Masami Nakano

Tohoku University | Tohokudai · New Industry Creation Hatchery Center

Shape memory alloy (SMA) wires are one of the widely used materials for soft artificial muscles. However, SMA artificial muscles have two problems, including limited load holding ability due to their soft nature and slow response due to their long cooling time. The main contributions of this article are the developments of a controllable magnetorhe...

This study reports the development of a Magneto-Rheological Foam, which consists in a porous matrix filled by ferromagnetic particles. The porous matrix of such a composite being easily deformable, large magnetic properties changes are expected. The measurements of the magnetic properties of such a Magneto-Rheological Foam submitted to a compressiv...

The paper is concerned with a partly analytical, partly numerical study of acoustic trapped modes in a cylindrical cavity (expansion chamber), placed in between two semi-infinite pipes acting as a waveguide. Trapped mode solutions are expressed in terms of Fourier–Bessel series, with the expansion coefficients determined from a determinant conditio...

Traditional MR seat suspension without stiffness control is not able to avoid the resonance between the excitation and the seat, though it can dampen the vibration energy. To solve this problem, this paper proposed a variable stiffness (VS) magnetorheological (MR) damper to implement an advanced seat suspension. Its natural frequency can be shifted...

The group of active suspensions with controllable actuating force is noted with their excellent performance in reducing vibrations, however, their demanding requirements for high power consumption and high cost as well as the highly potential instability issue have hindered their practical usage. Semi-active suspensions with controllable stiffness...

Magneto Rheological Elastomers (MREs) are composite materials based on an elastomer filled by magnetic particles. Anisotropic MRE can be easily manufactured by curing the material under homogeneous magnetic field which creates column of particles. The magnetic and elastic properties are actually coupled making these MREs suitable for energy convers...

The particle sedimentation of the dispersed particles in magnetorheological (MR) fluids when off-working has been a challenging problem, causing adverse effect to their practical applications. In order to solve this problem, ‘MR fluid porous composite’ made of porous materials impregnated with MR fluid has been fabricated in this work. Its effect t...

Base isolator is one of the most adopted and effective means of mitigating unwanted and harmful vibrations to protect buildings and other key civil infrastructure from seismic events. For this reason, the base isolation technology has advanced greatly in recent years, especially the magnetorheological elastomer (MRE) isolator. However, the operatio...

The present purpose is to reveal the mechanism of a flying pipe from an aerodynamic point of view. At first, we conduct field observations of a flying pipe using a pair of high-speed video cameras, together with three-dimensional motion analyses. In addition, we conduct numerical analyses by a finite difference method based on the MAC scheme. As a...

The noise and vibration effects of rails can have a significant impact on the environment surrounding the railways. Rail dampers are elements that are attached to the sides of the rail and can improve the track decay rate of rail and then enhance the rails’ ability to attenuate noises and vibrations. However, in practical applications, the most eff...

Magnetic microspheres in a concentrated suspension can be self-assembled to form chain structures under a magnetic field, resulting in an enhanced viscosity and elasticity of the suspension (i.e., the magnetorheological (MR) effect). Recently, interest has been raised about the relationship between nonspherical particles, such as octahedral particl...

A model of structured Magneto-rheological Elastomer made of a soft matrix filled by magnetic particles was studied for energy harvesting, in pure shear condition. The particles were supposed to be aligned in a chain along which the magnetic field is applied and considering a shear strain applied in a plane perpendicularly to the chain. As the strai...

The present purpose is to reveal the mechanism of a flying pipe from an aerodynamic point of view. At first, we conduct field observations of a flying pipe using a pair of high-speed video cameras, together with three-dimensional motion analyses. In addition, we conduct numerical analyses by a finite difference method based on the MAC scheme. As a...

The generation of sound by flow through a closed, cylindrical cavity (expansion chamber) accommodated with a long tailpipe is investigated analytically and numerically. The sound generation is due to self-sustained flow oscillations in the cavity. These oscillations may, in turn, generate standing (resonant) acoustic waves in the tailpipe. The main...

