A full-scale, remotely operable Lateral Support System (LSS) for fixed missile vertical launch tubes that features controllable shock and vibration mitigation damping and electromechanical actuation were designed, built and tested. The next generation payload LSS eliminates the need for hydraulically operated jacking feet and manual installation that is required in the legacy system. The primary objective of the project was to give the US Navy the ability to maximize their payload capacity and reduce the time and cost associated with installation and removal payload tubes. This work presents the development of a system that increases the capacity to protect payload canisters-from underwater shock and vibration events, increases the available volume within a fixed launch tube, and reduces installation and removal times via remote operation. A full-scale system with integrated smart-material damping capability was designed and validated in a laboratory environment. The electromechanical actuation can apply preloads ranging from 5-20 kips, and the controllable damping system can provide optimized protection at all shipboard vibration frequencies and shock levels. A Graphical User Interface (GUI) was developed to remotely operate and monitor the status of the LSS. The functionality of the full-scale LSS was demonstrated in the laboratory environment by performing pre-load tests, damping tests on the smart damping subsystem and the GUI. The technology maturity is at Technology Readiness Level (TRL) of 6.

Current passive elastomeric mounts are designed to provide mitigation for a given shock and vibration exposure and are not capable of supporting variable payload systems, due to variation in the overall system dynamics. A novel magnetorheological elastomer (MRE) mount that can reduce or increase its stiffness based on payload and shock and vibration input is designed, fabricated, and tested to provide a wide controllable stiffness range for protecting sensitive systems that may require variable weight from external shock and vibration loading. A MRE is a field-controllable material in which the stiffness properties can be altered by changing the applied magnetic field. The two-way controllable MRE mount is designed by using three-dimensional electromagnetic finite element analysis. MRE mounts were developed by using relatively thick MRE layers and built-in electromagnets and permanent magnets. A two-layer MRE mount prototype is characterized by compression and shear tests. Control system hardware and software were developed to detect shock and vibration events, and activate the two-way controllable MRE mount, accordingly. The MRE mount and the control system were tested with variable representative weights. It was demonstrated that the designed control system can detect whether the incoming input is a shock event or a vibration event. The MRE mount demonstrated the ability to soften of stiffen based on the incoming input.

This study investigates the response of flexible piezoelectric materials exposed to blast wave pressure impulses from inair and underwater explosions. A shock tube was used to produce reproducible shock waves from explosions with average peak pressures in excess of 1,000 kPa for underwater experiments and 100 kPa for in-air experiments. Flexible piezoelectric polyvinylidene fluoride (PVDF) and lead zirconate titanate Pb(Zr,Ti)O3 (PZT) materials were tested for sensing the pressure impulse generated from an explosion. The rise time, peak amplitude, and duration of the blast wave pressure impulse were measured for each piezoelectric material and compared to an OEM blast wave sensor. This study uniquely identifies flexible piezoelectric materials that can accurately measure the blast wave pressure impulse from both in-air and underwater explosions. The accurate response and flexibility of the selected piezoelectric materials demonstrate the potential to be integrated into several forms of sensors, including wearable. Military and industrial applications can potentially benefit from a wearable blast wave sensor to improve medical diagnosis and treatment of blast exposure.

Dynamic performance of a compressible magnetorheological fluid (CMRF) damper with an asymmetric damping performance was examined. Due to the 400°F operational environment , a high-temperature silicone damping fluid was utilized as the base of the CMRF. The CMRF damper valve was designed and optimized using two-dimensional axisymmetric electromagnetic finite element analysis. A secondary piston that incorporates check valves was attached to the CMRF valve, which provides the asymmetry under jounce and rebound. The CMRF damper utilizes a twin tube structure, whereas the space between the inner and outer tubes was used as a high-pressure accumulator for operation at elevated temperatures. Up to a certain temperature, the designed CMRF damper acts as a liquid spring, whereas after certain in-chamber pressure is exceeded, the CMRF damper behaves as a conventional damper. Dynamic characterization of the CMRF damper was performed under sinusoidal excitation for velocities up to 1.27 m/s (50 in/s). This study also examined the CMRF damper under several different environmental conditions including, humidity, salt fog, extreme temperatures and sand exposure. It was demonstrated that the CMRF damper can provide asymmetric and controllable rebound and compression forces. It was also shown that the selected components such as CMRF base fluid, seals and electromagnet wires can withstand the several different operating conditions.

