This paper presents the mechanical design and modeling of an active segment of a bioinspired piezocomposite aquatic pump. The design and analysis is based on an electromechanical Euler-Bernoulli beam model. The self-contained propulsion/pumping system is composed of a series of piezo-active soft cymbal-like segments that are connected by passive soft films. By applying coordinated excitations for expansion and contraction to different active segments, the design creates a traveling wave along the pump axis, which in return propels the fluid to generate a unidirectional thrust force. In the model, the insulation and mechanical properties of the waterproofing sealant layer are considered. Using the proposed electromechanical model, a parametric analysis is conducted to understand the effectiveness of the cymbal-like piezocomposite active segment. Two performance metrics are considered, including the area change of the enclosed by the cymbal-like segment, and the work done by the actuators. The optimal structural parameters of the piezocomposite pump are decided by these performance metrics.

We propose a planar hydrogel-based micro-valve design which is modeled as a library element for Matlab Simulink. For this test case, a pressure pump (voltage source) in series with a micro-valve model (variable fluidic resistance) is built up. The micro-valve subsystem is separated in four main parts. Based on the applied temperature stimulus, the equilibrium length is determined according to an experimentally verified fit function. Furthermore, the equilibrium length considers a static hysteresis effect which is modeled in analogy to the saturation of magnetization in electric transformers. In a second step, the transient behavior follows a first order differential equation, but the cooperate diffusion coefficient is size dependent affecting the rise time of the system. This causes a faster swelling than deswelling of the hydrogel. In the third section, the stiffness property is implemented to calculate the maximum sealing pressure and the resulting gap between the hydrogel and the wall. The fluidic resistance of the micro-valve considers a three-dimensional geometry and is calculated based on a look-up table, extracted from a fluid-structure-interaction (FSI) model generated from a finite element structure. The proposed model allows a full description of the fluidic hydrogel-based micro-valve and is part of an upcoming microfluidic toolbox for Matlab Simulink containing passive elements and optional chemical reactions like mixing fluids and enzyme reactions for future applications.

This paper investigates the optimal geometric parameters for a bioinspired peristaltic piezocomposite pump with the use of an electromechanical Euler-Bernoulli beam model. The peristaltic pump is a self-contained propulsion system involving a series of piezo-active soft cymbal-like segments that are connected with passive soft connective segments. A series of phased excitations in expansion and contraction applied to different active segments of the channel create a traveling wave along the axis of the channel, which in return “propels” the fluid in one direction. A parametric analysis, based on the Euler-Bernoulli beam model, is conducted to improve the effectiveness of the cymbal-like piezocomposite actuators. Area change of the cymbal-like actuators, which is correlated to the propulsion power, is studied based on the analysis of the moment, curvature, and area change due to excitation. Area change is also used to evaluate the effectiveness, and to decide the optimal geometric parameters of the piezocomposite actuators.

Squid are the fastest aquatic invertebrates through jetting locomotion. This done through a mantle that quickly compresses an internal fluid, forcing fluid out through a funnel. The squid mantle has a complex collagen fiber and muscular system and squid propulsion is primarily done through circumferential muscles (90°) contracting around the mantel, forcing fluid out of the mantel. However, jetting is also increased through elastic energy stored in the helically-wound IM-1 collagen fibers, which have been measured between 28° to 32° in different species of squid. Inspired by the muscular and collagen fiber configuration found in the squid mantel, new composite pumps with active fibers oriented at precise angles around a cylindrical tube are proposed. An analytical model of the active fiber composite pump is developed. Results show that maximum pumping power and efficiency is achieved with a wind angle of 90° and a matrix modulus that is equal to the fiber modulus.

