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Technical Paper

Technical Challenges for Vehicle 14V/28V Lithium Ion Battery Replacement

2011-04-12
2011-01-1375
Modern commercial and military vehicles are equipped with more electrical accessories and demand more power than ever before. This causes an increase in the weight of the battery as well as drives the battery to end of life when the vehicle is stationary with the engine off. Lithium ion batteries, which are known for their high power and energy to weight density, long cycle life, and low self-discharge rate, are considered to be an alternative for the replacement of existing Starting, Lighting, and Ignition (SLI) lead acid batteries. Lithium ion battery chemistry offers double the reserve time of the stock battery and a significantly greater number of charging and discharging cycles while providing weight savings. There is no acid inside a lithium ion battery to cause corrosion, which eliminates potential damage to a vehicle from chemical spills and poisonous gases.
Technical Paper

Simulation for the Response of a Structure Subjected to a Load from an Explosion

2008-04-14
2008-01-0781
Utilizing simulation technology is important for designing a structure with increased survivability to a load from an explosion. The pressure wave from the blast and the fragments hitting the structure must be simulated in such an analysis. Commercial software can be utilized through the development of appropriate interfaces for performing such computations. In this paper an approach is presented for combining commercially available Eulerian and Lagrangian solvers for performing blast event simulations. A capability has been developed for automatically creating the Eulerian finite element given the finite element model for the structure. The effect of moisture in the soil properties is considered during the generation of the soil - explosive - air model used by the Eulerian solver. Tracers are defined in the Eulerian model for all structural finite elements which are on the outer part of the structure and are subjected to the load from the blast.
Technical Paper

Fuel Efficiency Effects of Lubricants in Military Vehicles

2010-10-25
2010-01-2180
The US Army is currently seeking to reduce fuel consumption by utilizing fuel efficient lubricants in its ground vehicle fleet. An additional desire is for a lubricant which would consist of an all-season (arctic to desert), fuel efficient, multifunctional Single Common Powertrain Lubricant (SCPL) with extended drain capabilities. To quantify the fuel efficiency impact of a SCPL type fluid in the engine and transmission, current MIL-PRF-46167D arctic engine oil was used in place of MIL-PRF-2104G 15W-40 oil and SAE J1321 Fuel Consumption In-Service testing was conducted. Additionally, synthetic SAE 75W-140 gear oil was evaluated in the axles of the vehicles in place of an SAE J2360 80W-90 oil. The test vehicles used for the study were three M1083A1 5-Ton Cargo vehicles from the Family of Medium Tactical Vehicles (FMTV).
Journal Article

Feasibility of Using Full Synthetic Low Viscosity Engine Oil at High Ambient Temperatures in Military Vehicles

2010-10-25
2010-01-2176
The US Army is currently assessing the feasibility and defining the requirements of a Single Common Powertrain Lubricant (SCPL). This new lubricant would consist of an all-season (arctic to desert), fuel-efficient, multifunctional powertrain fluid with extended drain capabilities. As a developmental starting point, diesel engine testing has been conducted using the current MIL-PRF-46167D arctic engine oil at high temperature conditions representative of desert operation. Testing has been completed using three high density military engines: the General Engine Products 6.5L(T) engine, the Caterpillar C7, and the Detroit Diesel Series 60. Tests were conducted following two standard military testing cycles; the 210 hr Tactical Wheeled Vehicle Cycle, and the 400 hr NATO Hardware Endurance Cycle. Modifications were made to both testing procedures to more closely replicate the operation of the engine in desert-like conditions.
Technical Paper

Analysis and Control of Displacement Transmissibility and Force Transmissibility for a Two DOF Model Based on Quarter Car Concept using a Mixed Mode Magnetorheological Fluid Mount

2010-10-05
2010-01-1911
The chassis are subject to both road profile and engine or pump/motor vibration when a vehicle is moving on the road. The suspension is developed to reduce the effect of the road conditions to the chassis. The vibration from engine or pump/motor of hydraulic hybrid vehicles (HHV) will be also transmitted to the chassis and needs to be isolated. A mixed mode magnetorheological (MR) fluid mount is presented to isolate force vibration for a two degree of freedom (DOF) model based on quarter car concept. The MR fluid mount is designed to work in flow mode and squeeze mode separately and simultaneously. The skyhook control for the MR fluid mount is also been designed and simulated. Both displacement transmissibility and force transmissibility for each mode and for combined modes have been obtained. These simulation results present a basis for designing a more effective controller to control both the displacement transmissibility and force transmissibility.
Technical Paper

