Nonlinear Input Power Flow Analysis of a Plate with a Breathing Crack

2014 ◽  
Vol 638-640 ◽  
pp. 163-167
Author(s):  
Zhong Hao Pang ◽  
Xiang Zhu ◽  
Tian Yun Li ◽  
Ling Zhang
Keyword(s):  
Nonlinear Dynamic ◽  
Power Flow ◽  
Damage Identification ◽  
Flow Analysis ◽  
Nonlinear Dynamic Analysis ◽  
Nonlinear Behavior ◽  
Input Power ◽  
Breathing Crack ◽  
Engineering Structures ◽  
Power Characteristics

Plates are commonly used in engineering structures. However crack is the most common form of damages in the plate structures. The crack in the plate will open and close during vibrational cycle, making the cracked structure with nonlinear dynamic characteristics. Based on vibrational power flow theory, the nonlinear dynamic analysis of a plate structure is carried out. The contact elements are used to simulate the nonlinear behavior of the breathing crack. Aiming to study the input power characteristics and the super harmonic resonance of a breathing cracked plate which is under the resonant excitation. By the finite element calculation, the structural input power curve is analyzed, which provides a theoretical basis for the damage identification of cracked structures.

scholarly journals Nonlinear Dynamic Behaviors of Rotated Blades with Small Breathing Cracks Based on Vibration Power Flow Analysis

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Hailong Xu ◽  
Zhongsheng Chen ◽  
Yeping Xiong ◽  
Yongmin Yang ◽  
Limin Tao
Keyword(s):  
Nonlinear Dynamic ◽  
Power Flow ◽  
Flow Analysis ◽  
Crack Model ◽  
Breathing Crack ◽  
Dynamic Behaviors ◽  
Power Flow Analysis ◽  
Local Flexibility ◽  
Vibration Power Flow ◽  
Nonlinear Behaviors

Rotated blades are key mechanical components in turbomachinery and high cycle fatigues often induce blade cracks. Accurate detection of small cracks in rotated blades is very significant for safety, reliability, and availability. In nature, a breathing crack model is fit for a small crack in a rotated blade rather than other models. However, traditional vibration displacements-based methods are less sensitive to nonlinear characteristics due to small breathing cracks. In order to solve this problem, vibration power flow analysis (VPFA) is proposed to analyze nonlinear dynamic behaviors of rotated blades with small breathing cracks in this paper. Firstly, local flexibility due to a crack is derived and then time-varying dynamic model of the rotated blade with a small breathing crack is built. Based on it, the corresponding vibration power flow model is presented. Finally, VPFA-based numerical simulations are done to validate nonlinear behaviors of the cracked blade. The results demonstrate that nonlinear behaviors of a crack can be enhanced by power flow analysis and VPFA is more sensitive to a small breathing crack than displacements-based vibration analysis. Bifurcations will occur due to breathing cracks and subharmonic resonance factors can be defined to identify breathing cracks. Thus the proposed method can provide a promising way for detecting and predicting small breathing cracks in rotated blades.

Vibrational Power Flow Analysis of Stiffened Plate and Shell Structures

2011 ◽  
Vol 66-68 ◽  
pp. 1897-1901 ◽  
Author(s):  
Xiang Zhu ◽  
Gong Yu Xiao ◽  
Tian Yun Li ◽  
Xiao Fang Hu
Keyword(s):  
Cylindrical Shell ◽  
Power Flow ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Input Power ◽  
Shell Structures ◽  
Stiffened Plate ◽  
Simply Supported ◽  
Plate And Shell ◽  
Flow Vectors

In this paper, the vibration and power flow characteristics of stiffened plate and cylindrical shell structures are investigated by using finite element method. The power flow formulas of basic shell structural elements are given at first. Then a simply supported plate and stiffened plate’s input power flow characteristics and power flow vectors are investigated. The effects of stiffeners in plates are discussed. For a simply supported cylindrical shell, the influence of the structural damping, viscous damper and stiffeners on the cylindrical shell’s input power flow characteristics and propagated power flow characteristics are discussed in detail. The power flow vectors are visualized to reveal the distribution of energy in the shell structures. Some useful conclusions are drown and helpful for the vibration control of plate and shell structures.

scholarly journals Use of Bispectrum Analysis to Inspect the Non-Linear Dynamic Characteristics of Beam-Type Structures Containing a Breathing Crack

