Pendulum Method Research Articles

An Improved Trajectory of a Bipedal Robot Walking along a Step with the Dual Length Linear Inverted Pendulum Method

An Improved Trajectory of a Bipedal Robot Walking along a Step with the Dual Length Linear Inverted Pendulum Method

Effect of Aging Treatment on Damping Capacity in Mncunife Alloy

M2052 alloys with various aging treatments are obtained in order to investigate the relationship between aging treatment and damping capacity by the torsion pendulum, X-Ray Diffraction (XRD) and Transmission Electron Microscope (TEM) methods. The results show that M2052 can obtain high damping capacity (δ>0.2) when aged at a range from 400°C to 450°C, and the damping capacity after aged at a lower temperature is higher than that aged at a higher temperature for the maximum values. TEM and XRD results show that fcc-fct transformation occurs after aging treatment. The volumes of fct structures are one of reason to affect the damping capacity in M2052 alloy. The better understanding aging treatment could promote the applications of M2052 alloy.

Investigation of Damping Characteristics of Metals by the Use of Inverted Torsion Pendulum Method

Damping characteristics of metals are measured by the use of inversed torsion pendulum method. As the materials, aluminum alloys, magnesium alloys, Inconel etc are used with the temperature and frequency parameters. Mild steel is employed as a reference material for calibrating the apparatus. The measured damping coefficient of magnesium alloys is larger than that of aluminum alloys indicating that the HCP crystal structure has more damping effect than the FCC structure. The damping of these metals increases with temperature. The manner of increment of damping is investigated to analyses the microscopic mechanism of damping.

Surface tension and viscosity of the molten (LiF–NaF–KF)eut–K2ZrF6 system

Surface tension and viscosity of the system (LiF–NaF–KF)eut–K2ZrF6 were measured in its entire concentration range. Surface tension was measured by the maximal bubble pressure method, and viscosity was measured using the computerized torsion pendulum method. Concentration dependencies of both quantities were calculated for three selected temperatures T = 1,123, 1,173, and 1,223 K on the basis of the experimental data. The values of the surface tension lie in the region 96–160 mN m−1 and the values of the viscosity are in the region 0.86–3.06 mPa s.

Assessment of the mass, length, center of mass, and principal moment of inertia of body segments in adult males of the brown anole (Anolis sagrei) and green, or carolina, anole (Anolis carolinensis)

This study provides a morphometric data set of body segments that are biomechanically relevant for locomotion in two ecomorphs of adult male anoles, namely, the trunk-ground Anolis sagrei and the trunk-crown Anolis carolinensis. For each species, 10 segments were characterized, and for each segment, length, mass, location of the center of mass, and radius of gyration were measured or calculated, respectively. The radii of gyration were computed from the moments of inertia by using the double swing pendulum method. The trunk-ground A. sagrei has relatively longer and stockier hindlimbs and forelimbs with smaller body than A. carolinensis. These differences between the two ecomorphs demonstrated a clear relationship between morphology and performance, particularly in the context of predator avoidance behavior, such as running or jumping in A. sagrei and crypsis in A. carolinensis. Our results provide new perspectives on the mechanism of adaptive radiation as the limbs of the two species appear to scale via linear factors and, therefore, may also provide explanations for the mechanism of evolutionary changes of structures within an ecological context.

1413 倒立型ねじり振り子試験機を用いたニッケル基超合金の粘弾性挙動に関する研究(OS15-3 諸観点からの物質・材料の特性評価III,OS15 諸観点からの物質・材料の特性評価)

Nickel-based superalloys are widely used as the heat-resistant materials in various engineering fields. Therefore, it is very important to clarify the viscoelastic properties of these materials because they are often used under elevated temperatures. The final object of this study is to clarify the viscoelastic constitutive relation of Inconel 718 which is one of the most popular nickel-based superalloys. As the preliminary research for this final object, the internal friction (logarithmic decrement) has been measured by the inverted torsion pendulum method with changing the atmospheric temperature. Prior to the measurement, three types of specimens with different grain sizes were prepared by changing the annealing temperature. As the results, it has been clarified that the logarithmic decrement of the large grain size superalloy is smaller than that of the small grain size superalloy and that in some cases, the logarithmic decrement takes a peak value at the atmospheric temperature of approximately 820-850K.