A magnetorheological elastomer (MRE) shock and vibration isolation mount with a semi-active control system was designed, built and tested. The stiffness of the MRE mount can be increased or decreased with respect to a fail-safe stiffness value, based on the control system feedback for effective shock and vibration mitigation. The 12.7mm (0.5") thick MREs of the mount were specifically formulated to achieve a fail-safe static stiffness of the system equal to the legacy mount to be replaced. The magnetic circuit of the mount was designed and optimized using three-dimensional electromagnetic finite element analysis. A control algorithm was developed that detects and differentiates between both shock and vibration events to adjust the MRE mount stiffness properties accordingly to mitigate the event. The control algorithm was developed, incorporated with hardware and tested for functionality. The shock and vibration mitigation performance of the MRE mount with control system was examined via an experimental study. It was demonstrated that the MRE mount and control system mitigates up to 15g shock and 25 Hz vibration events for weights up to 550 lbs attached to the mount. The mount was also tested under various atmospheric conditions (temperature, pressure, relative humidity, water submergence), and no variation in performance of the MRE mount was observed.

In this effort, a reusable Forward Closure System (FCS) prototype was designed, built and tested. The FCS prototype is designed to eliminate pyrotechnic, or fly through rupture; thus, eliminating conditions that produce debris. In addition, the FCS prototype is reusable, providing cost-effectiveness and does not damage the hatch or the hull, during normal and fail-safe operating conditions. Unlike the legacy closures, this FCS is an electromechanically actuated system that syncs with missile launch. The FCS also features a fail-safe mechanism that lets the closure to be opened by the missile nose, while the loads on the missile nose are below the maximum allowable nose tip loads. The FCS was tested for leak tightness and the elastomeric seal toughness was demonstrated. A computer controlled underwater test facility was built to test the FCS prototype for leak tightness, operational pressure, adjacent launch pressure, and cyclical pressure requirements. The underwater test facility is equipped with cameras, instrumentation and is computer controlled to provide visual feedback of system properties underwater. The FCS prototype operation is controlled by a system that communicates with the electromechanical actuators and the position sensors of the closure. The functionality of the control system was demonstrated in a laboratory environment.

A controllable damper that utilizes a friction type magnetorheological gel (MRG) valve and liquid spring technology was designed, built, and characterized under this study. A high-performance MRG material was developed for this damper, where the design space constraints minimized the damper dimensions. Electromagnetic finite element analyses were performed to optimize the controllable and liquid spring valve dimensions. The liquid spring valve utilized shim stacks for asymmetric rebound and compression loading. System modeling was performed where the effectiveness of various control system algorithms in reducing the transmitted acceleration levels were analyzed. The fabricated liquid spring controllable damper was characterized, and then installed on a single degree-of-freedom quarter-car experimental system. The characterization study demonstrated the liquid spring effect, as well as the controllability of the device. The quarter car experiments revealed that the device is more effective in reducing the acceleration levels at relatively higher operating speeds (up to 11 in/s). The device was also tested for spring stiffness at elevated temperatures. It was demonstrated that the liquid spring stiffness changes minimally at high operating temperatures.

This Chapter presents a new unified approach for the flow analysis of magneto-rheological (MR) fluids through channels without using the shear yield stress property of MR fluids. For modeling of MR fluid flow behavior, customarily, a constitutive model, such as a Bingham Plastic or Herschel–Bulkley model, is utilized, both of which depend on the definition of a shear yield stress. However, if the material and geometric characteristic of the wall surface change, different shear yield stress values are obtained. An extensive experimental study is conducted to investigate the relationship between the pressure drop, which is directly proportional to the shear stress, of MR fluids as a function of the applied magnetic field strength, volumetric flow rate, and surface roughness, without utilizing the concept of shear yield stress. This chapter will demonstrate that the shear yield stress is not unique; thus, it is not a material property. The shear yield stress is a system property. A unified method is developed in order to determine the non-dimensional friction factor, which is defined as normalized shear stress, in terms of a modified dimensionless Mason number and dimensionless surface morphology parameters. The modified Mason number incorporates surface morphology effects and surface-independent MR fluid properties. For a given surface morphology, the developed unified method can estimate the friction factor of MR fluid flow with a single curve, similar to a Moody diagram for Newtonian fluids, for all flow rates and magnetic fields that are considered in this chapter, without using a shear yield stress.

A novel CMRF is synthesized from modified silicone oil, containing composite polyurethane microsphere additives, and surface-coated iron particles. The CMRF is designed to act as a liquid spring with controllable damping properties in a damper system. The fluid compressibility is characterized by force/displacement measurements. The addition of composite polyurethane-microspheres increases the strength and compressibility of the fluid. It also decreases the concentration of iron particles needed in order to achieve the same yield stress as commercially available MRF. Surface coating surface of the iron particles with poly(2,3,4,5,6-pentafluorostyrene) via RAFT provides dispersion stability.