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1177
Author(s):  
Li Cui ◽  
Hao Xu ◽  
Jing Ge ◽  
Maosen Cao ◽  
Yangmin Xu ◽  
...  
Keyword(s):  
Damage Detection ◽  
Dynamic Characteristics ◽  
Structural Damage ◽  
Damage Identification ◽  
Crack Depth ◽  
Excitation Frequency ◽  
Breathing Crack ◽  
Engineering Structures ◽  
Linear Dynamic ◽  
Non Linear

A breathing crack is a typical form of structural damage attributed to long-term dynamic loads acting on engineering structures. Traditional linear damage identification methods suffer from the loss of valuable information when structural responses are essentially non-linear. To deal with this issue, bispectrum analysis is employed to study the non-linear dynamic characteristics of a beam structure containing a breathing crack, from the perspective of numerical simulation and experimental validation. A finite element model of a cantilever beam is built with contact elements to simulate a breathing crack. The effects of crack depth and location, excitation frequency and magnitude, and measurement noise on the non-linear behavior of the beam are studied systematically. The result demonstrates that bispectral analysis can effectively identify non-linear damage in different states with strong noise immunity. Compared with existing methods, the bispectral non-linear analysis can efficiently extract non-linear features of a breathing crack, and it can overcome the limitations of existing linear damage detection methods used for non-linear damage detection. This study’s outcome provides a theoretical basis and a paradigm for damage identification in cracked structures.

scholarly journals Accounting for Quasi-Static Coupling in Nonlinear Dynamic Reduced-Order Models

2020 ◽  
Vol 15 (7) ◽  
Author(s):  
Evangelia Nicolaidou ◽  
Venkata R. Melanthuru ◽  
Thomas L. Hill ◽  
Simon A. Neild
Keyword(s):  
High Frequency ◽  
Nonlinear Dynamic ◽  
Nonlinear Dynamic Analysis ◽  
Low Frequency ◽  
Nonlinear Effects ◽  
Fe Model ◽  
Engineering Structures ◽  
Reduced Order ◽  
Modal Coupling ◽  
High Frequency Modes

Abstract Engineering structures are often designed using detailed finite element (FE) models. Although these models can capture nonlinear effects, performing nonlinear dynamic analysis using FE models is often prohibitively computationally expensive. Nonlinear reduced-order modeling provides a means of capturing the principal dynamics of an FE model in a smaller, computationally cheaper reduced-order model (ROM). One challenge in formulating nonlinear ROMs is the strong coupling between low- and high-frequency modes, a feature we term quasi-static coupling. An example of this is the coupling between bending and axial modes of beams. Some methods for formulating ROMs require that these high-frequency modes are included in the ROM, thus increasing its size and adding computational expense. Other methods can implicitly capture the effects of the high-frequency modes within the retained low-frequency modes; however, the resulting ROMs are normally sensitive to the scaling used to calibrate them, which may introduce errors. In this paper, quasi-static coupling is first investigated using a simple oscillator with nonlinearities up to the cubic order. ROMs typically include quadratic and cubic nonlinear terms, however here it is demonstrated mathematically that the ROM describing the oscillator requires higher-order nonlinear terms to capture the modal coupling. Novel ROMs, with high-order nonlinear terms, are then shown to be more accurate, and significantly more robust to scaling, than standard ROMs developed using existing approaches. The robustness of these novel ROMs is further demonstrated using a clamped–clamped beam, modeled using commercial FE software.

scholarly journals A New Method to Perform Direct Efficiency Measurement and Power Flow Analysis in Vibration Energy Harvesters

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2388
Author(s):  
Jan Kunz ◽  
Jiri Fialka ◽  
Stanislav Pikula ◽  
Petr Benes ◽  
Jakub Krejci ◽  
...  
Keyword(s):  
Lead Zirconate Titanate ◽  
Polyvinylidene Fluoride ◽  
Power Flow ◽  
Flow Analysis ◽  
Lead Zirconate ◽  
Input Power ◽  
Mechanical Power ◽  
Vibration Source ◽  
Energy Harvesters ◽  
The Difference

Measuring the efficiency of piezo energy harvesters (PEHs) according to the definition constitutes a challenging task. The power consumption is often established in a simplified manner, by ignoring the mechanical losses and focusing exclusively on the mechanical power of the PEH. Generally, the input power is calculated from the PEH’s parameters. To improve the procedure, we have designed a method exploiting a measurement system that can directly establish the definition-based efficiency for different vibration amplitudes, frequencies, and resistance loads. Importantly, the parameters of the PEH need not be known. The input power is determined from the vibration source; therefore, the method is suitable for comparing different types of PEHs. The novel system exhibits a combined absolute uncertainty of less than 0.5% and allows quantifying the losses. The approach was tested with two commercially available PEHs, namely, a lead zirconate titanate (PZT) MIDE PPA-1011 and a polyvinylidene fluoride (PVDF) TE LDTM-028K. To facilitate comparison with the proposed efficiency, we calculated and measured the quantity also by using one of the standard options (simplified efficiency). The standard concept yields higher values, especially in PVDFs. The difference arises from the device’s low stiffness, which produces high displacement that is proportional to the losses. Simultaneously, the insufficient stiffness markedly reduces the PEH’s mechanical power. This effect cannot be detected via the standard techniques. We identified the main sources of loss in the damping of the movement by the surrounding air and thermal losses. The latter source is caused by internal and interlayer friction.