Comparison of a Hydraulic Engine Mount to a Magnetorheological Engine Mount

2010-10-05
2010-01-1910
A comparison between a hydraulic engine mount and a mixed mode magnetorheological (MR) fluid engine mount is presented. MR fluid is a smart material that changes viscosity in the presence of a magnetic field. In other words, without the presence of a magnetic field, the fluid is classified as a Newtonian fluid, however; with the presence of a magnetic field, the fluid becomes classified as a Bingham plastic. The working modes of the MR mount are squeeze and flow. Hydraulic mounts were developed to address the conflicting requirements of the engine vibration profile. The engine vibration profile can be classified as large displacement in the low frequency range and small displacement in the high frequency range. The hydraulic mount used in this study is an as received OEM mount. The elastomeric top and bottom of the hydraulic mount were used to create the MR mount. In the paper, the advantages and disadvantages of each mount are discussed in detail.
Technical Paper

Yaw Stability Control and Emergency Roll Control for Vehicle Rollover Mitigation

2010-10-05
2010-01-1901
In this paper a yaw stability control algorithm along with an emergency roll control strategy have been developed. The yaw stability controller and emergency roll controller were both developed using linear two degree-of-freedom vehicle models. The yaw stability controller is based on Lyapunov stability criteria and uses vehicle lateral acceleration and yaw rate measurements to calculate the corrective yaw moment required to stabilize the vehicle yaw motion. The corrective yaw moment is then applied by means of a differential braking strategy in which one wheel is selected to be braked with appropriate brake torque applied. The emergency roll control strategy is based on a rollover coefficient related to vehicle static stability factor. The emergency roll control strategy utilizes vehicle lateral acceleration measurements to calculate the roll coefficient. If the roll coefficient exceeds some predetermined threshold value the emergency roll control strategy will deploy.
Journal Article

Development of JP-8 Surrogates and their Validation using Ignition Quality Tester

2014-04-15
2014-01-9077
This paper presents a new approach for the development of six different JP-8 surrogates for application in diesel cycle simulation. The approach involves a step-wise formulation of 2-, 3-, and 4-component surrogates from a list of pure compounds which are selected based on several criteria. A MATLAB code is developed and is used in conjunction with the Ignition Quality Tester (IQT) and HYSYS software in order to formulate optimal surrogates. The first part of the results shows a comparison between the calculated and the measured DCNs for six surrogates. The differences in the properties such as the density, volatility, lower heating value, H/C ratio, molecular weight, and threshold sooting index of the surrogates and the JP-8 are also highlighted. This is followed by the evaluation of the surrogates with respect to the target JP-8 fuel. The evaluation is made in terms of ignition delays and the rate of heat release at three different IQT test temperatures.
Technical Paper

Mountain Braking Test Venue Study

2014-09-28
2014-01-2526
Assessment of braking performance that includes brake fade is a critical part of the evaluation of military light tactical vehicles as it is for conventional light cars and trucks. These vehicles are sometimes called upon to operate in severe mountain regions that challenge the braking performance well beyond the environment in which these vehicles are normally operated. The U.S. Army Test Operating Procedure (TOP) 2-2-608 includes a test schedule conducted in the mountainous region near Jennerstown, Pennsylvania. While this test procedure represents a typical mountain environment, it does not represent the most severe mountain descents that can be encountered across the United States. As a preliminary step to developing a representative severe mountain descent braking test, mountain roads throughout the United States were evaluated analytically to identify potential test venues.
Technical Paper

Performance Evaluation of a Semi-Active Magnetorheological Mount

2008-04-14
2008-01-0429
The paper presents the design and control aspects of a magnetorheological (MR) fluid based mount. The proposed design yields a high static stiffness and a low dynamic stiffness in the working frequency range of the mount, enhancing the vibration isolation capabilities of the mount compared to existing hydraulic mounts. Vertical vibrations, namely displacement/force transmissibility, can be isolated or significantly reduced, in real time, by controlling the fluid yield stress through an applied electric current. The mount governing equations are derived and the effectiveness of the mount is evaluated for two cases: low frequency-high displacement and at high frequency-low displacement. These cases correspond to the operation of the mount in squeeze mode and in flow mode, respectively. Preliminary results on the implementation of a skyhook control strategy are also presented.
Technical Paper

