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Human Factors and Mechanical Engineering for Defense and Safety
Number of Followers: 1  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2509-8004 - ISSN (Online) 2367-2544
Published by Springer-Verlag Homepage  [2469 journals]
  • The Critical Role of a Backing Material in Assessing the Performance of
           Soft Ballistic Protection

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      Abstract: Abstract Penetrating trauma by energised fragments is the most common injury from an explosive event. Fragment penetrations to the truncal region can result in lethal haemorrhage. Personal armour is used to mitigate ballistic threats; it comprises hard armour to protect from high-velocity bullets and soft armour to protect against energised fragments and other ballistic threats (such as from a hand gun) with low impact velocities. Current testing standards for soft armour do not focus on realistic boundary conditions, and a backing material is not always recommended. This study provides a comprehensive set of evidence to support the inclusion of a backing used in testing of soft body armour. Experiments were performed with a gas-gun system using fragment-simulating projectiles (FSPs) of different shapes and sizes to impact on a woven aramid and a knitted high-performance polyethylene ballistic fabric, with and without the ballistic gelatine soft tissue simulant as the backing material. The results showed statistically significant differences in the impact velocities at 50% risk (V50) of fabric perforation across all test configurations when the gelatine backing was used. Furthermore, the backing material enabled the collection of injury-related metrics such as V50 of tissue-simulant penetrations as well as depth of penetration against impact velocity. The normalised energy absorbed by the fabric could also be calculated when the backing material was present. This study confirms that a backing material is essential, particularly when assessing the performance of single layer fabrics against FSPs of low mass. It also demonstrates the additional benefits provided by the backing for predicting injury outcomes.
      PubDate: 2022-07-27
       
  • Protective Clothing Reduces Lower Limb Injury Severity Against Propelled
           Sand Debris in a Laboratory Setting

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      Abstract: Abstract The contribution of energised environmental debris to injury patterns of the blast casualty is not known. The extent to which personal protective equipment (PPE) limits the injuries sustained by energised environmental debris following an explosive event is also not known. In this study, a cadaveric model exposed to a gas-gun mediated sand blast was utilised which reproduced soft-tissue injuries representative of those seen clinically following blast. Mean sand velocity across experiments was 506 ± 80 ms−1. Cadaveric samples wearing standard-issue PPE were shown to have a reduced injury severity to sand blast compared to control: a statistically significant reduction was seen in the total surface area (143 mm2 vs. 658 mm2, p = 0.004) and depth of injuries (0 vs. 23 deep injuries, odds ratio = 0.0074, 95% confidence intervals 0.0004–0.1379). This study is the first to recreate wounds from propelled sand in a human cadaveric model. These findings implicate environmental debris, such as sand ejected from a blast event, as a critical mechanism of injury in the blast casualty. Tier 1 pelvic PPE was shown to reduce markedly the severity of injury. This injury mechanism should be a key focus of future research and mitigation strategies.
      PubDate: 2022-06-13
      DOI: 10.1007/s41314-022-00050-3
       
  • Reliability Assessment by Factor of Safety on the Tensile Failure
           Behaviour on Military Grade Armour Steel Weldment

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      Abstract: Abstract Welding armour steel plate is a crucial task in the construction of combat vehicle structures. The shield metal arc welding (SMAW) with austenitic stainless steel (ASS) filler is used to prepare the defect free weld joints under suitable welding parameters. Tensile property enhancement in the fusion zone of the weld joint inhibits bullet penetration in a combat environment. An examination has also been conducted into the effect of microstructures in base metal, weldments, and the influence on tensile fractured surfaces. Tensile failure occurs in the weld centreline due to the reduced tensile strength of the filler material. When compared to the relevant literature, these welds demonstrated 48% joint efficiency and good tensile strength. This present work was development of a finite element analysis (FEA) model to analyse the tensile failure of base metal and weld joints with different factors of safety (FOS) such as FOS 0, FOS 1.5, and FOS 3. The FEA was carried out to predict the load-carrying capacity under tensile load. The simulation and experimental findings concur, implying that the suggested approaches were utilized effectively for structural analysis of armour weld joint using typical FEA techniques.
      PubDate: 2022-05-25
      DOI: 10.1007/s41314-022-00051-2
       
