Viscous Criterion Research Articles

Behind Armor Blunt Trauma: Liver Injuries Using a Live Animal Model.

While the 44-mm clay penetration criterion was developed in the 1970s for soft body armor applications, and the researchers acknowledged the need to conduct additional tests, the same behind the armor blunt trauma displacement limit is used for both soft and hard body armor evaluations and design considerations. Because the human thoraco-abdominal contents are heterogeneous, have different skeletal coverage, and have different functional requirements, the same level of penetration limit does not imply the same level of protection. It is important to determine the regional responses of different thoraco-abdominal organs to better describe human tolerance and improve the current behind armor blunt trauma standard. The purpose of this study was to report on the methods, procedures, and data collected from swine. Live swine tests were conducted after obtaining approvals from the local institution and the Army Care and Use Review Office of the U.S. Department of Defense. Trachea tubes and an intravenous line were introduced before administering anesthesia. Pressure transducers were inserted into the lungs and aorta. An indenter simulating the backface deformation profiles produced by body armor from military-relevant ballistics to human cadavers was used to deliver impact loading to the liver region. A triaxial accelerometer was included in the indenter design. The animals were monitored for 6 hours, necropsies were performed, and injuries were identified. Biomechanical data of the energy, velocity, deflection, viscous criterion, force, and impulse variables were obtained for each test. Peak accelerations, velocities, deflections, forces, impulse, and energies ranged from 897 to 5,808 g, 21 to 59 m/s, 1.96 to 8.87 cm, 2.3 to 13.1 kN, 1.1 to 7.1 Ns, and 58 to 387 J, respectively. The peak viscous criterion ranged from 0.8 to 5.8 m/s. All animals survived the 6-hour survival period. Three animals responded with liver lacerations while the remaining 4 did not have any injuries. The experimental design based on parallel tests with whole body human cadavers and cadaver swine was found to be successful in delivering controlled impacts to the liver region of live swine and reproducing liver injuries. Previously used biomechanical measures as potential candidates for injury criteria development were obtained. Using this proven model, tests with additional samples are needed to develop injury risk curves for liver impacts and obtain regional (liver) injury criteria.

Warps and breaks in circumbinary discs

ABSTRACT Disc warping, and possibly disc breaking, has been observed in protoplanetary discs around both single and multiple stars. Large warps can break the disc, producing multiple observational signatures. In this work, we use comparisons of disc time-scales to derive updated formulae for disc breaking, with better predictions as to when and where a disc is expected to break and how many breaks could occur. Disc breaking is more likely for discs with small inner cavities, cooler temperatures, and steeper power-law profiles, such that thin, polar-aligning discs are more likely to break. We test our analytical formulae using three-dimensional grid-based simulations of protoplanetary discs warped by the gravitational torque of an inner binary. We reproduce the expected warp behaviours in different viscosity regimes and observe disc breaking at locations in agreement with our derived equations. As our simulations only show disc breaking when disc viscosity is low, we also consider a viscous criterion for disc breaking, where rapid alignment to the precession vector can prevent a break by reducing the maximum misalignment between neighbouring rings. We apply these results to the GW Orionis circumtriple disc and find that the precession induced from the central stars can break the disc if it is relatively thin. We expect repeated or multiple disc breaking to occur for discs with sufficiently steep power-law profiles. We simulate a polar-aligning disc around an eccentric binary with steep power-law profiles and observe two separate breaking events at locations in rough agreement with our analytical predictions.

Ballistic impact wave and back bulge propagation mechanism and blunt trauma assessment of ceramic/UHMWPE composite body armor

