Dynamic Characteristics of a Hydraulic Damper

2002 ◽  
Author(s):  
Vishnu Verma ◽  
A. K. Ghosh ◽  
H. S. Kushwaha
Keyword(s):  
Pressure Drop ◽  
Dynamic Response ◽  
Analytical Model ◽  
Dynamic Characteristics ◽  
System Parameters ◽  
Hydraulic Damper ◽  
Dynamic Excitation ◽  
Sinusoidal Motion ◽  
Bypass Line

The response of a structure to earthquake or any other dynamic excitation can be brought down by using a suitable damper such as a hydraulic damper. An analytical model has been developed for hydraulic damper, which consists of a cylinder and piston arrangement with a bypass pipeline. The stiffness of the system is primarily due to the compressibility of the fluid and the damping is largely due to the pressure drop in the bypass line. The dynamic response of the hydraulic damper has been evaluated for an assumed sinusoidal motion of the piston. The paper presents detailed results of the study of the dynamic response of the damper to variations in input and system parameters. The characteristics of the damper, thus obtained, will be useful in determining the dynamic response of the whole system to which this damper will be attached.

DYNAMIC BEHAVIOR OF TELESCOPIC CRANES BOOM

2013 ◽  
Vol 13 (01) ◽  
pp. 1350010 ◽  
Author(s):  
IOANNIS G. RAFTOYIANNIS ◽  
GEORGE T. MICHALTSOS
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Analytical Model ◽  
Constant Velocity ◽  
Steel Beam ◽  
Continuum Approach ◽  
Theoretical Formulation ◽  
Modal Superposition ◽  
Superposition Technique

Telescopic cranes are usually steel beam systems carrying a load at the tip while comprising at least one constant and one moving part. In this work, an analytical model suitable for the dynamic analysis of telescopic cranes boom is presented. The system considered herein is composed — without losing generality — of two beams. The first one is a jut-out beam on which a variable in time force is moving with constant velocity and the second one is a cantilever with length varying in time that is subjected to its self-weight and a force at the tip also changing with time. As a result, the eigenfrequencies and modal shapes of the second beam are also varying in time. The theoretical formulation is based on a continuum approach employing the modal superposition technique. Various cases of telescopic cranes boom are studied and the analytical results obtained in this work are tabulated in the form of dynamic response diagrams.

scholarly journals Dynamic Response of a Road Bridge Subjected to Passing a Heavy Vehicle over a Standard Irregularity - Numerical Modelling and Experimental Testing

2022 ◽  
Vol 24 (1) ◽  
pp. D37-D45
Author(s):  
Milan Moravčík
Keyword(s):  
Numerical Modelling ◽  
Dynamic Response ◽  
Numerical Simulations ◽  
Experimental Testing ◽  
Heavy Vehicle ◽  
Dynamic Effects ◽  
Actual Problem ◽  
Box Girder ◽  
Dynamic Excitation ◽  
Girder Bridge

The paper presents an analysis of an actual problem related to dynamic effects to road bridges due to travelling a heavy vehicle over the bridge. Numerical simulations of the dynamic response are applied on a fictitious simple beam of the length Lb = 52 m with an artificial irregularity at midspan, corresponding to a characteristic span L (b5) = 52 m of the ten-span continuous box girder bridge. A heavy four-axle truck m v = 32 t is used for dynamic excitation, travelling over the bridge at passing speed of 70km / h. The obtained results are compared to results of the experimentally tested ten-span continuous pre-stressed reinforced concrete girder bridge at the same speed.

Performance comparison of electrorheological valves with two different geometric configurations: Cylinder and plate

2008 ◽  
Vol 223 (3) ◽  
pp. 573-581 ◽  
Author(s):  
Y-M Han ◽  
K-G Sung ◽  
J W Sohn ◽  
S-B Choi
Keyword(s):  
Pressure Drop ◽  
Response Time ◽  
Analytical Model ◽  
Performance Comparison ◽  
Time Varying ◽  
Control Performance ◽  
Electrode Gap ◽  
Design Constraint ◽  
Geometric Configurations ◽  
Er Fluid

This article presents a control performance comparison of electrorheological (ER) fluid-based valves between cylindrical and plate configurations. After identifying Bingham characteristics of chemical starch-based ER fluid, an analytical model of each valve is established. In order to reasonably compare valve performance, design constraint is imposed by the choosing the same electrode gap and length, and each ER valve is manufactured. Valve performances such as pressure drop and response time are then evaluated and compared through analytical model and experiment. In addition, a time-varying pressure tracking controllability of each ER valve is experimentally realized.

