Browse Topic: Protective systems
ABSTRACT The modeling of a buried charge is a very complex engineering task since many Design Variables need to be considered. The variables in question are directly related to the method chosen to perform the analysis and the process modeled. In order to have a Predictive Tool two main objectives have to be carried out, the first is a verification of the numerical approach with experimental data, the second objective is a sensitivity study of the numerical and process parameters. The emphasis of the present study covers the second objective. To perform this task a comprehensive sensitivity study of fourteen Design Variables was completed which required 1000+ computational hours. The modeling approach that was chosen was the Discrete Particle Method (DPM) to model the Soil and HE and the Finite Element Method for the Structure. The basis for the study was a blast event applied to a model of the TARDEC Generic Vehicle Hull. The Response Parameter was chosen to be the Total Blast Impulse
ABSTRACT This paper reviews the Army Generic Hull [1-5] as a vital developmental tool for underbody blast modeling and simulation applications. Since 2010, it has been used extensively to help calibrate and validate various numerical software codes and methodologies. These are being used extensively today in the development of underbody armor, as well as mine blast subsystems such as seats, to protect both military vehicles and their occupants. In the absence of easily shareable information in this domain due to data classification, this specially formulated product is a valuable part of any toolset for underbody blast development and product design. Citation: K. Kulkarni, S. Kankanalapalli, V. Babu, J. Ramalingam, R. Thyagarajan, “The Army Generic Hull As A Vital Developmental Tool For Underbody Blast Applications,” In Proceedings of the Ground Vehicle Systems Engineering and Technology Symposium (GVSETS), NDIA, Novi, MI, Aug. 16-18, 2022
ABSTRACT Over the course of typical survivability analyses for underbody blast events, a multitude of individual cases are examined where charge size, charge location relative to the vehicle, and vehicle clearance from the ground are varied, so as to arrive at a comprehensive assessment. While multi-physics computational tools have reduced the expense and difficulty of testing each loading case experimentally, these tools still often require significant execution and wall-clock times to perform the simulations. In efforts to greatly reduce the time required to conduct a holistic survivability analysis, Fast Running Models (FRMs) have been implemented and validated to act as a surrogate for the computationally expensive finite element tools in use today. Built using a small set of simulations, FRMs generate loading data in a matter of seconds, representing a significant improvement in survivability analysis turnaround time
ABSTRACT The study describes the development of a plug-in module of the realistic 3D Digital Human Modeling (DHM) tool RAMSIS that is used to optimize product development of military vehicle systems. The use of DHM in product development has been established for years. DHM for the development of military vehicles requires not only the representation of the vehicle occupants, but also the representation of equipment and simulation of the impact of such equipment on the Warfighter. To simulate occupants in military vehicles, whether land or air based, realistically, equipment must become an integral part of the extended human model. Simply attaching CAD-geometry to one manikin’s element is not sufficient. Equipment size needs to be scalable with respect to anthropometry, impact on joint mobility needs to be considered with respect to anatomy. Those aspects must be integrated in posture prediction algorithms to generate objective, reliable and reproducible results to help design engineers
ABSTRACT This study applies an augmentation to systems engineering methodology based on the integration of adaptive capacity, which produces enhanced resilience in technological systems that operate in complex operating environments. The implementation of this methodology enhances system resistance to top-level function failure or accelerates the system’s functional recovery in the event of a top-level function failure due to functional requirement shift, evolutions, or perturbations. Specifically, this study employs a methodology to integrate adaptive resilience and demonstrates key aspects of its implementation in a relevant explosive reactive armor (ERA) system case study. The research and resulting methodology supplements and enhances traditional systems engineering processes by offering systems designers a method to integrate adaptive capacity into systems, enhancing their resilient resistance, or recovery to top-level function failure in complex operating environments. This
ABSTRACT: Ground vehicle survivability and protection systems and subsystems are increasingly employing sensors to augment and enhance overall platform survivability. These systems sense and measure select attributes of the operational environment and pass this measured “data” to a computational controller which then produces a survivability or protective system response based on that computed data. The data collected is usually narrowly defined for that select system’s purpose and is seldom shared or used by adjacent survivability and protection subsystems. The Army approach toward centralized protection system processing (MAPS Modular APS Controller) provides promise that sensor data will be more judiciously shared between platform protection subsystems in the future. However, this system in its current form, falls short of the full protective potential that could be realized from the cumulative sum of sensor data. Platform protection and survivability can be dramatically enhanced if
ABSTRACT This paper focuses on the application of a novel Additive Molding™ process in the design optimization of a combat vehicle driver’s seat structure. Additive Molding™ is a novel manufacturing process that combines three-dimensional design flexibility of additive manufacturing with a high-volume production rate compression molding process. By combining the lightweighting benefits of topology optimization with the high strength and stiffness of tailored continuous carbon fiber reinforcements, the result is an optimized structure that is lighter than both topology-optimized metal additive manufacturing and traditional composites manufacturing. In this work, a combat vehicle driver’s seatback structure was optimized to evaluate the weight savings when converting the design from a baseline aluminum seat structure to a carbon fiber / polycarbonate structure. The design was optimized to account for mobility loads and a 95-percentile male soldier, and the result was a reduction in
