Development of a New Added Mass Model and Dynamic Analysis for Cylindrical Tank

2006 ◽  
Author(s):  
Z. Zhuang ◽  
H. Z. Liu ◽  
Q. Li ◽  
S. Yamaguchi ◽  
M. Toyoda
Keyword(s):  
Mass Formula ◽  
Seismic Loading ◽  
Element Model ◽  
Rigid Wall ◽  
Added Mass ◽  
Mass Model ◽  
External Work ◽  
Tank Model ◽  
Key Factor ◽  
Dynamic Nonlinear Analysis

In order to investigate dynamic response under seismic loading for liquid tank, a new added mass formula and finite element model has been developed in this paper, which is implemented into ABAQUS as the user element subroutine. The simulation results for elastic-plastic Elephant Foot Bulging (EFB) and Diamond Shape Bulging (DSB) are validated the reliability for the added mass formula. Some shortcoming has been appointed out for the classical added mass equation, which is only suited for the liquid tank with rigid wall. Used the new added mass model, the dynamic nonlinear analysis for the tank has been carried out under dynamic loading. Through the response history and frequency analysis, it indicates that the external work on the tank model by earthquake loading is a key factor to result in plastic deformation of EFB and DSB.

A Simplified Finite Element for Added Mass and Inertial Coupling in Arrays of Cylinders

1985 ◽  
Vol 107 (2) ◽  
pp. 118-125 ◽  
Author(s):  
R. E. Harris ◽  
M. A. Dokainish ◽  
D. S. Weaver
Keyword(s):  
Finite Element ◽  
Time Integration ◽  
Element Model ◽  
Added Mass ◽  
Cylindrical Structures ◽  
Beam Elements ◽  
Inertial Coupling ◽  
Fundamental Frequencies ◽  
Tube Bundles ◽  
Primary Advantage

A simplified finite element has been developed for modeling the added mass and inertial coupling arising when clusters of cylinders vibrate in a quiescent fluid. The element, which is based on two-dimensional potential flow theory, directly couples two adjacent beam elements representing portions of the adjacent cylindrical structures. The primary advantage of this approach over existing methods is that it does not require the discretization of the surrounding fluid and, therefore, is computationally much more efficient. The fundamental frequencies of tube bundles of various pitch ratios have been predicted using this method and compared with experimental data. Generally, the agreement is good, especially for the bandwidth of fluid coupled natural frequencies. The transient response of tube bundles is also examined using time integration of the finite element model. The beating phenomenon and time decay characteristics exhibited by the experimental bundles under single-tube excitation are well predicted and valuable insights are gained into the measurement of damping in tube bundles.

Modal and Aeroelastic Analysis of a Compressor Blisk Considering Mistuning

2011 ◽  
Author(s):  
Jens Nipkau ◽  
Arnold Ku¨hhorn ◽  
Bernd Beirow
Keyword(s):  
Equations Of Motion ◽  
Computing Time ◽  
Element Model ◽  
Forced Response ◽  
Lumped Mass ◽  
Aerodynamic Forces ◽  
Mass Model ◽  
Influence Coefficients ◽  
Aeroelastic Analysis ◽  
Lumped Mass Model

Focussing on three basic blade modes the effect of the flow’s influence on the forced response of a mistuned HPC-blisk is studied using a surrogate lumped mass model called equivalent blisk model (EBM). Both measured and intentionally allowed mistuning is considered to find out in principle if the flow contributes to a slowdown of blade displacements with increasing mistuning. In a first step the mechanical properties of the EBM are adjusted to a finite element model and known mistuning distributions given in terms of blade frequencies and damping. Taking into account the flow structure interaction CFD-computations are carried out in order to derive aerodynamic influence coefficients (AIC) which are used to describe the aerodynamic forces coming along with the motion of each blade in the flow. These aerodynamic forces can be included directly in the EBM equations of motion or alternatively be used to calculate aeroelastic eigenvalues from which additional equivalent aerodynamic elements representing the co-vibrating air mass as well as aerodynamic stiffening and damping effects are derived. Both kinds of EBM are applied to study the forced response at least in a qualitative manner aiming to demonstrate some basic effects at low computing time.

