Localization and Quantification of Breathing Crack

2005 ◽  
Vol 128 (2) ◽  
pp. 458-462 ◽  
Author(s):  
Milos Musil
Keyword(s):  
Approximate Analytical Solution ◽  
Second Harmonic ◽  
Bilinear System ◽  
Measured Data ◽  
Harmonic Load ◽  
The Finite Element Method ◽  
Breathing Crack ◽  
Series Representations ◽  
Nonlinear Analytical Model ◽  
The Mathematical Model

The possibility of localizing and quantifying a crack in a vibrating structure based on measured vibration amplitudes of the first and second harmonic in some locations of the structure and utilizing the mathematical model of an undamaged system, will be the focus of this paper. The structure is modeled by means of the finite element method. The effect of the breathing crack is modeled by the nonlinear (bilinear) stiffness of the element with the crack. The excitation of the system is characterized by the simultaneous effect of static and dynamic harmonic load. The Fourier series representations of the approximate analytical solution of a weakly bilinear system was used to obtain the localization and quanification a weak bilinearity. The method was documented on an elementary example, in which simulated measured data were determined by the use of the numerical solution of the nonlinear analytical model of a structure with a crack.

Analysing Mechanical Systems in Domestic and Foreign CAD Systems

2018 ◽  
pp. 10-17
Author(s):  
V. A. Martynyuk ◽  
V. A. Trudonoshin ◽  
V. G. Fedoruk
Keyword(s):  
Sheet Material ◽  
The Finite Element Method ◽  
Cad Systems ◽  
Cad System ◽  
Software Products ◽  
Foreign Products ◽  
Nonlinear Algebraic Systems ◽  
Software Product ◽  
Pipeline Design ◽  
The Mathematical Model

The article considers applications of foreign CAD-systems in creating the challenging projects at domestic enterprises and design bureaus. As stated in the article "... presently, there is no domestic CAD-system that could completely replace such foreign products as NX, CATIA, Credo". Besides, due to international cooperation in creating the challenging projects (for example, the project to create a modern wide-body aircraft, proposed jointly with China), it makes sense to use the worldwide known and popular CAD systems (the aforementioned NX, CATIA, Credo). Therefore, in the foreseeable future, we will still have to use foreign software products. Of course, there always remains a question of the reliability of the results obtained. Actually, this question is always open regardless of what software product is used - domestic or foreign. This question has been haunting both developers and users of CAD systems for the last 30 to 40 years. But with using domestic systems, it is much easier to identify the cause of inaccurate results and correct the mathematical models used, the methods of numerical integration applied, and the solution of systems of nonlinear algebraic systems. Everything is much more complicated if we use a foreign software product. All advertising conversations that there is a tool to make the detected errors available to the developers, remain only conversations in the real world. It is easily understandable to domestic users, and, especially, to domestic developers of similar software products. The existing development rates and competition for potential buyers dictate a rigid framework of deadlines for releasing all new versions of the product and introducing the latest developments into commercial product, etc. As a result, the known errors migrate from version to version, and many users have accepted it long ago. Especially, this concerns the less popular tools rather than the most popular applications (modules) of a CAD system. For example, in CAD systems, the "Modeling" module where geometric models of designed parts and assembly units are created has been repeatedly crosschecked. But most of the errors are hidden in applications related to the design of parts from sheet material and to the pipeline design, as well as in applications related to the analysis of moving mechanisms and to the strength or gas dynamic analysis by the finite element method.The article gives a concrete example of a moving mechanism in the analysis of which an error was detected using the mathematical model of external influence (a source of speed) in the NX 10.0 system of Siemens.

Damping characteristics of a magneto-rheological damper with dual independent controllable ducts

2021 ◽  
pp. 1045389X2110188
Author(s):  
Jianqiang Yu ◽  
Xiaomin Dong ◽  
Tao Wang ◽  
Zhengmu Zhou ◽  
Yaqin Zhou
Keyword(s):  
Dynamic Range ◽  
Fluid Flows ◽  
Mr Damper ◽  
Viscous Damping ◽  
The Novel ◽  
The Finite Element Method ◽  
Damping Force ◽  
Damping Characteristics ◽  
Magneto Rheological ◽  
The Mathematical Model

This paper presents the damping characteristics of a linear magneto-rheological (MR) damper with dual controllable ducts based on numerical and experimental analysis. The novel MR damper consisting of a dual-rod cylinder system and a MR valve is used to reduce the influences of viscous damping force and improve dynamic range. Driven by the dual-rod cylinder system, MR fluid flows in the MR valve. The pressure drop of the MR valve with dual independent controllable ducts can be controlled by tuning the current of two independent coils. Based on the mathematical model and the finite element method, the damping characteristics of the MR damper is simulated. A prototype is designed and tested on MTS machine to evaluate its damping characteristics. The results show that the working states and damping force of the MR damper can be controlled by the two independent coils.

