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Abstract Compared to other age groups, older adults are at more significant risk of hip fracture when they fall. In addition to the higher risk of falls for the elderly, fear of falls can reduce this population’s outdoor activity. Various preventive solutions have been proposed to reduce the risk of hip fractures ranging from wearable hip protectors to indoor flooring systems. A previously developed rubberized asphalt mixture demonstrated the potential to reduce the risk of head injury. In the current study, the capability of the rubberized asphalt sample was evaluated for the risk of hip fracture for an average elderly male and an average elderly female. A previously developed human body model was positioned in a fall configuration that would give the highest impact forces toward regular asphalt.

Abstract The use of appropriate loads and regulations is of great importance in weld fatigue assessment of rail on-track maintenance equipment and similar vehicles for optimized design. The regulations and available loads, however, are often generalized for several categories, which proves to be overly conservative for some specific categories of machines. EN (European Norm) and AAR (Association of American Railroads) regulations play a pivotal role in determining the applicable loads and acceptance criteria within this study. The availability of track-induced fatigue load data for the cumulative damage approach in track maintenance machines is often limited. Consequently, the FEA-based validation of rail track maintenance equipment often resorts to the infinite life approach rather than cumulative damage approach for track-induced travel loads, resulting in overly conservative designs.

Abstract In this article, an improved brake cooling simulation method is introduced. By this method, the vehicle parameters, such as weight, height of the center of gravity, wheelbase, and the like can be included to calculate the braking thermal load under different operating conditions. The effect of the brake kinetic energy regeneration (BKER) on the braking thermal load can also be calculated by this method. The calculated braking thermal load is then input to a coupled 3D simulation model to conduct flow and thermal simulation to calculate brake disc temperature. It is demonstrated that by this simulation method, the difference between the brake disc temperatures obtained from simulation and vehicle test can be controlled below 5%.

Abstract Composite ceramic brake discs are made of ceramic material reinforced with carbon fibers and offer exceptional advantages that translate directly into higher vehicle performance. In the case of an electric vehicle, it could increase the range of the vehicle, and in the case of conventional internal combustion engine vehicles, it means lower fuel consumption (and consequently lower CO2 emissions). These discs are typically characterized by complex internal geometries, further complicated by the presence of drilling holes on both friction surfaces. To estimate the aerothermal performance of these discs, and for the thermal management of the vehicle, a reliable model for predicting the air flowing across the disc channels is needed. In this study, a real carbon-ceramic brake disc with drilling holes was investigated in a dedicated test rig simulating the wheel corner flow conditions experimentally using the particle image velocimetry technique and numerically.

Abstract One of the key problems of battery electric vehicles is the risk of severe range reduction in winter conditions. Technologies such as heat pump systems can help to mitigate such effects, but finding adequate heat sources for the heat pump sometimes can be a problem, too. In cold ambient conditions below −10°C and for a cold-soaked vehicle this can become a limiting factor. Storing waste heat or excess cold when it is generated and releasing it to the vehicle thermal management system later can reduce peak thermal requirements to more manageable average levels. In related architectures it is not always necessary to replace existing electric heaters or conventional air-conditioning systems. Sometimes it is more efficient to keep them and support them, instead. Accordingly, we show, how latent heat storage can be used to increase the efficiency of existing, well-established heating and cooling technologies without replacing them.

Abstract Neutron diffraction is a powerful tool for noninvasive and nondestructive characterization of materials and can be applied even in large devices such as internal combustion engines thanks to neutrons’ exceptional ability to penetrate many materials. While proof-of-concept experiments have shown the ability to measure spatially and temporally resolved lattice strains in a small aluminum engine on a timescale of minutes over a limited spatial region, extending this capability to timescales on the order of a crank angle degree over the full volume of the combustion chamber requires careful design and optimization of the engine structure to minimize attenuation of the incident and diffracted neutrons to maximize count rates.