A novel bridged-microfluidic for cell-based assays was developed by combining a microstructured optical fiber (MOF) with a microfluidic network with the purpose of continuously monitoring the state of hepatocellular carcinoma (HepG2) cells. In this configuration a solid core MOF with channels in the cladding serves as a bridge for cell transport as well as an evanescent wave-based monitoring system to detect cells labeled with fluorescent nanomaterials. The device was fabricated by positioning an MOF to bridge two polydimethylsiloxane (PDMS) microfluidic networks. Alignment strategies and pressurization considerations to produce this system are presented. Pump systems that support fluid transport through the MOF demonstrated the tendency of flow rate fluctuations even for constant microfluidic pump rates. Spectroscopic measurements confirm the delivery and motion of cells between the two neighboring microfluidic chips. The linewidth of the spectra demonstrated oscillations that were consistent with pressure broadening caused by hydrodynamic fluctuations. Fluctuations in the microfluidic flow ranging from 0.005 to 0.016 Hz were observed. These results are consistent with theoretical principles and provide important information regarding syringe pump artifacts, i.e. fluctuations, observed during spectroscopic measurements in MOF/microfluidic systems.

Inspired by the fibrillar network in plant cell walls and the helical fibers found in soft bodied hydrostats (e.g. worms, squid, elephant trunks, and octopus arms), fluidic flexible matrix composites (F2MCs) are composite tubes that consist of multiple layers of oriented, high performance fibers, such as carbon, precisely placed in a flexible matrix resin to form high-mechanical advantage actuators and variable stiffness materials. Unique to the F2MC tube is its ability to generate high pressures and volume change with a small external load as a result of the stiff reinforcement fiber orientation in the wall of the tube and the soft supporting elastomer. When a load is applied to the tubes, the volume of the composite pump is reduced and fluid is forced out of the tube by the reinforcing fibers. The objective of this research is to design, fabricate and characterize F2MCs for use in wave energy conversion where ocean waves provide the axial load to drive fluid through the pumps. F2MCs pumps are tested in a water basin and mechanically cycled between 0 Hz and 2 Hz at up to 17 percent strain. Instantaneous input power is found by measuring the displacement and applied force to the actuators, while output power values are derived from pressure and flow rate measurements at the tube outlet. From these measurements the actuator efficiency is subsequently determined.

Fluidic artificial muscles have the potential for a wide range of uses; from injury rehabilitation to high-powered hydraulic systems. Their modeling to date has largely been quasi-static and relied on the operator to adjust pressure so as to control force output and utilization while little work has been done to analyze the kinematics of the driving-systems involved in their operation. This paper utilizes an established electro-hydraulic model to perform a study of the components of a fluidic artificial muscle actuated climbing robot. Its purpose is to determine the effect of the robotic subsystems on function and efficiency for a small-scale system in order to extrapolate more general design and analysis schemes for future use. Its results indicate that important aspects to consider in design of the hydraulic system are system payload, operating pressure, pump selection, and FAM construction.

This article exploits nonlinear modal interactions, namely, a two-to-one internal resonance energy pump to improve the steady-state bandwidth of vibratory energy harvesters. To demonstrate the enhanced performance, an L-shaped cantilevered structure laminated with a piezoelectric patch and augmented with frequency tuning magnets is considered. The magnets serve to adjust the first two modal frequencies of the structure such that the second modal frequency is twice that of the first mode activating a nonlinear energy transfer mechanism. The structure is then subjected to a harmonic excitation with a frequency close to the first modal frequency of the structure. The voltage frequency-response curves are generated for different excitation levels, illustrating an improved bandwidth and output voltage over a case involving no nonlinearly-interacting modes.

Fluidic artificial muscles have the potential for a wide range of uses; from injury rehabilitation to high-powered hydraulic systems. Their modeling to date has largely been quasi-static and relied on the operator to adjust pressure so as to control force output and utilization while little work has been done to date to analyze the kinematics of the driving-systems involved in their operation. This paper establishes a combined electro-hydraulic model of a fluidic artificial muscle actuated climbing robot to establish a method for studying the relationships between muscle size, robot size and function, and system design. The study indicates a strong relationship between appropriate system component selection and not only system efficiency but individual component effectiveness. The results of the study show that robot mass, operating pressure, muscle size, and motor-pump selection have noteworthy impacts on the efficiency and thereby longevity of the robot for performing its task.

