Jeff Crandall

University of Virginia | UVa · Center for Applied Biomechanics

The THOR-NT dummy has been developed and continuously improved by NHTSA to provide manufactures an advanced tool that can be used to asses injury risk in crash tests. With the recent improvements of finite element (FE) technology and the increase of computational power, a validated FE model of the THOR-NT provides an efficient tool for design optim...

Understanding the in-game demands placed on athletes may allow practitioners to design improved training protocols to prepare athletes for competitive demands. This study aimed to quantify the competitive movement demands of professional American football athletes and to determine any inter-positional differences that may exist. Player tracking dat...

The use of head kinematic measurement devices has recently proliferated owing to technology advances that make such measurement more feasible. In parallel, demand to understand the biomechanics of head impacts and injury in sports and the military has increased as the burden of such loading on the brain has received focused attention. As a result,...

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Objective: Automated driving systems (ADS) are actively being deployed within the driving fleet. ADS are designed to safely navigate roadways, which entails an expectation of encountering varying degrees of potential conflict with other road users. The ADS design and evaluation process benefits from estimating injury severity probabilities for coll...

The Guardian Cap NXT (GC NXT) and the ProTech Helmet Cap (ProTech) are commercially available aftermarket products designed to augment the energy attenuation characteristics of American football helmets. The ability of these helmet shell add-on products to mitigate the severity of impacts typically experienced by professional offensive and defensiv...

Instrumented mouthpieces (IM) offer a means of measuring head impacts that occur in sport. Direct measurement of angular head kinematics is preferential for accuracy; however, existing IMs measure angular velocity and differentiate the measurement to calculate angular acceleration, which can limit bandwidth and consume more power. This study presen...

Understanding the size and shape variations of the head is important to the design of football helmets used to mitigate the risk of head injury. Current guidelines for selecting helmets use only the circumference of the player’s head to determine an appropriate size that may not offer the best fit and protection for every player. The goal of this s...

While the seatbelt restraint has significantly improved occupant safety, the protection efficiency still needs further enhance to reduce the consequence of the crash. Influence of seatbelt restraint loading on chest injury under 40 km/h has been tested and documented. However, a comprehensive profiling of the efficiency of restraint systems with va...

The use of standardized anthropomorphic test devices and test conditions prevent current vehicle development and safety assessments from capturing the breadth of variability inherent in real-world occupant responses. This study introduces a methodology that overcomes these limitations by enabling the assessment of occupant response while accounting...

As more is learned about injury mechanisms of concussion and scenarios under which injuries are sustained in football games, methods used to evaluate protective equipment must adapt. A combination of video review, videogrammetry, and laboratory reconstructions was used to characterize concussive impacts from National Football League games during th...

Sports concussions offer a unique opportunity to study head kinematics associated with mild traumatic brain injury. In this study, a model-based image matching (MBIM) approach was employed to analyze video footage of 57 concussions which occurred in National Football League (NFL) games. By utilizing at least two camera views, higher frame rate foot...

The relationship between laboratory and on-field performance of football helmets was assessed for 31 football helmet models selected from those worn by players in the 2015–2019 National Football League (NFL) seasons. Linear impactor tests were conducted with helmets placed on an instrumented Hybrid III head and neck assembly mounted on a sliding ta...

Wearable sensors that accurately record head impacts experienced by athletes during play can enable a wide range of potential applications including equipment improvements, player education, and rule changes. One challenge for wearable systems is their ability to discriminate head impacts from recorded spurious signals. This study describes the dev...

Consideration of position-specific features of the NFL concussion environment could enable improved risk mitigation through the design of position-specific helmets to improve self-protection as well as protection for the other player with whom the contact occurs. The purpose of this paper is to quantify position-specific features of scenarios resul...

This paper reports the development of a test device for replicating unique features of concussion-causing helmet-to-ground impacts. Helmet-to-ground impacts are characterized by an oblique impact velocity vector, preimpact rotational motion of the helmeted head, and an impact into a compliant frictional surface of unknown effective mass. No helmet...

The goal of the current study was to develop a method to estimate whole-body injury metrics (WBIMs), which measure the overall impact of injuries, using stochastic injury prediction results from a computational human surrogate. First, hospitalized pedestrian data was queried to identify injuries sustained by pedestrians and their frequencies. Secon...