Optimized Pressure Determined in Accordance with Variable Plunger Stroke of Internal Injector NGV

2017 ◽  
Vol 370 ◽  
pp. 41-51 ◽  
Author(s):  
Kwon Se Kim ◽  
Doo Seuk Choi
Keyword(s):  
Pressure Drop ◽  
Natural Gas ◽  
Analytical Model

Using an analytical model, a clear investigation was performed into the phenomenon of decreasing overall pressure and velocity of a plunger when its stroke within a natural gas injector changes. The results indicated the following mesh sizes from the mesh matrix: 0.0005 mm minimum, 12.7 mm maximum, 1,107,420 nodes, and 5,856,567 elements. Consequently, the pressure was affected by the stroke height from the designed plunger shape, and although the height of the plunger stroke changes over 0.150 mm, the absence of the phenomenon of pressure drop was noticeable.

Modeling and electromechanical performance analysis of frequency-variable piezoelectric stack transducers

2020 ◽  
Vol 31 (6) ◽  
pp. 897-910
Author(s):  
Jianjun Wang ◽  
Shuyuan Cai ◽  
Lei Qin ◽  
Donghuan Liu ◽  
Peijun Wei ◽  
...  
Keyword(s):  
Experimental Study ◽  
Performance Analysis ◽  
Analytical Solution ◽  
Resonance Frequency ◽  
Analytical Model ◽  
Dynamic Characteristics ◽  
Active Element ◽  
Underwater Sound ◽  
Layer Number ◽  
Electromechanical Performance

An exact analytical model of frequency-variable piezoelectric stack transducers is proposed, and their dynamic characteristics are studied in this article. Based on the linear piezoelasticity theory, the dynamic analytical solution is first derived, and then its correctness is validated by comparing it with the results of a special example in the previous literature and the ones of the experimental study. The effects of the tuning resistance and the layer number of the active element on the dynamic characteristics are discussed. Numerical results show that tuning the resistance and the layer number of the active element can enable the multi-frequency characteristics of the piezoelectric stack transducers. A proper layer number of the active element can minimize the short-circuited resonance frequency and the open-circuited anti-resonance frequency. These findings provide guidelines to design and optimize the piezoelectric stack transducers, which have promising potential in developing the multi-frequency Langevin transducers for some underwater sound and ultrasonic applications, such as ultrasonic cleaning, ultrasonic chemistry, and sonar radiators.

scholarly journals 4D Printing of NiTi Auxetic Structure with Improved Ballistic Performance

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 745
Author(s):  
Hany Hassanin ◽  
Alessandro Abena ◽  
Mahmoud Ahmed Elsayed ◽  
Khamis Essa
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Analytical Model ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
4D Printing ◽  
Auxetic Structures ◽  
Negative Poisson's Ratio ◽  
The Impact ◽  
Auxetic Structure

Auxetic structures have attracted attention in energy absorption applications owing to their improved shear modulus and enhanced resistance to indentation. On the other hand, four-dimensional (4D) printing is an emerging technology that is capable of 3D printing smart materials with additional functionality. This paper introduces the development of a NiTi negative-Poisson’s-ratio structure with superelasticity/shape memory capabilities for improved ballistic applications. An analytical model was initially used to optimize the geometrical parameters of a re-entrant auxetic structure. It was found that the re-entrant auxetic structure with a cell angle of −30° produced the highest Poisson’s ratio of −2.089. The 4D printing process using a powder bed fusion system was used to fabricate the optimized NiTi auxetic structure. The measured negative Poisson’s ratio of the fabricated auxetic structure was found in agreement with both the analytical model and the finite element simulation. A finite element model was developed to simulate the dynamic response of the optimized auxetic NiTi structure subjected to different projectile speeds. Three stages of the impact process describing the penetration of the top plate, auxetic structure, and bottom plate have been identified. The results show that the optimized auxetic structures affect the dynamic response of the projectile by getting denser toward the impact location. This helped to improve the energy absorbed per unit mass of the NiTi auxetic structure to about two times higher than that of the solid NiTi plate and five times higher than that of the solid conventional steel plate.

Comparative Analysis of Frame-Core Wall Structure for Seismic Design

2012 ◽  
Vol 256-259 ◽  
pp. 2028-2033
Author(s):  
Jing Yang ◽  
Jiang Fan ◽  
Ji Xing Yuan ◽  
Qing Zhang
Keyword(s):  
Comparative Analysis ◽  
Dynamic Response ◽  
Seismic Performance ◽  
Seismic Design ◽  
Dynamic Characteristics ◽  
Wall Structure ◽  
Elastic Plastic ◽  
Linear Elastic ◽  
Plastic Phase

In this paper a skyscrapers frame-core wall structure as an example in Kun Ming, using two independent software, SATWE and ETABS, analyzed the dynamic characteristics and dynamic response of structures with earthquake in linear elastic phase and the elastic-plastic phase respectively, so that could evaluate rationality of the design of the structure as a whole and seismic performance superior or not, and it could provide an idea for audit drawing or proofread their own.

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