  • Not Non-Lethal Weapons: the Counter-Personnel Behavioral Effects Weapons
           Framework for Armament Engineers

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      Abstract: Abstract Behavioral effects weapons (BEW) are devices that are intended to change the behavior of their human target. The article describes the critical considerations and a framework to guide the development of BEW. Human physiology is the fundamental basis for the theoretical framework of BEW engineering. Effectiveness of BEW starts with the physiological effects induced by stimuli or energy generated by a weapon. These physiological effects, in turn, affect target behavior. Behaviors are altered by (1) changing the motivation of the targeted individual(s) to perform the behavior and (2) changing the ability of the targeted individual(s) to perform the behavior. In addition to the thresholds for effectiveness of BEW, the limitations due to risk of signification injury (RSI) define the solution space for armament engineers. Finally, ethical considerations for the armaments developer are presented. It is hoped that the information in this article will serve as a guide for the armaments engineering community in order to fill a critical weapon capability gap.
      PubDate: 2022-04-27
      DOI: 10.1007/s41314-022-00047-y
       
  • Safety Assessment of Soil-Filled HESCO® Bastion Wall Concept for
           Modular Munition Storage

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      Abstract: Abstract The use of modular munition storage systems for military purposes has grown significantly in the recent years. They have improved the flexibility and decreased the logistical burden of both domestic and international missions. This study aims at developing a modernized, economic, and effective way of using modular systems to temporarily store munitions in an operational environment. This design had to ensure that (1) no sympathetic detonation of munition stored in adjacent cells would occur, (2) the danger radii due to the fragmentation and the blast overpressure could be reduced, and (3) the proposed solution would be practical. Based on recent events, the use of the HESCO® Bastion, a commonly found modular hardening system in modern operations, will be considered in this research. The combined effects of blast and fragments were both taken into consideration to properly develop and model the loading scenario on the system. Calculations based on analytical models and experimental data were then performed to properly characterize and quantify the system response.
      PubDate: 2022-04-05
      DOI: 10.1007/s41314-022-00049-w
       
  • Geometrical Characteristics of a 50th Anthropometric Head Finite Element
           Model: Literature Review

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      Abstract: Abstract Military forces are confronted with an increasing threat of small caliber rounds and fragments (HE projectile, IEDs, etc.) in current operational theatres. This had led to the development of adapted body armour solutions. But, these solutions when impacted may lead to head blunt injuries (behind helmet blunt trauma (BHBT)) that can be severe, even fatal. Apart from the conventional missions, military forces are more and more called to intervene in homeland or abroad in policing missions in which the Kinetic Energy Non-Lethal Weapon (KENLW) solutions are widely used to avoid severe injuries to the targeted people. In both cases, there is a need to make an injury risk assessment in order to prevent or avoid severe or life-threatening injuries. For that purpose, one of the tools that are used is head biofidelic finite element models. The first step in developing a head model is to generate the head geometry. Most of the developed head models are based on the geometry of one specific subject derived from MRI or CT imaging, and the baseline model that is generally considered is the 50th percentile adult male corresponding to an average adult male. Therefore, it is important before any modelling to gather information on the human head characteristics like organ’s size and shape. The basic geometric characteristics that are mostly taken into account to build the models are the head external dimensions. In this paper, the goal is to gather information on head organs of an average adult male by taking into account not only the external dimensions but also mean geometric characteristics of the head (size of different head organs, skull thickness, etc.) in order to build an averaged geometry of the head.
      PubDate: 2022-04-05
      DOI: 10.1007/s41314-022-00043-2
       
  • A Comment on the Prediction of Metallic Plate Penetration by
           Fragment-Simulating Projectiles