Product Design Aspects for Design of Accurate Mass Properties Measurement System for Aerospace Vehicles

Mass properties of aerospace vehicle viz Weight, Center of Gravity (Xcg, Ycg, Zcg) & Mass Moment of Inertia (Ixx, Iyy & Izz) are critical inertial parameters which are vital to meet the intended mission objectives. Accurate mass properties measurement is needed for fast maneuvering aerospace vehicles to meet the Control and Guidance requirements within the tolerable limits generated by the System Designer. Mass properties estimation is vital during the configuration design phase of an aerospace vehicle. Assumptions and Constraints during the configuration design, limits the accuracy of estimations making the mass properties measurement mandatory. The mass properties of the aerospace vehicle can be measured by numerous methods, but for achieving high accuracies within the tolerable limits, the measurement system should have advanced technologies and measurement methodologies. Based on the experience, mass properties measurement systems were designed using Load Cells and Cross-Flexural Pivots in two different systems (Weight and CG in System-1, MOI in System-2), which have limited accuracy and also involves tedious external measurements. Adopting Air-Bearing (T / H / Spherical shape) supported with accurate sensors using Inverted Torsion Pendulum method, Multiple Point Weighing method and a proper measurement methodology, enhances the accuracy of the measurement system. Usage of spherical bearing yields a better accurate system but has the difficulty in realization of the system indigenously, whereas use of T or H-shape bearing is a feasible solution for achieving the desired accurate mass properties specifications. This paper gives an insight into to the product design aspects to be considered for realization of accurate mass properties measurement system.

An improved pendulum method for the determination of the center of gravity and inertia tensor for irregular-shaped bodies

An improved Trifilar Torsional Pendulum (TTP) for the experimental determination of the Center of Gravity (C.G.) and inertia tensor (the three moments of inertia and the three products of inertia) for an irregular-shaped body is proposed and developed. In the improved apparatus, a universal joint is adopted to facilitate the adjustments of the C.G. of the body in line with the pendulum axis. To enhance the precision of the measurement, a tri-coordinate measuring machine is employed to measure the coordinates of the predefined points and vectors of axes, which are then used for calculating the C.G. and inertia tensor for an irregular-shaped body. The theoretical fundaments of an improved TTP, the experimental setup, data processing procedures, and error estimation for measuring C.G. and inertia tensor are presented. With the proposed TTP and data processing procedure, the relative error in the determination of the moments of inertia can be estimated within 1%, and the deviation of the measured C.G. to the theoretical C.G. is within 1.5 mm. An example is given to demonstrate the effectiveness of the new approaches.

Slip Safety Analysis of Differently Surface Processed Dimension Marbles

Abstract The present work attempts to determine the most suitable surface processing techniques to reduce the slipping risk of pedestrians while walking barefoot and wearing shoes on marble coverings. In this study, slip angles of surface-processed marbles in different plate dimensions have been determined by using DIN EN 51097, DIN EN 51130, and TS EN 14231 Standards “The determination of the characteristics that reduce slipping on wet, barefoot surfaces.” Slip angles and surface slip resistances have been determined by using ramp test equipment and pendulum method on five different types of classified marbles applied polishing and honing surface processing techniques. It was found that the parameters which affected slip resistance and slip angle values of the marbles were plate size and the applied surface processing techniques. The marbles were then grouped according to safe utilization places depending on slip angles and slip resistances, according to the statistical results.

High-Precision Moment of Inertia Testing System and Error Analysis

Pointed at low precision of great object’s moment of inertia, high-precision moment of inertia testing system is developed. Comparing with several measurement methods, we adopt method of torsion pendulum. We design mechanical structure and analyze error which is compensated in software. According to our experiment, precision of this system can achieve 5‰.