The reduction of consumption and emissions is a key factor in modern vehicle design. The overall vehicle efficiency is pursued in several ways, including the reduction of consumption of the auxiliary devices (e.g. water pumps, oil pumps, vacuum pumps etc.). In this paper, using two different smart materials (i.e. magnetorheological fluids and shape memory alloys) a device aimed at disengaging the vacuum pump was developed. The conceived device is composed of a magnetorheological (MR) clutch excited by permanent magnets coaxially manufactured with a sliding spline sleeve moved by shape memory alloys (SMA) springs. In the MR clutch, the magnet can move under the effect of a passive pneumatic system. The magnetic field in the fluid varies with the magnets displacement and two steady positions are possible: the engaged clutch (ON) and the disengaged clutch (OFF). The torque in the ON configuration is high enough to drive the vacuum pump during normal operating conditions, whereas the low torque value in the OFF condition guarantees power saving up to 150 W. In particular operating conditions (i.e. at low environmental temperatures) the torque necessary to start the vacuum pump may exceed the maximum transmissible torque of the MR clutch. For this reason a sliding spline sleeve, led by two SMA springs which counteract the force of two traditional springs was developed. A dummy plain sliding sleeve with SMA and conventional springs was numerically developed and tested. The fairly good agreement of the results confirmed the feasibility of the combined SMA/MR device.

Dielectric electro-active polymer (DEAP) technology holds promise enabling lightweight, energy efficient and scalable sensors and actuators [1]. The circular DEAP configuration (also known as cone or diaphragm actuator) in particular shows potential in applications such as pressure or weight sensors [2, 3], pumps [4, 5], valves, micro-positioners and loudspeakers [6]. The geometric parameters of the circular DEAP dictate the stroke and work output performance of actuators and the sensitivity as well as the resolution of sensors. The scalable geometric design allows DEAP actuators and sensors to be adapted to a variety of different applications. This paper presents a rapid prototyping technique and experimental characterization of DEAP actuators with various geometries. The DEAP’s consist of a silicone based elastomer and a carbon ink based electrode held together with a rigid frame. The rapid prototyping utilizes high resolution 3D printing technology to manufacture various shaped framing structures designed with computer aided design (CAD) software. The framing structure defines the DEAP geometry resulting in quick prototyping of various DEAP shapes and sizes. After prototyping, these DEAP’s are tested for mechanical and electrical properties while loaded mechanically and electrically (constant voltage and constant force test). The measurement results for the different size actuators are then documented and compared. The measurements reveal that for increased size of the manufactured actuators, there is a linear increase in force and stroke output. This information allows us to predict the actuation performance and will be used for future modeling efforts.

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.

Dielectric Elastomers (DEs) are a very promising technology for the development of energy harvesting devices based on the variable-capacitance electrostatic generator principle. As compared to other technologies, DE Generators (DEGs) are solid-state energy conversion systems which potentially feature: 1) large energy densities, 2) good energy conversion efficiency that is rather independent of cycle frequency, 3) easiness of manufacturing and assembling, 4) high shock resistance, 5) silent operation, 6) low cost. Envisioned applications for DEGs are in devices that convert ocean wave energy into usable electricity. This paper introduces the Lozenge-Shaped DEG (LS-DEG) that is a specific type of planar DE transducer with one degree of freedom. A LS-DEG consists of a planar DE membrane that is connected along its perimeter to the links of a parallelogram four-bar mechanism. As the mechanism is put into reciprocal motion, the DE membrane varies its capacitance that is then employed as a charge pump to convert external mechanical work into usable electricity. Specifically, this paper describes the functioning principle of LS-DEGs, and provides a comparison between different hyper-elastic models that can be used to predict the energy harvesting performances of realistic prototypes. Case studies are presented which address the constrained optimization of LS-DEGs subjected to failure criteria and practical design constraints.