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      Abstract: Abstract Metallic targets impacted by blunt-nosed projectiles typically fail via shear plugging. Various models exist that predict the onset of this failure threshold, which can be used to determine the ballistic limit velocity for a particular combination of projectiles and targets. In a previous study, nine existing penetration models were evaluated for their ability to predict the ballistic limit velocity of monolithic titanium alloy, aluminum alloy, and steel plates under small caliber fragment-simulating projectile impact. In a second study, a series of changes to these nine models were proposed, typically based on empirical adjustments, reformulation of the target strength dependency, or a combination of both. The effectiveness of these changes in improving the predictive capabilities of these nine models was assessed by comparing model predictions against more than 650 ballistic limit measurements. In this paper, we compare the ballistic limit velocities predicted by these nine models against ballistic limit measurements not included in the original 650 + dataset that guided the development of model improvements. It was found that the nine penetration models considered in these two previous studies are most suited for applications in which target plates can be considered “hard” or “high-strength.” In situations where target plates are made of “softer” materials, the predictive ability of these nine models was less than desirable.
      PubDate: 2022-03-09
      DOI: 10.1007/s41314-022-00048-x
       
  • Validation of the Facial Ocular CountermeasUre for Safety (FOCUS) Headform
           for the Injury Risk Assessment of Less Lethal Impact Munitions

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      Abstract: Abstract Injury patterns of various less-lethal impact munitions (LLIMs) including 40-mm sponge rounds and a 12-gauge drag-stabilized, bean bag round were collected. Relating real-world injury to forces measured by a biomechanical surrogate, the Facial and Ocular CountermeasUre for Safety (FOCUS) headform is investigated for its utility for future injury evaluation of LLIMs. An online search for cases of LLIM impacts to the head from May 15 to July 15, 2020, was conducted. A total of 107 cases were identified, and potential study subjects were sent a questionnaire with demographical, incidental, and experiential data collected. Ten (10) responses were obtained, leading to six (6) recreations using the FOCUS headform. Facial load cells measured forces ranging from 534 to 4364 N from which the risk of injury (ROI) was calculated. The abbreviated injury scale (AIS), maximum AIS (MAIS), and Injury Severity Scale (ISS) values were determined along with the head injury criterion (HIC) for all cases. For cases with eye injury, the Duma Eye Score (DES) was determined, and the probability of globe rupture was calculated. There is a high probability that an impact to the face from a LLIM can lead to soft tissue injuries, fractures, and even more severe injuries. As a preliminary study, there were a limited number of cases to study and high variability. Therefore, further testing including increased sample size and additional munitions is needed to better determine the sensitivity and specificity of the FOCUS headform to measure the risk of injuries from LLIMs.
      PubDate: 2022-03-07
      DOI: 10.1007/s41314-022-00044-1
       
  • The Risk of Skin Injury Caused by High-Rate Blunt Impacts to the Human
           Thorax

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      Abstract: Abstract Less-lethal weapons (LLWs) based on blunt impactors are seeing increased usage during crowd-control scenarios, and it is crucial that these devices do not inflict significant injuries when used. The guidelines for safe impactor design can be informed by rigorous biomechanical testing and injury risk analysis. In this study, high-rate blunt impact testing was conducted on five 50th percentile male post-mortem human surrogates to assess the tolerance of human skin to blunt impacts in situ. Six sectional-density matched cylindrical and spherical impactors ranging from 13 to 25 mm (0.5–1.0 in.) in diameter and 2.9–11.6 g in mass were used to impact four regions within the thorax at velocities ranging from 60 to 167 m/s. The free-flight impactor velocity was measured using high-speed video, and autopsies were performed to determine whether skin injury was induced at each impact site. Additionally, B-mode ultrasound imaging was employed to determine the tissue thickness at each impact location prior to test. Then, injury risk functions (IRFs) were developed to predict skin injury risk as a function of various test parameters. Regional anatomical differences were determined to have the greatest influence on the injury risk beyond velocity. Similarly, spherical impactors produced greater skin injury risk than the cylindrical impactors, and larger diameter impactors produced greater risk than smaller diameter impactors. The IRFs developed in this study will help guide future LLW design toward improved human safety and lower the risk of significant injury. Finally, this study will also help develop computational human body models capable of simulating skin injury response.
      PubDate: 2022-03-05
      DOI: 10.1007/s41314-022-00046-z
       