Previous studies indicate that seatbelts may require supplementary restraints to increase their effectiveness in far-side impacts. This study aimed to evaluate the effectiveness of a novel, far-side-specific airbag in restraining and preventing injuries in far-side impacts, and to evaluate the WorldSID's response to the presence of a far-side airba...

Seventeen concussive helmet-to-helmet impacts occurring in National Football League (NFL) games were analyzed using video footage and reconstructed by launching helmeted crash test dummies into each other in a laboratory. Helmet motion on-field and in the laboratory was tracked in 3D before, during, and after impact in multiple high frame rate vide...

Background: On-field visible signs (VS) are used to help identify sport-related concussion (SRC) in the National Football League (NFL). However, the predictive utility of a VS checklist for SRC is unknown. Objective: To report the frequency, sensitivity, specificity, and predictive value of VS in a cohort of NFL athletes. Methods: On-field VS...

The current Euro NCAP pedestrian head test procedure encourages the industry to optimise their vehicle design towards a simplistic, sub-system test procedure instead of the full-scale pedestrian impact. Thus, the effectiveness of this procedure in reducing real-world pedestrian injury risk and severity depends on how accurately the sub-system test...

Background: The use of video review to document visible signs (VS) of sport-related concussion in the National Football League (NFL) is a novel method to recognize head injuries. Hypothesis/Purpose: The current pilot studies used varying methodologies to: 1) examine the frequency of VS in concussed NFL players using the Australian Football League’s...

Objective: Knee airbags (KABs) have become increasingly common in the vehicle fleet. Previous studies (Weaver et al., 2013 Weaver A, Loftis K, Stitzel J. 2013. Investigation of the safety effects of knee bolster air bag deployment in similar real-world crash comparisons. Traffic Injury Preven. 14(2):168–180. doi:10.1080/15389588.2012.697643[Taylor...

This paper presents a detailed characterization of helmet-to-ground impacts in the National Football League. Video analysis was performed for 16 head-to-ground impacts that caused concussions. Average resultant closing velocity was 8.3 m/s at an angle nearly 45° to the surface. Preimpact rotational velocity of the helmet ranged from negligible to a...

Far-side kinematics and injury are influenced by the occupant environment. The goal of the present study was to evaluate in-vehicle human far-side kinematics, kinetics and injury and to assess the ability of the WorldSID to represent them. A series of tests with five Post-Mortem Human Subjects and the WorldSID were conducted in a vehicle-based sled...

Far-side kinematics and injury are influenced by the occupant environment. The goal of the present study was to evaluate in-vehicle human far-side kinematics, kinetics and injury and to assess the ability of the WorldSID to represent them. A series of tests with five Post-Mortem Human Subjects and the WorldSID were conducted in a vehicle-based sled...

The seatbelt restraint load is one of the primary sources of occupant chest injury. Thus, studying the different biomechanical responses of chest by varying the seatbelt loads will result in a significant improvement in seatbelt protection performance. Based on the high-biofidelity mechanical dummy model, a sled-dummy test was conducted to investig...

Restraint system, especially the seatbelt, is the critical load source of the chest injury. The consequence has become the crucial part of the traffic accident, which is a great burden to the society in terms of money loss. Thus, when protecting the occupant’s safety, chest injuries from the restraint loading on the occupants should also be reduced...

Far-side impacts represent 9.5% of all automobile crashes and 8.3% of all MAIS3+ injuries. This type of event generates loads that challenge current restraint systems by setting the occupant in an inward motion. This complex motion, influenced by a number of restraint and impact parameters, often results in a loss of shoulder-to-belt contact. Exist...

This report presents corridors for the biomechanical response of 10 female cadaver subjects, similar in mass and size to a 5th percentile female, in 30 km/h frontal sled tests performed under the gold standard test conditions. The corridors were based on tests conducted at UVA in 2013 (DTNH22-09-H-00247) and 2016 (DTNH2215D00022).The subjects were...

Approximately 1.6-3.8 million sports-related traumatic brain injuries occur each year in the US. Researchers track the head motion using a variety of techniques to study the head injury biomechanics. To understand how helmets provide head protection, quantification of the relative motion between the head and the helmet is necessary. The purpose of...

Diffuse brain injuries are assessed with deformation-based criteria that utilize metrics based on rotational head kinematics to estimate brain injury severity. Although numerous metrics have been proposed, many are based on empirically-derived models that use peak kinematics, which often limit their applicability to a narrow range of head impact co...