Internal friction measurement of Zr0.8R0.2O1.9 ceramics (R=Y, Sm, and Nd)

The internal friction in three cubic zirconias, Zr0.8R0.2O1.9 where R=Y, Nd and Sm, was compared in the temperature range of 30-400°C using forced torsion pendulum method. The internal friction of Zr0.8Y0.2O1.9 was characterized to two peaks, however that of Zr0.8Sm0.2O1.9 were shown with low amplitude of high temperature peak, as well as that of Zr0.8Nd0.2O1.9 was shown as a single peak at around 100-300°C at 9Hz. The comparative result suggests the effect of the larger cation doping to cubic zirconia, which induced to suppress some kind of oxygen relaxation in cubic fluorite structured zirconia.

Modeling of an inverted pendulum based on fuzzy clustering techniques

The inverted pendulum is a highly nonlinear and open loop unstable system. To develop an accurate model of the inverted pendulum, different linear and nonlinear methods of identification will be used. However one of the problems encountered during modeling is the collection of experimental data from the inverted pendulum system. Since the output data from the unstable system does not show enough information or dynamics of the system. This can be overcome by designing a feedback controller, which stabilize the system before identification can takes place. Recently Takagi–Sugeno (T–S) fuzzy modeling based on clustering techniques have shown great progress in identification of nonlinear systems. Hence in this paper, Takagi–Sugeno (T–S) model is proposed for an inverted pendulum based on fuzzy c-means, Gustafson–Kessel (G–K) and Gath–Geva clustering techniques. Simulation results show that Gustafson–Kessel (G–K) clustering technique produces satisfactory performance.

The Application of Inertial Measurement Unit in Inertia Parameter Identification

This paper presents a simple but effective method for inertial parameter identification with symmetrical trifilar pendulum and inertial measurement unit (IMU). An improvement upon conventional pendulum method is described by introducing IMU to identify the orientation of specimen by self-alignment, and then complicated equipment and experimental manipulation are not needed any more. Based on the excellent capacity of motion tracking, the IMU is also used for recording the characteristic of periodic movement by collected the information about acceleration and angular velocity. The main sources of identification errors are discussed from a set of examples. Then an experiment is carried out, and Fourier analysis is used to gain the oscillation period, which made the measurement much more convenient and accurate. The identification results are also presented by comparing with reference values computed from geometrical considerations, which proves the effectiveness of such method.

Modeling of an Inverted Pendulum based on Fuzzy Clustering Techniques

inverted pendulum is a highly nonlinear and open loop unstable system. To develop an accurate model of the inverted pendulum, different linear and nonlinear methods of identification will be used. However one of the problems encountered during modeling is the collection of experimental data from the inverted pendulum system. Since the output data from the unstable system does not show enough information or dynamics of the system. This can be overcome by designing a feedback controller , which stabilize the system before identification can takes place. Recently TakagiSugeno (TS) fuzzy modeling based on cluster ing techniques have shown great progress in identification of nonlinear systems. Hence in this paper, TakagiSuge no (TS) model is proposed for an inverted pendulum based on fuzzy c means , GustafsonKessel (GK) and GathGeva (GG) clustering techniques. Simulation results show that Gustafson Kessel (GK) clustering technique produces satisfactory performance.

239 竹の減衰特性のねじり振動法による測定(生体・環境適合型材料の創製と特性評価(2),ものづくりにおける基礎研究と先端技術の融合)

The viscous characteristics of bamboo is experimentally studied. Attenuation of the free oscillation is measured in inverted torsion pendulum method. The damping of bamboo is compared with that of steel.

Effect of solution treatment on damping capacity and shape memory effect of a CuAlMn alloy

Abstract The effect of solution temperature on martensite transformation temperatures, damping capacity and shape memory effect of a Cu–7.66Al–9.52Mn alloy was investigated by resistivity–temperature method, reversal torsion pendulum method and bend test. The results showed that with increasing temperature, the transformation temperatures and shape memory effect first remarkably increased and then almost remained constant. The damping capacity significantly increased with temperature up to 1098 K and then decreased. The damping capacity was dependent on not only the amount but also the thickness of the martensite plates, while the shape memory effect was mainly determined by the amount of the martensite.