Dynamic Behavior of Finite Coupled Mindlin Plates With a Blocking Mass

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
XianZhong Wang
Keyword(s):  
Dynamic Behavior ◽  
Power Flow ◽  
Equations Of Motion ◽  
Flow Analysis ◽  
Input Power ◽  
Dynamic Responses ◽  
Structural Damping ◽  
Arbitrary Angle ◽  
Plate Equations ◽  
Coupled Plates

A power flow analysis of finite coupled Mindlin plates with a blocking mass at the junction of the coupled plates is investigated using the method of reverberation-ray matrix (MRRM). An exact solution is derived by the plate equations of motion to satisfy the boundary condition. The wave amplitude coefficients are obtained from the continuity conditions at driving force locations, and the line junction of two plates connected at an arbitrary angle. The blocking mass located at the junction of the two plates is modeled as a Timoshenko beam. The dynamic responses of the finite coupled Mindlin plates are verified by comparing with finite element method (FEM) results. The effects of the connected angles, blocking mass, and structural damping on the input power and transmitted power are calculated and analyzed. Numerical simulations of the finite coupled Mindlin plates with a blocking mass show that the present method can predict the dynamic behavior.

A Systematic Approach to Power-Flow and Static-Force Analysis in Epicyclic Spur-Gear Trains

1993 ◽  
Vol 115 (3) ◽  
pp. 639-644 ◽  
Author(s):  
E. Pennestri` ◽  
F. Freudenstein
Keyword(s):  
Power Flow ◽  
Systematic Approach ◽  
Flow Analysis ◽  
Spur Gear ◽  
Input Power ◽  
Static Force ◽  
Force Analysis ◽  
Systematic Method ◽  
Gear Trains ◽  
Gear Drives

It is well known that the circulating power in gear trains can be many times greater than the input power. Such circumstances require that in the design of split-power gear drives, a preliminary power-flow analysis be carried out. In this investigation a systematic method for the power-flow and static-force analysis of spur-gear drives is presented. The manner in which the procedure is applied has some similarities with an algorithm for kinematic analysis previously suggested by one of the authors. Following a brief review of previous work, the theoretical bases of the new methodology of analysis are discussed and numerical examples developed.

scholarly journals DC RAILWAY POWER FLOW ANALYSIS FOR ADDIS ABABA LIGHT RAIL TRANSIT USING NEWTON RAPHSON METHOD

2021 ◽  
Vol 9 (5) ◽  
pp. 744-759
Author(s):  
Mugisho Mugaruka Josue ◽  
◽  
Regis Nibaruta ◽  
Keyword(s):  
Power Flow ◽  
Addis Ababa ◽  
Flow Analysis ◽  
Input Power ◽  
Light Rail ◽  
Rail Transit ◽  
Dc Power ◽  
Tractive Effort ◽  
Line Section ◽  
Raphson Method

This paper uses Newton–Raphson method for DC power flow analysis of the Addis Ababa light Rail Transit (AALRT). The study focuses onthe line section from Menilik II square station up to Lideta station. First the tractive effort required by the trains for different scenarios such as train movement in a straight line, a curved line, and a line with gradient is computed as the chosen line section contains all these scenarios. Then the total input power will be calculated using computed tractive effort obtained for each scenario and using other input parameters obtained from AALRT, and different papers. The input power for the different loads is computed, and the input power is used to analyse the bus voltage for different loads and train positions. Newton Raphson Method is used to solve the DC Power bus problem assuming that the train requires constant power while moving between two feeding stations. Even if using the rail as the return conductor for DC traction systems has economic advantages, it has some limitations like the rail potential and stray current. A rail potential study is carried out and conclusions are drawn. The result shows that the maximum voltage drop was 0.1 p.u and the train power consumption increases by 136.73 kW as the train takes a gradient of 3.92% and keep increasing again by 29.17kw with a curve resistance (100 meters). The Rail potential moves from 6.0139V to 29.85V proportionally with the variation of the total ground resistance.

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