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Biomechanics of Chest and Abdomen Impact

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... Both model the thorax' mechanical response by viscoelastic material behavior following the early approach by Bowen et al. [13][14][15] as well as a common modeling paradigm for physical loads as e.g. mechanical impacts resulted during car crashes [16,17]. These models regard the velocity of the chest wall as the fundamental variable [18][19][20][21][22], proposing adapted criteria for lung injury. ...
... This elementary analysis shows that the Axelsson model does not properly account for the presumed viscoelastic response of the thorax, because of its inability to appropriately represent stress relaxation. But, in view of the paradigm that the response of the thorax to complex pressure signals is modeled by a viscoelastic material, which is the focus of our analysis in this article, stress relaxation is expected to play a role when various periods of external loading and unloading are encountered [9,14,16,17,37]. Moreover, the instantaneous compliance ( J g ) vanishes, which is indicated by the (t)-contribution in Eq. (8). ...
... basic viscoelastic behavior [36] in the clearest way (Fig. 5a, b) as suggested in [13][14][15][16][17]. Using Eqs. 5 and 7, one finds: ...
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Article
Shock waves from explosions can cause lethal injuries to humans. Current state-of the-art models for pressure induced lung injuries were typically empirically derived and are only valid for detonations in free-feld conditions. In built-up environments, though, pressure–time histories difer signifcantly from this idealization and not all explosions exhibit detonation characteristics. Hence, those approaches cannot be deployed. However, the actual correlation between dynamic shock wave characteristics and gradual degree of injury have yet to be fully described. In an attempt to characterize the physical response of the human body to complex shock-wave efects, viscoelastic models were developed in the past (Axelsson and Yelverton, in J Trauma Acute Care Surg 40, 31S–37S, 1996; Stuhmiller et al., in J Biomech. https ://doi.org/10.1016/0021-9290(95)00039-9, 1996). We discuss those existing modeling approaches especially in view of their viscoelastic behavior and point out drawbacks regarding their response to standard stimuli. Further, we suggest to fully acknowledge the experimentally anticipated viscoelastic behavior of the efective thorax models by using a newly formulated standard model for viscoelastic solids instead of damped harmonic oscillators. Concerning injury assessment, we discuss the individual injury criteria proposed along with existing models pointing out desirable improvements with respect to complex blast situations, e.g. the necessity to account for repeated exposure (criteria with time-memory), and further adaption with respect to nonlinear gas dynamics inside the lung. Finally, we present an improved modeling approach for complex blast overpressure efects to the thorax with few parameters that is more suitable for the characteristics of complex blast wave propagation than other current models.
... The amount of compression or deflection of the rib cage has also been determined as a key factor in determining injuries ( Kroell et al., 1971;Kroell et al., 1974). The current deflection tolerance for automotive impacts is 76 mm or 3 inches, which represents 34 % compression ( Viano & King, 1995). Given this compression, skeletal injuries of AIS = 2 are likely. ...
... The blunt ballistic impacts of 140 g at 20 and 40 m/s have an initial slope that represents a peak force being achieved in the first 5 cm of deflection. This is also represented in the automotive force-deflection curves (Viano & King, 1995). However, the C impact condition of 30 g at 60 m/s demonstrates a peak force in the first 2-cm of deflection. ...
... The automotive industry has extensively explored the effects of blunt trauma in an effort to reduce injuries associated with vehicular accidents (Cavanaugh, 1993;Kroell et al., 1973;Viano & King, 1995;Viano, 1988). As the research on blunt thoracic impacts has evolved, various injury tolerance criteria have been associated with chest impacts. ...
