scholarly journals Review on Vibration Analysis of Cracked Cantilever Beam

2021 ◽  
Vol 9 (9) ◽  
pp. 536-541
Author(s):  
Mohd Anas Ansari
Keyword(s):  
Composite Materials ◽  
Cantilever Beam ◽  
Comprehensive Evaluation ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Crack Depth ◽  
Crack Location ◽  
Inherent Frequency ◽  
Voigt Model ◽  
The Impact

Abstract: A unique feature of fiber-reinforced composite materials is that it allows structural tailoring for favorable dynamic performance, due to the directional nature of composite materials. Because of the directed character, material coupling occurs, resulting in coupled vibration modes and complicating dynamic analysis. A transverse triangular force impulse modulated by a harmonic motion excites the beam. For the substance of the beam, the Kelvin–Voigt model is employed. The fractured beam is represented by two sub-beams linked by a massless elastic rotating spring. The beams are designed to function in wet environments, which cause rusting. Corrosion causes cracks to form in beams, altering their inherent frequency and mode shape. The present paper examines the different investigations that have been done to investigate the impact of fracture on the dynamic properties of beams. The researchers provided a comprehensive evaluation of the impact of crack design factors (crack depth, crack location) on cantilever beam transverse and torsional frequencies. It is also given the analytical approach, numerical method, and experimental methods for studying the impact of fracture on vibration characteristics. Keywords: Cantilever Beam, Crack dimensions, Damage, Kelvin–Voigt model.

scholarly journals Bird-Strike Resistance of Composite Laminates with Different Materials

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 129 ◽  
Author(s):  
Yadong Zhou ◽  
Youchao Sun ◽  
Tianlin Huang
Keyword(s):  
Composite Materials ◽  
Composite Laminates ◽  
Impact Damage ◽  
Dynamic Properties ◽  
Dynamic Structure ◽  
Strength Properties ◽  
Bird Strike ◽  
Particle Hydrodynamics ◽  
Bird Impact ◽  
The Impact

To obtain some basic laws for bird-strike resistance of composite materials in aeronautical application, the high-velocity impact behaviors of composite laminates with different materials were studied by numerical methods. The smoothed particle hydrodynamics (SPH) and finite element method (FEM) coupling models were validated from various perspectives, and the numerical results were comparatively investigated. Results show that the different composite materials have relatively little effect on projectile deformations during the bird impact. However, the impact-damage distributions can be significantly different for different composite materials. The strength parameters and fracture energy parameters play different roles in different damage modes. Lastly, modal frequency was tentatively used to explain the damage behavior of the composite laminates, for it can manifest the mass and stiffness characteristics of a dynamic structure. The dynamic properties and strength properties jointly determine the impact-damage resistance of composite laminates under bird strike. Future optimization study can be considered from these two aspects.

scholarly journals Influence of Crack on Modal Parameters of Cantilever Beam Using Experimental Modal Analysis

2018 ◽  
Vol 1 (1) ◽  
pp. 16-23 ◽  
Author(s):  
Siva Sankara Babu Chinka ◽  
Balakrishna Adavi ◽  
Srinivasa Rao Putti
Keyword(s):  
Numerical Analysis ◽  
Modal Analysis ◽  
Natural Frequency ◽  
Cantilever Beam ◽  
Damping Ratio ◽  
Crack Depth ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Crack Location

In this paper, the dynamic behavior of a cantilever beam without and with crack is observed. An elastic Aluminum cantilever beams having surface crack at various crack positions are considered to analyze dynamically. Crack depth, crack length and crack location are the foremost parameters for describing the health condition of beam in terms of modal parameters such as natural frequency, mode shape and damping ratio. It is crucial to study the influence of crack depth and crack location on modal parameters of the beam for the decent performance and its safety. Crack or damage of structure causes a reduction in stiffness, an intrinsic reduction in resonant frequencies, variation of damping ratios and mode shapes. The broad examination of cantilever beam without crack and with crack has been done using Numerical analysis (Ansys18.0) and experimental modal analysis. To observe the exact higher modes of beam, discretize the beam into small elements. An experimental set up was established for cantilever beam having crack and it was excited by an impact hammer and finally the response was obtained using PCB accelerometer with the help sound and vibration toolkit of NI Lab-view. After obtaining the Frequency response functions (FRFs), the natural frequencies of beam are estimated using peak search method. The effectiveness of experimental modal analysis in terms of natural frequency is validated with numerical analysis results. This paper contains the study of free vibration analysis under the influence of crack at different points along the length of the beam.