State-of-the-art hydraulic hose and piping systems employ integral sensor nodes for structural health monitoring in order to avoid catastrophic failures. These systems lend themselves to energy harvesting for powering sensor nodes. The foremost reason is that the power intensity of hydraulic systems is orders of magnitude higher than typical energy harvesting sources considered to date, such as wind turbulence, water flow, or vibrations of civil structures. Hydraulic systems inherently have a high energy intensity associated with the mean pressure and flow. Accompanying the mean pressure is what is termed dynamic pressure ripple caused by the action of pumps and actuators. Pressure ripple is conducive to energy harvesting as it is a deterministic source with an almost periodic time domain behavior. Pressure ripple generally increases in magnitude with the mean pressure of the system, which in turn increases the power that can be harvested. The harvested energy in hydraulic systems could enable self-powered wireless sensor nodes for applications such as energy-autonomous structural health monitoring and prognosis. An energy harvester prototype was designed for generating low-power electricity from dynamic pressure ripples. The prototype employed an axially-poled off-the-shelf piezoelectric stack. A housing isolated the stack from the hydraulic fluid while maintaining mechanical coupling to the system to allow for dynamic pressure induced deflection of the stack. The system exhibits an attractive off-resonance energy harvesting problem since the fundamental resonance of the piezoelectric stack is much higher than the frequency content of ripple. Although the energy harvester is not excited at resonance, the high energy intensity of the ripple results in significant electrical power output. The prototype provided a maximum output of 1.2 mW at 120Ω. With these results, it is clear that the energy harvester provides non-negligible power output suitable for powering sensors and other low power components. This work also presents electromechanical model simulations for predicting the piezoelectric power output in terms of the force transmitted from the pressure ripple as well as experimental characterization of the power output as a function of the force from the ripple.

Smart Material Hydraulic Actuators (SMEHAs) allow high-energy-density materials, such as piezoelectrics and magnetostrictives, to be used to develop compact, high-power actuators. Hydraulic rectification using check valves converts the high-frequency, small-displacement motion of a smart material to large displacements of a hydraulic actuator. In this paper, the performance of a magnetostrictive actuator is evaluated over a range of input frequencies and loading conditions and compared to model results of the overall system. The system’s dynamic performance is found to depend highly on the response of both the check valves used to rectify the motion of the smart material driver and the fluid system, including the passages connecting the smart material pump to the output hydraulic cylinder. Using AMESim, a model is developed for the response of the system and compared to experimental results.

According to U.S. Nuclear Regulatory Commission (NRC) Generic Letter 2008, the gas accumulation in the nuclear emergency core cooling systems is concerned since it may critically damage pipes, pumps and valves. There is a need to detect the inside gas accumulation including the quantification of gas location and volume. In this paper, we propose a in-situ technique for gas detection in a gas tank by using Lamb waves. Lamb wave propagation in a plate-like structure is affected by the boundary conditions. For structures in air or submerged in liquid, wave propagations are different. When the structure is in contact with liquid such as water, wave energy leaks into it from the solid material. Therefore, the way of gas detection is related to the detection of change in wave propagation characteristics. Experimental tests in a steel water tank were conducted and shown the Lamb wave’s response to the water presence. Theoretical study of Lamb waves propagation on a free plate in air and on a plate with one surface submerged in liquid were then conducted and compared. Further investigation to understand the change in Lamb wave propagation when water is present was conducted with frequency-wavenumber analysis. In the frequency-wavenumber space, it was found that a new plate wave mode, quasi-Scholte wave showed up. A0 Lamb mode showed a decreased propagation while S0 Lamb wave showed no changes. The change in the Lamb wave propagation is found to be frequency dependent.

An analytical model of a composite structure consisting of an F 2 MC tube embedded in epoxy is used to study the impact of confining structural media on the ability of F 2 MC tubes to pump fluid and change stiffness. The surrounding stiff epoxy reduces the performance relative to an isolated F 2 MC tube, but this disadvantage can be minimized by tailoring the tube wall thickness and fiber angle. The composite can pump 250 times more fluid than a piston of the same diameter if the F 2 MC tube has a thick shell wall and a near-axial fiber orientation. With a moderately thick wall and low fiber angle, the closed valve axial stiffness can be increased by a factor of 2.2 relative to the open valve stiffness. The maximum pumping factor and modulus ratio, however, are 80% and 2.6% of the F 2 MC tube without the surrounding epoxy.