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Article
The specific aims of this study included: (1) the determination of human response corridors for blunt ballistic impacts of the thorax and comparison with established biomechanical responses from the automotive safety literature, (2) the determination of an injury criterion to assess the continuum of injuries related to blunt ballistic impacts of the thorax, (3) the refinement and validation of a biomechanical surrogate and subsystem test procedure for the evaluation of blunt ballistic impacts, and the evaluation and comparison of existing methods used by the non-lethal community in terms of biofidelity and injury assessment, (4) the development of theoretical models to estimate the effects of blunt ballistic impacts to the human and existing surrogates. ^ Three impact conditions were selected to biomechanically assess blunt ballistic impacts to the thorax. The conditions included (A) 140 g mass at 20 m/s (B) 140 g mass at 40 m/s and (C) 30 g mass at 60 m/s. Testing was conducted on cadaveric specimens, existing simulants used for penetrating munitions (clay and gelatin), a biomechanical surrogate (3-RCS), and a mathematical model (Lobdell). The cadaveric specimens provided information needed to develop human response corridors for the test conditions. After these responses were determined, the remaining surrogates were tested and compared to the corridors established. ^ The results indicate that ordinance gelatin does not display agreement with the human response corridors. Modification of the current behind body armor standard of clay indicates agreement with the human thorax but the information provided by this assessment is limited. A biomechanical surrogate, the 3-RCS, displays an adequate correlation with the force-time corridors established. A correlation factor between the 3-RCS and the human response was also established based on the injury parameter of the viscous response or VC. Logistic regression analysis was conducted on experimental data, which indicated the VC could predict the injuries seen with blunt ballistic impacts. Refinement of the Lobdell mathematical model was also completed in order to assess blunt ballistic impacts. ^ The results of this research provide an initial biomechanical assessment of blunt ballistic impacts. Further refinement of the biomechanical surrogate and the injury parameter in the future will allow for a complete assessment to be conducted in this area of impact biomechanics. ^
... Water solutions containing 10 % to 30 % mass of gelatin have been studied extensively and are considered to be good human muscle tissue biosimulants (Harvey et al., 1962, Lewis et al., 1982, Bir, 2000, Ankersen et al., 1999, Viano and King, 2008, Koene and Papy, 2011. Experimental work on the use of gelatin as a human muscle tissue biosimulant started in the 1940s (Harvey et al., 1962, Lewis et al., 1982, and, due to the importance of this subject, a large volume of publications has been produced. ...
... For non-penetrating injuries, a water solution containing 20 % mass of gelatin gives a good representation of muscle tissue impact response (Bir, 2000). For penetrating injuries, a water solution containing 10 % mass of gelatin is more appropriate (Viano and King, 2008). Distilled water should be used for the gelatin solutions to avoid contaminants and acidity variations (Jussila, 2004). ...
Article
Purpose The purpose of this paper is a description of DITCI, its drop loads and sensors, the impact tools, the robot dynamic impact safety artifacts, data analysis, and modeling of test results. The dynamic impact testing and calibration instrument (DITCI) is a simple instrument with a significant data collection and analysis capability that is used for the testing and calibration of biosimulant human tissue artifacts. These artifacts may be used to measure the severity of injuries caused in the case of a robot impact with a human. Design/methodology/approach In this paper, we describe the DITCI adjustable impact and flexible foundation mechanism, which allows the selection of a variety of impact force levels and foundation stiffness. The instrument can accommodate arrays of a variety of sensors and impact tools, simulating both real manufacturing tools and the testing requirements of standards setting organizations. Findings A computer data acquisition system may collect a variety of impact motion, force and torque data, which are used to develop a variety of mathematical model representations of the artifacts. Finally, we describe the fabrication and testing of human abdomen soft tissue artifacts with embedded markers, used to display the severity of impact injury tissue deformation. Research limitations/implications DITCI and the use of biosimulant human tissue artifacts will permit a better understanding of the severity of injury, which will be caused in the case of a robot impact with a human, without the use of expensive cadaver parts. The limitations are set by the ability to build artifacts with material properties similar to those of various parts of the human body. Practical implications This technology will be particularly useful for small manufacturing companies that cannot afford the use of expensive instrumentation and technical consultants. Social implications Impact tests were performed at maximum impact force and average pressure levels that are below, at and above the levels recommended by a proposed International Organization for Standardization standard. These test results will be used to verify whether the adopted safety standards will protect interactive robots human operators for various robot tools and control modes. Originality/value Various research groups have used human subjects to collect data on pain induced by industrial robots. Unfortunately, human safety testing is not an option for human–robot collaboration in industrial applications every time there is a change of a tool or control program, so the use of biosimulant artifacts is expected to be a good alternative.
