Analysis of Plate Vibrations Using Superelements

1982 ◽  
Vol 104 (2) ◽  
pp. 439-444 ◽  
Author(s):  
O. A. Pekau ◽  
H. P. Huttelmaier
Keyword(s):  
Flat Plate ◽  
Dynamic Properties ◽  
Mass Matrix ◽  
Vibrational Analysis ◽  
Plate Vibrations ◽  
Inertia Properties ◽  
Basic Features ◽  
Solution Accuracy

A rectangular substructure or superelement is described for use in the vibrational analysis of plates and flat plate assemblies. Basic features include elimination of internal nodes and flexibility in the location of nodes along the boundaries. Illustrative examples demonstrate the efficient and versatile application of the element. The main focus, however, is on solution accuracy for different representations of mass. In particular, it is found that the homogeneous inertia properties of a plate must be expressed by a consistent substructure mass matrix in order to model dynamic properties accurately.

Elastic Stiffness of Volcanic Sand through Resonant Column Tests

2015 ◽  
Vol 775 ◽  
pp. 292-297
Author(s):  
Kostas Senetakis ◽  
Anastasios Anastasiadis
Keyword(s):  
Dynamic Properties ◽  
Experimental Testing ◽  
Elastic Stiffness ◽  
Laboratory Method ◽  
Granular Soils ◽  
Resonant Column ◽  
Torsional Mode ◽  
Resonant Column Test ◽  
Basic Features ◽  
Low Amplitude

The resonant column method is established as a standard laboratory method for the study of the elastic properties of soils. The study presents low-amplitude resonant column test results on volcanic sands with intra-particle voids. The experiments were performed on dry samples prepared at variable relative densities and tested in torsional mode of vibration. In the first part of the article, the important factors that control the elastic stiffness of uncemented sands are described shortly and recent findings on granular soils dynamic properties are presented briefly. The second part describes the basic features of the resonant column used in the investigation and the materials of the study and in the third part representative results of an extensive experimental testing program on volcanic granular soils are presented and discussed with a focus on comparisons between the elastic stiffness of volcanic and quartz granular soils. The importance of the effect of the presence of intra-particle voids within the particle mass of the volcanic soils is emphasized, which in turn affects markedly the global void ratio of the samples.

scholarly journals Destabilizing damping effect on flat-plate vibrations due to flow-induced flutter

2017 ◽  
Vol 199 ◽  
pp. 790-795
Author(s):  
Luca Pigolotti ◽  
Claudio Mannini ◽  
Gianni Bartoli
Keyword(s):  
Flat Plate ◽  
Plate Vibrations ◽  
Damping Effect

Vibration Analysis of Continuous Systems by Dynamic Discretization

1980 ◽  
Vol 102 (2) ◽  
pp. 391-398 ◽  
Author(s):  
B. Downs
Keyword(s):  
Power Series ◽  
Shear Deformation ◽  
Vibration Analysis ◽  
Dynamic Properties ◽  
Mass Matrix ◽  
Continuous System ◽  
Mode Shapes ◽  
Continuous Systems ◽  
Stress Distributions ◽  
Equivalent Mass

An equivalent mass matrix may be defined, for a segment of a continuous system, as one which retains precisely the dynamic properties of the original segment in discretized form. Dynamic Discretization, which makes use of a particular form of Stodola iteration, progressively generates the equivalent mass matrix in ascending powers of frequency squared, whilst simultaneously generating deformation functions in a similar power series. The method is quasi-static and readily copes with shear deformation, rotary inertia and quite complex segment geometry. Accurate vibration analysis in terms of frequencies, mode shapes and corresponding stress distributions is achieved using an extremely coarse system subdivision for a variety of geometries.

DYNAMIC PROPERTIES OF A BIOLOGICALLY MOTIVATED NEURAL NETWORK MODEL

1992 ◽  
Vol 03 (04) ◽  
pp. 371-378 ◽  
Author(s):  
FRANÇOIS CHAPEAU BLONDEAU ◽  
GILBERT CHAUVET
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Transfer Function ◽  
Network Model ◽  
Neural Network Model ◽  
Dynamic Properties ◽  
Biological Significance ◽  
Neural Architecture ◽  
The Stability ◽  
Basic Features

We develop a neural network model based on prominent basic features of biological neural networks. The description keeps a simple but coherent link between the subneuronal, neuronal and network levels. In addition, the variables of the model are endowed with realistic numerical values together with their physical units. This permits to reach quantitative significance for the results. To describe the operation of the neuron, a transfer function is used that is believed to convey more biological significance compared to the usual sigmoid transfer function. It is shown that the dynamic properties of the network, which can vary from stability to chaos, are significantly influenced by the choice of the neuron transfer function. Constraints on the synaptic efficacies, as imposed by Dale’s rule, are also shown to modify the dynamic properties by increasing the stability of the network. A simple neural architecture is presented that leads to a controllable time evolution of the network activities.

scholarly journals Multiple Crack Detection in Thick-walled Pipes Using Artificial Bee Colony Algorithm