The effect of crack geometry on non-destructive fault detection of EN 8 and EN 47 cracked cantilever beam

2019 ◽  
Vol 50 (3) ◽  
pp. 92-100 ◽  
Author(s):  
V Khalkar ◽  
S Ramachandran
Keyword(s):  
Free Vibration ◽  
Natural Frequency ◽  
Cantilever Beam ◽  
Crack Detection ◽  
Crack Depth ◽  
Free Vibration Analysis ◽  
Crack Location ◽  
Crack Geometry ◽  
Shaped Crack ◽  
Non Destructive

Since long it has been observed that the size of the crack in structures increases with time, and finally, it may lead to its catastrophic failure. Hence, it is crucial to do the vibration study of cracked structures with regard to vibration-based crack detection and the classification of cracks. So far, vibration-based non-destructive testing method is applied to many spring steel cracked cantilever beams for its possible crack detection. However, the effect of various kinds of practical cracks, that is, V-shaped and U-shaped, on the applicability of these methods has been overlooked. To investigate this issue, artificially cracks are made on the cantilever beam. By free vibration analysis, the effect of crack geometry, crack depth, and crack location on natural frequency is investigated. The natural frequency results obtained from V-shaped and U-shaped models for the same crack configurations are compared with each other and it is revealed that the results are not much sensitive for the change of crack geometry. Hence, it is clear that free vibration-based crack detection method approximately predicts the crack parameters, that is, crack location and crack depth, in structures irrespective of the crack geometry. It is also found that for the same configuration, results of natural frequency are comparatively on the lower side for U-shaped crack models than V-shaped crack models. In this study, the natural frequency of each cracked case is computed by a theoretical method and numerical method and shows good agreement. Finally, it is also observed that structural integrity of a cracked cantilever beam is a function of crack location.

Coupled Transverse and Axial Vibrations of Cracked Cantilever Beams With Roving Mass and Rotary Inertia

2010 ◽  
Author(s):  
Hurang Hu ◽  
Akindeji Ojetola ◽  
Hamid Hamidzadeh
Keyword(s):  
Cantilever Beam ◽  
Natural Frequencies ◽  
Coupling Effect ◽  
Rectangular Cross Section ◽  
Crack Depth ◽  
Rotary Inertia ◽  
Mode Shapes ◽  
Axial Deformation ◽  
Crack Location ◽  
Axial Vibrations

The vibration behavior of a cracked cantilever beam with a stationary roving mass and rotary inertia is investigated. The beam is modeled as an Euler-Bernoulli beam with rectangular cross section. The transverse deformation and axial deformation of the cracked beam are coupled through a stiffness matrix which is determined based on fracture mechanics principles. The analytical solutions are obtained for the natural frequencies and mode shapes of a cracked cantilever beam with a roving mass and rotary inertia. The effects of the location and depth of the crack, the location and the weight of the roving mass and rotary inertia on the natural frequencies and mode shapes of the beam are investigated. The numerical results show that the coupling between the transverse and axial vibrations for moderate values of crack depth and/or roving mass and rotary inertia is weak. Increasing the crack depth and the mass and rotary inertia will increase the coupling effect. Detection of the crack location using natural frequencies and mode shapes as parameters is also discussed.

scholarly journals ANALYSIS OF THE IMPACT OF SPECIAL CONSTRUCTIONS OF GAP SEALS ON THE DYNAMICS OF CENTRIFUGAL MACHINES

ScienceRise ◽  
2020 ◽  
pp. 3-13
Author(s):  
Serhii Shevchenko
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Operating Conditions ◽  
Centrifugal Pumps ◽  
Labyrinth Seals ◽  
Research Results ◽  
The Impact ◽  
Technological Product