... Forces are produced on a bullet when it hits tissue and a good simulant should produce very similar forces on the bullet in the same conditions. According to Viano and King (2008), the biomechanical response of the body has three components a inertial resistance by acceleration of body masses b elastic resistance by compression of stiff structures and tissues c viscous resistance by rate-dependent properties of tissue. ...
... This method has been extensively used to model penetrating impacts. For penetrating impacts, 10% gelatine is considered better (Viano and King, 2008). This material can be used to determine the rate of energy deposition and the total energy within a target by a penetrating projectile. ...
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Article
A review of relevant existing experimental methods to evaluate so-called kinetic non-lethal weapons is presented. Next performance tests of two existing non-lethal weapon systems are shown and compared with other projectiles. Tissue simulants and an accurate determination of their physical properties are important to improve evaluation methods of non-lethal projectiles. Knowledge of physical properties is necessary to allow the physical modelling of the human body and interaction with projectiles. Presumably, for this purpose plasticine (clay), soap and gelatine are relevant tissue simulants. The present status of knowledge in this field is discussed. In addition, expectations and possibilities for the future are discussed.
...  k r : Based on high values of stiffness and damping of the human chest (Viano and King, 2000), a weak influence on F T was assumed for k r . For baboons, this was supported by the fact that the shoulder was allowed to move freely during electrical stimulation , causing a lower compression on the ribs compared to an isometric contraction (with shoulder and sternum fixed). ...
... The transverse viscoelastic properties of Pmajor and Pminor (Van Loocke et al., 2008) were simplified astransverse stiffness k t1 and k t2 , respectively. The transverse stiffness of the rib cage(Viano and King, 2000) was simplified as transverse stiffness k r .The experimental measurement of in-line force F IL and transverse force F T of the Pmajor sternum in the baboon in a related study has been described in the Supplement and in detail by. ...
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Article
With the steady technological development enabling reduced device dimensions and new patient populations, detailed data on mechanical in vivo loads become increasingly important to ensure reliability of implantable medical devices. Based on an intra-species correlation of in-line and transverse force of the Pectoralis major established previously for the Chacma baboon (de Vaal et al., 2010a), a simplified physiological model and a mechanical equivalent model were developed for a sub-muscular pectoral device implant considering Pectoralis major, Pectoralis minor and rib cage. By assessing the morphometric and mechanical parameters of these musculo-skeletal structures and the associated model parameters, the intra-species correlation was shown to exhibit (a) robustness for a larger intra-species subject population and (b) linear scale variance allowing application for humans under consideration of the inter-species difference of the attachment angles of Pectoralis major. The transfer function provides a basis for the prediction of patient-specific maximum mechanical loadings on a sub-muscular pectoral cardiac pacemaker implant through non- or minimal invasive measurements on the patient.
... Generally, injuries inflicted to the thorax are related to its amount of deformation. Additionally, it is commonly admitted that the damage mechanisms of its internal organs are rate dependent and classified as follows (Bir, 2000;Nsiampa, 2016;Robbe, 2013;Viano and King, 2002): ...
Article
Studying the mechanical response of the human thorax submitted to ballistic impact is a challenging field of research. For ethical reasons, it is not possible to perform tests on the human body. Numerical simulations are therefore one of the alternatives for evaluating the mechanical response of the human thorax. In earlier research, a simplified human thorax submitted to low-velocity impacts without ballistic protection was modelled. Not all internal organs in the thorax were taken into account. The only considered organs were the heart, lungs, trachea and aorta, with the space between them being void. The organs were covered by an idealized structure simulating the rib cage, spine and muscles. Such a simplified model was however sufficient in the field of less-lethal impact assessment. Indeed, in this case, only forces and displacements are taken into account. In the field of behind armor blunt trauma (BABT), spherical pressure or shock waves are expected to appear and propagate into internal organs. Nevertheless, the presence of the void space makes it impossible to evaluate the propagation of the considered waves. This paper focuses on a method for filling the void space and making the model more comprehensive. Starting from the initial meshed geometry of this simulated thorax, it uses a coupling between Lagrangian and arbitrary Lagrangian-Eulerian (ALE) objects. Finally, the use of the filled model is extended to a BABT case study. From the simulations, it could be concluded that BABT should be related to “blast” instead of “viscous” solicitations.
