On-line Estimation of Effective Bulk Modulus in Fluid Power Systems Using Piezoelectric Transducer Impedance

Kim, Gi Woo; Wang, Kon Well

doi:10.1177/1045389x09345558

Cited by 13 publications

(9 citation statements)

References 7 publications

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“…In another similar work, Kim and Wang (2009) utilized measurements of the impedance of a piezoelectric transducer to estimate on-line effective bulk modulus. This idea was based on the fact that any change in the effective bulk modulus would affect the system resonant frequencies.…”

Section: Effective Bulk Modulus Measurement Techniquesmentioning

confidence: 99%

Modeling and Experimental Validation of the Effective Bulk Modulus of a Mixture of Hydraulic Oil and Air

Gholizadeh

Bitner

Burton

et al. 2014

Journal of Dynamic Systems, Measurement, and Control

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It is well known that the presence of entrained air bubbles in hydraulic oil can significantly reduce the effective bulk modulus of hydraulic oil. The effective bulk modulus of a mixture of oil and air as pressure changes is considerably different than when the oil and air are not mixed. Theoretical models have been proposed in the literature to simulate the pressure sensitivity of the effective bulk modulus of this mixture. However, limited amounts of experimental data are available to prove the validity of the models under various operating conditions. The major factors that affect pressure sensitivity of the effective bulk modulus of the mixture are the amount of air bubbles, their size and the distribution, and rate of compression of the mixture. An experimental apparatus was designed to investigate the effect of these variables on the effective bulk modulus of the mixture. The experimental results were compared with existing theoretical models, and it was found that the theoretical models only matched the experimental data under specific conditions. The purpose of this paper is to specify the conditions in which the current theoretical models can be used to represent the real behavior of the pressure sensitivity of the effective bulk modulus of the mixture. Additionally, a new theoretical model is proposed for situations where the current models fail to truly represent the experimental data.

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Section: Effective Bulk Modulus Measurement Techniquesmentioning

confidence: 99%

Modeling and Experimental Validation of the Effective Bulk Modulus of a Mixture of Hydraulic Oil and Air

Gholizadeh

Bitner

Burton

et al. 2014

Journal of Dynamic Systems, Measurement, and Control

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“…From this lumped model, the large chamber on the low pressure (head) side of the double-acting hydraulic cylinder can act as a Helmholtz resonator consisting of an effective hydraulic spring rate (k 1 ) and a fluid mass (M 1 ). It has been recognized that the fluid effective bulk modulus is a critical parameter that will affect the apparent 'stiffness' of the working fluid [13,15]. The term stiffness is frequently referred to as the effective hydraulic spring rate in a hydraulic control (or fluid power) system…”

Section: Helmholtz Resonance Modelmentioning

confidence: 99%

“…Next, the effect of the effective bulk modulus on Helmholtz resonance is also investigated by replacing the working fluids. Since it is well recognized that the effective bulk modulus of the water-based Hydrolubric ® oil is higher than that of petroleum-based hydraulic oil, such as DEXRON-III ® , under the same pressure [13,17], these two fluids are used alternately as working fluids for the PHP actuator. As in figure 10, the simulated first peak frequency shown in figure 11 is shifted from 170 to 250 Hz with the A type cylinder using the working fluid with the higher effective bulk modulus.…”

Section: Experimental Validationmentioning

confidence: 99%

Helmholtz resonance in a piezoelectric–hydraulic pump-based hybrid actuator

Kim

Wang

2010

Smart Mater. Struct.

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This paper demonstrates that a hydraulically acting Helmholtz resonator can exist in a piezoelectric-hydraulic pump (PHP) based hybrid actuator, which in turn affects the volumetric efficiency of the PHP. The simulation and experimental results illustrate the effect of Helmholtz resonance on the flow rate performance of the PHP. The study also shows how to shift the Helmholtz resonant frequency to a higher value through changing parameters such as the cylinder diameter and the effective bulk modulus of the working fluid, which will improve the volumetric efficiency and broaden the operating frequency range of the PHP actuator.

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“…It is possible to determine the mixture's bulk modulus by different experimental methods, e.g. by acoustic [4] and [5], capacity [6], piezoelectric impedance [7] or volume [8] methods.…”

Section: Introductionmentioning

confidence: 99%

“…Strojniški vestnik -Journal of Mechanical Engineering 61(2015)[7][8][477][478][479][480][481][482][483][484][485] …”

mentioning

confidence: 99%

Determination of Undissolved Air Content in Oil by Means of a Compression Method

Bureček

Hružík

Vašina

2015

SV-JME

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This article describes a combination of experimental and mathematical methods for the determination of undissolved air content in hydraulic oil. The experimental part consists of the determination of the oil bulk modulus, considering the influence of undissolved air by means of a volume compression method in a steel pipe. A multiphase model of an oil/undissolved air mixture is subsequently defined using Matlab SimHydraulics software. The multiphase model permits the volume compression of oil and air bubbles independently of each other. Furthermore, time dependencies of pressures are mathematically simulated during the compression of the multiphase mixture of oil and undissolved air for different concentrations of the latter. The undissolved air content is determined by comparing the mathematically simulated and experimentally measured time dependencies of pressure increases. Highlights • Experimental determination of secant bulk modulus and tangent bulk modulus of oil by means of a compression method. • Multiphase mathematical model of compressibilityof oil/undissolved air mixture. • Mathematical simulation and measurement of time dependence of pressure during compression of oil/undissolved air mixture in steel pipe. • Determination of undissolved air content in oil by comparing the mathematical model with the measurement. • The undissolved air concentrations in the measured hydraulic system were determined in the range of 0.22 % to 0.49 %.

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On-line Estimation of Effective Bulk Modulus in Fluid Power Systems Using Piezoelectric Transducer Impedance

Cited by 13 publications

References 7 publications

Modeling and Experimental Validation of the Effective Bulk Modulus of a Mixture of Hydraulic Oil and Air

Modeling and Experimental Validation of the Effective Bulk Modulus of a Mixture of Hydraulic Oil and Air

Helmholtz resonance in a piezoelectric–hydraulic pump-based hybrid actuator

Determination of Undissolved Air Content in Oil by Means of a Compression Method

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