The work is concerned with an analytical study of acoustic trapped modes in a cyhndrical expansion chamber, placed in between two semi-infinite pipes (waveguides). Trapped mode solutions are expressed in terms of Fourier-Bessel series, with the expansion coefficients determined from a determinant condition. The roots of the determinant, expressed i...

This study investigated and evaluated a semi-active tuned mass damper which incorporated four multi-layered structures fabricated using magnetorheological elastomers. The four magnetorheological elastomer structures formed a square and provided the tuned mass damper variable stiffness used to track the excitation frequencies. This design not only i...

The present aim is to reveal the mechanism of a flying pipe from an aerodynamic point of view. At first, we conduct field observations of a flying pipe using a pair of high-speed video cameras, together with three-dimensional motion analyses. In addition, we conduct numerical analyses by a finite difference method based on the MAC scheme. As a resu...

Magneto-rheological (MR) elastomers contain micro-/nano-sized ferromagnetic particles dispersed in a soft elastomer matrix, and their rheological properties (storage and loss moduli) exhibit a significant dependence on the application of a magnetic field (namely MR effect). Conversely, it is reported in this work that this multiphysics coupling is...

MagnetoRheological Elastomers (MREs) have been widely used for actuation purposes in numerous applications (e.g., vibration damping), thanks to their magnetic-field controllable shear modulus. Nevertheless, the converse effect, namely, the modification of the magnetic properties through the application of a shear strain or stress has been barely st...

This paper proposes a self-powered magnetorheological (MR) seat suspension on the basis of a rotary MR damper and an electromagnetic induction device. By applying the self-powering component to the MR seat suspension, the operation cost of the semi-active seat is much cheaper because no external energy is required to control the MR damper. In this...

In this study, anisotropic magnetorheological elastomers with 0% and 15% weight fractions of silicone oil were fabricated under a magnetic field that was rotated with a 45° angle so that the iron particle alignment inside the magnetorheological elastomer was 45° to the direction of flat magnetorheological elastomer. Scanning electron microscopic im...

Simultaneous observations of the electro-rheological (ER) effect and flow behavior within micro-gap were performed for a nano-suspension based on nano-particles of titanium dioxide and a chemically modified silicone oil stored for a long time. The ER effect and flow behavior in the presence of sinusoidal electric field simultaneously observed were...

A rotational brake working with shear thickening fluid (STF) was designed and tested in this study. With the optimisation in design, most of the STF in the brake can receive the same shear rate when the brake rotates. The parts of this brake were fabricated with a 3D printer and then assembled manually. Three types of STFs with various carrier flui...

We have presented the first direct observation of electric field induced rotation of epoxy based polymer rotors. Polymer disks and gears were prepared in few micrometer dimensions as rotors. Electrorotation of these sub-millimeter sized tools was studied under uniform DC electric field. The rotational speed of micron-sized polymer rotors can be con...

To reveal the mechanism of a flying pipe, we conduct field observations of the flying pipe in rotation using a pair of high-speed video cameras, together with 3D motion analyses based on their recorded images. Moreover, we attempt numerical analyses. As a result, the field observations show the statics of flying-pipe aerodynamics for both commercia...

The paper is concerned with the generation of sound by the flow through a closed, cylindrical expansion chamber, followed by a long tailpipe. The sound generation is due to self-sustained flow oscillations in the expansion chamber which, in turn, may generate standing acoustic waves in the tailpipe. The main interest is in the interaction between t...

This paper reports an isolator whose damping and stiffness can be simultaneously controlled by magnetorheological (MR) fluids and MR elastomers. A hydraulically actuated MTS machine was used to test this variable stiffness and damping isolator after its prototype. The field-dependent responses including stiffness variability and damping variability...