With increasing local conflicts worldwide, studying the impact response of body armor is crucial for enhancing soldier survival rates. However, there is still insufficient understanding of the back bulge expansion patterns, the impact waves transmission features, and blunt injury assessing method of body armor. To investigate these problems deeply, the three-dimensional digital image correlation method and numerical models were employed to reveal the ballistic response mechanism of ceramic/ultra-high-molecular-weight polyethylene (UHMWPE) composite body armor impacted by 7.62 mm rifle bullet. This study built theoretical function for the bulge expansion, revealed the wave transmission mechanism and fractures in both materials and their interaction. Firstly, the experiment revealed that the back-face bulge transverse expansion velocity exhibits a double exponential decrease. Secondly, the contour of back-face bulges consistently demonstrated excellent hyperbolic characteristics at various moments. Thirdly, the average Viscous Criterion (VC) and Blunt Criterion (BC) values were 5.37 and 0.95, corresponding to Abbreviated Injury Scale (AIS) values of 6 and 4. Fourthly, the simulation revealed that the ceramics transverse and radial cracks seems primarily induced by shear stress xy; ceramics conical cracks occurring at the boundaries of equivalent stress seems primarily induced by stress in x and y directions. Fifthly, numerical results revealed that the velocity of compression waves within the laminate increases over time in the impact direction and consistent with ceramic velocity impacted on the laminate. These findings lead to experimental and theoretical advances in the impact response mechanism of composite body armor and provide index for improving the protective performance.

Analysis of Injury Metrics From Experimental Cardiac Injuries From Behind Armor Blunt Trauma Using Live Swine Tests: A Pilot Study.

Warfighters are issued hard body armor designed to defeat ballistic projectiles. The resulting backface deformation can injure different thoracoabdominal organs. Developed over decades ago, the behind armor blunt impact criterion of maximum 44 mm depth in clay continues to be used independent of armor type or impact location on the thoracoabdominal region covered by the armor. Because thoracoabdominal components have different energy absorption capabilities, their mode of failures and mechanical properties are different. These considerations underscore the lack of effectiveness of using the single standard to cover all thoracoabdominal components to represent the same level of injury risk. The objective of this pilot study is to conduct cardiac impact tests with a live animal model and analyze biomechanical injury candidate metrics for behind armor blunt trauma applications. Live swine tests were conducted after obtaining approvals from the U.S. DoD. Trachea tubes. An intravenous line were introduced into the swine before administering anesthesia. Pressure transducers were inserted into lungs and aorta. An indenter simulating backface deformation profiles produced by body armor from military-relevant ballistics to human cadavers delivered impact to the heart region. The approved test protocol included 6-hour monitoring and necropsies. Indenter accelerometer signals were processed to compute the velocity and deflection, and their peak magnitudes were obtained. The deflection-time signal was normalized with respect to chest depth along the impact axis. The peak magnitude of the viscous criterion, kinetic energy, force, momentum and stiffness were obtained. Out of the 8 specimens, 2 were sham controls. The mean total body mass and soft tissue thickness at the impact site were 81.1 ± 4.1 kg and 3.8 ± 1.1 cm. The peak velocities ranged from 30 to 59 m/s, normalized deflections ranged from 15 to 21%, and energies ranged from 105 to 407 J. The range in momentum and stiffness were 7.0 to 13.9 kg-m/s and 22.3 to 79.9 N/m. The maximum forces and impulse data ranged from 2.9 to 11.7 kN and 1.9 to 5.8 N-s. The peak viscous criterion ranged from 2.0 to 5.3 m/s. One animal did not sustain any injuries, 2 had cardiac injuries, and others had lung and skeletal injuries. The present study applied blunt impact loads to the live swine cardiac region and determined potential candidate injury metrics for characterization. The sample size of 6 swine produced injuries ranging from none to pure skeletal to pure organ trauma. The viscous criterion metric associated with the response of the animal demonstrated a differing pattern than other variables with increasing velocity. These findings demonstrate that our live animal experimental design can be effectively used with testing additional samples to develop behind armor blunt injury criteria for cardiac trauma in the form of risk curves. Injury criteria obtained for cardiac trauma can be used to enhance the effectiveness of the body armor, reduce morbidity and mortality, and improve warfighter readiness in combat operations.

Preparation of Nonlethal Projectiles by Polyurethane Foam with the Dynamic and Microscopic Characterization for Risk Assessment and Management.