The object of research: the influence of the design features of special gap seals on the dynamic characteristics of centrifugal machines. Investigated problem: harmonization of the consumption and dynamic characteristics of the seals of the rotors of high-speed machines by applying special design methods. Main scientific results: The mechanism and operating conditions of seals with floating rings are described. It is determined that the most effective from the point of view of dynamic characteristics is the variant of the semi-movable ring. Expressions for determining the conditions of angular and radial immobility of a floating ring are obtained. The design options for deformable gap seals, including deformable floating rings, deformable interwheel seals and seals with an axially movable deformable sleeve, have been investigated. The scope of their application for unique machines with high requirements for tightness and vibration reliability has been determined. Variants of the design of labyrinth seals have been investigated. The analysis shows that the dynamic properties of labyrinth seals significantly depend on the relative position of the ridges. Overlapping ridged seals have the worst dynamic performance of the labyrinth seal designs. The honeycomb seal has more favorable dynamic properties, and the well seal has the best combination of consumption and dynamic characteristics. The dynamic characteristics are especially important for the seals of high-speed rotors of centrifugal machines. The area of practical use of the research results: Enterprises that manufacture centrifugal machines: pumps and compressors. Innovative technological product: a methodology for the selection, design and calculation of special designs of gap seals with optimization of dynamic and flow characteristics. Scope of application of the innovative technological product: The obtained research results will be useful in the design and manufacture of centrifugal pumps and compressors for any parameters.

Structural Damage Detection by Fuzzy Logic Technique

2014 ◽  
Vol 592-594 ◽  
pp. 1175-1179 ◽  
Author(s):  
Rabinarayan Sethi ◽  
S.K. Senapati ◽  
Dayal R. Parhi
Keyword(s):  
Fuzzy Logic ◽  
Cantilever Beam ◽  
Structural Damage ◽  
Fuzzy Controller ◽  
Crack Depth ◽  
Crack Location ◽  
Novel Approach ◽  
Vibration Parameters ◽  
Fuzzy Logic Technique

In this paper, a novel approach for detecting crack location and its intensity in cantilever beam by Fuzzy logic techniques is established. The analysis has been done by using ANSYS FE software. The fuzzy controller with Bell shaped membership functions are used here which consists of three input parameters are relative deviation of first three natural frequencies and two output parameters are relative crack depth and relative crack location respectively. A series of fuzzy rules are resulting from vibration parameters which are finally used for prediction of crack location and its intensity. This method provides the knowledge towards the detection, location and characterization of the damage in the cantilever beam.

scholarly journals The effect of crack geometry on stiffness of spring steel cantilever beam

2018 ◽  
Vol 37 (4) ◽  
pp. 762-773 ◽  
Author(s):  
V Khalkar ◽  
S Ramachandran
Keyword(s):  
Free Vibration ◽  
Cantilever Beam ◽  
Crack Detection ◽  
Crack Depth ◽  
Steel Structures ◽  
Spring Steel ◽  
Cantilever Beams ◽  
Crack Location ◽  
Crack Geometry ◽  
Shaped Crack

The survival of the crack in structures always keeps the structure away from performing well in applications due to significant changes in its dynamic response. It has been observed that in service the size of the crack in structures increases with time and finally it leads to its catastrophic failure. Hence it is crucial to do the vibration study of cracked beams in regard of free vibration-based crack detection and its crack classification. Until now the vibration-based nondestructive testing methods are applied to many spring steel cracked cantilever beams for its possible crack detection. However, the effect of various kinds of practical cracks, i.e. V-shaped, U-shaped and rectangular-shaped open cracks, on the applicability of these methods has been overlooked. In order to investigate this issue, artificially cracks are made on the cantilever beam. By free vibration analysis, the effect of crack geometry, crack depth, and crack location on the beam stiffness is investigated. In this study, the stiffness of each cracked case is computed by the deflection methods and vibration methods to ensure the strong validation. The stiffness results obtained from V-shaped, U-shaped and rectangular-shaped crack models for the same configuration are compared with each other and it is found that the results of the stiffness are comparatively more sensitive to U-shaped crack models. Through vibration study, it is found that spring steel structures are slightly sensitive to the change in crack geometries as long as the vibration characteristics are concerned. Hence, it is obvious that free vibration-based crack detection method can satisfactorily predict the location and depth of the crack in any spring steel structures irrespective of the crack geometries. Apart from this, it is also found that for the same configurations, EN 8 and EN 47 cracked cantilever beams give the identical structural integrity or structural stability property for all the cracked cases. Lastly, it is also found that as the crack depth increases by keeping the crack location constant, the stiffness of the beam decreases.