  • Evaluation of an In Situ Ovine Model as a Surrogate for Human Skin Injury
           Caused by High-Rate Blunt Impact

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      Abstract: Abstract Understanding the risk of skin injury caused by impacts from blunt less lethal weapons (LLW) is critical for designing safer devices, but the tolerances of injury are still understudied. Previous research has utilized post-mortem human surrogates (PMHS) to investigate the injury thresholds of various soft tissues; however, PMHS testing is often limited by low sample size and questions surrounding the biofidelity of the tissue for approximating the living response. Animal surrogates are often used to supplement these known limitations. In this study, eight in situ ovine specimens were tested under high-rate, blunt impacts to assess the viability of this model as a surrogate for human skin. All tests were conducted using a 6.5 g, 19 mm (0.75 in.) diameter cylindrical impactor with impact velocities up to 162 m/s. Injury assessments were performed to study the effect of body region, tissue storage condition, and flesh temperature on the likelihood of skin injury. Injury risk functions (IRFs) were developed relating skin injury risk to impactor velocity and the impacted body region. Impact location was a significant factor for injury risk, with the tissues in the shoulder and ribs demonstrating lower tolerances for skin injury than in the stomach and rump. By the comparing IRF responses to that of PMHS, the cadaveric ovine tissue showed viability as a potential surrogate for human skin (from the upper chest and abdomen regions) under high-rate blunt impacts. Furthermore, there were no significant differences in IRFs produced with fresh and frozen-thawed tissue. Anecdotally, variation in flesh temperature produced different injury results, but statistically this effect was insignificant due to the limited sample size of the study.
      PubDate: 2022-02-23
      DOI: 10.1007/s41314-022-00041-4
       
  • Assessment of Less Lethal Impact Munitions Using the Facial and Ocular
           CountermeasUre for Safety (FOCUS) Headform

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      Abstract: Abstract Recent social protests and gatherings in the USA have prompted law enforcement agencies to increase their use of less lethal impact munitions (LLIMs) for crowd control. Media reports and firsthand accounts have indicated that many of the LLIMs are impacting individuals in the head and neck regions. There is very little data available on the risk of injury (ROI) from LLIM impacts to these body regions. The Facial and Ocular CountermeasUre for Safety (FOCUS) surrogate headform was used to assess the ROI (fracture) from LLIM impacts. LLIMs were fired at the FOCUS headform to determine the ROI to the frontal and maxilla bones. Sixteen different LLIMs were assessed which included 12-gauge, 37-mm, and 40-mm caliber projectiles from five manufacturers. The LLIMs included bean bag style, rubber, and foam/sponge projectiles. Each LLIM was tested multiple times to determine the average ROI. The average peak resultant frontal bone force ranged from 2.0 to 7.6 kN which represented ROIs from ~ 30% up to 95%. The average peak resultant maxilla bone force ranged from 1.0 to 4.4 kN which represented ROIs from ~ 30% up to 99%. In general, 12-gauge LLIMs had a lower ROI than the larger caliber LLIMs and the rubber projectiles had a lower ROI than the bean bag style projectiles. Due to the relative thickness, the maxilla has a much lower fracture force than the frontal bone, and this was borne out in the ROIs from the maxilla impacts. Impacts to both bones showed a positive correlation between normalized energy and resultant force (p < 0.01). The slope of the plotted resultant force against the normalized energy for the 12-gauge munitions was significantly smaller compared to larger calibers for both impact sites, frontal (p = 0.031), and maxilla (p < 0.001).
      PubDate: 2022-02-16
      DOI: 10.1007/s41314-022-00045-0
       
