Browse Topic: Leg
Indian passenger car accident data indicates that approximately 44% of crashes are frontal impacts (Refer fig 1). Among the injuries sustained in these crashes, lower leg injuries are notably critical, contributing to nearly 25% of driver occupant injuries (Refer fig 2). To evaluate such injuries, the Bharat New Car Assessment Program (BNCAP) includes lower leg injury metrics as part of the Frontal Offset Deformable Barrier (ODB64) test. While the overall injury performance is assessed at the vehicle level, BNCAP also monitors vehicle interior intrusions—particularly pedal intrusions—as key contributors to lower limb injury severity. A major challenge in frontal crashes is the intrusion of the vehicle's front-end structure into the occupant compartment. Rigid components, particularly the brake pedal assembly, can be displaced rearward during a crash, significantly increasing the risk of lower leg injuries. Therefore, minimizing pedal intrusions into the driver foot-well is critical for enhancing lower leg protection. As part of an innovative safety initiative, Tata Motors has developed a collapsible brake pedal mechanism designed to mitigate lower leg injuries during frontal crashes. This patented system incorporates a series of levers and linkages that disengage upon impact, allowing the brake pedal to collapse and thereby reducing the risk of intrusion-related injuries to the driver lower legs. The mechanism is engineered to be robust, ensuring that normal braking performance and pedal operation remain unaffected during everyday vehicle use, while providing effective injury mitigation in crash scenarios.
In an era where technology increasingly merges with healthcare to enhance patient outcomes, a groundbreaking study conducted by Fuyang Yu and his colleagues introduces an innovative approach to lower limb rehabilitation. Their research, published in Cyborg Bionic Systems, outlines the development of a lower limb rehabilitation robot designed to significantly improve the safety and effectiveness of gait training through a novel method based on human-robot interaction force measurement.
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. Topics included a variety of body regions and injury scenarios such as: Head: Defining the mass, center of mass, and anatomical coordinate system of the pig head and brain; the influence of friction on oblique helmet testing; validation of an in-ear sensor for measuring head impact exposure in American football Neck and spine: Design of paramedic mannequin neck informed by adult passive neck stiffness and range of motion data; identifying injury from flexion-compression loading of porcine lumbar intervertebral disc Thorax: Tensile material properties of costal cartilage perichondrium; finite element models of both an ovine thorax and adipose tissue for high-rate non-penetrating blunt impact Pelvis: Injurious pelvis deformation in high-speed rear-facing frontal impacts Lower extremities: Generation of 3D pediatric femur models from 2D radiographs; plantar thickness and stiffness using ultrasound; knee injuries in skiing and snowboarding using artificial intelligence 3D modeling; jumping kinematics, and kinetics in athletes with secondary task of heading a soccer ball Full body, vehicle occupants: Comparison of Hybrid III, THOR mid-size male, and small female ATDs in frontal sled tests; effects of booster seat on reclined small females during lateral oblique low-acceleration impacts; airbag deployment for out-of-position 50th percentile male human body model Full body, unique loading scenarios: Development of seat fixture and restraints for FE human body model during vertical loading; methodology for PMHS-occupied powered two wheeler and motor vehicle crash scenario
The purpose of this document is to provide the user with the procedures needed to properly assemble and disassemble the 50th percentile male Hybrid III dummy, certify its components and verify its mass and dimensions. Also within this manual are guidelines for handling accelerometers, repairing flesh and setting joints.
Four Army pilots participated in a simulation experiment to examine the influence of stick location and sensitivity (gain) on pilot neuromuscular (NM) response, performance, and workload. The experiment employed an active inceptor that was positioned between the pilot's legs or, adjacent to the pilot's right side with an armrest. Two stick sensitivities that varied by a factor of four were evaluated using a single-axis compensatory tracking task in the longitudinal and the lateral axes. The experiment results identified two prominent NM modes at roughly 10 and 25 rad/s; stabilizing the elbow implicated the 10 rad/s mode with forearm motion, and wrist/finger motion with the mode at 25 rad/s. With the longitudinal task using the low stick gain, workload ratings were significantly higher for the side stick than the center stick. A preliminary analysis indicated that the greater resisting force between the forearm and non-compliant armrest (side stick configuration) relative to the resisting force between the forearm and leg (center stick configuration) may be a key factor in the higher workload. This suggests that a side stick's gain in the longitudinal axis should be a function of task such that control displacements are generally small. Overall workload during manual tasks would benefit if this approach were applied to all control axes. A second study was conducted to investigate the significant effect of stick gain on crossover frequency that was observed in the first experiment. These results showed that the ratio of stick rate to stick amplitude is directly proportional to crossover frequency, and that a tradeoff between rate and amplitude reflected by changing crossover is similar to the phenomenon described by Fitts Law, where manual movement time is related to the distance travelled. The implications for design are that stick travel can affect performance much more than stick force provided the stick dynamics do not adversely interact with the NM system. It is recommended that the feel system mode should lie between the forearm and wrist/finger NM modes, and that stick sensitivity selection should be based on mission and operating environment.