Nonlethal projectiles are manufactured and designed proportionately, with a minimal likelihood of mortality or harm. However, numerous real-world examples indicate that nonlethal projectiles can potentially inflict severe lesions and death in some circumstances. As a result, it is essential to design and manage the manufacture of projectile materials to achieve maximum efficacy with the least amount of collateral damage. The current paper provides a technique for generating and analyzing filled polyurethane (PU) foams and studying their viscoelastic characteristics. The sand and graphite composition ranged between 5 and 10% by weight. The suggested technique seeks to exert control over the evolution of the microstructure. The mechanical characteristics were obtained by dynamic mechanical analysis (DMA) testing. We made a pneumatic launcher and a sturdy rigid wall. In addition, the artificial human head is covered with force sensors to perform dynamic characterization. Also, scanning electron microscopy (SEM) of the polyurethane foam cross sections demonstrated that the average cell size of 98 μm was unaffected by the fillings’ content. Furthermore, X-ray diffraction analysis (XRD) characterized the developmental foams’ physicochemical properties. Finally, we assessed the dynamic search for nonlethal projectiles. We recorded the viscous criteria (VCmax) values to check for nonlethal projectiles.

Linear stability of a rotating liquid column revisited

We revisit the somewhat classical problem of the linear stability of a rigidly rotating liquid column in this article. Although the literature pertaining to this problem dates back to 1959, the relation between inviscid and viscous stability criteria has not yet been clarified. While the viscous criterion for stability, given by$We < n^2 + k^2 -1$, is both necessary and sufficient, this relation has only been shown to be sufficient in the inviscid case. Here,$We = \rho \varOmega ^2 a^3 / \gamma$is the Weber number and measures the relative magnitudes of the centrifugal and surface tension forces, with$\varOmega$being the angular velocity of the rigidly rotating column,$a$the column radius,$\rho$the density of the fluid and$\gamma$the surface tension coefficient;$k$and$n$denote the axial and azimuthal wavenumbers of the imposed perturbation. We show that the subtle difference between the inviscid and viscous criteria arises from the surprisingly complicated picture of inviscid stability in the$We$–$k$plane. For all$n > 1$, the viscously unstable region, corresponding to$We > n^2 + k^2-1$, contains an infinite hierarchy of inviscidly stable islands ending in cusps, with a dominant leading island. Only the dominant island, now infinite in extent along the$We$axis, persists for$n=1$. This picture may be understood, based on the underlying eigenspectrum, as arising from the cascade of coalescences between a retrograde mode, that is the continuation of the cograde surface-tension-driven mode across the zero Doppler frequency point, and successive retrograde Coriolis modes constituting an infinite hierarchy.

Injury Risks of Rear Occupant in Typical Four-door Type of Pick-up Truck under Vehicle Collision

This research explores the injury risks of occupants in four-door type of pick-up truck using experimental based collision with Hybrid III dummy for occupant injury indicators. The full-sized crash laboratory was developed to conduct full frontal impact based on standard regulation. To verify performance of full-sized crash laboratory and vehicle deceleration, low and high speed tests were conducted at the same vehicle. The Hybrid III dummy with head and chest sensors was used at the rear outboard seat during high speed test. Consequently, the deflection and thoracic viscous criteria, which represent the chest injuries, are up to 93 mm and 3.96 m/s, respectively, high beyond the standard requirement. Moreover, the most important finding of this research is that the four-door pickup truck is subjected to the 2nd impact up to 116.51 G at dummy head with higher resultant acceleration than the 1st impact (65.62 G) due to the limited space behind the rear headrest and thinner backrest of rear seat. This research also investigates the post-crash results to illustrate the suggestive idea for improving crashworthiness of future design resulting in mitigation of occupant injuries.