Internal friction of polycrystalline Zr 0.8R 0.2O 1.9 (R = Nd, Y)

The oxygen relaxation in two cubic zirconias, Zr 0.8R 0.2O 1.9 where R = Nd and Y, was compared with internal friction in the temperature range of 300–685 K using forced torsion pendulum method. The internal friction of Zr 0.8Nd 0.2O 1.9 was shown as a single peak at around 350–450 K at frequencies of 0.32–9 Hz. The activation enthalpy of relaxation in Zr 0.8Nd 0.2O 1.9 was determined to be 1.12 ± 0.1 eV. The amplitude of the high-temperature peak in Y-doped zirconia was not observed for Zr 0.8Nd 0.2O 1.9. The result suggests that the relatively lower mobility of oxygen is due to the doping of larger Nd cation to ZrO 2 lattice.

Numerical and experimental study of microwave-excited microplasma and micronozzle flow for a microplasma thruster

Plasma and aerodynamic features have been investigated for a microplasma thruster of electrothermal type using azimuthally symmetric microwave-excited microplasmas. The thruster developed consisted of a microplasma source 1.5 mm in diameter, 10 mm long with a rod antenna on axis, and a converging-diverging micronozzle 1 mm long with a throat 0.2 mm in diameter. The feed or propellant gas employed was Ar at pressures of 10–50 kPa with flow rates of 10–70 SCCM (SCCM denotes standard cubic centimeter per minute at STP) and the surface wave-excited plasmas were established by 4.0 GHz microwaves at powers of ≤6 W. Numerical analysis was made for the plasma and flow properties by developing a self-consistent, two-dimensional model, where a two-temperature fluid model was applied to the entire region through the microplasma source to the micronozzle (or through subsonic to supersonic); in the former, an electromagnetic model based on the finite difference time-domain approximation was also employed for analysis of microwaves interacting with plasmas. In experiments, optical emission spectroscopy was employed with a small amount of additive gases of H2 and N2, to measure the plasma electron density and gas temperature in the microplasma source around the top of the microwave antenna, just upstream of the micronozzle inlet; in practice, the numerical analysis exhibited a maximum thereabout for the microwave power density absorbed, plasma density, and gas temperature. The Stark broadening of H Balmer line and the vibronic spectrum of N2 second positive band indicated that the electron density was in the range of (3–12)×1019 m−3 and the gas or rotational temperature was in the range of 700–1000 K. The thrust performance was also measured by using a microthrust stand with a combination of target and pendulum methods, giving a thrust in the range of 0.2–1.4 mN, a specific impulse in the range of 50–80 s, and a thrust efficiency in the range of 2%–12%. These experimental results were consistent with those of numerical analysis, depending on microwave power and gas flow rate.

Vibration damping of high-chromium ferromagnetic steel and its dependence on magnetic domain structure

The aim of the present work is to study the vibration damping capacity of annealed high-chromium (16%) ferromagnetic steel. The alloys were prepared from raw materials of 99.9% purity melted in a high frequency induction furnace under high vacuum. The samples were heat-treated in vacuum at various temperatures (800–1200 °C) for 1 h followed by slow cooling (120 °C/h). The duration of 1 h considered was the same for all the specimens and no other duration was considered for evaluation. The inverted torsional pendulum method was used to evaluate the vibration damping capacity. The results indicated that the vibration damping capacity of the alloys is influenced by annealing and there exists a critical annealing temperature after 1000 °C. When the alloy is annealed over the critical temperature, the size of the magnetic domains becomes larger so that the domain wall area in metal decreases, making the damping capacity decrease as well.

Phase Equilibria, Volume Properties, Surface Tension, and Viscosity of the (FLiNaK)eut + K2NbF7 Melts

Physicochemical properties of the system (FLiNaK)eut (1) + K2NbF7 (2) were investigated. Phase equilibria were studied by a thermal analysis method. Density of the investigated system was measured by the Archimedean method. On the basis of these data, molar volumes were calculated for selected temperatures, and the partial molar volume of K2NbF7 in (FLiNaK)eut was evaluated adopting the value V̅2/cm3·mol−1 = (121.1 ± 0.4) at 1073 K, indicating volume contraction. Surface tension was measured by the maximal bubble pressure method, and viscosity was measured using the computerized torsion pendulum method.