... The deformation velocity is an essential factor regarding target damage, as biomechanical responses differ for low-and high-speed impact (Viano & King, 2000). ...
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Preprint
In this study, the independent relative contribution of rotation and translation in straight lead punch execution to the energy-transfer to a standardized target is determined with an empirical experiment. To create a set of standardized straight lead punch variations, a qualitative theoretical model is created to help dissecting the straight lead punch into key elements. Measurements are made with a high-speed camera and the data is further analyzed with specialized software. The data is statistically analyzed using SPSS. Results show that there is a significant difference in energy-transfer to the target, between several straight lead punch variations. It is recommended to further refine and improve the straight lead punch model and use it in conjunction with other existing models to form a complete mathematical biomechanical model of the straight lead punch, including the target, from start to finish. It would be interesting to see further research in the 'timing' aspect of the straight lead punch, in combination with reaction times, to determine which straight lead punch variation has the best chance of landing.
... Les niveaux de force ont été calibrés subjectivement au cas par cas en recherchant la force statique maximale à la limite du confort pour le sujet passif. [54], que pour de faibles vitesses de déformation de l'abdomen (moins de 3 m/s -la vitesse cartésienne moyenne des cobots) la flèche est un meilleur indicateur de risque que la force ou l'accélération. Dans ce travail, nous préférons un critère basé sur la déflexion avec la limite de = 20 mm comme seuil tolérable de déformation de l'abdomen. ...
Thesis
Au cours des dernières années, nous avons assisté à un changement de paradigme, passant de la fabrication de robots rigides à des robots compliants. Ceci est dû à plusieurs raisons telles que l'amélioration de l'efficacité des robots dans la réalisation des mouvements explosifs ou cycliques. En fait, l'une des premières motivations à l'origine de ce changement est la sécurité. Parlant de la sécurité à la fois du sujet humain et du robot, tout en s'engageant dans des tâches collaboratives. Ainsi la désignation des cobots. Les cobots peuvent aider un opérateur humain expérimenté dans plusieurs domaines où la précision est essentielle, comme les applications industrielles ou les tâches médicales. Jusqu'à présent, les cobots présentent toujours des problèmes de sécurité, même avec des recommandations réglementaires telles que ISO / TS 15066 et ISO 10218-1 et 2 qui limitent leurs avantages économiques. Dans cette vue, plusieurs projets de recherche ont été lancés dans le monde entier pour améliorer la dynamique des cobots par rapport à la sécurité, ANR-SISCob (Safety Intelligent Sensor for cobots) étant l'un de ces projets. Les travaux menés au cours de cette thèse ont pour but de concevoir des dispositifs de sécurité qui sécuriseront les robots en y introduisant l’aspect de compliance. En effet, nous avons développé deux dispositifs dans lesquels l'aspect sécurité est atteint avec deux approches différentes :- Prismatic Compliant Joint (PCJ) : qui vise à la mise en œuvre dans les articulations linéaires, car peu de travaux ont traité de tels systèmes d'actionnement. Ici, la sécurité est atteinte biomimétiquement tout en faisant face à d'autres critères de sécurité liés aux propriétés mécaniques du corps humain.- Variable Stiffness Safety Oriented Mechanism (V2SOM) : Contrairement au premier dispositif d'inspiration biomimétique qui sert aux systèmes d'actionnement linéaires, le profil de sécurité du V2SOM est axé sur la sécurité selon deux critères de sécurité: force d’impact et HIC. L'aspect ‘orienté sécurité’ est dû à ce que nous appelons la capacité de découplage d'inertie de son profil de rigidité. V2SOM est actuellement dans ses dernières étapes de brevetage.Ces deux appareils seront intégrés dans un robot sériel réalisé dans notre laboratoire.