Most injury risk functions for dynamic axial loading of the leg have been targeted toward automotive applications such as predicting injury caused by intrusion into the occupant compartment from frontal collisions. Recent focus on leg injuries in the military has led to questions about the applicability of these injury risk functions shorter durati...

Background:: Concussions in American football remain a high priority of sports injury prevention programs. Detailed video review provides important information on causation, the outcomes of rule changes, and guidance on future injury prevention strategies. Purpose:: Documentation of concussions sustained in National Football League games played...

Professional American football games are recorded in digital video with multiple cameras, often at high resolution and high frame rates. The purpose of this study was to evaluate the accuracy of a videogrammetry technique to calculate translational and rotational helmet velocity before, during and after a helmet impact. In total, 10 football impact...

Far-side impacts represent 9.5% of all automobile crashes and 8.3% of all MAIS3+ injuries. This type of event generates loads that challenge current restraint systems by setting the occupant on an inward motion. This complex motion, influenced by a number of restraint and impact parameters, often results in a loss of shoulder-to-belt contact. Reduc...

Diffuse brain injuries are caused by excessive brain deformation generated primarily by rapid rotational head motion. Metrics that describe the severity of brain injury based on head motion often do not represent the governing physics of brain deformation, rendering them ineffective over a broad range of head impact conditions. This study develops...

The inertial properties of a helmet play an important role in both athletic performance and head protection. In this study, we measured the inertial properties of 37 football helmets, a NOCSAE size 7 ¼ headform, and a 50th percentile male Hybrid III dummy head. The helmet measurements were taken with the helmets placed on the Hybrid III dummy head....

Objective: Evaluating the biofidelity of pedestrian finite element models (PFEM) using post-mortem human subjects (PMHS) is a challenge as differences in anthropometry between PMHS and PFEM could limit a model's capability to accurately capture cadaveric responses. Geometrical personalization via morphing can modify the PFEM geometry to match the s...

Background: Head kinematics generated by laboratory reconstructions of professional football helmet impacts have been applied to computational models to study the biomechanics of concussion. Since the original publication of this data, techniques for evaluating accelerometer consistency and error correction have been developed. This study applies...

Objective: Recent field data analysis has demonstrated that knee airbags (KABs) can reduce occupant femur and pelvis injuries but may be insufficient to decrease leg injuries in motor vehicle crashes. An enhanced understanding of the associated injury mechanisms requires accurate assessment of physiological-based occupant parameters, some of which...

Objective: The goal of this study was to explore a framework for developing injury risk functions (IRFs) in a bottom-up approach based on responses of parametrically variable finite element (FE) models representing exemplar populations. Methods: First, a parametric femur modeling tool was developed and validated using a subject-specific (SS)-FE mod...

The manuscript 'Car safety seats for children: Rear facing for best protection' was published in Injury Prevention in 2007, after peer review. The paper used US data from the National Automotive Sampling System Crashworthiness Data System to conclude that children 0-23 months were less likely to be severely injured when using a rear-facing car seat...

Objectives The National Highway Traffic Safety Administration and the American Academy of Pediatrics recommend children be placed in rear-facing child restraint systems (RFCRS) until at least age 2. These recommendations are based on laboratory biomechanical tests and field data analyses. Due to concerns raised by an independent researcher, we re-e...

Linking head impact kinematics to injury risk has been the focus of numerous brain injury criteria. Although many early forms were developed using mechanics principles, recent criteria have been developed using empirical methods based on subsets of head impact data. In this study, a single-degree-of-freedom (sDOF) mechanical analogue was developed...

Objective: This study was designed to evaluate the performance of a pelvic restraint cushion (PRC), a submarining countermeasure that deploys under the thighs when a crash is detected in order to block the forward motion of the pelvis. Methods: Sled tests approximating low and high speed frontal impacts were conducted with four PMHS female subjects...

This study aimed to identify common patterns of pre-ballistic vehicle kinematics and roadway characteristics of real-world rollover crashes. Rollover crashes that were enrolled in the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) between the years 2000 and 2010 were analyzed. A descriptive analysis was performed to unde...

Far-side impacts represent 9.5% of all crashes and 8.3% of all MAIS 3+. Consumer groups and manufacturers are gaining interest in evaluating vehicle performance in this crash mode; however there is limited information regarding ATD performance in this loading configuration. Current state of the art dummies are designed to meet biofidelity standards...

The Test Device for Human Occupant Restraint (THOR) 50th percentile male anthropomorphic test device (ATD) aims to improve the ability to predict the risk of chest injury to restrained automobile occupants by measuring dynamic chest deflection at multiple locations. This research aimed to describe the methods for developing a thoracic injury risk f...