Research on characteristics of occupant’s chest responses in oblique impact

The oblique impact is the second most common frontal impact, in which both the forward and lateral accelerations are applied to the occupant. It is noticed that the oblique impact is a primary source of serious injuries, in which the chest injuries are mostly fatal through the statistics of traffic accidents. This study aims to investigate the characteristics of the occupant’s chest injury in the frontal oblique impact. First, a model with a sled and a Test Human Occupant Restraint (THOR) dummy is established. Second, an acceleration curve with a peak of 9.0 g is applied to the sled. Then 11 sets of simulations with different impact angles and belt peak loads are conducted to evaluate the occupant’s chest responses. Results indicate that there is a negative correlation between belt peak force and injury outcomes, while there is a weak correlation between chest injury and impact angle. With the increase of the belt force limit, the chest deflection at Lower Left (LL) would increase by 37.9%, and the acceleration at LL would increase by 23.1%. Meanwhile, the Viscous Criterion (VC) at LL would increase by 61.4%. However, the relationship between the impact angle and injury drawn by VC and acceleration is inconsistent. Additionally, in all simulations, the maximum deflections are captured at the LL, while the maximum VCs happens at Upper Right (UR) or LL. It is demonstrated that a seatbelt with a lower peak force is friendly to the occupant’s chest under all the impact angles. This study can provide a reference to the study of chest injury in the oblique impact.

Importance of impact boundary conditions and pre-crash arm position for the prediction of thoracic response to pendulum, side sled, and near side vehicle impacts

Two contemporary finite element Human Body Models (HBMs) were subjected to five lateral impact scenarios to investigate the sensitivity of thorax response to impact scenario and pre-crash arm position. The greatest increase in chest compression (UW-HBM: +140%, GHBMC-HBM: +100%) and Viscous Criterion (UW-HBM: +467%, GHBMC-HBM: +245%) occurred when the arm was aligned with the thorax in a full vehicle impact, moderate change for sled impacts, and only a minor change in response for pendulum impacts. This study highlights the importance of including full vehicle impact boundary conditions in parametric studies of occupant response in side impacts and assessing side-impact protection.

Compression-based injury variables from chestbands in far-side impact THOR sled tests

Objective: This study seeks to determine compression (Cmax) and compression-related injury variables (velocity and viscous injury criterion: Vmax and VCmax) from chestband data in pure lateral and oblique far-side impact sled tests.Methods: The 3-point belt–restrained mid-sized male Test Device for Human Occupant Restraint (THOR) dummy was placed on a buck and subjected to side impacts with and without center-mounted airbags. The change in velocity was 8.3 m/s for all conditions. Two chestbands were routed around the outer circumference of the THOR at the levels of the third and sixth ribs. Maximum chest deflections were computed using strain gauge signals from the chestbands and their temporal contours. Three methods were used to determine deflection metrics. The first method paralleled methods used in previously published human cadaver studies; the second method used the actual anchor point location and actual alignment of the dummy’s internal sensors; and the third method used the anchor location of the internal sensor but determined the sensor’s locations on the contour confining to the aspect of the sensor. These 3 approaches are abbreviated as the SD, ID, and TD variables. The injury variables Cmax, Vmax, and VCmax were determined according to accepted procedures. Their peak magnitudes were extracted and an evaluation of their accuracy was made based on the SD method.Results: The average SD-based Cmax magnitudes for the upper and lower chest levels were 0.12 and 0.17 m/s, the Vmax magnitudes were 5.3 and 1.8 m/s, and the VCmax magnitudes were 0.24 and 0.15 m/s, respectively. Other data are given for all variables at the 2 levels of the thorax in the body of this paper. The ID-based peak variables were the lowest, and this observation was true regardless of the aspect, right or left side. In contrast, the SD method produced the greatest magnitudes of the variables. The VCmax variable had the greatest normalized difference among all 3 injury variables.Conclusions: Though the present study is limited in scope, the predetermined placement of the internal sensors in the THOR dummy underpredicted chest deflection-related injury variables, and the viscous criterion was the least reliable variable in these lateral and oblique far-side impact sled tests.