... These last concepts have been developed in the literature for different parts of the human body, leading to the definition of numerical predictors and metrics for instance for the head 12-14 and for the lungs. 15,16 Concerning the thoracic part, global criteria which are widely used in the literature to quantify the severity of a loading can be cited 17-25 : the acceleration criteria (the peak chest acceleration, the Average Spine Acceleration (ASA), the Thoracic Trauma Index (TTI)), 17-19,21 the force criteria, 17,18 the compression criteria (chest deflection) 17,18,20,22,23,25 and the viscous criterion [VCðtÞ max ] which is defined as \the peak of the product between compression [CðtÞ] and the velocity of compression [V ðtÞ]". 24 Lot of studies of the literature use these criteria, attempting to derive injury mechanism for various loadings such as ballistic 3 or automotive, 18 whereas very few are investigated in the context of free falls, which represents an important part of thoracic injuries. ...
Article
This study deals with free fall accident analysis involving adults, and their numerical replications using a finite element model of the human thorax. The main purpose is to determine the role of body position at impact in the thorax injury risk appearance. For this study, cases of real-world free-fall provided by an emergency department were selected and investigated. These cases involved both male and female with an age range of 20 to 63 years, who sustained accidental free-fall with both injured and uninjured cases. The examination of the patients’ medical record provided helpful information to accurately perform numerical replications with the finite element model HUByx (Hermaphrodite Universal Biomechanical yx model) which was already validated for various experimental tests in the field of automobile, ballistic impacts and blast. The results of simulations at different impact location allowed highlighting the crucial influence of the body orientation in the risk of thoracic injury occurrence.
... According to Viano and King [4] the biomechanical response of the body has three components: (a) inertial resistance by acceleration of body masses, (b) elastic resistance by compression of stiff structures and tissues, and (c) viscous resistance by rate-dependent properties of tissue. Three classical experimental evaluation methods exist, i.e. (1) clay back face signature tests, (2) ballistic gelatine tests, and (3) biomechanical surrogates (crash dummies) tests. ...
... For nonpenetrating injuries, a water solution containing 20 % mass of gelatin gives a better representation of muscle tissue impact response [19]. For penetrating injuries, a water solution containing 10 % mass of gelatin is more appropriate [20]. Distilled water should be used for the gelatin solutions to avoid contaminants and acidity variations [21]. ...
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Conference Paper
This paper presents the design of a disposable biosimulant human tissue artifact system for robot safety testing. It is used to show a clear sign of the severe injuries caused in the case of a robot impact with a human. The fabrication method is described including the design and fabrication of the calcium alginate bead and the embedding procedure of the beads into the biosimulant artifact. The artifact system is tested with a Dynamic Impact Testing and Calibration Instrument (DITCI) from the National Institute of Standards and Technology (NIST). The design is useful for the preparation of new robot safety standards.
... This includes bullets from smaller weapons, fragments from explosions Feinsteain et al. (1968); Henderson (2010), debris from accidents Cole et al. (1997); Longinow et al. (1976); Robinson et al. (2013), less-lethal projectiles Widder et al. (1998);Lyo et al. (1999); Bir (2000); Bir and Viano (2004); Koene and Papy (2011), melee weapons, both sharp and blunt, behind armor trauma Bass et al. (2006), and impact injuries in baseball, hockey, lacrosse Maron et al. (1995). A good overview of the biomechanics of chest and abdomen impacts is Viano and King (2008). ...
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Today it is possible to buy small and cheap drones in toy stores, super markets, and on numerous online shops. Often, these drones are very light-weight and are flown in back yards, sport fields, parking lots, and such places. They typically pose no lethal threat to people in the vicinity of the drone. Nonetheless, in many countries such drones are regulated by aviation rules that does not (sufficiently well) distinguish between these drones and the larger hobby or professional drones. Consequently such small drones are flow illegally. This has prompted some national aviation authorities to consider a form of ’harmless’ category, which ideally should be based on a mass threshold. To aid such a classification this work proposes a mass threshold of 250 gram, below which, we argue, it is reasonable to classify drones as ’harmless’ in the sense that the expected fatality rate is equivalent to that of manned aviation. In this work we combine a series of models and methods to provide a foundation for giving a mass threshold. the approach is probabilistic and focuses on the relation between mass and human injury in the case of small drones. The approach is also parameterized such that readers can substitute other probabilities and conduct their own calculations, possibly determining a different mass threshold.