A novel compressible magnetorheological fluid (CMRF) has been synthesized with additives that provide compressibility to the fluid. This CMRF has been designed to provide an elastic component to a magnetorheological fluid (MRF) that can be used as a springless damper. CMRF provides controllable compressibility to the MRF. The controllability of the fluid is achieved by the use of magnetic particles and an external magnetic field, and the fluid is made compressible by the addition of suspended compressible polymer particles. The compressibility of the fluid has been characterized with force-displacement measurements. This CMRF has controllable off-state viscosity and high shear yield stress. The incorporation of polymeric particles into the MRF also decreases the settling of iron particles and improves the redispersion of the fluid. To make the fluid more redispersible, the surface of the iron particles is coated with a high-temperature fluorinated polymer. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 3348-3356, 2010

We present a study of powder agglomeration and thermal conductivity in copper-based nanofluids. Synthesis of the copper powders was achieved by the use of three different surfactants (polyvinylpyrrolidone, oleic acid, and cetyl trimethylarnmonium bromide). After careful determination of morphology and purity, we systematically and rigorously compared all three of the surfactants for the production of viable copper-based nanofluids using dynamic light scattering. Our results show that the use of surfactants during synthesis of copper nanopowders has important consequences on the dispersion of the powders in a base fluid. The oleic-acid-prepared powders consisted of small particles of similar to 100 nm that did not change with the addition of dispersant. The CTAB-prepared powders exhibited the best dispersion characteristics, as they formed small particles of approximately 80 nm in the presence of SDBS. The thermal conductivity enhancement in our nanofluids exhibited a linear relationship with powder loading for an average particle size of similar to 100 nm and similar particle size distributions that range from similar to 50 to 650 nm, but independent of crystallite size and with all other factors maintained constant (surface area, surface additives, levels of oxidation) such that a 0.55 vol % loading results in a thermal conductivity enhancement of 22% over water and a 1.0 vol % loading results in a thermal conductivity enhancement of 48% over water. This study is the first to decouple the effect of a carefully characterized particle size distribution using dynamic light scattering versus crystallite size from X-ray line broadening on the thermal conductivity enhancement of a nanofluid.

A novel magnetorheological elastomer (MRE) mount is designed, fabricated, and tested to provide a wide controllable compression static stiffness range for protecting a system with variable payload from external shock and vibration. The shear static stiffness and compression dynamic stiffness were also studied. MRE is a field-controllable material in which the stiffness properties can be altered by changing the applied magnetic field. A MRE mount is developed by using 0.5-inch thick MRE layers and built-in electromagnets. The performance of the 2-layer MRE mount is characterized by compression, shear, vibration, and shock tests. The tests demonstrate that the variable-stiffness MRE mount can be used for shock and vibration isolation applications.

A magnetorheological fluid (MRF) device is designed to provide a static locking force caused by the operation of a controllable MRF valve. The intent is to introduce an MRF device which provides the locking force of a fifth wheel coupler while maintaining the "powerless" locking capability when required. A passive magnetic field supplied by a permanent magnet provides a powerless locking resistance force. The passively closed MRF valve provides sufficient reaction force to eliminate axial displacement to a pre-defined force value. Unlocking of the device is provided by means of an electromagnet which re-routes the magnetic field distribution along the MR valve, and minimizes the resistance. Three dimensional electromagnetic finite element analyses are performed to optimize the MRF lock valve performance. The MRF locking valve is fabricated and tested for installation on a truck fifth wheel application. An experimental setup, resembling actual working conditions, is designed and tests are conducted on vehicle interface schemes. The powerless-locking capacity and the unlocking process with minimal resistance are experimentally demonstrated.

We present an analysis of the dispersion characteristics and thermal conductivity performance of copper-based nanofluids. The copper nanoparticles were prepared using a chemical reduction methodology in the presence of a stabilizing surfactant, oleic acid or cetyl trimethylammonium bromide (CTAB). Nanofluids were prepared using water as the base fluid with copper nanoparticle concentrations of 0.55 and 1.0 vol.%. A dispersing agent, sodium dodecylbenzene sulfonate (SDBS), and subsequent ultrasonication was used to ensure homogenous dispersion of the copper nanopowders in water. Particle size distribution of the copper nanoparticles in the base fluid was determined by dynamic light scattering. We found that the 0.55 vol.% Cu nanofluids exhibited excellent dispersion in the presence of SDBS. In addition, a dynamic thermal conductivity setup was developed and used to measure the thermal conductivity performance of the nanofluids. The 0.55 vol.% Cu nanofluids exhibited a thermal conductivity enhancement of approximately 22%. In the case of the nanofluids prepared from the powders synthesized in the presence of CTAB, the enhancement was approximately 48% over the base fluid for the 1.0 vol.% Cu nanofluids, which is higher than the enhancement values found in the literature. These results can be directly related to the particle/agglomerate size of the copper nanoparticles in water, as determined from dynamic light scattering.