Simulations Under Uncertainty for Occupant Safety for a Vehicle Subjected to a Blast Load

2006-04-03
2006-01-0762
One of the main threats to military vehicles originates from landmine blasts. In order to improve the survivability of the occupants it is important to design a military vehicle for increased occupant safety. Simulation technology that combines modeling of the blast loads from the landmine explosion, the response of the vehicle to the blast load, and the loads developed on the members of an occupant are important factors in this effort. Uncertainties from the soil properties can influence the blast loads and thus the occupants' safety. In this paper, principal component analysis along with metamodel theory are employed for developing fast running models for the response functions of interest. The response functions of interest are the time domain loads which are developed on an occupant's members due to the blast. The fast running models allow assessing the probability level associated with injury for an occupant.
Technical Paper

Characterization of a Multiple-Evaporator Capillary Pumped Loop

2005-07-11
2005-01-2884
The current work addresses efforts to characterize multiple-evaporator capillary pumped loops. Both experimental and analytical approaches were used to predict performance of parallel evaporators and corresponding effects from adjacent operating evaporators. The effects of low and high power dissipation and the distribution of powers among the evaporators were tested. Additionally, a pressure balance model is given where the maximum heat transfer capacity for an evaporator operating under a multi-evaporator condition is determined based on pressure distribution throughout the loop. The model and experiment comparisons demonstrated how the heat load distribution among evaporators affects the maximum capillary limit for individual evaporators operating in a multiple evaporator mode.
Technical Paper

Next Generation Li-Ion Technology from SAFT

2008-11-11
2008-01-2921
At the end of 2007 SAFT developed the next generation of power Lithium Ion and delivered first prototypes. This work is funded by US Army TACOM and is continuation of US Air Force AFRL sponsored effort aimed at meeting the needs of both aircraft power as well as emerging Directed Energy applications. Ultra High Power (UHP) Li-ion cells offer unparalleled continuous and pulse power. Additionally the technology is capable of excellent charge acceptance and power delivery at low temperature. These specific characteristics could enable a floating on the bus aviation battery in the near future. The extreme pulse power capability coupled with limited heat generation make the technology a leading candidate for a Directed Energy intermediate energy storage power system.
Technical Paper

Blast Event Simulation for a Structure Subjected to a Landmine Explosion

2006-04-03
2006-01-0931
One of the main threats to military vehicles originates from landmine blasts. In order to improve the survivability of the occupants it is important to design a military vehicle for increased occupant safety. Simulation technology that combines modeling of the blast loads from the landmine explosion, the response of the vehicle to the blast load, and the loads developed on the members of an occupant are important factors in this effort. The ability to simulate the landmine explosion is validated first by comparing simulation results to test data collected by gages placed in the ground and above the ground. Combined simulations predicting the damage to a target structure due to a landmine explosion are also compared to test data for further validation. Principal component analysis and metamodel theory is employed for generating fast running models in order to adjust the soil parameters in the simulation models during the correlation effort.
Technical Paper

Spray Characterization in a DISI Engine During Cold Start: (1) Imaging Investigation

2006-04-03
2006-01-1004
Spray angle and penetration length data were taken under cold start conditions for a Direct Injection Spark Ignition engine to investigate the effect of transient conditions on spray development. The results show that during cold start, spray development depends primarily on fuel pressure, followed by Manifold Absolute Pressure (MAP). Injection frequency had little effect on spray development. The spray for this single hole, pressure-swirl fuel injector was characterized using high speed imaging. The fuel spray was characterized by three different regimes. Regime 1 comprised fuel pressures from 6 - 13 bar, MAPs from 0.7 - 1 bar, and was characterized by a large pre-spray along with large drop sizes. The spray angle and penetration lengths were comparatively small. Regime 2 comprised fuel pressures from 30 - 39 bar and MAPs from 0.51 - 0.54 bar. A large pre-spray and large drop sizes were still present but reduced compared to Regime 1.
Technical Paper