Vibration of Nonuniform Beams Under Moving Point Loads: An Approximate Analytical Solution in Time Domain

2017 ◽  
Vol 17 (03) ◽  
pp. 1750035 ◽  
Author(s):  
C. P. Sudheesh Kumar ◽  
C. Sujatha ◽  
K. Shankar
Keyword(s):  
Approximate Analytical Solution ◽  
Time Integration ◽  
Single Mode ◽  
Mode Analysis ◽  
Moving Loads ◽  
The Finite Element Method ◽  
Require Time ◽  
Analytical Formulae ◽  
Clamped Beams ◽  
Forced Responses

The forced-free responses of nonuniform beams under moving point loads are analyzed in this paper. Simple approximate analytical formulae for the forced responses of undamped nonuniform beams, derived using the fundamental mode by the Rayleigh–Ritz (R–R) method, are presented. The responses of both simply supported and clamped–clamped beams are analyzed. The responses are also determined by the finite element method (FEM) in which nonuniform elements are used for fast convergence. It is found that the present method yields results that are very close to those obtained by the FEM. As this method does not require time integration, it is faster and computationally more efficient. Though the single-mode analysis of forced vibration of uniform beams under moving loads has been done by several researchers, its application to nonuniform beams has not been reported.

Design of an Induction Glass Melting Furnace by Means of Mathematical Modelling Using the Finite Element Method

2007 ◽  
Vol 553 ◽  
pp. 124-129 ◽  
Author(s):  
Isaac Arellano ◽  
Gabriel Plascencia ◽  
Elías Carrillo ◽  
Miguel A. Barrón ◽  
Adolfo Sánchez ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Glass Melting ◽  
Melting Furnace ◽  
The Finite Element Method ◽  
Glass Melting Furnace ◽  
High Frequencies ◽  
Harmful Emissions ◽  
The Mathematical Model ◽  
Element Method

In this paper we propose the design of a novel induction furnace for glass melting. The design is based on a mathematical analysis and performed numerically by means of the Finite Element Method. Several induction coils configurations were tested. The results from the mathematical model show that it is possible to melt glass in a furnace whose hearth is no larger than half a metre by using axial induction coils and high frequencies. This furnace configuration may result in increased glass melting rates along with the elimination of harmful emissions.

scholarly journals Crack Parameters Identification Based on a Kriging Surrogate Model for Operating Rotors

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Danyang Wang ◽  
Chunrong Hua ◽  
Dawei Dong ◽  
Biao He ◽  
Zhiwen Lu
Keyword(s):  
Surrogate Model ◽  
Parameters Identification ◽  
The Finite Element Method ◽  
Breathing Crack ◽  
Kriging Surrogate Model ◽  
Crack Location ◽  
Rotor Bearing ◽  
Location Depth ◽  
Nondominated Sorting ◽  
Bearing System

Parameters identification of cracked rotors has been gaining importance in recent years, but it is still a great challenge to determine the crack parameters including crack location, depth, and angle for operating rotors. This work proposes a new method to identify crack parameters in a rotor-bearing system based on a Kriging surrogate model and an improved nondominated sorting genetic algorithm-III (NSGA-III). A rotor-bearing system with a breathing crack is established by the finite element method and the superharmonic components are used as index to detect the cracks, the Kriging surrogate model between crack parameters and the superharmonic component amplitudes of the vibration response for rotors are constructed, and an improved NSGA-III is proposed to obtain the optimal crack parameters. Numerical experiments show that the proposed method can identify the crack location, depth, and angle accurately and efficiently for operating rotors.

scholarly journals The Influence of PZT Actuators Positioning in Active Structural Acoustic Control

10.14311/968 ◽  
2007 ◽  
Vol 47 (4-5) ◽  
Author(s):  
P. Švec ◽  
V. Jandák
Keyword(s):  
Sound Field ◽  
Structural Vibration ◽  
Structural Acoustics ◽  
The Finite Element Method ◽  
Ansys Software ◽  
Structural Vibrations ◽  
Radiated Power ◽  
Acoustic Control ◽  
Radiated Sound ◽  
The Mathematical Model