  • Modeling Complex Behavior of Multi-projectile Counter UAV 12 Gauge
           Ammunition

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      Abstract: Abstract The misuse of low cost and effortlessly accessible unmanned aerial vehicles is a swiftly growing phenomenon. The uncomplicated employment of these systems and the conceivable magnitude of their effect at short engagement distances facilitate adverse exploitation in a wide range of scenarios. These facts merge into the urgent need for a flexible, economical, and promptly deployable short-range weapon system. The properties of a specific 12 Gauge ammunition fit as a response to deter the imminent threat. The considered non-conventional projectile behaves as a slug for the initial part of its trajectory. Then, it endures a tilt after which a cloud of pellets is discharged. This complex behavior appears effective but must be investigated for adequate operation in pragmatic scenarios. This is achieved with a theoretical analysis and a semi-empirical assessment of the weapon system characteristics. Present work provides the current progress state on a two-dimensional Point Mass Model for the trajectory of the considered projectile, complemented with the empirical assessment of several model parameters allowing to approach the physical trajectory. This work serves as a contribution in the development of the trajectory model to assess the considered weapon system in its operational use for short-range scenarios.
      PubDate: 2022-02-16
      DOI: 10.1007/s41314-022-00040-5
       
  • Modeling of the kinetic element interaction with biological object

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      Abstract: Abstract Paper presents a numerical simulation of the process of functioning of a kinetic element and its interaction with a complex target. The simulation was performed in the LS-DYNA environment. The kinetic element is a thin, multi-layered, nylon shell with a thickness of about 0.4 mm. The shell, which is empty in its initial state, fills with air very quickly and expands. When expanding, the shell interacts with the target, which should lead to its neutralization. To simulate the expansion of an air-filled impactor, the method of corpuscular particles was used. In accordance with this method, the impactor inflates under the action of a flow of spherical particles, which are essentially ensembles of many real gas molecules. In this case, the equality of the specific translational kinetic energy of molecules and particles is ensured. The interactions between the particles themselves and the particles and the fabric are perfectly elastic collisions. Targets (bioobjects) are represented using finite element models of anthropometric dummies of the Hybrid III 50th Male type. The data obtained during the simulation were used to evaluate the traumatic effect of the kinetic element according to the viscosity criterion (VC) and to estimate the probability of a target falling. As a result of the calculation, the value of VCmax was determined, which was 0.274 m/s, which corresponds to the absence of traumatic impact. At the same time, the maximum impact pulse was 41.25 N/s, which corresponds to the probability of a fall of 90.5% and 63% for women and men, respectively.
      PubDate: 2022-02-15
      DOI: 10.1007/s41314-022-00042-3
       
  • Application of TOPSIS Optimization in Abrasive Water Jet Machining of
           Military Grade Armor Steel

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      Abstract: Abstract Rolled Homogeneous Armor (RHA) is a high tensile strength, toughness, and hardness is widely used in defense battlefield vehicles. RHA is high-strength low alloy steel and it is best suited for all battlefield applications in defense vehicles as it withstands any projectile attack. The TOPSIS method was used in this study to conduct an experimental investigation of abrasive water jet machining (AWJM) cutting on RHA steel. Process parameters like jet water pressure (P), jet traverse rate (T), and standoff distance (SOD) are optimized with multiresponse output characteristics such as kerf angle (Ka), material removal mate (MRR), and surface roughness (Ra). The experiments are conducted under L27 factorial design, and Simos’ weightage approach is used to calculate the weight of the output parameter. The ANOVA test is employed to determine the level of contribution of each input parameter. The optimal closeness output response gives maximum MRR and minimum Ka and Ra values. T is the most influencing factor in the three output responses and SOD is the second influencing factor. The better optimal process parameter SOD = 1 mm, T = 5 mm/min and P = 240 MPa is identified using the TOPSIS method.
      PubDate: 2021-08-21
      DOI: 10.1007/s41314-021-00039-4
       