Field accident data and vehicle crash and sled testing indicate that occupant kinematics, loading, and associated injury risk generally increase with crash severity. Further, these data demonstrate that the use of restraints, such as three-point belts, provides mitigation of kinematics and reduction in loading and injury potential. This study evaluated the role of seat belts in controlling occupant kinematics and reducing occupant loading in moderate severity frontal collisions. Frontal tests with belted and unbelted anthropomorphic test devices (ATDs) in the driver and right front passenger seats were performed at velocity changes (delta-Vs) of approximately 19 kph (12 mph) and 32 kph (20 mph) without airbag deployment. At the lower-moderate severity (19 kph), motion of the belted ATDs was primarily arrested by seat belt engagement, while motion of the unbelted ATDs was primarily arrested by interaction with forward vehicle structures. Occupant loading and injury risk was generally lower with proper belt use as compared to an unbelted occupant. At the higher-moderate severity (32 kph), both the belted and unbelted ATDs demonstrated lower extremity engagement with forward vehicle structures, though femur compression loads were substantially attenuated for the belted ATDs. With belt use, the pelvis and torso were restrained by the seat belt which reduced overall forward torso and head excursion. As the neck flexed due to torso restraint, increased lower neck flexion was observed relative to the unbelted ATDs, though upper neck flexion remained greater for the unbelted ATD. In the higher-moderate severity test, neck flexion about the torso restraint resulted in the belted driver ATD’s head contacting the steering wheel. The unbelted ATDs moved forward in an unrestrained fashion until motion was arrested via contact with forward vehicle structures, resulting in generally higher occupant loading in comparison to their belted counterparts. These findings support the effectiveness of seat belts in controlling occupant kinematics and reducing injury potential in moderate severity frontal collisions.
The Insurance Institute of Highway Safety (IIHS) introduced driver side small overlap test in 2012 and added the passenger side small overlap test in 2018 to the top safety pick plus ratings requirement. The injury of a passenger’s outboard right foot in the passenger-side small overlap rigid barrier (PSORB) test is of more concern compared to the driver’s outboard left foot in the driver-side small overlap rigid barrier (DSORB) test. The reason is, the passenger’s right foot is positioned just above the carpet on the toe pan, and is closer to the barrier during the PSORB impact event, unlike the driver’s outboard left foot in DSORB, which rests on a stiff foot rest. So it is often necessary to develop countermeasures to protect the passenger from lower leg injuries. This paper describes a time efficient method to model the PSORB occupant sled model using finite element modeling and it also demonstrates the model’s application in the process of countermeasure development for the protection of a passenger from lower leg injuries. Finite element (FE) models of the Hybrid-III dummy, passenger airbag, knee airbag, seat belt system and other critical vehicle components and assemblies were modeled as required and integrated in the sled model. A detailed finite element model of the carpet assembly was also modeled. The paper also explains a quick and simple scaling method used to generate the Ls-Dyna material properties of the different grades of carpet foam, from its respective compression test data. The overall results of the base model and the countermeasure model were validated and confirmed with their respective internal small overlap rigid barrier tests. The proposed method of modeling the sled model has shown to be effective with respect to computational time and robust in predicting the passenger’s lower tibia axial force response for a given intrusion rate of the toe pan.
This document describes the 2-D computer-aided design (CAD) template for the HPM-1 H-point machine or HPD available from SAE. The elements of the HPD include the curve shapes, datum points and lines, and calibration references. The intended purpose for this information is to provide a master CAD reference for design and benchmarking. The content and format of the data files that are available are also described.
Researchers have developed new software that can enable people using robotic prosthetics or exoskeletons to walk in a safer, more natural manner on different types of terrain. The new framework incorporates computer vision into prosthetic leg control and includes robust artificial intelligence (AI) algorithms that allow the software to better account for uncertainty.
This document describes the 3D computer-aided design (CAD) parts and file formats for the HPM-1 H-point machine available from SAE. The intended purpose for this information is to provide a master CAD reference for design and benchmarking.
