Modal Approximation of Distributed Dynamics for a Hydraulic Transmission Line With Pressure Input-Flow Rate Output Causality

2004 ◽  
Vol 127 (3) ◽  
pp. 503-507 ◽  
Author(s):  
Beshahwired Ayalew ◽  
Bohdan T. Kulakowski
Keyword(s):  
Transmission Line ◽  
Flow Rate ◽  
Hydraulic System ◽  
Friction Model ◽  
System Model ◽  
Input Flow ◽  
Approximation Techniques ◽  
Linear Friction ◽  
Short Connection ◽  
Modal Approximation

Based on analytical results obtained in the frequency domain, modal approximation techniques are employed to derive transfer function and state space models applicable to a pressure input-flow rate output causality case of a transmission line. The causality case considered here arises while modeling short connection lines to hydraulic accumulators. However, the modal approximation results presented apply also to other cases where the linear friction model is considered applicable. It is highlighted that the results presented can reduce the overall order of the hydraulic system model containing the transmission line being considered.

Dissipative Modal Approximation of Fluid Transmission Lines Using Linear Friction Model

1991 ◽  
Vol 113 (1) ◽  
pp. 152-162 ◽  
Author(s):  
W. C. Yang ◽  
W. E. Tobler
Keyword(s):  
Transmission Lines ◽  
Friction Model ◽  
Step Response ◽  
Frequency Dependent ◽  
Approximation Techniques ◽  
Linear Friction ◽  
Computer Calculations ◽  
Complex Fluid ◽  
Dependent Viscosity ◽  
Modal Approximation

For both hydraulic and pneumatic transmission lines, analytical dissipative modal approximation techniques, which take into account the frequency dependent viscosity and heat transfer effects, are developed by introducing frequency dependent damping and natural frequency modification factors to the quadratic modes obtained analytically from linear friction model. The main advantage over the existing dissipative modal approximations is that the modal parameters of the resulting modal transfer function matrices and modal state space equations can be determined analytically rather than determined by table and/or numerical computer calculations. This introduces modeling flexibilities and greatly alleviates the difficulties of modeling complex fluid networks but still maintaining the modal accuracy and complexities. Unit step response comparisons are made with quasi-method of characteristics showing good agreements for both hydraulic and pneumatic lines.

Study on the Spring-Piston External Mesh Gear Pump with Low Flow Fluctuation

2011 ◽  
Vol 201-203 ◽  
pp. 2200-2205
Author(s):  
Jian Zhuo Zhang ◽  
Kang Kang Li ◽  
Meng Gao ◽  
Tian Zi Zhu
Keyword(s):  
Flow Rate ◽  
Fourier Transformation ◽  
Hydraulic System ◽  
Low Flow ◽  
Gear Pump ◽  
Input Flow ◽  
Matlab Software ◽  
Flow Fluctuation ◽  
Piston System ◽  
External Mesh

The cycle function of input flow rate was obtained by Fourier transformation of the instantaneous input flow rate of external mesh gear pump. The model of hydraulic system consisting of gear pump, spring, piston and load was established, the differential functions of the model were established too. The influence of dynamic compensating characteristics in the system caused by both pistons with different area and stiffness of spring was analyzed with MATLAB software and the change of fluctuating flow in the same system was obtained. The simulation result shows that the flow fluctuation of external mesh gear pump could be reduced by using the spring-piston system.

Modeling of Mechanical Systems Using Rigid Bodies and Transmission Line Joints

1999 ◽  
Vol 121 (4) ◽  
pp. 606-611 ◽  
Author(s):  
Petter Krus
Keyword(s):  
Transmission Line ◽  
Hydraulic System ◽  
Large Scale ◽  
Mechanical Systems ◽  
Rigid Bodies ◽  
Large Scale Systems ◽  
Distributed Parameters ◽  
Transmission Line Modeling ◽  
Integration Algorithms ◽  
Transmission Line Models

Dynamic simulation of systems, where the differential equations of the system are solved numerically, is a very important tool for analysis of the detailed behavior of a system. The main problem when dealing with large complex systems is that most simulation packages rely on centralized integration algorithms. For large scale systems, however, it is an advantage if the system can be partitioned in such a way that the parts can be evaluated with only a minimum of interaction. Using transmission line models, with distributed parameters, physically motivated pure time delays are introduced in the communication between components. These models can be used to represent both lines in a hydraulic system and springs in mechanical systems. As a result, components and subsystems can be simulated more independently of each other. In this paper it is shown how flexible joints based on transmission line modeling (TLM) with distributed parameters can be used to simplify modeling of large mechanical link systems interconnected with other physical domains. Furthermore, it provides a straightforward formulation for parallel processing.