The concept of self-healing materials has gained widespread acceptance in the research community. Over recent years a diverse array of bio-inspired self-healing concepts, from solid-state diffusion to liquid-phase healing in a broad range of engineering materials, embracing ceramics, polymers and fibre reinforced polymer composite materials have been proposed in the open literature. In this research study the liquid-phase healing of operational damage, namely impact damage, is being addressed. The challenge of self-healing advanced fibre reinforced polymer composites is ensuring healing success without degrading the host composite’s performance, a problem not encountered in the self-healing of generic polymeric systems. In the genre of self-healing fibre reinforced composite materials, autonomous healing has been undertaken by a healing medium already located within the damage zone and released through the damage site either passively or actively through human invention. This approach requires the ‘engineering’ control of the storage medium’s toughness for release and the development of bespoke resin chemistries to be compatible with the manufacturing route, to remain active whilst latent and then to recover full mechanical performance once a damage event occurs. This study has generated a proof of concept whereby the healing medium is only deployed to the damage site once a sensor has been triggered. In essence this study aims to develop stimuli triggered deployment of a healing medium held remotely in a storage reservoir to repair impact damage to a composite material. The principle of the concept is revolves around the ability of a reservoir to deliver a healing medium to a damage site via a network of vessels contained in the centerline of the composite laminate. A Labview controlled peristaltic pressure rig containing the reservoirs for the resin and hardener, their independent pumps, pressure gauges, control switches and indicators was developed. Through the application of an impact event successfully deliver and subsequent healing of the damage event was achieved showing the potential of this concept for minimising parasitic mass and maximising healing potential in fibre reinforced composite materials.

In this paper, a pre-stressed piezoelectric unimorph made by a new fabrication method in room temperature, and an active vibration isolation system using the pre-stressed unimorph actuators are introduced. The fabricated piezoelectric unimorph, called PUMPS (piezoelectric unimorph with mechanically pre-stressed substrate), is an actuator in which actuation level is enhanced by displacement amplification mechanism that converts piezoelectric extension and contraction to large bending/pumping motion without sacrificing the actuation force. Preliminary vibration tests were performed to check the performance of PUMPS as actuators for active vibration control in a lab environment. Two feedback control schemes, the positive position feedback (PPF) and negative velocity feedback (NVF), were applied for active vibration control. Using a smart vibration isolation system with improved load capacity obtained by stacking pre-stressed piezoelectric unimorph actuators, about 10dB vibration reduction of the system was achieved near the resonant frequency region. With the preliminary vibration test results showing promising performance of PUMPS actuator in active vibration control, an integrated active vibration isolation system composed of PUMPS actuators is developed. The developed system contains compact analogue circuits and a sensor for PUMPS actuation and control, and power is supplied by Li-Polymer battery which means the system is completely standalone and portable. In addition, an integrated jitter isolation demonstration system was developed to demonstrate the degrading effect of jitter and the effectiveness of the developed integrated active vibration isolation system in improving the performance of optical payloads. Comparison of image qualities taken before and after the operation of vibration control system indicates that effective suppression of vibration disturbances can be achieved using the developed vibration isolation system with PUMPS actuators.

Piezoelectric actuators operate when the electric field (voltage) is applied to them. This piezoelectric behavior is defined using piezoelectric strain coefficients which are generally assumed to be constant. However, when high electric fields are applied to the piezoelectric actuators the piezoelectric strain constant may increase up to more than twice of the nominal value and, thus, cannot be considered as a constant value. Besides, in case of the pre-stressed piezoelectric unimorph actuators, the stress conditions inside piezoelectric actuators can affect piezoelectric behaviors. For reasons mentioned above, actuation performance of PUMPS actuator, which is one of the pre-stressed piezoelectric actuators developed by present authors, cannot be predicted accurately without consideration of piezoelectric nonlinearities such as voltage and stress effects. Generally, the piezoelectric behavior is mainly affected by the piezoelectric strain coefficient and the elastic modulus. Therefore, the voltage and stress effects on the piezoelectric strain coefficient and the elastic modulus of piezoelectric layer were investigated, and the results were used for prediction of actuation performance of PUMPS. Taking the nonlinear material properties of the piezoelectric layer into account, the actuation performance of PUMPS was accurately predicted in this study.