Automotive accidents and subsequent personal injury claims incur substantial costs annually. While three-point restraint usage, dual-stage airbags, and knee bolster and side curtain airbags have become more ubiquitous and, in some cases, governmentally mandated for front seat occupants, occupant safety and injury risk assessment continue to be at the forefront of automotive innovation. In this study, we combined analyses of the National Automotive Sampling System Crashworthiness Data System (NASS-CDS; 2007-2015) and the Crash Investigation Sampling System (CISS; 2017) with data acquired from vehicle-to-vehicle crash tests conducted with instrumented anthropomorphic test device (ATD) occupants. Together, these analyses were used to compare and relate field injury rates with potential injury mechanisms in low- to moderate-speed frontal collisions. First, low- to moderate-speed (delta-V ≤ 24 km/h) frontal crash data from NASS-CDS and CISS were analyzed to estimate the rate of AIS 2+ and AIS 3+ cervical spine, lumbar spine, and lower extremity injuries, as well as a subset of AIS 2+ and 3+ head injuries including recorded unconsciousness and concussion. The results of these analyses were related to occupant loading data from comparative frontal crash tests, conducted at delta-Vs ranging from 6 to 19 km/h. Kinematic and kinetic data for the head, cervical spine, lumbar spine, and femur collected in the frontal crash tests were well below injury thresholds. Analysis of the NASS-CDS and CISS data demonstrated low rates of injury to the head, cervical spine, lumbar spine, and lower extremities in low- to moderate-speed frontal collisions. Review of these frontal crashes revealed that several factors, outside of collision severity, may affect injury likelihood, including muscle activation, seatbelt status, frontal and knee bolster airbag deployment, seat track position, out-of-positioning, age, gender, interaction with vehicle interior structures, and vehicle-to-vehicle impact orientation, which includes both degree of overlap and obliquity.
The objective of this study was to generate biomechanical corridors from post-mortem human subjects (PMHS) in two different seatback recline angles in 56 km/h sled tests simulating a rear-facing occupant during a frontal vehicle impact. PMHS were placed in a production seat which included an integrated seat belt. To achieve a repeatable configuration, the seat was rigidized in the rearward direction using a reinforcing frame that allowed for adjustability in both seatback recline angle and head restraint position. The frame contained instrumentation to measure occupant loads applied to the head restraint and seatback. To measure PMHS kinematics, the head, spine, pelvis, and lower extremities were instrumented with accelerometers and angular rate sensors. Strain gages were attached to anterior and posterior aspects of the ribs, as well as the mid-shaft of the femora and tibiae, to determine fracture timing. A chestband was installed at the mid sternum to quantify chest deformation. Biomechanical corridors for each body and seat location were generated for each recline angle to provide data for quantitatively evaluating the biofidelity of ATDs and HBMs. Injuries included upper extremity injuries, rib fractures, pelvis fractures, and lower extremity injuries. More injuries were documented in the 45-degree recline case than in the 25-degree recline case. These injuries are likely due to the excessive ramping up and corresponding kinematics of the PMHS. Biomechanical corridors and injury information presented in this study could guide the design of HBMs and ATDs in rigid, reclined, rear-facing seating configurations during a high-speed frontal impact.
As pedestrian protection tests and evaluations have been officially incorporated into new C-NCAP, more stringent requirements have been placed on pedestrian protection performance. In this study, in order to reduce the injury of the vehicle front end structure to the pedestrian's lower extremity during the collision, the advanced pedestrian legform impactor (aPLI) model was used in conjunction with the finite element vehicle model for collision simulation based on the new C-NCAP legform test evaluation regulation. This paper selected the key components which have significant influences on the pedestrian's leg protection performance based on the CAE vehicle model, including front bumper, front-cover plate, upper impact pillar, impact beam and lower support plate, to form a simplified model and conducted parametric modeling based on it. Then, the variable correlation analysis was carried out on the sample results obtained from the design of experiment (DOE), and the contribution analysis of design variables to the injury measures was discussed. The sample variables and responses were also used to construct the approximate models for further optimization studies. Taking the pedestrian lower extremity injuries as the optimization target, the front end structural parameters were matched and optimized. Finally, an optimal configuration for parameter matching of key components of the front end structure for pedestrian protection was established, which effectively improve the protection of pedestrian lower extremity.
With growing environmental concerns associated with gas-powered vehicles and busier city streets, micro-mobility modes, including traditional bicycles and new technologies, such as electric scooters (e-scooters), are becoming solutions. In 2018, e-scooter usage overtook other shared micro-mobility modes with over 38 million e-scooter trips taken. Concurrently, the societal concern regarding the safety of these devices is also increasing. To examine the types of injuries associated with e-scooters and bicycles, the National Electronic Injury Surveillance System (NEISS), a probability sample of US hospitals that collects information from emergency room (ER) visits related to consumer products, was utilized. Records from September 2017 to December 2018 were extracted, and those associated with powered scooters were identified. Injury distributions by age, sex, race, treatment, diagnosis, and location on the body were explored. The number of person-trips was obtained to perform a risk analysis. An estimated 17,772 injuries were associated with powered scooters. Nearly 45% of injuries occurred in persons aged 10-29 years. Almost 87% of ER visits consisted of patients being treated and released, whereas nearly 11% were hospitalized (the remaining 2% either received no treatment or the disposition was unknown). Common injuries included contusions/abrasions, fractures, and lacerations. Almost 15% of the injuries associated with powered scooters occurred to the face; the head, ankle, lower leg, and knee were other common body parts injured. An estimated 51 million person-trips were taken during this time period, resulting in an injury rate of 346 injuries/million trips. In comparison, 4.7 billion person-trips were taken on bicycles, resulting in an injury rate of 114 injuries/million trips.