Abstract Electrical connection plays an important role in not only direct heat transfer, but also the transmission of electric energy and the transformation of electrothermal effect in the parallel battery modules. The thermal propagation simulation research model was established based on the equivalent circuit and thermal runaway experimental research of a module formed by four parallel cells, which superimposes the discharge process and corresponding electrothermal effect in the process of thermal runaway and thermal propagation, and pays attention to the SoC (state of charge) state and corresponding thermal runaway energy release changes after cell discharged. Thermal runaway and propagation characteristics of parallel and non-parallel battery modules were analyzed and results showed that without considering the energy exchange between the system and the environment, the parallel battery module will accelerate the process of thermal propagation.

Abstract Adaptive neural networks (ANNs) have become famous for modeling and controlling dynamic systems. However, because of their failure to precisely reflect the intricate dynamics of the system, these have limited use in practical applications and perform poorly during training and testing. This research explores novel approaches to this issue, including modifying the simple neuron unit and developing a generalized neuron (GN). The revised version of the neuron unit helps to develop the system controller, which is responsible for providing the desired control signal based on the inputs received from the dynamic responses of the vehicle suspension system. The controller is then tested and evaluated based on the performance of the magnetorheological (MR) damper for the main suspension system.

Abstract For spacecraft with high power consumption, it is reasonable to build the thermal control system based on a two-phase mechanically pumped loop. The heat-controlled accumulator is a key element of the two-phase mechanically pumped loop, which allows for the control of pressure in the loop and maintains the required level of coolant boiling temperature or cavitation margin at the pump inlet. There can be two critical modes of loop operation where the ability to control pressure will be lost. The first critical mode occurs when the accumulator fills with liquid at high heat loads. The second critical mode occurs when the accumulator is at low heat loads and partial loss of coolant, for example, due to the leak caused by micrometeorite breakdown. Both modes are caused by insufficient accumulator volume or working fluid charge.

Abstract Computational and experimental studies have been undertaken to investigate injurious head-first impacts (HFI), which can occur during automotive rollovers. Recent studies assume a torso surrogate mass (TSM) boundary condition, wherein the first or first two thoracic vertebrae are potted and constrained to only move in the vertical loading direction. The TSM boundary condition has not been compared with a full body (FB) model computationally or experimentally for HFI. In this study, the Global Human Body Models Consortium 50th percentile male detailed human body model (M50-O, Version 6.0) was applied to compare the kinematic, kinetic, and injury response of an HFI with a TSM boundary condition (M50-TSM), and a full body boundary condition (M50-FB). Impacts (to M50-TSM and M50-FB) were simulated between the head and a rigid plate using a commercial FE code (LS-DYNA).

Abstract Rib fractures are associated with high rates of morbidity and mortality. Improved methods to assess rib bone quality are needed to identify at-risk populations. Quantitative computed tomography (QCT) can be used to calculate volumetric bone mineral density (vBMD) and bone mineral content (BMC), which may be related to rib fracture risk. The objective of this study was to determine if vBMD and BMC from QCT predict human rib structural properties. 127 mid-level (5th–7th) ribs were obtained from adult female (n = 67) and male (n = 60) postmortem human subjects (PMHS). Isolated rib QCT scans were performed to calculate vBMD and BMC.

Abstract Traumatic brain injury is a leading cause of global death and disability. Clinically relevant large animal models are a vital tool for understanding the biomechanics of injury, providing validation data for computation models, and advancing clinical translation of laboratory findings. It is well-established that large angular accelerations of the head can cause TBI, but the effect of head impact on the extent and severity of brain pathology remains unclear. Clinically, most TBIs occur with direct head impact, as opposed to inertial injuries where the head is accelerated without direct impact. There are currently no active large animal models of impact TBI. Sheep may provide a valuable model for studying TBI biomechanics, with relatively large brains that are similar in structure to that of humans. The aim of this project is to develop an ovine model of impact TBI to study the relationships between impact mechanics and brain pathology.

