International Journal of Hydromechatronics (5 papers in press)
A Lumped Parameter Vane Pump Model for System Stability Analysis
by Ryan Jenkins, Monika Ivantysynova
Abstract: This paper presents a semi-empirical lumped parameter model developed for analysing the dynamic stability and performance limitations of a pressure compensated vane pump for an automotive application with low-cost components. The model calculates continuous displacement chamber pressure profiles and inertial effects for the determination of the internal forces acting on the vane pumps pivoting cam. Measurements conducted on a custom test stand were used to define a nonlinearly progressive bias spring model and a black-box representation of the pump control system valves. Analysis of the complete model reveals that the performance limitations imposed by the control system valves, in terms of system stability and achievable controller bandwidth, are more restrictive than the limitations imposed by the low-cost vane pump and limit the that bandwidth to 1.84Hz. The control system also imposes limitations to the system performance based on resonance phenomena which may be significant in some applications.
Keywords: pressure compensation; vane pumps; pivoting cam; internal forces; stability analysis; lumped parameter models; black-box models; resonant behaviour; progressive spring rate; nonlinear simulation models; experimental validation; automatic transmission.
Tool wear estimation method in milling process using air turbine spindle rotation-control system equipped with disturbance force observer
by Tomonori Kato, Tatsuki Otsubo, Kohei Shimazaki, Shotaro Matsuguchi, Yusuke Okamoto, Takanori Yazawa
Abstract: The authors investigate a disturbance-compensating and energy-saving control method for air turbine spindles equipped with a rotation control system designed for use in ultra-precision milling. The controllability and energy-conserving characteristics of the proposed method using the proposed pneumatic regulating device, called a high-precision quick-response pneumatic pressure regulator, were demonstrated experimentally previously. Herein, the proposed rotation-controlled air turbine spindle is first summarised. Subsequently, the proposed rotation-controlled air turbine spindle is set to a milling machine and applied to the milling of an alloy tool steel, to gain data and validate the effectiveness of the in-process tool wear estimation method that have been recently developed and proposed by the authors. Particularly, to evaluate the possibility of applying the proposed estimation method to three-dimensional milling, milling experiments where the air turbine spindle is set at a 45
Keywords: pneumatics;air turbine spindle;disturbance force;milling;tool wear estimation.
Buckling and reliability analysis of CNT-reinforced-beams based on Hasofer-Lind and Rackwitz- Fiessler methods
by Reza Kolahchi
Abstract: In this paper, the nonlinear conjugate map based on the conjugate Rackwitz- Fiessler and Hasofer-Lind (CHL-RF) method is used to evaluate the reliability using first order reliability method of the embedded noanocompsite beam, which is made from polymer reinforced with carbon nanotubs (CNTs). The structure is simulated with Timoshenko beam model. The Mori-Tanaka method is applied for obtaining the effective properties of nanocomposite beam. The surrounding elastic medium is considered by spring and shear constants. Utilizing energy method and Hamilton's principal, the governing equations are obtained. Using an analytical method, the buckling performance function of structure is obtained. The influences of the basic random variables including the length to thickness ratio of beam (L/h), spring constant and shear constant of foundation with respect to the volume fraction of CNTs are investigated on the reliability index of the nanocomposite beam subjected to axial force of 20 GPa. The results indicated that the failure probabilities of the studied the nanocomposite beam are the sensitive to the length to thickness of beam (L/h) and spring constant of foundation variables.
Keywords: Nanocomposite beam; Conjugate HL-RF; first order reliability method; Timoshenko beam model.
Dynamic buckling in lamina plates reinforced by CNTs in each layer using exact solution
by M. Cinefra
Abstract: In this work, dynamic buckling of a rested lamina nanocomposite plate is considered. The plates are armed with single walled carbon nanotubes (SWCNTs) to obtain the effective characteristic of them, Mori-Tanaka model is applied. According to sinusoidal shear deformation theory (SSDT), the equations of governing are obtained using Hamilton's principal and energy method. For calculating the dynamic stability region (DIR) of the structure Bolotin's and Naviers methods are applied. The influences of number and orientation angle of layers volume percent of SWCNTs, geometrical parameters and elastic medium of plates are shown on the DIR of system. Results show that enhancing volume percent of SWCNTs increases the resonance frequency. Also, the accuracy of this study is compared by other works.
Keywords: Dynamic buckling; Nanocomposite laminated plates; elastic medium; SSDT; Bolotin method.
Dynamic analysis in three layered conical shells utilizing numerical methods
by Subrata Kumar Panda, Reza Kolahchi
Abstract: In this work, dynamic composite analysis truncated sandwich conical shells (STCS) with different boundary conditions under low velocity impact was investigated analytically, according higher order sandwich panel theory. Impact is occurred at the top facesheet and the contact force history is predicted using two solution models are calculated applying principal of Hamilton by considering the displacement continuity conditions between the layers. For obtaining the displacement and contact force histories, the differential quadrature method (DQM) is utilized. In this investigation, the effect of layer lamina number, cone semi vertex angle, boundary conditions, impact velocity on the impact response are studied.
Keywords: Low velocity impact; STCS; DQM; Hertzian contact law; complete model.