Large stable ferroelectricity in hafnium zirconium oxide (HZO) solid solution ultrathin films (including pure zirconia (ZrO 2 ) and hafnia (HfO 2 )) and ZrO 2 /HfO 2 bilayer ultrathin films of thickness ranging from 5–12 nm, prepared by thermal atomic layer deposition or remote plasma atomic layer deposition (RP-ALD) has been demonstrated. Ferroelectric crystallization of the ZrO 2 ultrathin film with high-pressure orthorhombic ( o ) space group Pbc 2 1 could be achieved without post-annealing due to the plasma-induced thermal stresses experienced by the film during the RP-ALD process. In contrast, for the ZrO 2 /HfO 2 bilayer ultrathin film, due to the high crystallization temperature of HfO 2 , post-annealing was needed to achieve sufficient confinement of the sandwiched HfO 2 layer by the ZrO 2 top layer and Si bottom substrate to promote the high-pressure ferroelectric o -phase in HfO 2 . The ferroelectric properties of the HZO ultrathin films prepared by RP-ALD were highly dependent on the Hf-to-Zr ratio — an increasing amount of HfO 2 has been found to be detrimental to the ferroelectricity, mainly due to the high crystallization temperature of HfO 2 . Without post-annealing, the ferroelectricity of the HZO ultrathin films was governed by the relative amounts of the amorphous phase and the ferroelectric o -phase induced by the plasma treatment. While with post-annealing, the ferroelectricity was governed by the relative amounts of the ferroelectric o -phase and the non-ferroelectric monoclinic ( m ) phase.

Inflatable deployable structures are practical and promising candidates for serving various aerospace missions, for instance, as solar sails, antennas, space suits, and especially Lunar and Mars habitats. These structures feature flexible composites folded at high packing efficiency, which can drastically reduce launch costs. However, they can also be damaged due to the harsh extraterrestrial operating conditions, which can propagate to cause catastrophic mission failure and endanger crew safety. Therefore, it is imperative to integrate a robust structural health monitoring (SHM) system, so that damage and faults can be detected for ensuring their safe and reliable operations. While a variety of SHM technologies have been developed for monitoring conventional, rigid, structural systems, they are faced with challenges when used for these unconventional flexible and inflatable systems. Therefore, a flexible carbon nanotube-fabric nanocomposite sensor is proposed in this study for monitoring the integrity of inflatable space structures. In particular, CNT-based thin films were fabricated by spraying and then integrated with flexible fabric to form the lightweight sensor. By coupling fabric sensors with an electrical impedance tomography (EIT) algorithm, the fabric’s distribution of spatial resistivity can be mapped using only electrical measurements obtained along the material’s boundaries. The severity and location of localized pressure and impact damage can be captured by observing changes in the EIT-calculated resistivity maps. They can be embedded in inflatable habitat structures to detect and locate abnormally high pressure regions and impact damage.

This paper describes the design and manufacture of a monolithic high-pressure diaphragm pump made entirely of soft elastomer material and driven by a combustion chamber incorporated within the soft pump structure. The pump can deliver pressures up to 60 kPa and can reach output flows up to 40 ml/min. Methane (CH 4 ) combustion is used as the actuation source. The pump uses two soft flap-structured check valves for directing the flow. Pumping pressure and frequency dependence were measured and analyzed. Results show that controlled and repeatable combustion of methane is possible without damaging the soft structure. Experimentally, 6–10% methane is identified as the ideal air-fuel ratio for combustion. With continuous delivery of reactants, a 1 Hz pumping frequency was achieved. The volume of the combustion chamber and the material stiffness are identified to be major determinants of the stroke volume.

A hydraulic pressure energy harvester (HPEH) device, which utilizes a housing to isolate a piezoelectric stack from the hydraulic fluid via a mechanical interface, generates power by converting the dynamic pressure within the system into electricity. Prior work developed an HPEH device capable of generating 2187 microWatts from an 85 kPa pressure ripple amplitude using a 1387 mm 3 stack. A new generation of HPEH produced 157 microWatts at the test conditions of 18 MPa static pressure and 394 kPa root-mean-square pressure amplitude using a 50 mm 3 stack, thus increasing the power produced per volume of piezoelectric stack principally due to the higher dynamic pressure input. The stack and housing design implemented on this new prototype device yield a compact, high-pressure hydraulic pressure energy harvester designed to withstand 35 MPa. The device, which is less than a 2.54 cm in length as compared to a 5.3 cm length of a previous HPEH, was statically tested up to 21.9 MPa and dynamically tested up to 19 MPa with 400 kPa root-mean-square dynamic pressure amplitude. An inductor was included in the load circuit in parallel with the stack and the load resistance to increase the power output of the device. A previously developed electromechanical power output model for this device that predicts the power output given the dynamic pressure ripple amplitude is compared to the power results. The power extracted from this device would be sufficient to meet the proposed applications of the device, which is to power sensor nodes in hydraulic systems.