Occupant dynamics during passenger vehicle underride has not been extensively evaluated. The present study examined the occupant data from IIHS rear underride crash tests. A total of 35 crash tests were evaluated. The tests were classified as full-width (n = 9), 50% overlap (n = 11), and 30% overlap (n = 15). A 2010 Chevrolet Malibu impacted the rear underride guard of a stationary trailer at 35 mph. Several occupant kinematics and dynamics data including head accelerations, head injury criteria, neck shear and axial forces, neck moments, neck indices, chest acceleration, chest displacement, chest viscous criterion, sternum deflection rate, and left/right femur forces/impulses, knee displacements, tibia axial forces, upper/lower tibia moments, upper/lower tibia indices, and foot accelerations were measured. The vehicle accelerations, delta-Vs, and occupant compartment intrusions were also evaluated. The results indicated that the head and neck injury parameters were positively correlated with driver A-pillar rearward intrusion. The 30% overlap crashes showed significantly higher intrusion and head and neck injury values than the 50% and full-width crashes. No strong relationship between head and neck injury parameters and vehicle delta-V or peak acceleration was observed. None of the chest injury criteria exceeded the chest IARV tolerances in the crash tests examined. No relationship between chest injury parameters and vehicle delta-V, acceleration or driver A-pillar rearward intrusion was observed. No strong relationship was observed between left/right leg injury parameters and vehicle delta-V, acceleration or driver A-pillar intrusion. Only for two crash tests, the “left upper tibia A-P moment”, “left upper tibia resultant moment” and “left upper tibia index” exceeded the IARV tolerances. This study suggested that in underride crashes there is a higher chance of head/neck injuries than other body regions. Also, in addition to delta-V, other parameters such as percent overlap and occupant compartment intrusion should be taken into consideration when analyzing the biomechanics of underride.
Lower extremity injuries caused by floor plate impacts through the axis of the lower leg are a major source of injury and disability for civilian and military vehicle occupants. A collection of PMHS pendulum impacts was revisited to obtain data for paired booted/unbooted test on the same leg. Five sets of paired pendulum impacts (10 experiments in total) were found using four lower legs from two PMHS. The PMHS size and age was representative of an average young adult male. In these tests, a PMHS leg was impacted by a 3.4 or 5.8 kg pendulum with an initial velocity of 5, 7, or 10 m/s (42-288 J). A matching LS-DYNA finite element model was developed to replicate the experiments and provide additional energy, strain, and stress data. Simulation results matched the PMHS data using peak values and CORA curve correlations. Experimental forces ranged between 1.9 and 12.1 kN experimentally and 2.0 and 11.7 kN in simulation. Combat boot usage reduced the peak force by 36% experimentally (32% in simulation) by compressing the sole and insole with similar mitigations for calcaneus strain. The simulated Von Mises stress contours showed the boot both mitigating and shifting stress concentrations from the calcaneus in unbooted impacts to the talus-tibia joint in the booted impacts, which may explain why some previous studies have observed shifts to tibia injuries with boot or padding usage.
Limited data exist on the injury tolerance and biomechanical response of humans to high-rate, under-body blast (UBB) loading conditions that are commonly seen in current military operations, and there are no data examining the influence of occupant posture on response. Additionally, no anthropomorphic test device (ATD) currently exists that can properly assess the response of humans to high-rate UBB loading. Therefore, the purpose of this research was to examine the response of post-mortem human surrogates (PMHS) in various seated postures to high-rate, vertical loading representative of those conditions seen in theater. In total, six PMHS tests were conducted using loading pulses applied directly to the pelvis and feet of the PMHS: three in an acute posture (foot, knee, and pelvis angles of 75°, 75°, and 36°, respectively), and three in an obtuse posture (15° reclined torso, and foot, knee, and pelvis angles of 105°, 105°, and 49.5°, respectively). Tests were conducted with a seat velocity pulse that peaked at ~4 m/s with a 30-40 ms time to peak velocity (TTP) and a floor velocity that peaked at 6.9-8.0 m/s (2-2.75 ms TTP). Posture condition had no influence on skeletal injuries sustained, but did result in altered leg kinematics, with leg entrapment under the seat occurring in the acute posture, and significant forward leg rotations occurring in the obtuse posture. These data will be used to validate a prototype ATD meant for use in high-rate UBB loading scenarios.
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