Rib intrusion is the main injury metric to evaluate thoracic injury in front and side impacts. For years, the WorldSID ATD has evaluated this metric with an IRTRACC system. This system tracks the distance and the angle in the transverse plane between two points: one on the spine, and one on the rib. In recent years another technology has appeared:...

Far-side impacts represent 9.5% of all crashes and 8.3% of all MAIS3+. Consumer groups and manufacturers are gaining interest in evaluating vehicle performance in this crash mode, but there is a lack of information regarding the performance of the anthropomorphic test device (ATD) in this loading configuration. Current state-of-the-art dummies are...

This study evaluated biofidelity and repeatability of THOR-Lx under two axial impact loading conditions. Four cadaveric lower limbs were tested under a 3.1 m/s axial impact condition. Then, the responses were normalized to those of the 50th percentile male and the 5th percentile female using a mass scaling technique. The response corridors for foot...

The goal of this study was to predict the structural response of the femoral shaft under dynamic loading conditions using subject-specific finite element (SS-FE) models and to evaluate the prediction accuracy of the models in relation to the model complexity. In total, SS-FE models of 31 femur specimens were developed. Using those models, dynamic t...

Objective: The goal of this study was to evaluate the biofidelity of the Total Human Model for Safety (THUMS; Ver. 4.01) pedestrian finite element models (PFEM) in a whole-body pedestrian impact condition using a well-characterized generic pedestrian buck model. Methods: The biofidelity of THUMS PFEM was evaluated with respect to data from 3 full-s...

Risk assessment models are developed to estimate the probability of brain injury during head impact using mechanical response variables such as head kinematics and brain tissue deformation. Existing injury risk functions have been developed using different datasets based on human volunteer and scaled animal injury responses to impact. However, many...

Current state-of-the-art vehicles implement pedestrian protection features that rely on pedestrian detection sensors and algorithms to trigger when impacting a pedestrian. During the development phase, the vehicle must "learn" to discriminate pedestrians from the rest of potential impacting objects. Part of the training data used in this process is...

ABSTRACT Player-to-player contact inherent in many unhelmeted sports means that head impacts are a frequent occurrence. Model-Based Image-Matching (MBIM) provides a technique for the assessment of three-dimensional linear and rotational motion patterns from multiple camera views of a head impact event, but the accuracy is unknown for this applicati...

This study aims to investigate the chest injury in terms of chest deflections and rib fracture risks based on the stress/strain analysis via a belted occupant finite element model (BOM). The BOM was established using a human body model from the Global Human Body Models Consortium (GHBMC) and the model was validated against a frontal sled test with...

Background: Foot and ankle injuries are common in sports, particularly in cleated athletes. Traditionally, the athletic shoe has not been regarded as a piece of protective equipment but rather as a part of the uniform, with a primary focus on performance and subjective feedback measures of comfort. Changes in turf and shoe design have poorly under...

The usage of the seatbelt as a part of the vehicle protection system has immensely promoted occupant safety. However, recent accident investigation shows that it is necessary to increase the chest injury protective e_ciency in frontal impact condition. This study aims to investigate the influence of seatbelt system design variables on occupant ches...

Purpose: The purpose of this quantitative study is to investigate the differences of the injury mechanism caused by two different types of seatbelt loads on the occupant's chest. Methods: The finite element analysis is employed to compare the different responses of the human body model, including comparison of kinematics, chest accelerations, se...

Objective: To provide an objective basis on which to evaluate the repeatability of vehicle crash test methods, a recently developed signal analysis method was used to evaluate correlation of sensor time history data between replicate vehicle crash tests. The goal of this study was to evaluate the repeatability of rollover crash tests performed wit...

Dimensional scaling approaches are widely used to develop multi-body human models in injury biomechanics research. Given the limited experimental data for any particular anthropometry, a validated model can be scaled to different sizes to reflect the biological variance of population and used to characterize the human response. This paper compares...

Background and objective: Abrupt accelerations or decelerations can cause large strain in brain tissues and, consequently, different forms of Traumatic Brain Injury (TBI). In order to predict the effect of the accelerations on the soft tissues of the brain, many different injury metrics have been proposed (typically, an injury metric is a real val...

Abstract The strength and compliance of the dense cortical layers of the human skull have been examined since the beginning of the 20th century with the wide range in the observed mechanical properties attributed to natural biological variance. Since this variance may be explained by the difference in structural arrangement of bone tissue, micro-co...