In order to develop of MR fluid of extremely low no-field viscosity and higher operating temperature, we have fabricated novel "dry MR fluids", and have measured and evaluated the fluidity and MR properties. The dry MR fluid is a novel MR fluidic powder, which is mainly composed of micron-sized carbonyl iron particles coated with nano-sized particl...

Quincke rotation is the rotation of non-conducting objects immersed in dielectric liquid and subjected to a strong homogenous DC electric field. The rotation is spontaneous when the field exceeds a threshold value. In this research, for the purpose of developing a micro motor utilizing the Quincke rotation, polymer composites have been developed as...

Behavior of magnetic fine particles in a MR fluid in the presence of magnetic field was investigated using the hybrid method of .HSMAC method and discrete particle method. Simple shear flows of MR fluid between two parallel plates were calculated when magnetic field perpendicular to the flow direction was applied. Many chain-like clusters are forme...

A magnetic field applicable MR fluid shear flow device consisting of circular gap between rotational and fixed disks has been developed to visualize the formation and breaking behavior of the particle cluster or column in shear flow mode of MR fluids under relatively strong magnetic field up to about 0.8 T. The closed magnetic circuit with less mag...

MR (Magnetorheological) fluids are the suspensions composed of micron-sized ferromagnetic particles dispersed into carrier oil, and are one of smart fluids which can be changed their rheological properties in reversible manner by applying magnetic field. From the viewpoint of the applications, the no-field initial viscosity of the MR fluids should...

We have presented the first direct observation of electric field induced rotation of epoxy based polymer rotors. Polymer disks, hollow cylinders and gears were prepared in few micrometer dimensions as rotors. Electrorotation of these sub-millimeter sized tools was studied under uniform dc electric field. The effects of shape, size and thickness wer...

Magnetorheological (MR) fluids are suspensions of micron-sized magnetic particles dispersed into carrier oils, and behave like a Bingham fluid with magnetic-field responsive yield stress. In this research, bidisperse MR suspensions consisting of micro (6.6 μm) and nano (110 nm) iron particles dispersed into silicone oil were fabricated to investiga...

Electro-rheological (ER) nano-suspensions based on titanium dioxide nano-particles with particle diameter around 400 nm and a chemically modified silicone oil with a viscosity of 0.04 Pa·s were prepared. Microgap flow behavior in the absence of an external electric field and the ER responses were investigated in relation to the microstructure obser...

Protecting civil engineering structures from uncontrollable events such as earthquakes while maintaining their structural integrity and serviceability is very important; this paper describes the performance of a stiffness softening magnetorheological elastomer (MRE) isolator in a scaled three storey building. In order to construct a closed-loop sys...

We propose a novel control algorithm for hydrogen ventilation, utilizing a dynamic restriction mechanism for the upper limit of exhaust flow rates, extending the real-time sensing-based forced ventilation control algorithm of leaking hydrogen we proposed previously for a partially open space. This upper limit is determined using a correlation betwe...

The paper is concerned with the generation of sound by the flow through a closed, cylindrical expansion chamber, follower by a long tailpipe. The sound generation is due to self-sustained flow oscillations in the expansion chamber which, in turn, may generate standing acoustic waves in the tailpipe. The main interest is in the interaction between t...

Adaptive tuned vibration absorbers (ATVAs) featuring magnetorheological elastomers (MREs) have attracted considerable research interests because of the advantages of fast response, controllable frequency, and broad working range. Generally, the ATVA uses single layer of MRE sheet, which has some issues such as small oscillator stroke and being effe...

Magnetorheological shear thickening fluid is a smart material that exhibits both magnetorheological and shear thickening effects. This study focuses on the design and development of a novel magnetorheological shear thickening fluid-based linear damper. First, micron-sized carbonyl iron particles, at a 20% and 80% weight fraction, were immersed amon...