Thesis
Dans le contexte de la biomécanique, les outils numériques constituent des moyens puissants et indispensables dans la compréhension des mécanismes de blessures. Ils permettent de pallier les freins que sont les expérimentations sur l'humain, liés à des raisons d'éthique qui limitent la possibilité d'essais sur des SHPM (Sujets Humain Post Mortem). Le développement de ces outils numériques a conduit à celui de plusieurs mannequins numériques permettant de stimuler diverses sollicitations (civiles ou militaires), nous donnant ainsi accès à des limites de tolérances.En vue d'explorer la réponse dynamique du corps humain soumis à des sollicitations diverses, un modèle de mannequin numérique a été développé au sein du laboratoire. Ce travail de thèse tente donc d'apporter une contribution dans la recherche sur la définition d'un critère de blessure et l'établissement de limites de tolérance du corps humain soumis aux chargements violents de la partie thoracique dans des contextes militaires.
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Most studies reported in the literature on the performance of chest protectors in preventing blunt impact trauma deal with sport-related chest protectors and impacts generated by projectiles such as baseballs. In other fields, such as Crowd Management Intervention (CMI), chest protectors are used to parry not only impacts originating from projectiles but also blows of hand-held weapons such as batons and baseball bats. No assessment of chest protection when impacted by hand-held weapons was reported in the literature. The purpose of this study was to evaluate and compare the performance of two commercially available chest protectors typically used in CMI, using a realistic threat simulator of the baseball bat and a surrogate torso. The chest protectors assessed here are closed-cell foam protectors, one with a hard frontal plastic shell and the other without. Results revealed that the protector with a hard plastic shell reduced peak deflection of the chest by 36% compared to the unprotected case, whereas the protector with only closed-cell foam gave an 8% reduction. The corresponding attenuations for maximum velocity of chest deflection were 39% and 27%. It was concluded that either protector would prevent serious chest injuries.
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Chapter
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With the onset of improved protective equipment against fragmentation, blast-induced neurotrauma has emerged as the "signature wound" of the current conflicts in the Middle East. Current research has focused on this phenomenon; however, the exact mechanism of injury and ways to mitigate the ensuing pathophysiology remain largely unknown. The data presented and literature reviewed formed the fundamentals of a successful grant from the U.S. Office of Naval Research to Wayne State University. This work is a culmination of specialized blast physics and energy-tissue coupling knowledge, recent pilot data using a 12-m shock tube and an instrumented Hybrid III crash test dummy, modeling results from Conventional Weapons effects software, and an exhaustive Medline and government database literature review. The work supports our hypothesis of the mechanism of injury (described in detail) but sheds light on current hypotheses and how we investigate them. We expose two areas of novel mitigation development. First, there is a need to determine a physiologic and mechanism-based injury tolerance level through a combination of animal testing and biofidelic surrogate development. Once the injury mechanism is defined experimentally and an accurate physiologic threshold for brain injury is established, innovative technologies to protect personnel at risk can be appropriately assessed. Second, activated pathophysiological pathways are thought to be responsible for secondary neurodegeneration. Advanced pharmacological designs will inhibit the key cell signaling pathways. Simultaneously, evaluation of pharmacological candidates will confirm or deny current hypotheses of primary mechanisms of secondary neurodegeneration. A physiologic- or biofidelic-based blast-induced tolerance curve may redefine current acceleration-based curves that are only valid to assess tertiary blast injury. Identification of additional pharmaceutical candidates will both confirm or deny current hypotheses on neural pathways of continued injury and help to develop novel prophylactic treatments.