Human Effects Assessment of 40-mm Nonlethal Impact Munitions

An extensive human effects study was conducted on 40-mm nonlethal impact munitions having two different projectile nose configurations: a compliant sponge nose and a frangible foam nose carrying a powder payload. The study included an initial characterization of the rounds using the blunt criterion (BC). Injury risk assessment was done using two previously validated surrogates; thoracic blunt impact assessment utilized the 3-rib ballistic impact dummy (3RBID), and penetrating trauma assessment utilized a biomechanical surrogate consisting of ordnance gelatin and a specific combination of layers to simulate skin and underlying soft tissue. Production impact munitions were manufactured to produce a range of energy levels on impact by adjusting the propellant charge in the smokeless propulsion system, resulting in different projectile muzzle velocities. Twenty-three impacts were performed on the 3RBID biomechanical surrogate at kinetic energy levels in the range of 148–257 J to generate viscous criterion (VCmax) levels for injury assessment. The production configurations of the sponge and frangible-nose munitions were compared to the acceptable values for blunt trauma (VCmax ≤ 0.8). Thirty-nine impacts were done on a skin penetration surrogate at kinetic energy levels in the range of 170–305 J and the impact energies corresponding to penetrations were identified and compared with the production configurations for these munitions and with the expected energy density values for a 50% risk of penetration for specific areas of the body.

Rib fractures prediction method for kinetic energy projectile impact: from blunt ballistic experiments on SEBS gel to impact modeling on a human torso FE model

The present paper aims to assess the risk of rib fractures caused by any rigid less-lethal kinetic energy projectiles. To that end, a coupled experimental and numerical approach is proposed to relate ballistic experiments with the risk of blunt trauma. A polymer gel block is employed as ballistic testing medium to interpret ballistic impacts through the measurement of the dynamic gel wall displacement. Moreover, a biofidelic 50th percentile human torso finite element model created in the code Hypermesh (Altair HyperWorks ©) is used to replicate experiments and real world accidents. Then, the probability curve of rib fractures is a function of the viscous criterion and derives from a study on human cadaver mid-sternum available in the literature. Twelve impact conditions of rigid projectiles are applied to a SEBS gel block and are replicated on the human torso model mid-sternum. A statistical analysis is performed by virtue of a Spearman's correlation matrix in order to identify relations between experimental measurements and the viscous criterion evaluated numerically. The determination of both statistical significances and correlation coefficients results in several strong correlations between experimental measurements and the viscous criterion evaluated numerically. These relations imply the establishment of transfer functions between experimental metrics on the gel block (the maximum gel wall displacement and a gel wall displacement – rate of displacement based metric) and the probability of rib fractures. Finally, these correlations constitute a primary and an up-and-coming predicting tool for the risk of rib fractures.

Dynamic response and material sensitivity analysis of pelvic complex numerical model under side impact.

The surrogate design and clinical diagnostic suggest that the pelvic dynamic response should be the basis of bone fracture mechanism study under side impact. Pelvic response indicators are the impact force, compression (C), viscous criterion (VC), bone stress, and bone strain. However, no evaluation of these indicators has been conducted. To evaluate pelvic response indicators under side impact. A sitting pelvic finite element (FE) complex model comprising bone, artery, ligaments, and soft tissue was constructed. The dynamic response of the model under side impact with initial velocity of 3 m/s was investigated and material sensitivity analysis was complemented by changing bone elastic modulus. The pelvic FE model could predict response under side impact. Specifically, the indicators such as artery pressure and strain, together with the ligaments axial force and strain were provided. The sensitivity analysis showed the impact force, bone stress, and axial force were sensitive to the elastic modulus, whereas, C, VC, bone strain, and artery pressure were not. The sitting FE model in this study can predict pelvic dynamic response, and C, VC, bone strain and artery pressure are proposed for pelvic tolerance instead of impact force under side impact.

Thoracic response of the Chinese human body model in 50th percentile male size (CHUBM-M50) in blunt impacts – investigation in speed, direction and location

ABSTRACTThoracic injury is one of the leading causes of fatalities from automotive collisions. This paper integrated the features and conditions into numerical finite element analysis on thoracic mechanical responses with CHUBM-M50, to realise peak force, maximum compression, viscous criterion (VCmax), effective stiffness (EF) and rib fractures of the thorax, under various blunt loadings of impact speeds, locations and directions. The model was validated by test simulations via the cadaver pendulum tests. A total of 30 cases designed by two vertical alignments × five directions × three speeds were carried out. Additionally, t-test was performed in order to identify the correlation of impact direction and location. It indicated that the thoracic characteristics had significant correlation with impact location, and the mechanical responses at midsternal level were much stiffer than those at xiphoid process. It also demonstrated that the impact at xiphoid process causes more severe injuries even at low speed. The thoracic response pattern was similar between left and right side impact, which showed that the symmetrical characteristic in spite of asymmetric anatomical features of viscera. This study also figured out that the lateral EF was significantly higher than the oblique. The ribs tended to fracture most in the connection with costal cartilage in oblique impacts while the ribs were broken laterally in the costal angle position.

