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The interdependency between propulsion, power, and thermal subsystems on military aircraft such as the F-35 Joint Strike Fighter (JSF) and F-22 Raptor continues to increase as advanced war-fighting capabilities including solid-state radars, electronic attack, electric actuation, and Directed Energy Weaponry (DEW) expand to meet Air Force needs. Novel analysis and testing methodologies are required to predict these interdependencies and address adverse interactions prior to costly hardware prototyping. As a result, the Air Force Research Laboratory (AFRL) has established a dynamic hardware-in-the-loop (HIL) test-bed wherein transient simulations can be integrated through advanced real-time simulation with prototype hardware for integrated system studies and analysis. This paper details a test-bed configuration where a dynamic simulation of an aircraft turbine engine is utilized to control a dual-head electric drive stand.

Directed Energy weapon (DEW) systems are being developed for both ground and airborne applications. Typically, they consist of microwave or laser powered guns. Both the microwave application and the diode based laser applications require significant amount of power. This power ranges from several hundred kilowatts (kW) for microwave applications to Megawatts (MW) for laser applications. The laser application requires that the full power be available for short duration, typically 5 seconds, which could be repeated several times with short pauses in between. The control of a generator, which delivers Megawatt of the intermittent power greatly differs from the of normal steady state generator control. It poses significant challenges. Application of power (and for this matter its removal) is a transient phenomenon that takes time and its effects ripple through the whole system.

This paper compares several different test methods used to test maintenance chemicals for potential to induce hydrogen embrittlement in high-strength steel. The program was structured to accomplish three main objectives with regard to hydrogen embrittlement testing: 1) compare various test methods used to qualify maintenance chemicals, 2) compare various coatings used to protect high-strength steel parts such as landing gear, and 3) compare various high-strength steel substrates specified for aircraft landing gear. The coatings selected included electrodeposited cadmium (baseline), ion vapor deposited (IVD) aluminum, SermeTel 984, and Zinc-Nickel plate. Substrates tested included AISI 4340 (260-280 ksi HT), 300M (280-300 ksi HT), and AerMet 100 (minimum 290 ksi HT).

Aircraft power demands continue to increase with the increase in electrical subsystems. These subsystems directly affect the behavior of the power and propulsion systems and can no longer be neglected or assumed linear in system analyses. The complex models designed to integrate new capabilities have a high computational cost. Hardware-in-the-loop (HIL) is being used to investigate aircraft power systems by using a combination of hardware and simulations. This paper considers three different real-time simulators in the same HIL configuration. A representative electrical power system is removed from a turbine engine simulation and is replaced with the appropriate hardware attached to a 350 horsepower drive stand. Variables are passed between the hardware and the simulation in real-time to update model parameters and to synchronize the hardware with the model.

As aircraft continue to increase their power and thermal demands, transient operation of the power and propulsion subsystems can no longer be neglected at the aircraft system level. The performance of the whole aircraft must be considered by examining the dynamic interactions between the power, propulsion, and airframe subsystems. Larger loading demands placed on the power and propulsion subsystems result in thrust, speed, and altitude transients that affect the aircraft performance and capability. This results in different operating and control parameters for the engine that can be properly captured only in an integrated system-level test. While it is possible to capture the dynamic interactions between these aircraft subsystems by using simulations alone, the complexity of the resulting system model has a high computational cost.

The escalation of vehicle operating costs due to continuously rising fuel prices has prompted aircraft designers to focus on more energy efficient designs. Among the heavy energy consumers in aircraft operations, the thermal management system is one of the largest. This is especially true of the refrigeration system powered by engine bleed air power. With the push towards more electric vehicles, an entirely new trade space has been opened up with regards to electric thermal management and the cost of bleed air versus electrical power. Despite favorable energy savings, the electric approach has increased the burden on the propulsion engine shaft power extraction systems (gearbox and drive train), electrical generators, power conditioning units, and electrical distribution systems. This paper presents potential architectures which utilize energy recovery and integration principles to address the challenges on the power generating system.