AN EFFICIENT FINITE ELEMENT MODEL FOR ANALYSIS OF SINGLE WALLED BORON NITRIDE NANOTUBE-BASED RESONANT NANOMECHANICAL SENSORS

NANO ◽  
2013 ◽  
Vol 08 (01) ◽  
pp. 1350011 ◽  
Author(s):  
MITESH B. PANCHAL ◽  
S. H. UPADHYAY ◽  
S. P. HARSHA
Keyword(s):  
Finite Element ◽  
Boron Nitride ◽  
Resonant Frequency ◽  
Continuum Mechanics ◽  
Element Model ◽  
Added Mass ◽  
Simulation Approach ◽  
Attached Mass ◽  
Resonant Frequency Shift ◽  
Nanomechanical Sensors

In this paper, the dynamics analysis of single walled boron nitride nanotubes (SWBNNT) as a resonant nanomechanical sensor by using the finite element method has been reported. Molecular structural mechanics-based finite element model (FEM) has been developed by using three-dimensional elastic beams and point masses, such that the proximity of the model to the actual atomic structure of nanotube is significantly retained. Different types of armchair layups of SWBNNTs are considered with cantilevered and bridged end constraints. By implementing the finite element simulation approach, the resonant frequency shift-based mass sensitivity analysis is performed for both types of end constraints for considered armchair form of the SWBNNTs with different aspect ratios. For both types of end constraint, continuum mechanics-based analytical formulations, considering effective wall thickness of nanotubes are used to validate the present FEM-based simulation approach. The intermediate landing position of the added mass is analyzed, considering variations in resonant frequency shifts of the different fundamental modes of vibrations for both types of end constraints. The FEM-based simulation results for both types of end constraints found in good agreement with the continuum mechanics-based analytical results for the aspect ratio of range of 9–15. The mass sensitivity limit of 10-1 zg is achieved for SWBNNT-based resonant nanomechanical sensors. The resonant frequency shift for higher-order fundamental vibrational modes become stable as the attached mass moves away from the fixed ends for particular magnitude of attached mass. The present finite element-based approach is found to be effectual in terms of dealing different atomic structures, boundary conditions and consideration of added mass to analyze the dynamic behavior of the SWBNNT-based resonant nanomechanical sensors.

Added mass effect and an extended unsteady blade element model of insect hovering

2011 ◽  
Vol 8 (4) ◽  
pp. 387-394 ◽  
Author(s):  
Xingyao Yan ◽  
Shanan Zhu ◽  
Zhongdi Su ◽  
Hongjun Zhang
Keyword(s):  
Mass Effect ◽  
Element Model ◽  
Added Mass ◽  
Blade Element

scholarly journals Prediction of railway induced ground vibration through multibody and finite element modelling

2013 ◽  
Vol 4 (1) ◽  
pp. 167-183 ◽  
Author(s):  
G. Kouroussis ◽  
O. Verlinden
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Vertical Plane ◽  
Time History ◽  
Ground Vibration ◽  
Element Model ◽  
Contact Forces ◽  
Railway Transportation ◽  
Lumped Mass ◽  
Mass Model

Abstract. The multibody approach is now recognized as a reliable and mature computer aided engineering tool. Namely, it is commonly used in industry for the design of road or railway vehicles. The paper presents a framework developed for predicting the vibrations induced by railway transportation. Firstly, the vehicle/track subsystem is simulated, on the basis of the home-made C++ library EasyDyn, by mixing the multibody model of the vehicle and the finite element model of the track, coupled to each other through the wheel/rail contact forces. Only the motion in the vertical plane is considered, assuming a total symmetry between left and right rails. This first step produces the time history of the forces exerted by the ballast on the foundation, which are then applied to a full 3-D FEM model of the soil, defined under the commercial software ABAQUS. The paper points out the contribution of the pitch motion of the bogies and carbodies which were neglected in previous publications, as well as the interest of the so-called coupled-lumped mass model (CLM) to represent the influence of the foundation in the track model. The potentialities of the model are illustrated on the example of the Thalys high-speed train, riding at 300 km h−1 on the Belgian site of Mévergnies.