2021 ◽  
Author(s):  
Amir Banimahd ◽  
Mohammad Amir Rahemi
Keyword(s):  
Objective Function ◽  
Stiffness Matrix ◽  
Crack Detection ◽  
Artificial Bee Colony ◽  
Dynamic Properties ◽  
Mass Matrix ◽  
Multiple Cracks ◽  
Unknown Parameters ◽  
Abc Algorithm ◽  
Bee Colony

An analytical method for diagnosis of cracks in thick-walled pipes with a circular hollow section is investigated in this study. In the proposed method, the defect is assumed to be a non-leaking crack, which is modeled by a massless linear spring with infinitesimal length at the crack location. In order to find the cracks in the pipe, the vibration-based method related to the modal properties of the pipe is utilized. In the modal analysis, the mass and stiffness matrices influence the dynamic properties of the pipe. It is assumed that the mass matrix remains unchanged after the crack initiation, while the corresponding stiffness matrix changes. The stiffness matrix of a cracked element can be formulated by the finite element method with two unknown parameters: location and depth of the crack. Using the eigensolution for an undamped dynamic system to formulate the objective function yields to a complicated optimization problem, which can be solved by an iterative numerical optimization method. Among the optimization approaches, the Artificial Bee Colony (ABC) algorithm is a simple and flexible technique for minimizing the objective function. In this paper, the analytical model is utilized to find the size and position of cracks in a pipe using the ABC algorithm and subsequently some numerical examples are examined in order to assess the accuracy of the method. The results show that the proposed method is able to acceptably estimate the location and depth of multiple cracks in the straight pipes as well as curved ones.

scholarly journals Analysis of flat plate vibrations by varying frontal area to the flow

2019 ◽  
Author(s):  
Shravan Koundinya Vutukuru ◽  
Janis Viba ◽  
Igors Tipans ◽  
Ilmars Viksne ◽  
Martins Irbe
Keyword(s):  
Flat Plate ◽  
Frontal Area ◽  
Plate Vibrations

Forced Vibration Testing and Finite Element Modeling of a Nine-Story Reinforced Concrete Flat Plate-Wall Building

2015 ◽  
Vol 31 (2) ◽  
pp. 1069-1081 ◽  
Author(s):  
Ozan Cem Celik ◽  
Haluk Sucuoğlu ◽  
Ugurhan Akyuz
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Flat Plate ◽  
Forced Vibration ◽  
Structural Model ◽  
Dynamic Properties ◽  
Mode Shapes ◽  
Structural System ◽  
Vibration Testing ◽  
Forced Vibration Testing

Tunnel form buildings, owing to their higher construction speed and quality, lower cost, and superior earthquake resistance over that of conventional reinforced concrete buildings, have been widely used for mass housing, urban renewal, and post-earthquake reconstruction projects all over the world as well as in Turkey. However, there have been few dynamic tests performed on existing buildings with this structural system. This study investigates the dynamic structural properties of a typical nine-story reinforced concrete flat plate-wall building by forced vibration testing and develops its three-dimensional (3-D) linear elastic finite element structural model. The finite element model that uses the modulus of elasticity for concrete in ACI 318 predicts the natural vibration periods well. Mode shapes are also in good agreement with the test results. Door and window openings in the shear walls, and the basement with peripheral wall emerge as modeling considerations that have the most significant impact on structural system dynamic properties.

Vibrational Analysis of a Dual-Motive Locomotive and Evaluation by Experimental Methods and Modal Analysis

2012 ◽  
Author(s):  
Jesús Otero Yugat ◽  
Gorka Agirre Castellanos ◽  
Igor Alonso Portillo
Keyword(s):  
Modal Analysis ◽  
Dynamic Behavior ◽  
Dynamic Properties ◽  
Vibrational Excitation ◽  
Vibrational Analysis ◽  
Experimental Methods ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Hydraulic Actuator ◽  
Diesel Locomotive

This paper presents a theoretical and experimental study done on an electro-diesel locomotive in order to evaluate the dynamic behavior of the vehicle in terms of safety, running performance and wheel-track interaction. The vibration analysis has been made by means of different experimental methodologies. The first one consists on the acquisition of accelerations at points located at the wheelset, the truck frame and the coach, using piezorresistive accelerometers. The registered signals allow to validate the locomotive in terms of safety against derailment and running behavior, according the UIC 518 leaflet. The second method is based on the modal analysis theory and includes the dynamic properties estimation under vibrational excitation. This procedure takes into account the determination of modal parameters such as natural frequencies, modal damping ratios and mode shapes, by means of a control hydraulic actuator. The third methodology consists on the operational modal analysis done with the experimental measurements acquired on track tests, in order to validate the results obtained by modal analysis and evaluate the dynamic behavior under different speed ranges and cant deficiencies. Several tests have been done by means of the described methods in an electro-diesel locomotive composed by a primary suspension with dampers and a secondary suspension with rigid stiffness. In addition, two types of dampers have been evaluated with the purpose of optimizing the damping properties of the vehicle’s primary suspension. Through these experimental methods, a useful tool for the prediction and analysis of the dynamic behavior is provided. Additionally, the results obtained by means of these methodologies permit examining the influence of different running conditions and vehicle properties on the modal parameters.

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