Given the goal of developing energy-optimized aircraft that employ increasingly higher power loads such as electric flight control actuation, directed energy weapon systems and on-demand cooling systems, advances in battery technology and associated integration methodology will be required to achieve a robust electrical power system design. Batteries based on various Lithium-Ion chemistry technologies represent a 50% improvement in both specific energy and specific power over legacy NiCad and Lead-Acid chemistries. However, along with these benefits come challenges in terms of overall safety, cost and availability. Safety considerations primarily include failure modes that result from the battery being subjected to short-circuit conditions and over-charge conditions. Cost and availability challenges arise primarily from one-off point designs and ensuing low production volumes, but also stem from limited marketplace competition.

The University of Texas Center for Electromechanics (UT-CEM) has been developing active suspension technology for off-road vehicles since 1993. The UT-CEM approach employs fully controlled electromechanical actuators to control vehicle dynamics and passive springs to efficiently support vehicle static weight. The project described in this paper is one of a succession of projects toward the development of effective active suspension systems, primarily for heavy off-road vehicles. Earlier projects targeted the development of suitable electromechanical actuators. Others contributed to effective control electronics and associated software. Another project integrated a complete system including actuators, power electronics and control system onto a HMMWV and was demonstrated at Yuma Proving Grounds in Arizona.

In this paper, a parametric average-value modeling approach is applied to a high-frequency six-phase aircraft generation subsystem. This approach utilizes a detailed switch-level model of the system to numerically establish the averaged dynamic relationships between the ac inputs of the rectifier and the dc-link outputs. A comparison between the average-value and detailed models is presented, wherein, the average-value model is shown to accurately portray both the large-signal time-domain transients and the small-signal frequency-domain characteristics. Since the discontinuous switching events are not present in the average-value model, significant gains can be realized in the computational performance. For the study system, the developed average-value simulation executed more than two orders of magnitude faster than the detailed simulation.

Future Air Force intelligence, surveillance, and reconnaissance (ISR) platforms, such as high-altitude Uninhabited Aerial Vehicles (UAV), may drastically change the requirements of aircraft power systems. For example, there are potential interactions between large pulsed-power payloads and the turbine engine that could compromise the operation of the power system within certain flight envelopes. Until now, the development of large-scale, multi-disciplinary (propulsion, electrical, mechanical, hydraulic, thermal, etc.) simulations to investigate such interactions has been prohibitive due to the size of the system and the computational power required. Moreover, the subsystem simulations that are developed separately often are written in different commercial-off-the-shelf simulation programs.

With the developments of Industry 4.0, data analytics solutions and their applications have become more prevalent in the manufacturing industry. Currently, the typical software architecture supporting these solutions is modular, using separate software for data collection, storage, analytics, and visualization. The integration and maintenance of such a solution requires the expertise of an information technology team, making implementation more challenging for small manufacturing enterprises. To allow small manufacturing enterprises to feasibly obtain the benefits of Industry 4.0 data analytics, a full-stack data analytics framework is presented, and its performance evaluated as applied in the common industrial analytics scenario of predictive maintenance. The predictive maintenance approach was achieved by using a full-stack data analytics framework comprised of the PTC Inc. Thingworx software suite.

With the growth of Industry 4.0 in recent years, Augmented Reality (AR) technologies are changing the way operators work by increasing their efficiency and operational performance. A common use of AR is providing operators helpful work instructions for assembly by presenting relevant digital information in the context of the physical environment. These AR experiences can be viewed via several devices such as mobile, wearable, and stationary devices, each being useful for different applications. While in the experience, instructions are provided by means of 3D animation, text, images, and interactive buttons, all of which are directly overlaid onto the physical product or equipment being worked on. This work presents a closed-loop, enterprise connected, AR system for post end Printed Circuit Board (PCB) assembly work instructions.

The movement to more-electric architectures during the past decade in military and commercial airborne systems continues to increase the complexity of designing and specifying the electric power system. In particular, the electrical power system (EPS) faces challenges in meeting the highly dynamic power demands of advanced power electronics based loads. This paper explores one approach to addressing these demands by proposing an electrical equivalent of the widely utilized hydraulic accumulator which has successfully been employed in hydraulic power system on aircraft for more than 50 years.