ABSTRACT The main aspect of this investigation is the fast calculation of jet break-up from incoherent shape charge effects on targets. Several examples are used to verify force protection with Hard Kill Active Protection Systems. The first example showed how SC3D can be used to estimate the RHA equivalence of a layered armor recipe against a shape charge threat at standoff. The RHA equivalence can then be used in traditional vulnerability assessments. In the second example, a stochastic analysis was done of an Early Initiated Normal Jet event against a target vehicle to evaluate occupant survivability. Although Monte Carlo was used to calculate vulnerability, this was representative of a singular, deterministic HK-APS intercept of a threat (Pk given an intercept). In the third example, an additional layer of stochastic analysis evaluated probability of intercept, accounting for Circle Error Probable of a threat as it is intercepted by an APS along a protection hemisphere. The
ABSTRACT A proposed new method of energy absorption in multilayered plates is to implement shear-thickening fluids between the plate layers to act as a damping mechanism. Research into the implementation of shear thickening fluids (STF) in Kevlar body armor has yielded positive results for ballistic loadings. The objective of this integrated computational materials engineering (ICME) study is to accurately model the behavior of shear thickening fluids using the discrete element method (DEM) to better understand shear-thickening mechanisms and how shear thickening fluids behave under high shear rates experienced during impulse loading. These results are implemented in a reduced order model of a multilayered plate to determine the effect of shear thickening fluids on energy absorption capabilities
ABSTRACT Optical distortion measurements for transparent armor (TA) solutions are critical to ensure occupants can see what is happening outside a vehicle. Unfortunately, optically transparent materials often have poorer mechanical properties than their opaque counterparts which usually results in much thicker layups to provide the same level of protection. Current standards still call for the use of a double exposure method to manually compare the distortion of grid lines. This report presents provides a similar method of analysis with less user input using items typically available in many mechanics labs: machine vision cameras and digital image correlation software. Citation: J. M. Gorman, “An Easier Approach to Measuring Optical Distortion in Transparent Armor”, In Proceedings of the Ground Vehicle Systems Engineering and Technology Symposium (GVSETS), NDIA, Novi, MI, Aug. 11-13, 2020. The views presented are those of the author and do not necessarily represent the views of DoD or
ABSTRACT In monolithic protection materials, a threat increase correlates to an increased material thickness. This is evident in V50 armor material specifications, such as Rolled Homogeneous Armor (RHA) MIL-DTL-12560K. This relationship translates to combat system level weight; the higher the performance, the higher the material weight, the higher the system weight. For ground combat systems, the total platform weight indicates relative protection. Hence, the M1 Abrams weight and protection level is greater than the Bradley Family of Vehicles, and the Bradley weight and protection level is greater than the M113. The weight procurement dollarization impacts are known during developmental efforts, but weight relationships also impact training and sustainment costs. Thus armor based weight changes have at least three cost relationships: procurement, training, and sustainment. These cost relationships are useful to understand in the context of the Army’s annual budget cycle. Citation: RA
ABSTRACT In this paper a new bolt attachment method was explored, where the attaching bolts were divided into two sets. The first set of bolts was tightened and was used to connect the underbody plate to the hull under ordinary operations. The second set of bolts connecting the plate and the hull were not tightened and had some extra axial freedom. Under blast loading, the first set of bolts would break due to high tensile and shear loads, but the second set of bolts would survive due to extra axial freedom which allows the plate and the hull vibrate and separate from each other to a certain extent. A simulation model was developed to verify this concept. Three underbody plate-hull connection approaches were simulated and analyzed: 1) all tightened bolts, 2) some bolts not fully seated, 3) all bolts not fully seated. The simulation results show that with option 1), 100% of the bolts broke under the blast loading. With option 2) the not fully seated bolts survived and continued to
ABSTRACT Midé Technology Corporation (Midé), a Hutchinson company, in collaboration with The University of Texas at Austin (UTA), have investigated the potential for novel negative stiffness (NS)-based structures as blast resistant vehicle panels. Protecting vehicles from blast shockwaves would ideally minimize added weight and maximize reusability. Homogenous metal panels provide such protection but without the benefit of reusability, absorbing energy via plastic deformation, while also adding significant weight to a vehicle, thereby sacrificing mobility. Although various emergent approaches, including the use of hexagonal honeycombs and auxetic materials, have proved promising in terms of higher energy absorption per unit mass, such approaches also rely on plastic deformation additionally suffering from the drawback of occasionally transmitting a higher peak force as compared to the incident
ABSTRACT TARDEC researched head impact protective, energy attenuating materials for use in U.S. Army Ground System Vehicle (GSV) applications. The purpose of the project is to reduce potential head impact related mounted crew injuries and deaths which may occur during underbody blast, crash and rollover events. Commercial-off-the-shelf materials were evaluated for their energy attenuating performance. Exposed surface materials in combination with core material were also researched and evaluated. Baseline vehicle testing was conducted to understand the current head impact criterion. The results of this effort identified solutions which may potentially meet the needs of the Army to reduce head impact related injuries which may occur during crash, rollover and blast events. TARDEC used the knowledge gained from this project to create performance specification requirements for interior head impact protective components and materials for use in U.S. Army vehicles
ABSTRACT Motorized ground forces spend considerable resources in equipping for situational awareness capabilities. Given requirements spanning command, control, surveillance, and reconnaissance of a battlefield, there has been no single mast technology that can support each of these with elevated sensors and weapons. A tough, extremely low weight modular mast system has been designed to be quickly attached or removed from a ground vehicle to provide different operational capabilities depending on the payload. The design allows for easy modification to fit functional needs on different vehicles and platforms. At the heart of the technology is a proprietary super-fiber pressurized tube which elevates the payload on a column of moderate gas pressure eliminating cumbersome hydraulic/mechanical systems. An internal, simple alignment system and gyroscope-maintained verticality allow a stable, elevated platform without introducing instability to the vehicle. The system is capable of
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