Numerical Analysis of Mechanical Properties of Precast Segmental Concrete Test Beam with External Tendons

2013 ◽  
Vol 639-640 ◽  
pp. 460-469
Author(s):  
Hai Bo Jiang ◽  
Yan Song Deng ◽  
Yun Qiu ◽  
Chun Gen Wei ◽  
Li Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Numerical Analysis ◽  
Finite Element Model ◽  
Simulation Analysis ◽  
Crack Opening ◽  
Element Model ◽  
Test Beam ◽  
External Tendons ◽  
Key Factor

A finite element model is proposed for numerical analysis of mechanical properties of precast segmental concrete test beam with external tendons. The 3D finite element model of test beam is established by SOLID65 element in ANSYS software, while the dry joint between segments is simulated by contact element, and the attachment between concrete beam and external prestressed tendons is achieved by node coupling method. Numerical simulation analysis reveals structural behavior, stress variations and crack opening cases of joints of the test beam by considering the concrete material and geometric nonlinearity. Influencing factors of the bending mechanical properties of the test beam are researched with different tendon types, secondary effect of external tendons and external tendon slip at deviation. Results of the numerical analysis reveal that the segmental joints are in the compressive state below the 300kN.Crack opening is the key factor of the mechanical properties of the test beam above the 300kN.The results can be used for structural design of precast segmental bridge.

scholarly journals Joint Elasticity Effect on the Failure Behaviours of Rock Masses using a Discrete Element Model

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2968
Author(s):  
Yong Yuan ◽  
Changtai Zhou ◽  
Zhihe Wang ◽  
Jifang Du
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Failure Mode ◽  
Element Model ◽  
Discrete Element ◽  
Discrete Element Model ◽  
Rock Masses ◽  
Joint Orientation ◽  
Mass Model ◽  
Joint Elasticity

It is widely accepted that the mechanical properties and failure behaviours of a rock mass are largely dependent upon the geometrical and mechanical properties of discontinuities. The effect of joint elasticity on the failure behaviours of rock masses is investigated using a discrete element model, namely, the synthetic rock mass model. Here, uniaxial compression tests of the numerical model are carried out for the rock mass model with a persistent joint to analyse the role of joint elasticity in the failure process with various joint orientations, β. A strong correlation between the joint elasticity and failure strength is found from the simulation results: a positive relationship when the joint orientation β < φ j ; a negative relationship when the joint orientation φ j < β < 90 ° ; and a very limited effect when the joint orientation β = 90 ° . Additionally, it is shown that the joint elasticity is the governing factor in the transition of failure modes, especially from the sliding failure mode along the joint to the mixed sliding-tensile failure mode.

Dynamic Responses of Arch Dams Considering Different Reservoir Models

2011 ◽  
Vol 250-253 ◽  
pp. 3923-3926
Author(s):  
Shao Qing Hu ◽  
Bai Tao Sun
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Water Level ◽  
Element Model ◽  
Arch Dam ◽  
Dynamic Responses ◽  
Additional Mass ◽  
Mass Model ◽  
Arch Dams ◽  
Reservoir Models

In this paper, the dynamic responses of an arch dam in the case of normal water level and operating low water level were simulated by using additional mass model and incompressible finite element model for reservoir respectively. The results showed that the reservoir models have a great impact on dynamic response of arch dams. The maximum principle tensile stress using incompressible finite element model of fluid is less than that using additional mass model. With the depth of the reservoir water increasing, the hydrodynamic pressure acting ton the dam surface caused by earthquake force increased and the dynamic responses of dam also increased.

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