This paper is a study of the effect that temperature has on a shear thickening fluid made from ethylene glycol and fumed silica, with 20%-26% weight fractions. Three typical temperatures, ranging from 20°C to 60°C, were selected to study the shear rate dependence of viscosity. The temperature tests showed that a high temperature increased the criti...

Magnetorheological elastomers (MREs) are being used more and more for the development of isolators and absorbers to attenuate vibrations. In this study, four innovative multilayer MRE isolators with negative changing stiffness characteristics are prototyped for horizontal vibration reduction of a seat. For each MRE isolator, a magnetic system consi...

A TF (transfemoral) prosthesis with MR-SPCOM (MR (Magneto-Rheological) fluid brake-Stance Phase Controlled by Optional Motion) knee joint has been designed and developed, which mainly consists of a variable resistance knee joint with a developed MR fluid brake and a developed load cell detecting the wearer’s optional motions. The optional motions m...

An evaluation and training system of muscle strength for leg rehabilitation has been developed by using a new conceptual loading machine. This loading machine, which is called MR fluid active loading machine, mainly consists of a newly designed magneto-rheological (MR) fluid clutch and a reversible induction motor. The MR fluid clutch produces pass...

Magnetorheological (MR) fluids are suspensions of micron-sized magnetic particles dispersed into carrier oils, and behave like a Bingham fluid with magntic-field responsive yield stress. In this research, bidisperse MR suspensions consisting of micro (6.6 μm) and nano (110 nm) iron particles dispersed into silicone oil were fabricated to investigat...

This study investigates the suppression of the sound produced when a jet, issued from a circular nozzle or hole in a plate, goes through a similar hole in a second plate. The sound, known as a hole tone, is encountered in many practical engineering situations. The mean velocity of the air jet \$\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf...

Magento-rheological Fluid (MRF) and Shear Thickening Fluid (STF) have separately attracted considerable interest due to their fast and reversible response to an external magnetic field or an abrupt shearing loading. In this paper we fabricated a combined phase of Magento-rheological Shear Thickening Fluid (MRSTF) such that it has an MR and a shear...

Nowadays, both Magneto-rheological Fluid (MRF) and Shear Thickening Fluid (STF) have separately attracted considerable interest due to the fast reversible response to either external magnetic field or abrupt shearing loading. In this paper, we fabricated a combined phase of Magneto-rheological Shear Thickening Fluid (MRSTF), where the 25 wt% STF is...

This paper is concerned with a mathematical model of a simple axisymmetric silencer-like model, consisting of a hole-tone feedback system equipped with by a tailpipe. The unstable shear layer is modeled via a discrete vortex method, based on axisymmetric vortex rings. The aeroacoustic model is based on the Powell-Howe theory of vortex sound. Bounda...

This paper is concerned with a mathematical model of a simple axisymmetric silencer-like model, consisting of a hole-tone feedback system equipped with a tailpipe. The unstable shear layer is modeled via a discrete vortex method, based on axisymmetric vortex rings. The aeroacoustic model is based on the Powell-Howe theory of vortex sound. Boundary...

Magnetorheological (MR) fluids are one of smart fluids which can be changed their rheological properties in reversible manner by applying magnetic field. While a shear thickening (ST) fluid is speed-activated non-Newtonian fluid; it possesses a low viscosity until the transition of the critical shear rate where it increases dramatically. Their comb...

This paper is concerned with a mathematical model of a simple axisymmetric silencer model consisting of an expansion chamber followed by a tailpipe. The unstable shear layer is modeled via a discrete vortex approach, based on axisymmetric vortex rings. The aeroacoustic model, which is described in the present short paper, is based on the Powell-How...

This study investigates the suppression of the so-called hole tone produced when a jet, issued from a circular nozzle or hole in a plate, goes through a similar hole in a second plate. The mean velocity of the air jet u0 was 10 m/s. The nozzle and end plate hole both had a diameter of 51 mm, and the impingement length Lim between the nozzle and end...