Boundary and Mixed Friction in the Presence of Dynamic Normal Loads: Part I—System Model

1995 ◽  
Vol 117 (2) ◽  
pp. 255-260 ◽  
Author(s):  
Andreas A. Polycarpou ◽  
Andres Soom
Keyword(s):  
Important Variable ◽  
Friction Model ◽  
System Model ◽  
Dynamic Friction ◽  
Discrete Elements ◽  
Friction Forces ◽  
Contact Compliance ◽  
Stiffness Characteristics ◽  
Nonlinear Normal ◽  
Linearized Model

The instantaneous normal motion between bodies in a sliding contact is an important variable in determining dynamic friction under unsteady sliding conditions. In order to model friction under dynamic conditions, it is therefore necessary to combine a dynamic model of the sliding system with an accurate model of the friction process. In the present work, the nonlinear normal dynamics of a friction test apparatus are described by a linearized model at a particular steady loading and sliding condition in a mixed or boundary-lubricated regime. The geometry is a line contact. The Hertzian bulk contact compliance and film and asperity damping and stiffness characteristics are included as discrete elements. In Part I of the paper, a fifth-order model is developed for the normal dynamics of the system, using both the Eigensystem Realization Algorithm (ERA) and classical experimental modal analysis techniques. In Part II, this system model is combined with a friction model, developed independently, to describe dynamic friction forces under both harmonic and impulsive applied normal loads.

scholarly journals Construction of a comprehensive endovascular test bed for research and device development in mechanical thrombectomy in stroke

2020 ◽  
pp. 1-8 ◽  
Author(s):  
Adithya S. Reddy ◽  
Yang Liu ◽  
Joshua Cockrum ◽  
Daniel Gebrezgiabhier ◽  
Evan Davis ◽  
...  
Keyword(s):  
Flow Rate ◽  
Hydraulic System ◽  
Mechanical Thrombectomy ◽  
Low Cost ◽  
Quality Analysis ◽  
Test Bed ◽  
Vessel Occlusion ◽  
Physiological Flow ◽  
3D Printed ◽  
Device Interaction

OBJECTIVEThe development of new endovascular technologies and techniques for mechanical thrombectomy in stroke has greatly relied on benchtop simulators. This paper presents an affordable, versatile, and realistic benchtop simulation model for stroke.METHODSA test bed for embolic occlusion of cerebrovascular arteries and mechanical thrombectomy was developed with 3D-printed and commercially available cerebrovascular phantoms, a customized hydraulic system to generate physiological flow rate and pressure, and 2 types of embolus analogs (elastic and fragment-prone) capable of causing embolic occlusions under physiological flow.RESULTSThe test bed was highly versatile and allowed realistic, radiation-free mechanical thrombectomy for stroke due to large-vessel occlusion with rapid exchange of geometries and phantom types. Of the transparent cerebrovascular phantoms tested, the 3D-printed phantom was the easiest to manufacture, the glass model offered the best visibility of the interaction between embolus and thrombectomy device, and the flexible model most accurately mimicked the endovascular system during device navigation. None of the phantoms modeled branches smaller than 1 mm or perforating arteries, and none underwent realistic deformation or luminal collapse from device manipulation or vacuum. The hydraulic system created physiological flow rate and pressure leading to iatrogenic embolization during thrombectomy in all phantoms. Embolus analogs with known fabrication technique, structure, and tensile strength were introduced and consistently occluded the middle cerebral artery bifurcation under physiological flow, and their interaction with the device was accurately visualized.CONCLUSIONSThe test bed presented in this study is a low-cost, comprehensive, realistic, and versatile platform that enabled high-quality analysis of embolus–device interaction in multiple cerebrovascular phantoms and embolus analogs.

Calculation Method for Thermal-Hydraulic System Simulation

2008 ◽  
Vol 130 (8) ◽  
Author(s):  
Li Chenggong ◽  
Jiao Zongxia
Keyword(s):  
Mathematical Models ◽  
Calculation Method ◽  
Hydraulic System ◽  
System Simulation ◽  
Cross Coupling ◽  
System Model ◽  
Lumped Parameter ◽  
Simulation Results ◽  
Simulation Time ◽  
Hydraulic System Simulation

This paper presents the fundamental approaches of modeling thermal-hydraulic component briefly. A set of lumped parameter mathematical models is developed, which are based on conservation of mass and energy. Subsequently, the connection rule for basic thermal-hydraulic components and the method to automatically generate the complete thermal-hydraulic system model are put forward. The integration methods for solving the cross-coupling thermal-hydraulic equations are also discussed for a position-controlled thermal-hydraulic system. Simulation results show the interaction between pressure and temperature. The simplified representations of thermal-hydraulic differential equations are also proposed in this paper, which can reduce simulation time. The validity of the simplified representations is judged by simulation.

Design and Research of Hydraulic Station of Hydraulic Tire Curing Press

2012 ◽  
Vol 507 ◽  
pp. 172-175
Author(s):  
Rong Li
Keyword(s):  
Flow Rate ◽  
Hydraulic System ◽  
Switching Time ◽  
Piston Pump ◽  
Hydraulic Pressure ◽  
Pressure Relief ◽  
Hydraulic Station

Analyzes the change of hydraulic pressure and flow rate during the opening/closing and curing processes in the hydraulic system of hydraulic tire curing machine and proposes a new design of the hydraulic station. By using three groups of motors-variable piston pump to work independently, the new hydraulic station can reduce machine downtime. Through using accumulator to keep pressure and delaying switching time of the valve to gradually release pressure, the new hydraulic station solves the problem of the severe impact caused by pressure relief and improve the safety and relia-bility.

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