Article
Human responses are critical to understanding injury biomechanics in blunt ballistic impacts, which are defined as 20-200 g projectiles impacting at 20-250 m/s. 13 human cadavers were exposed to three distinct ballistic impacts of the chest to determine force-time, deflection-time and force-deflection responses. Comparisons were made between biomechanical responses for ballistic impacts and those previously reported for lower speed, higher mass impacts. Impact condition B (140 g at 40 m/s) gave the largest peak force 10,602+/-2226 N and deflection 54.7+/-14.6 mm. Impact condition A (140 g at 20 m/s) involved lower impact energy and produced lower peak force 3383+/-761 N and deflection 25.9+/-3.1 mm, as did impact condition C (40 g at 60 m/s), which gave 3158+/-309 N and 20.1+/-7.8 mm. The results indicate each impact condition gives distinctive responses, which differ from those previously reported in the automotive literature for lower speed impacts. This information provides the foundation for future biomechanical research in the area of blunt ballistic impacts, specifically the development of test surrogates and evaluation of protective equipment.
Article
Part I — Biomechanics Response Data — Thoracic impact response data for unembalmed human cadavers previously published by three of the authors are reviewed. These data are then “averaged,” adjusted to reflect an estimate for muscle tensing, and used as the basis for recommended force-deflection corridors to serve as dummy design guidelines. A volunteer study of muscle tensing, as related to thoracic stiffness at low force and deflection levels, is discussed, and comments are made concerning additional response data recently acquired by other investigators. Finally, consideration is given to possible “second order” refinements for future generations of a high fidelity dummy thorax.
Article
A number of tests conducted under the sponsorship of the FAT were reported in papers at two previous Stapp Conferences and an Experimental Safety Vehicle Conference. These tests featured human cadavers and three different Anthropomorphic Test Devices (ATD) designed for use in lateral impacts. Test subjects were placed in Opel car bodies and impacted laterally by CCMC moving deformable barriers. In the previous papers, the reported responses of the human cadavers had wide variability and none of the ATD's studied featured good biofidelity. In this effort, a reexamination of the available data was undertaken and the process and results of applying different analysis techniques to the cadaver data, which resulted in significantly reduced scatter and variability, are discussed.
Article
The discovery of the mechanism of impact-induced soft tissue injury has led to our introduction of a Viscous Injury Criterion, which predicts the severity and the time of occurrence of soft tissue injury induced by impact when other criteria have failed. Human tolerance has been defined by the Viscous response, left bracket VC right bracket , a time function generated by the instantaneous product of velocity of deformation left bracket V(t) right bracket and amount of compression left bracket C(t) right bracket of the body. left bracket VC right bracket max equals 1. 0 m/s corresponds experimentally to a 25% chance of sustaining severe thoracic injury (AIS greater than equivalent to 4) in a blunt frontal impact. A similar level of risk for critical abdominal injury (AIS greater than equivalent to 5) in a blunt frontal impact is left bracket VC right bracket max equals 1. 2 m/s. However, human tolerance is defined more completely by the probability function of injury risk versus left bracket VC right bracket max.
Article
This study describes the development of an animal model to characterize the mechanism of death by baseball impact of the chest in children. Sixteen anesthetized animals were subjected to midsternal, blunt chest trauma by a baseball accelerated to 95 mph (42.8 m/s). At this speed, death occurred by traumatic arrhythmia and apnea. The animals were divided into two groups: 10 were breathing spontaneously and six underwent controlled ventilation. All animals developing ventricular fibrillation as the initial arrhythmia died regardless of ventilatory status. Survival related to the use of ventilatory support. Four of the six (66.7%) ventilated animals survived, as opposed to two of 10 (20.0%) animals breathing spontaneously ([chi]2 = p < 0.06). Necropsy revealed minor myocardial contusions but none sufficient to cause death. The study has generated a reproducible model of pediatric cardiac arrest induced by high-speed baseball impact and emphasizes the role of ventricular fibrillation and adequate ventilatory support. (C) Lippincott-Raven Publishers.
Article
The central aspects of injury biomechanics research are defined and research approaches described. These aspects include the identification and definition of impact injury mechanisms, the quantification of biomechanical response to impact, the determination of impact tolerance levels, and the development and use of injury assessment devices and techniques for evaluating injury prevention systems. The current status of knowledge and technology is then reviewed for the head, cervical spine, thorax, abdomen, and lower extremity. Important gaps are identified, and research priorities emphasizing functional impairment are proposed.