This paper presents the fabrication and characterization of a new magnetorheological elastomer (MRE) by using polydimethylsiloxane (PDMS) as a matrix. The base and curing agent of PDMS with a weight ratio of 10:1 were mixed first as the carrying matrix, and then carbonyl iron particles were added to the matrix and stirred sufficiently. The final mi...

Electro-rheological (ER) nano-suspensions based on titanium dioxide nano-particles with particle diameter on the order of 100 nm were prepared. Micro-gap flow behavior and microstructure were evaluated for the suspensions with a particle volume fraction of 8.8 vol%. For the sample based on a silicone oil, the ER effect and flow behavior were found...

Magnetorheological (MR) fluids have many attractive features, including high yield strength, low viscosity and stable hysteretic behavior over a broad temperature range. In general, low viscosity MR fluids are widely acceptable to the applications to industrial devices with low energy loss under no magnetic field. While, although high viscosity MR...

Magnetorheological (MR) fluids behave like a Bingham fluid having yield stress which can be rapidly changed in a reversible manner by applying magnetic field, being expected the innovative applications to industrial devices such as damper, valve, clutch and brake. In applications of MR fluid damper to seismic isolation and suppression technologies,...

This study investigates the sound produced when a jet, issued from a circular nozzle or hole in a plate, goes through a similar hole in a second plate. The sound, known as a hole tone, is encountered in many practical engineering situations. Direct computations of a hole tone feedback system were conducted. The mean velocity of the air jet was 10 m...

A new conceptual loading machine using amagneto-rheological fluid (MRF) clutch has been proposed and developed to be used for evaluation and training system of muscle strength in leg rehabilitation. This loading machine, which is called MRF active loading machine, mainly consists of a newly designed MRF clutch and a reversible induction motor with...

Novel electroactive polymer composites have been developed that could spin in uniform DC and AC electric fields. The angular displacement as well as rotation of polymer disks around an axis that is perpendicular to the direction of the applied electric field was studied. It was found that the dynamics of the polymer rotor is very complex. Depending...

This paper treats the real-time sensing-based risk-mitigation control of hydrogen dispersion and accumulation in a partially open space with low-height openings by forced ventilation. A hunting-preventive control scheme that we previously proposed (Matsuura et al., Int J Hydrogen Energy, 2012;37(2):1972–84) has parameters such as the monitoring per...

Electro-rheological (ER) nano-suspensions based on titanium dioxide nano-particles with particle diameter on the order of 100 nm were prepared. Micro-gap flow behavior and microstructure were evaluated for the suspensions with a particle volume fraction of 8.8 vol%. For the nano-suspension based on a silicone oil, the ER effect and flow behavior we...

This paper presents the real-time sensing-based risk-mitigation control of hydrogen dispersion and accumulation in a partially open space with low-height openings by forced ventilation. In the partially open space we previously considered (Matsuura et al., Int J Hydrogen Energy, 35(10), p. 4776–4786 (2010)), a hydrogen buoyant plume is subjected to...

It was reported that under the simultaneous stimulus of an electric field and shear, the particles in an ER fluid form lamellar formations in the direction of shear (adhered to one of the electrodes) which may be responsible for the ER activity more than the strength of the chains. In this way, it would be expected that the shear stress should chan...

When an electrorheological fluid between two parallel disk electrodes is subjected to squeeze mode excitation, the microstructural flow behavior of the ER fluid has been investigated in close relation to the measured electrorheological properties. A dilute anhydrous ER fluid made of 10 vol% carbonaceous particles dispersed in silicone oil and two I...

In this work, the mechanical properties of an anhydrous electrorheological fluid made of carbonaceous particles dispersed in silicone oil were determined in tensile, compression and oscillatory squeeze tests. The mechanical tests were carried out on a Mechanical Testling Machine and the device developed for measuring the ER properties was composed...