Objective Advanced occupant protection systems in motor-vehicles (e.g., seat belts and airbags), while widely adopted for front-seat passengers, are either absent or offer disproportionally lower safety to rear-seat passengers in similar crashes. Optimization of advanced restraint systems for the rear-seat environment will require a detailed unders...

Poster presented at IRCOBI 2016

Objective: The functional capacity index (FCI) is designed to predict functional loss 12 months post-injury for each injury in the 2008 Abbreviated Injury Scale (AIS) manual on a scale from 0 (death) to 100 (full recovery), but FCI has never been validated. This study compared FCI predicted loss with patient-reported 12-month outcomes as measured t...

S Objective The lower extremity of the occupant represents the most frequently injured body region in motor vehicle crashes. Knee airbags (KABs) have been implemented as potential countermeasure to reduce lower extremity injuries. Despite the increasing prevalence of KABs in vehicles, the biomechanical interaction of the human lower extremity with...

The interaction of the shoulder complex of the pedestrian and the striking vehicle strongly influences the responses and injury risk of the head, neck and torso during vehicle-to-pedestrian impacts. While the current MADYMO facet pedestrian model met the shoulder force corridor provided by ISO9790, the kinematics of its shoulder complex during a la...

Model Based Image Matching (MBIM) has potential to assess three-dimensional linear and rotational motion patterns from multiple camera views of head impact events in contact sports. The goal of this study is to assess the accuracy of the MBIM method for estimating 6DOF head kinematics in a vehicle-cadaver impact scenario for which Vicon motion anal...

Numerous injury criteria have been developed to predict brain injury using the kinematic response of the head during impact. Each criterion utilizes a metric that is some mathematical combination of the velocity and/or acceleration components of translational and/or rotational head motion. Early metrics were based on linear acceleration of the head...

In American football, hyper-dorsiflexion of the first metatarsophalangeal (first MTP) joint is the predominant mechanism of first MTP joint sprains (turf toe). The risk of acute first MTP joint sprain has been found to increase as first MTP joint angle increases. The bending resistance of the shoe dictates the proportion of an externally applied lo...

A finger finite element (FE) model was created from CT images of a Japanese male in order to obtain a shape-biofidelic model. Material properties and articulation characteristics of the model were taken from the literature. To predict bone fracture and realistically represent the fracture pattern under various loading conditions, the ESI-Wilkins-Ka...

Objectives: The two objectives of this study are to 1) examine the rib and sternal fractures sustained by small stature elderly females in simulated frontal crashes and 2) determine how the findings are characterized by prior knowledge and field data. Methods: A test series was conducted to evaluate the response of five elderly (average age 76 y...

Background: Previous epidemiological studies have highlighted the high risk of injury to the head, thorax, and cervical spine in rollover crashes. However, such results provide limited information on whole-body injury distribution and multiple region injury patterns necessary for the improvement and prioritization of rollover-focused injury counte...

This study evaluated the biofidelity of the WorldSID and the ES-2re under whole-body side impact conditions with and without a side airbag using the biomechanical cadaveric response data generated from 4.3 m/s whole-body side impact tests. Impact forces, spinal kinematics, and chest deflections were considered in the biofidelity evaluation. Average...

Despite decades of research and regulation, brain injuries remain a leading cause of traffic related death and disability worldwide. In this study, the human tolerance to brain injury was investigated by applying pure angular and linear kinematic loading conditions in the sagittal plane to a finite element model of the head. The relationship betwee...

In the course of developing an alternative test condition to explore torso response, the NHTSA’s THOR Mod Kit Dummy was evaluated in two simulated frontal impact conditions. The recently proposed condition, which is less severe, produced less shoulder belt tension resulting in lower chest deflection. It also produced differences in the pattern of a...

Seatbelt contact friction coefficient may have some influence on chest injury prediction because it can affect the position of the seatbelt during the impact. The objective was to study the influence of the seatbelt contact friction coefficient on predicted rib fracture outcome in frontal impact. Four simulations of frontal impact sled tests in the...

Objective: The goal of this study was to characterize the rollover crash and to evaluate the repeatability of the Dynamic Rollover Test System (DRoTS) in terms of initial roof-to-ground contact conditions, vehicle kinematics, road reaction forces and vehicle deformation. Methods: Four rollover crash tests were performed on two pairs of replicate...