This study presents a new approach for flow analysis of magnetorheological (MR) fluids through channels with various surface topologies. Based on an experimental study an analytical method is developed to predict the pressure loss of a MR fluid as a function of the applied magnetic field strength, volumetric flow rate, and surface topology, without utilizing the concept of shear yield stress. A channel flow rheometer with interchangeable channel walls is built to demonstrate that the pressure loss across the MR fluid flow channel is significantly affected by the channel surface properties. Based on the experimental study it is concluded that a unique shear yield stress cannot be defined for a given MR fluid, since its pressure drop depends on the surface topology of the device. Therefore, a relation for nondimensional friction factor associated with MR fluid channel flow is developed in terms of a modified Mason number and dimensionless surface topology parameters. Using the nondimensional model, the pressure loss for various magnetic fields and volumetric flow rates can be represented by a single master curve for a given channel surface topology without the assumption of a constitutive model for MR fluids. [DOI: 10.1115/1.4003346]

Nanofluids consist of nanoparticles dispersed in heat transfer carrier fluid and are typically used for enhancing thermal conductivity in devices and systems. This study investigated the synthesis of iron and copper nanoparticle-based thermal fluids prepared using a two-step process. Chemical precipitation was used for the synthesis of the powders, and ultrasonic irradiation was used to disperse the nanoparticles in the carrier fluid (ethylene glycol). The size distributions of the nanopowders in the carrier fluid were determined using dynamic light scattering resulting in average particle sizes of around 500 nm. The crystallite sizes of the powders were below 20 nm. Thus, both types of nanofluids are comparable with regard to crystallite size, particle size, and morphology resulting in a direct comparison of material properties and their effect on thermal conductivity of the nanofluids. A guarded hot parallel-plate method and dynamic tests were used to compare the thermal conductivities of the nanofluids. It was shown that thermal conductivity can be enhanced by up to 70% for copper nanofluids. It was also demonstrated that for a given particle concentration, copper nanofluids are superior in thermal conductivity compared to iron nanofluids.

The currently available PEMs are suitable for use at maximum 80C because of the requirement of the presence of water for proton conductivity. However, for emerging applications, a fuel cell operating at temperatures as high as 120 C is required. This can possibly be achieved by creating novel PEMs. Supramolecular polymers are being investigated extensively and may be conjugated with heteropolyacids (HPAs) to prepare high performance PEMs. Metal coordinated polymers, such as: ruthenium or zinc bipyridine polybenzimidazole (PBI) will be synthesized during this project. Self assembled supramolecular structures are formed by the interaction of metal (Ru or Zn) and the nitrogen heterocycle from bipyridine PBI [1]. In addition, hydrophilic – hydrophobic blocks of polymer backbones also create supramolecular interactions, resulting in bi-directional proton conductivity.

Theoretical and experimental studies on heating of a high-torque, multi-plate magnetorheological (MR) fluid limited slip differential (LSD) clutch are presented. A lumped parameter system approach is assumed for theoretical heating analysis. The experimental study is conducted to examine the temperature rise of the clutch. Electric power input and slippage effects are investigated both theoretically and experimentally. The effect of temperature increase on the torque performance of the clutch is also examined. The results show that the transferred torque is insensitive to clutch temperature increase. For all cases, theoretical and experimental results are in good agreement.

in this study the performance of various magneto-rheological (MR) greases in a clutch is examined. An experimental study is conducted to determine the torque transfer capacity of a double-plate clutch for operating speeds up to 1,200 rpm. Six different MR greases with various particle loadings and particle sizes are evaluated in the clutch. The rheological properties of MR grease with 90% particle loading in weight are compared with a commercially available MR fluid. The torque performance of the MR grease clutch is also compared with that of the clutch using MR fluid. It is demonstrated that, the off-state (no applied magnetic field) torque output of the MR grease clutch is constant regardless of the operating speed. In contrast, the torque capacity of the clutch with MR fluid shows a great dependence on the operating speed. Moreover, it is shown that the iron particle size of the MR grease does not affect the torque output. The MR greases demonstrated up to 75% increase in the torque capacity compared to the commercial MR fluid.