Belted Safety Jacket: a new concept in Powered Two-Wheeler passive safety

Powered Two Wheelers (PTWs) offer a viable solution to reduce traffic congestion and promote personal mobility. However, vehicle characteristics and conspicuity issues lead to an overrepresentation of PTWs in accident statistics. This work presents an innovative approach for concept design of new passive safety devices and their development. The landscape of possible design solutions was examined with an in-depth analysis of the state of the art and with the use of conceptual design tools. Candidate solutions underwent a feasibility assessment and they were crossed-checked with the rider needs, identified via a specific on-line survey. The concept of a new passive safety device was born: a Belted Safety Jacket (BSJ). An initial assessment of the device effectiveness for the reduction of riders’ injuries was performed by comparison of the main biomechanical indexes (HIC, Nijmax, Chest Deflection and Viscous Criterion) in a relevant accident configuration, reproduced in a virtual environment, with and without the device. Later a full factorial Design of Experiment (DOE) was carried out to understand the influence of the device geometrical variables (i.e. possible design parameters) on the biomechanical indexes. The results demonstrated that the integration of BSJ onto the vehicle has the potential to significantly reduce the occurrence of serious injuries during a PTW accident versus a car, since it prevents the contact of the rider with the opponent vehicle. The analysis of the accident kinematic with BSJ suggests that the device will be beneficial also in accidents with other vehicle types.

DYNAMIC RESPONSE OF PELVIC COMPLEX FINITE ELEMENT STUDY AND VALIDATION UNDER SIDE IMPACT

Objective: To investigate and validate dynamic response of the pelvis, a finite element model of seated pelvic complex comprising of bone, ligaments, abdominal artery and soft tissue was developed and concurrently, a cadaver experiment was set up. Materials and Methods: Based on supine scanned CT images, we first developed an FE pelvic complex model and modified it to construct a seated pelvic model by anteriorly rotating the proximal femur to 90[Formula: see text]. For the cadaver experiment, a customized pelvic impact apparatus was designed and optical devices, strain gauges and pressure detectors were used to measure the pelvic response. Results: The results of the FE analysis and the cadaver tests were congruent in terms of impact force and fracture sites. Dynamic arterial response to the lateral impact showed hemodynamic instability that was displayed in pressure variation. The response of ligaments indicated that the posterior ligaments of pelvic ring experienced a larger amount of load. Conclusion: FE results provided the impact of ligaments and arteries besides impact force, compression (C) and viscous criterion (VC). Accordingly, the cadaver experiment measured arterial pressure, impact force, bone strain and compression. The compatibility between the FE and cadaver analyses demonstrates the high bio-fidelity of our pelvic complex model.

THORAX INJURY CRITERIA ASSESSMENT THROUGH NON-LETHAL IMPACT USING AN ENHANCED BIOMECHANICAL MODEL

Ballistic injury refers to the interaction of a projectile and the human body, resulting in penetration or blunt trauma. In order to consider both consequences, a hydrodynamic elastoplastic constitutive law was implemented in a numerical FE model of the human torso to simulate soft tissues behavior and to evaluate their injury risk. This law, derived from 20% ballistic gelatin, was proven to be very efficient and biofidelic for penetrating ballistic simulation in soft tissues at very high velocity. In this study, the ability of the hydrodynamic law to simulate blunt ballistic trauma is evaluated by the replication of Bir et al.’s (2004) experiments, which is a reference test of the literature for nonpenetrating ballistic impact. Lung injury criteria were also investigated through the Bir et al.’s experiments numerical replication. Human responses were evaluated in terms of mechanical parameters, which can be global (acceleration of the body, viscous criteria and impact force) or local (stress, pressure and displacement). Output results were found to be in experimental corridors developed by Bir et al., and the maximum pressure combined with the duration of the peak of pressure in the lungs seems to be a good predictor for lung injury.