High-pressure hydraulic hoses are used throughout industry to transmit fluid power. The current state of the art in hose replacement consists of two strategies; these are (1) replacement upon failure and (2) time-based replacement. For the replacement upon failure method, end users inspect hoses and either replace when there is obvious physical damage or the hose has burst and allowed the release of fluid under high pressure. Hose users that employ time-based replacement cycles often collect data and either subjectively or statistically choose a replacement frequency intended to prevent unexpected failures. Engineers at Eaton Corporation worked with Purdue University to develop an alternative. A novel hose construction using two conductors with an isolating layer provides a component in an electrical circuit which can be monitored to determine the status, or health, of a hose in operation. The first step in this development was the realization that hose failure is a process and not an event. By tracking a hose’s electrical signature and characterizing the change that occurs when the internal structure begins to break down, a user is alerted prior to a catastrophic hose failure. Eaton is developing notification systems capable of both monitoring the hose’s electrical signature and alerting an equipment user prior to unexpected failure. The system requires direct electrical connection to the hose fitting for monitoring. There are currently two strategies in development, a wired system and a wireless system. The wired system uses a remote diagnostic unit with cables running to each hose assembly to query the hose and alert an equipment user directly. The wireless system employs battery-powered sensors installed on a hose assembly which communicate with a gateway located nearby. When a hose approaches its end of life a warning is issued by illuminating a warning light or issuing a remote warning through a cellular or wireless network. There are significant gains in the ability to prevent hydraulic hose failures. These unexpected incidents lead to downtime, damage to equipment, environmental damage, and serious personal injury. Additionally, using this advanced warning system allows users to use nearly a hose’s entire life. This improves asset utilization considerable when compared to the useful life sacrificed by using time-based replacement schedules. This technology will reduce operating costs and prevent downtime, environmental incidents, and the threat of personal injury present when hydraulic hose fails.

Dual stage hydrogen compressor with high pressure compression ability can operate efficiently using geothermal, low temperature solar, waste energy as well as combination of these energy sources. In this study, a dual stage thermal compressor system for hydrogen compression was investigated using three different hydrogen storage materials: LaNi 5 , Ca 0.6 Mm 0.4 Ni 5 and Ca 0.2 Mm 0.8 Ni 5 . Compression ratio of Ca 0.2 Mm 0.8 Ni 5 was found to be 56% and 14.7% higher than those of LaNi 5 and Ca 0.6 Mm 0.4 Ni 5 respectively, for single stage thermal compressor system with inlet supply pressure of 600 psig. On the other hand, compression performance of Ca 0.2 Mm 0.8 Ni 5 was similar to that of LaNi 5 at low supply pressure (e.g. 200 psig) condition. In this paper, a dual stage hydrogen compressor system with LaNi 5 in first stage and Ca 0.2 Mm 0.8 Ni 5 in second stage is proposed for high pressure hydrogen compression based on the experimental results of single stage system. Results show that 53% higher compression ratio can be attained using dual stage hydrogen compressor when appropriate storage materials are selected for two stages.

One of the most compliant structures in aerospace applications that does not suffer from certification constraints is plain honeycomb. It is widely used in primary and secondary structure of FAR 23/25 certified aircraft. In this research, the compliant nature of this material is being exploited by inserting pouches in each of the honeycomb cells. Pressurizing these pouches results in a stiffening of the overall structure. By having an external (spring) force act on the honeycomb structure, this variable stiffness results in an overall deformation of the honeycomb. Strains in excess of 50% can be achieved through this mechanism without encountering the material (yield) limits. It can be shown that based on the maximum pressure that can be extracted from the High-Pressure Compressor in a typical jet engine, the energy density of pressure adaptive honeycomb is on the par with that of shape memory alloy, while exhibiting strains that are an order of magnitude larger at a transfer efficiency that is close to 1. The paper discusses the mechanics of pressure adaptive honeycomb and describes a simple reduced order model that can be used to simplify the geometric model in a finite element environment. The theory that underpins this reduced order model is shown to correlate well to experimental tests. In addition, a proof-of-concept application is presented where pressure-adaptive honeycomb is integrated over the aft 35% of a wing section. It is demonstrated that camber variations in excess of 5% can be generated by a pressure differential of 40kPa. Results of subsequent wind tunnel test show an increase in lift coefficient of 0.3 at a wind speed of 45kts across an angle of attack ranging from −6° to +20°.