Article
Experiments in our laboratory have documented that high-speed impact can cause severe injury to internal organs before either of the currently accepted chest injury criteria, which are based on spinal acceleration or chest compression, approach their tolerance limit. Those studies demonstrate an interdependence between the velocity of deformation and compression of the body on injury risk. A tolerable level of chest compression at a low velocity can prove to be fatal at higher velocities of deformation. The observation of a rate-sensitive tolerable compression led to the introduction of the Viscous criterion, VCmax, which accounts for the importance of both parameters. VCmax is the maximum of the product of velocity of deformation (V) and compression (C), and is derivable from the chest deflection response. This paper presents the empirical evidence and theoretical basis supporting the Viscous criterion, and shows it to be an indicator of the energy dissipated by soft tissue deformation. The Viscous criterion accurately predicts the risk of vital organ and soft tissue injury when other criteria fail.
Article
Abdominal injury induced by steering wheel contact at a velocity of 32 km/hr was investigated using anesthetized swine as the surrogate on a Hyge sled. The lower rim of the wheel was positioned 5 cm below the xyphoid. By varying wheel stiffness, wheel orientation, and column angle, resultant abdominal injury ranged from fatal or critical to minor or none. Wheel stiffness was found to be the primary determinant of abdominal injury severity. The mechanism of abdominal injury was identified to be the rim impacting the abdomen and exceeding a combined velocity and compression sensitive tolerance limit. Abdominal injury occurred within the initial 15 ms of wheel contact before whole body movement of the surrogate of column compression, which were initiated by hub contact with the thorax. The severity of abdominal injury correlated with the peak viscous response which can be represented by the product of the instantaneous velocity of abdominal deformation and abdominal compression. It did not correlate with spinal acceleration.
Article
The purpose of this investigation was to study the acute effects of blunt cardiac trauma upon left ventricular (LV) function. In 34 open-chest anesthetized dogs, direct impact to the anterior surface of the heart was produced by an air-pressurized impactor at 12 m/sec in 15 dogs and at 18 m/sec in 19 dogs. Impact displacement was limited to 2 cm. Seventeen dogs (50%) died of arrhythmias within a few minutes of impact. In nine surviving dogs impacted at 12 m/sec, there was an immediate reduction of LV function following impact. At 5 minutes following impact this reduction of LV function was characterized by a 19% reduction of cardiac output, 35% reduction of maximal isovolumic LV rate of change of pressure (dp/dt), a 12% reduction of peak aortic flow, and a 23% reduction of peak rate of change of flow. These indices of ventricular performance returned nearly to control levels 60 to 90 minutes following impact. In eight surviving dogs that experienced impact at 18 m/sec, impairment of LV function was greater in the immediate impact period following impact and impaired function remained throughout the 90-minute duration of observation. Autopsy of all dogs showed cardiac contusion. Following the more severe impact, contusions were more extensive and involved the left ventricular endocardial surface and intraventricular septum as well as the epicardial surface. Parallel changes, therefore, of the extent of pathologic changes and the extent of functional impairment were observed. Animals that survived the potentially fatal arrhythmias immediately after impact showed functional impairment of the heart that was only moderate and compatible with life.
Article
The effect on nonpenetrating hepatic injury of varying impact velocity was investigated in a series of abdominal impact experiments with rabbits. In these tests, a constant level of 16% anterposterior compression was produced by a flat aluminum disc driven by a pneumatic impactor at velocities of 5 to 20 m/s to investigate an impulsive as opposed to a crushing mechanism of injury. Laceration of the liver regularly occurred for impact velocity and available energy greater than 12 m/s and 9.1 joules, respectively (p less than 0.01). In addition, a gradation of hepatic injury, probably caused by local strain energy density in the soft tissue, was observed through the range of impact velocity, i.e., minor subcapsular contusion at low velocity to extensive deep laceration and hemoperitoneum at high velocity. With impact applied only to the abdomen, there were associated thoracic and renal injuries at impact velocities greater than 14 m/s. The Abbreviated Injury Scale (1) was extended for classification and quantification of injury. The peak reactive force, peak esophageal pressure, and impulse transfer increased with impact velocity. It appears that there may be two regions of biomechanical response, one at 12 m/s or below, and one at greater than 12 m/s.