Abstract Objective: This study aimed to optimize restraint systems and improve safety equity by using parametric human body models (HBMs) and vehicle models accounting for variations in occupant size and shape as well as vehicle type. Methodology: A diverse set of finite element (FE) HBMs were developed by morphing the GHBMC midsize male simplified model into statistically predicted skeleton and body shape geometries with varied age, stature, and body mass index (BMI). A parametric vehicle model was equipped with driver, front passenger, knee, and curtain airbags along with seat belts with pretensioner(s) and load limiter and has been validated against US-NCAP results from four vehicles (Corolla, Accord, RAV4, F150). Ten student groups were formed for this study, and each group picked a vehicle model, occupant side (driver vs. passenger), and an occupant model among the 60 HBMs.

Eighteen research posters were prepared and presented by student authors at the 18th Annual Injury Biomechanics Symposium. The posters covered a wide breadth of works-in-progress and recently completed projects.

Abstract Letter from the Special Issue Editors

Abstract Introduction: The use of less lethal impact munitions (LLIMs) by law enforcement has increased in frequency, especially following nationwide protests regarding police brutality and racial injustice in the summer of 2020. There are several reports of the projectiles causing severe injuries when they penetrate the skin including pulmonary contusions, bone fractures, liver lacerations, and, in some cases, death. The penetration threshold of skin in different body regions is due to differences in the underlying structure (varying degree of muscle, adipose tissue, and presence or absence of bone). Objective: The objective of this study was to further investigate what factors affected the likelihood of skin penetration in various body regions and to develop corresponding penetration risk curves.

Abstract Compressive impacts on the cervical spine can result in bony fractures. Bone fragments displaced into the spinal canal produce spinal canal occlusion, increasing the potential for spinal cord injury (SCI). Human body models (HBMs) provide an opportunity to investigate SCI but currently need to be improved in their ability to model compression fractures and the resulting material flow. Previous work to improve fracture prediction included the development of an anisotropic material model for the bone (hard tissues) of the vertebrae assessed in a functional spinal unit (FSU) model. In the FSU model, bony failure was modeled with strain-based element erosion, with a limitation that material that could occlude the spinal canal during compression was removed when an element was eroded.

Abstract Bilateral knee impacts were conducted on Hybrid III and THOR 5th percentile female anthropomorphic test devices (ATDs), and the results were compared to previously reported female PMHS data. Each ATD was impacted at velocities of 2.5, 3.5, and 4.9 m/s. Knee–thigh–hip (KTH) loading data, obtained either via direct measurement or through exercising a one-dimensional lumped parameter model (LPM), was analyzed for differences in loading characteristics including the maximum force, time to maximum force, loading rate, and loading duration. In general, the Hybrid III had the highest loading rate and maximum force, and the lowest loading duration and time to peak force for each point along KTH. Conversely, the PMHS generally had the lowest loading rate and maximum force, and the highest loading duration and time to peak force for each point along KTH.

Abstract The objective of this study was to compare head, neck, and chest injury risks between front and rear-seated Hybrid III 50th-percentile male anthropomorphic test devices (ATDs) during matched frontal impacts. Seven vehicles were converted to rear seat test bucks (two sedans, three mid-size SUVs, one subcompact SUV, and one minivan) and then used to perform sled testing with vehicle-specific frontal NCAP acceleration pulses and a rear seated (i.e., second row) Hybrid III 50th male ATD. Matched front seat Hybrid III 50th male ATD data were obtained from the NHTSA Vehicle Crash Test Database for each vehicle. HIC15, Nij, maximum chest acceleration, and maximum chest deflection were compared between the front and rear seat tests, as well as between vehicles with conventional and advanced three-point belt restraint systems in the rear seat. Additionally, a modified version of the NCAP frontal star rating was calculated for the front and rear seat tests.

Abstract Oblique motor vehicle crashes can cause serious head or brain injuries due to contact with interior vehicle structures even with the deployment of air bags, as they are not yet completely successful in preventing traumatic brain injury. Rotational head velocity is strongly correlated to the risk of brain injury, and this head motion is potentially related to the tangential friction force developed during contact between the head and air bags. Although crash test dummy head skins are designed with appropriate mass properties and anthropometry to simulate the normal direction impact response of the human head, it is not known whether they accurately represent the frictional properties of human skin during air bag interaction. This study experimentally characterized the dynamic friction coefficient between human/dummy skins and air bag fabrics using a pin-on-disc tribometer.