average male and female virtual dummy model (BioRID and EvaRID) simulations with two seat concepts in the Euro NCAP low severity rear impact test configuration

Soft tissue neck injuries, also referred to as whiplash injuries, which can lead to long term suffering accounts for more than 60% of the cost of all injuries leading to permanent medical impairment for the insurance companies, with respect to injuries sustained in vehicle crashes. These injuries are sustained in all impact directions, however they are most common in rear impacts. Injury statistics have since the mid-1960s consistently shown that females are subject to a higher risk of sustaining this type of injury than males, on average twice the risk of injury. Furthermore, some recently developed anti-whiplash systems have revealed they provide less protection for females than males. The protection of both males and females should be addresses equally when designing and evaluating vehicle safety systems to ensure maximum safety for everyone. This is currently not the case. The norm for crash test dummies representing humans in crash test laboratories is an average male. The female part of the population is not represented in tests performed by consumer information organisations such as NCAP or in regulatory tests due to the absence of a physical dummy representing an average female. Recently, the world first virtual model of an average female crash test dummy was developed. In this study, simulations were run with both this model and an average male dummy model, seated in a simplified model of a vehicle seat. The results of the simulations were compared to earlier published results from simulations run in the same test set-up with a vehicle concepts seat. The three crash pulse severities of the Euro NCAP low severity rear impact test were applied. The motion of the neck, head and upper torso were analysed in addition to the accelerations and the Neck Injury Criterion (NIC). Furthermore, the response of the virtual models was compared to the response of volunteers as well as the average male model, to that of the response of a physical dummy model. Simulations with the virtual male and female dummy models revealed differences in dynamic response related to the crash severity, as well as between the two dummies in the two different seat models. For the comparison of the response of the virtual models to the response of the volunteers and the physical dummy model, the peak angular motion of the first thoracic vertebra as found in the volunteer tests and mimicked by the physical dummy were not of the same magnitude in the virtual models. The results of the study highlight the need for an extended test matrix that includes an average female dummy model to evaluate the level of occupant protection different seats provide in vehicle crashes. This would provide developers with an additional tool to ensure that both male and female occupants receive satisfactory protection and promote seat concepts that provide the best possible protection for the whole adult population. This study shows that using the mathematical models available today can provide insights suitable for future testing.

Impacts to the chest of PMHSs - Influence of impact location and load distribution on chest response

The chest response of the human body has been studied for several load conditions, but is not well known in the case of steering wheel rim-to-chest impact in heavy goods vehicle frontal collisions. The aim of this study was to determine the response of the human chest in a set of simulated steering wheel impacts. PMHS tests were carried out and analysed. The steering wheel load pattern was represented by a rigid pendulum with a straight bar-shaped front. A crash test dummy chest calibration pendulum was utilised for comparison. In this study, a set of rigid bar impacts were directed at various heights of the chest, spanning approximately 120mm around the fourth intercostal space. The impact energy was set below a level estimated to cause rib fracture. The analysed results consist of responses, evaluated with respect to differences in the impacting shape and impact heights on compression and viscous criteria chest injury responses. The results showed that the bar impacts consistently produced lesser scaled chest compressions than the hub; the Middle bar responses were around 90% of the hub responses. A superior bar impact provided lesser chest compression; the average response was 86% of the Middle bar response. For inferior bar impacts, the chest compression response was 116% of the chest compression in the middle. The damping properties of the chest caused the compression to decrease in the high speed bar impacts to 88% of that in low speed impacts. From the analysis it could be concluded that the bar impact shape provides lower chest criteria responses compared to the hub. Further, the bar responses are dependent on the impact location of the chest. Inertial and viscous effects of the upper body affect the responses. The results can be used to assess the responses of human substitutes such as anthropomorphic test devices and finite element human body models, which will benefit the development process of heavy goods vehicle safety systems.