  • Blast-Related Lung Injury Risk Estimation Based on Chest Wall Velocity

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      Abstract: Abstract Exposure to a shock wave generated during an explosion may result in pulmonary trauma. For short-duration shock waves, the maximum of incident impulse is known to be correlated with the lung injury level of unprotected biological models. This study aims to correlate parameters related to large animal chest response under blast loading with a pulmonary injury level, which leads up to determine parameters which are themselves correlated with the maximum of incident impulse. Two groups of six post-mortem swine (PMS), lying on the ground, were exposed to shock waves of increasing intensity but constant positive-phase duration: 1.0 ms and 1.8 ms. Intra-thoracic pressure was recorded with a hydrophone placed into the esophagus while chest motion was obtained from an accelerometer screwed onto a mid-torso rib. Combining those scenarios with others performed on post-mortem swine at a duration of 1.4 ms showed that the maximum chest wall velocity (VMAX) was correlated with incident impulses ranging from 35 to 160 kPa ms. Lung injury tolerance limits from no injury to severe ones (hemorrhage involving up to 60% of the lung) were redefined with this parameter. The lung injury threshold for near-wall scenarios in terms of incident impulse is 58.3 kPa ms, corresponding to a VMAX of 2.78 m/s. The definition of lung injury criterion for unprotected biological models from blast exposure is a first step toward the proposition of tolerance limits to evaluate thoracic protective system regarding injury outcomes.
      PubDate: 2021-04-24
      DOI: 10.1007/s41314-021-00038-5
       
  • Effects of Personal Protective Equipment on Seated Occupant Spine Loads in
           Under-Body Blast: a Finite Element Human Body Modeling Analysis

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      Abstract: Abstract The effects of a personal protective equipment vest (PPE) on spine loads of occupants in vehicles subjected to under-body blast (UBB) events are not well understood. This study investigated the inertial and structural effects of PPE on the lower spine in UBB loading conditions using numerical modeling. A seated finite element (FE) human body model (HBM) with a spine designed for vertical acceleration load analysis was subjected to a 45g UBB representative acceleration. The HBM was modeled with and without PPE, in both upright (0°) and reclined (15°) seated postures. The PPE added 30% to the mass of the upper torso; however, it only increased the peak dynamic net spine load by approximately 20%. The added mass of PPE promoted additional flexion that shifted the overall loads toward the anterior aspect of the spine, which may contribute to an increased propensity for wedge compression fractures. The 15° reclined posture generated higher net spine loads than the upright posture. The additional forward flexion observed in the upright posture generated reduced peak net spine loads but increased the anterior aspect spine loads. The model, with and without PPE, identified regions and modes of elevated loading that were consistent with injuries observed in theater, suggesting that FE HBM modeling has potential to become a tool for injury prediction. A novel lower spine injury criterion, Lij, which combines axial compression and bending, was proposed to recognize injurious elevated anterior vertebral loading, which is not accounted for with separate compressive and bending criteria.
      PubDate: 2021-01-06
      DOI: 10.1007/s41314-020-00037-y
       
  • Comparison of Night Vision Technology for Close-Quarters Combat
           Operations: How Field of View Impacts Live-Fire Scenarios

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      Abstract: Abstract As early as the Vietnam War, the United States Military has employed various forms of night vision goggles (NVGs) to enhance warfighter capability under low light conditions. In recent years, the most common form of NVGs used by US ground forces has been the binocular or “dual tube” variety, such as the AN/PVS-15 and AN/PVS-31A. Compared to binocular NVGs, modern panoramic night vision goggles (PNVG), such as the GPNVG-18, provide potential benefits by more than doubling the field of view. This capability could be particularly useful in urban environments and specifically during room-clearing operations. However, previous human performance studies with NVGs have largely focused on aviation operations rather than ground forces undertaking a close-combat mission set. Combined with the emerging technology of the PNVG, and the lack of live fire during testing, there is little empirical evidence about the relative human performance benefits of having a wider field of view during close-combat operations. The current investigation addressed this issue by examining how wider peripheral vision impacted the process of dynamic room entries. Using highly trained military operators, live ammunition, and three separate live-fire room-clearing scenarios, we examined performance differences between the current technology in binocular and panoramic NVGs. Our results suggest that soldiers cleared rooms significantly faster when using PNVG than when using binocular NVGs. The largest benefit occurred for engaging targets placed in the extreme corners of rooms. Applications and trade-offs are discussed along with the need for increased human performance studies addressing close combat under NVGs.
      PubDate: 2020-10-24
      DOI: 10.1007/s41314-020-00036-z
       