This paper deals with the effect of secondary actuator positioning in an active structural acoustics control (ASAC) experiment. The ASAC approach is based on minimizing the sound radiation from structures to the far field by controlling the structural vibrations. In this article a rectangular steel plate structure was assumed with one secondary actuator attached to it. As a secondary actuator, a specially designed piezoelectric stripe actuator was used. We studied the effect of the position of the actuator on the pattern and on the radiated sound field of the structural vibration, with and without active control. The total radiated power was also measured. The experimental data was confronted with the results obtained by a numerical solution of the mathematical model used. For the solution, the finite element method in the ANSYS software package was used. 

scholarly journals Numerical simulation of the stress state of the layered gas-bearing rocks in the bottom of mine working

2019 ◽  
Vol 109 ◽  
pp. 00043 ◽  
Author(s):  
Oleksandr Krukovskyi ◽  
Viktoriia Krukovska
Keyword(s):  
Mine Working ◽  
Physical And Mechanical Properties ◽  
Coupled Processes ◽  
The Finite Element Method ◽  
Gas Filtration ◽  
Calculation Results ◽  
The Difference ◽  
The Mathematical Model ◽  
Gas Bearing ◽  
Brittle Destruction

The mathematical model has been developed for the coupled processes of the rock massif deformation and gas filtration in a disturbed area around mine working, in the bottom of which there are hard and soft gas-bearing rocks. When solving the problem, the finite element method was used. The calculation results of the displacements, stresses and pressures of methane in the studied area are represented in the paper. It is shown that the difference in the physical and mechanical properties of the bottom rocks of mine working causes the non-uniform distribution of geomechanics and filtration parameters. In more strong sandstone, the stresses concentration increases. Therewith, an intensive process of fractures formation takes place in the argillite and the coal. Methane from the upper part of the gas-bearing sandstone is filtered into the mine working, the destruction of the coal interlayer is accompanied by release of methane and its accumulation under the layer of a strong sandstone. The development of a zone of inelastic deformations leads to the destruction of sandstone. In case of brittle destruction, with the formation of fractures of a certain length, a breakthrough of methane may occur out of the bottom into mine working.

Dynamic Stability of a Cantilever Shaft-Disk System

1992 ◽  
Vol 114 (3) ◽  
pp. 326-329 ◽  
Author(s):  
Lien-Wen Chen ◽  
Der-Ming Ku
Keyword(s):  
Dynamic Stability ◽  
Dynamic Instability ◽  
Equations Of Motion ◽  
Beam Theory ◽  
The Finite Element Method ◽  
Disk System ◽  
Stability Behavior ◽  
Gyroscopic Moment ◽  
The Mathematical Model ◽  
Cantilever Shaft

The dynamic stability behavior of a cantilever shaft-disk system subjected to axial periodic forces varying with time is studied by the finite element method. The equations of motion for such a system are formulated using deformation shape functions developed from Timoshenko beam theory. The effects of translational and rotatory inertia, gyroscopic moment, bending and shear deformation are included in the mathematical model. Numerical results show that the effect of the gyroscopic term is to shift the boundaries of the regions of dynamic instability outwardly and, therefore, the sizes of these regions are enlarged as the rotational speed increases.

Development of Stacked-Type Electrostatic Actuator Using Two Ribbon Films

2013 ◽  
Vol 25 (2) ◽  
pp. 324-332 ◽  
Author(s):  
Kazuo Okuda ◽  
◽  
Keiji Saneyoshi ◽  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Reduction Rate ◽  
Measured Data ◽  
The Other ◽  
Artificial Muscles ◽  
Electrostatic Actuator ◽  
The Finite Element Method ◽  
Nonlinear Structural Analysis ◽  
Working Region

A new stacked-type electrostatic actuator with two ribbon films has been developed to be applied to artificial muscles. In this paper, spring characteristics of the actuator have been simulated and compared to measured data. There are two regions in spring characteristics of the actuator: one is the working region where the actuator contracts easily, and the other is the overload region where the actuator is extended only negligibly by the load. Spring characteristics of the actuator have been simulated by nonlinear structural analysis including the contact problem using the finite element method. It is understood that spring characteristics of working and overload regions can be improved by thinning the hinge and by thickening the electrode. The stroke of the actuator can be controlled, furthermore, by changing the length of the hinge. When the size of the actuator is reduced and actuators are integrated until they become the same volume, voltage applied to the actuator to generate the same force is reduced in proportion to the reduction rate while the actuator keeps the same spring characteristics and stroke.

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