Automated Evolutionary Design of a Hybrid-Electric Vehicle Power System Using Distributed Heterogeneous Optimization

2006-11-07
2006-01-3045
The optimal design of hybrid-electric vehicle power systems poses a challenge to the system analyst, who is presented with a host of parameters to fine-tune, along with stringent performance criteria and multiple design objectives to meet. Herein, a methodology is presented to transform such a design task into a constrained multi-objective optimization problem, which is solved using a distributed evolutionary algorithm. A power system model representative of a series hybrid-electric vehicle is considered as a paradigm to support the illustration of the proposed methodology, with particular emphasis on the power system's time-domain performance.
Technical Paper

Validation of Real-Time Multi-Body Vehicle Dynamics Models for Use in Product Design and Acquisition

2004-03-08
2004-01-1582
The United States Research, Development, and Engineering Command's Tank Automotive Research, Development and Engineering Center (U.S. Army RDECOM-TARDEC) laboratories, in accordance with a Science and Technology Objective (STO), are looking for both real-time and non real-time modeling and simulation methods to advance the capabilities and methodologies used in the Army's Modeling and Simulation areas. Advancing technologies require TARDEC to model new components and vehicles that may be significantly different from prior systems. TARDEC's ultimate goal is to develop the capability to model and accurately recreate the behaviors of advance technologies that may present themselves in the Army's Transformation and its Future Combat System (FCS) of vehicles in real-time with the soldier-in-the-loop. This paper discusses TARDEC's effort to accomplish this goal.
Technical Paper

Using 3D Multi-Body Simulation to Evaluate Future Truck Technologies

2005-04-11
2005-01-0934
This document presents the results of computer-based, vehicle dynamics performance assessments of Future Truck concepts with such features as a variable height, hydraulic, trailing arm suspension, skid steering, and in-hub electric drive motors. Fully three-dimensional Future Truck models were created using a commercially available modeling and simulation methodology and limited validation studies were performed by comparing model predictions with baseline, validated model predictions from another vehicle in the same size and class as the Future Truck concept vehicles. The models were considered accurate enough to predict various aspects of ride quality and stability performance, critical to US Army Objective Force mission needs. One-to-one comparisons of the Future Truck concepts and a standard, solid-axle, Heavy Tactical Vehicle (HTV) operating in various terrain and obstacle negotiation conditions were performed.
Journal Article

The Combustion and Ignition Characteristics of Varying Blend Ratios of JP-8 and a Coal to Liquid Fischer-Tropsch Jet Fuel in a Military Relevant Single Cylinder Diesel Engine

2015-06-01
2015-01-9073
The U.S. Army currently uses JP-8 for global operations according to the ‘one fuel forward policy’ in order to reduce the logistics burden of supplying a variety of fuels for given Department of Defense ground vehicle applications. One particular challenge with using global JP-8 is the lack of or too broad a range of specified combustion affecting properties including ignition quality, high temperature viscosity, and density. In particular, the ignition quality of JP-8 has dramatically varied throughout the past decade on a global basis covering a range of 29 to 70 cetane index. This key combustion affecting parameter was explored in this study by evaluating a synthesized low ignition quality jet fuel blended in 25% volumetric proportions with JP-8 to effectively cover a cetane number range of 25 to 45 in a single cylinder diesel engine operated at various light, medium, and high load operating conditions.
Journal Article

The Development of Terrain Pre-filtering Technique Based on Constraint Mode Tire Model

2015-09-01
2015-01-9113
The vertical force generated from terrain-tire interaction has long been of interest for vehicle dynamic simulations and chassis development. To improve simulation efficiency while still providing reliable load prediction, a terrain pre-filtering technique using a constraint mode tire model is developed. The wheel is assumed to convey one quarter of the vehicle load constantly. At each location along the tire's path, the wheel center height is adjusted until the spindle load reaches the pre-designated load. The resultant vertical trajectory of the wheel center can be used as an equivalent terrain profile input to a simplified tire model. During iterative simulations, the filtered terrain profile, coupled with a simple point follower tire model is used to predict the spindle force. The same vehicle dynamic simulation system coupled with constraint mode tire model is built to generate reference forces.
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