  • The Use of Wearable Assistive Technology to Increase Soldiers’
           Effectiveness

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      Abstract: Abstract The Australian Army contains more than 50 diverse employment specialisations and soldiers are exposed to a number of different tasks that may benefit from the introduction of wearable assistive technology. The aim of this paper was to identify the most common physically demanding activities performed by soldiers and to identify target use-cases that may benefit from the implementation of wearable assistive technology. A list of physically demanding tasks performed by Australian soldiers was clustered to identify the most common physically demanding activities. The clusters were created based on scenario and context where the task could be performed, the predominant physical capacity required to complete a task, the number of people involved in a task and details on the body worn clothing and equipment. Lifting and marching tasks were found to be the most common activities performed by soldiers. Wearable assistive technologies such as exoskeletons should target lifting and marching activities and be designed specifically for combat and non-combat applications. Design considerations should also include not only the execution of a specific task but also the different type of dresses worn during the execution of a task (e.g. combat uniform or body armour) and the main location (barracks, field) where the targeted task is commonly performed.
      PubDate: 2020-06-03
      DOI: 10.1007/s41314-020-00035-0
       
  • Multi-objective Goal Programming for Low Altitude Seat Ejections with
           Fuzzy Logic–Based Decision-making

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      Abstract: Abstract Aircraft seat ejection systems are essential lifesaving equipment for pilots. Although seat ejections have improved in terms of success rates over the past few decades, ejections at low altitudes (below 150 m) remain a serious concern. These are time critical events and demand optimal process parameters to improve the odds of successful ejection due to the lack of lifesaving height and various other factors. The study optimizes impulse applied and the angle of ejection of the pilot with a novel Multi-Objective optimization approach to minimize Dynamic Response Index (DRI, used to quantify spinal injury) and to maximize the ejection height. The Pareto-optimal solutions are obtained thereof for different scenarios of aircraft flight. A fuzzy logic system is used to handle the uncertainties due to the objective functions under different ejection scenarios of the aircraft; it is used as a decision-maker to choose the initial parameters for goal programming based on the severity of the ejection scenarios. The results were compared with ideal solutions obtained from Pareto fronts using the same fuzzy logic system as decision-maker. The goal programming gave similar results at a quicker time making it advantageous over the conventional “generate first choose later” methods.
      PubDate: 2020-02-06
      DOI: 10.1007/s41314-019-0031-7
       
  • A Simple Model for Estimating Blunt Impact Skull Force

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      Abstract: Abstract We use open-literature test data on human skull impacted by a rigid projectile to estimate parameters of a skull/skin impact model. The model comprises a mass and three-parameter spring/dashpot system. We solve the resulting equation of motion after impact analytically and determine the model parameters by minimizing errors between the experimental data and model predictions. Next, we consider a non-lethal SIR-X projectile; we model it as a mass with a nonlinear spring in front and determine the spring parameters by utilizing SIR-X rigid wall impact data published in open literature. We observe that analyzing a rigid projectile impacting a human skull leads to a simplified procedure for determining parameters of the human skull model; similarly, using rigid wall impact data allows us to estimate properties of the projectile in a relatively simple manner. Finally, we calculate the impact force as a function of the SIR-X impact velocity and show how nonlinear spring properties of the projectile nose material could be modified to minimize the maximum impact force.
      PubDate: 2020-01-30
      DOI: 10.1007/s41314-020-0034-4
       
 
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