Chest response assessment of post-mortem swine under blast loadings

To better protect soldiers from blast threat, that principally affect air-filled organs such a lung, it is necessary to develop an adapted injury criterion and, prior to this, to evaluate the response of a biological model against that threat. The objective of this study is to provide some robust data to quantify the chest response of post-mortem swine under blast loadings.7 post-mortem swine (54.5 ± 2.6 kg), placed side-on to the threat and against the ground, were exposed to 5 shock-waves of increasing intensities. Their thorax were instrumented with a piezo-resistive pressure sensor, an accelerometer directly exposed to the shock-wave and a target was mounted on the latter in order to track the chest wall displacement.For incident impulses ranging from 47 kPa ms±2% to 173 kPa ms ±6%, the measured maximum of linear chest wall acceleration (Γmax) goes from 5800 m/s2 ±16% to 41,000 m/s2 ± 8%, with a duration of 0.8 ms. Chest wall displacements ranging from 5 mm ± 20% to 20 mm ± 15%, with a duration of 9 ms, are reached. These reproducible data were used to find simple relations (linear, 2nd and 3rd order polynomials) between the kinematic parameters (plus the viscous criterion) and the incident and reflected impulses.Correlating the new reproducible data with the prediction from the Bowen curves showed a lung injury threshold in terms of Γmax similar to that of Cooper (10,000 m/s2). However, the limits defined for the viscous criterion in the automobile field and for non-lethal weapons seems not adapted for the blast threat.

A Special Collaborative Information System and Its Application in Kinetic Energy Impact

Although the benefits of the non-lethal kinetic energy projectiles are numerous, there is a need to assess the projectiles to assure their expected functions. In order to overcome the limitations of current research, a special collaborative information system based on Hybrid III 50th percentile male dummy (hybrid III dummy) was developed and validated to assess and predict the risk of non-lethal kinetic energy impact. Two types of non-lethal kinetic energy projectiles were used to attack the thorax region of the dummy surrogate at six levels of distance. Not only the sensors inside the dummy as a mechanics information system recorded all the kinetic energy impact measures accurately and effectively, but also other systems like acquiring and processing information system including hardware and software played their roles respectively. The acceleration response, displacement response showed consistent patterns with the kinetic energy measures. The results showed that the measurement from the special system was reliable for non-lethal kinetic energy projectiles. The maxima of displacement, viscous criterion (VC) and kinetic energy were both lower than correlative injury thresholds. Current study provided an alternative method to assess the performance of the non-lethal kinetic energy projectiles.

Occupant thorax response variations due to arm position and restraint systems in side impact crash scenarios

Recent epidemiological studies have identified that thoracic side airbags may vary in efficacy to reduce injury severity in side impact crash scenarios, while previous experimental and epidemiological studies have presented contrasting results. This study aimed to quantify the variations in occupant response in side impact conditions using a human body computational model integrated with a full vehicle model. The model was analyzed for a Moving Deformable Barrier side impact at 61km/h to assess two pre-crash arm positions, the incorporation of a seatbelt, and a thorax air bag on thorax response. The occupant response was evaluated using chest compression, the viscous criterion and thoracic spinal curvature. The arm position accounted for largest changes in the thorax response (106%) compared to the presence of the airbag and seatbelt systems (75%). It was also noted that the results were dependant on the method and location of thorax response measurement and this should be investigated further. Assessment using lateral displacement of the thoracic spine correlated positively with chest compression and Viscous Criterion, with the benefit of evaluating whole thorax response and provides a useful metric to compare occupant response for different side impact safety systems. The thoracic side airbag was found to increase the chest compression for the driving arm position (+70%), and reduced the injury metrics for the vertical arm position (−17%). This study demonstrated the importance of occupant arm position on variability in thoracic response, and provides insight for future design and optimization of side impact safety systems.