"MR fluid porous composite" made of a nonwoven containing MR fluid has been developed and the rheological properties in oscillatory shear mode under uniform magnetic field have been evaluated. MR fluid porous composite can prevent the dispersed particles from settling and doesn't need a seal that keeps the MR fluid in the machine. For the purpose o...

This study is concerned with an investigation into the sound produced when a jet, issued from a circular nozzle or hole in a plate, goes through a similar hole in a second plate. The sound, known as a hole-tone, is encountered in many practical engineering situation. Direct computations and experiments of a hole-tone feedback system are conducted....

An attempt has been made to develop a candidate for electro-rheological (ER) nano-suspensions based on anatase titanium dioxide with a particle diameter around 300nm. The micro-gap flow behavior and microstructure were evaluated for a suspension with a particle volume fraction of 8.8vol.%. The ER effect was investigated for the nano-suspension. The...

Electrorheological (ER) suspensions, which behaves like a Bingham fluid having yield stress, is believed to be capable of applying to various mechanical systems since it can be rapidly change in reversible manner by applying electric field. In this research, a Braille display system driven by micro-diaphragm ER actuators which can be driven by rela...

An evaluation method for the damping force characteristics of a passive-type MR damper with functional damping characteristics equivalent to a semi-active damper is developed. Although the MR damper is a fully passive device without any electrical components such as sensors, power supplies, or power controllers, it exhibits a functional variable da...

Direct computations and experiments of a hole-tone feedback system are conducted. The mean velocities of an air-jet are 8 and 10 m/s in the computations, 6–13 m/s in the experiments. The diameters of a nozzle and an end plate hole are both 50 mm, and an impingement length between the nozzle and the end plate is 50 mm. The computational results agre...

In check valves used in fluid equipments, the pendulum oscillation-like vibration motions of the plug are observed in a visualization experiment using a high speed camera, when heavy noises generate around the valves. The same kind of motion was re-created by a numerical simulation which is based on the coupled analysis of the plug motion with the...

Direct computations and experiments of a hole-tone feedback system are conducted. The mean velocities of an air-jet are 8 and 10 m/s in the computations, 6-13 m/s in the experiments. The diameters of a nozzle and an end plate hole are both 50 mm, and an impingement length between the nozzle and the end plate is 50 mm. The computational results agre...

A continuous inkjet printer is mainly used in industry for marking and coding of products and packages. Pressurized ink subjected to the piezoelectric vibration is continuously ejected from the nozzle vibrating at constant frequency. Ink droplets are formed beyond the breakup length due to Plateau-Rayleigh instability. The droplet formation process...

This paper is concerned with the hole-tone feedback cycle, where an air jet issuing from a circular nozzle impinges upon a plate with a similar hole located a little downstream, generating self-sustained flow oscillations. Focus is on the influence of (i) a closed cavity and (ii) a tail pipe. The system can be viewed as a simplified model of an aut...

This paper treats the real-time sensing-based risk-mitigation control of hydrogen jet leakage in a partially open space with low openings by forced ventilation. After describing the computational geometry and scenarios, and the mathematical model and numerical procedure, we propose a partially open space that is robust to external environment. Rela...

In this research, the transient response of induced shear stress and the related flow behavior of two types of the Electro-Rheological (ER) suspensions containing nano-sized or submicron-sized TiO2 particles dispersed in silicone oil have been investigated when it has been under the application of an electric field and shear using a parallel rotary...

The characteristics of a passive type MR damper were evaluated experimentally. The damper has variable damping characteristics as well as an existing semi-active damper, although it is fully passive device without any sensor, power supply and power controller. A prototype of the damper was manufactured in order to verify the damping and response ch...

A method for simulating the hole-tone feedback cycle (Rayleigh's bird-call), based on a three-dimensional discretc vortex method, is described. Evaluation of the sound generatcd by the self-sustained flow oscillations is bascd on the Powell-Howe theory of vortex sound and a boundary integral/element method. While the basic problem is inherently axi...