Study on Natural Vibration Characteristics of Large Scale Composite Wind Turbine Blades

2011 ◽  
Author(s):  
Yi Yang ◽  
Chengcheng Tan ◽  
Danmei Xie ◽  
Yangheng Xiong ◽  
Yang Shi ◽  
...  
Keyword(s):  
Finite Element ◽  
Wind Turbine ◽  
Modal Analysis ◽  
Turbine Blade ◽  
Torsional Vibration ◽  
Crack Depth ◽  
Wind Turbine Blade ◽  
Variable Cross ◽  
Crack Location ◽  
The Impact

As the single unit capacity has been increased, the length of wind turbine blade is becoming longer, and the blade vibration fatigue damage caused by impact of wind turbines has become an important issue of wind turbine security. Therefore, modal analysis and study on the impact of crack on the natural frequency of the wind turbine blade are of great significance. The finite element software ANSYS was used to establish a finite element model of a 1.5MW composite wind turbine blade, with a structure of twisted variable cross-section and hollow core in the first place of this paper. Modal analysis of the model established in this paper showed that the blade vibrates in 3 different forms, they are flap within the rotating plane, flutter vibration perpendicularity to the rotating plane and torsional vibration around the blade shaft. Among all the orders, flap and flutter vibration are predominent in low modes, while torsional vibration appears only in high modes (above the fifth order). Then blade models with cracks in the root were established to analyze the regularity of the blade natural frequencies with the crack location, depth and the variation of the angle. The results showed that: as the location of the crack changed in wingspan direction, the change of frequencies showed two basic trends: one was declining gradually; the other was decreasing and then increasing before decreasing again, and the minimum the maximum value appeared at location around 32.5% and 87.5% of the blade root respectively. As crack depth increased gradually, the frequencies reduced continuously, and compared to crack location, influence of crack depth was more prominent. For slant crack, when the crack angle, that is the angle between the crack section chord line and the foliosine plane, increased, all orders of frequencies gradually increased, indicating that the influence of the crack on the blade stiffness decreases as the angle increases.

Identification of Crack Parameters in a Cantilever Beam under Uncertain End Conditions

2009 ◽  
Vol 413-414 ◽  
pp. 117-124
Author(s):  
Zhi Hua Wang ◽  
Lin Jing ◽  
Wei Wei Zhang ◽  
Hong Wei Ma
Keyword(s):  
Cantilever Beam ◽  
Characteristic Equation ◽  
Present Model ◽  
Crack Depth ◽  
Local Effect ◽  
Crack Identification ◽  
Experimental Frequency ◽  
Crack Location ◽  
End Conditions ◽  
The Difference

The local effect of “softening” at the crack location can be simulated by an equivalent spring connecting the two segments of the beam. As modelling the crack, the non-perfectly rigid clamp is also simulated as a torsional spring of unknown stiffness. Combined with the Bernoulli-Euler theories of beam, the present model is applied to derive the characteristic equation of the cantilever beam under uncertain end conditions related to the crack parameters, namely, the location and the depth of the crack. Based on this characteristic equation, an accurate crack identification method is developed to identify the location and the depth of the crack by minimizing the difference between the analytical and experimental frequency values. The proposed approach is verified by two cantilever beam experiments under ideal boundary conditions and uncertain end conditions. It is found that the location and the depth of the crack can be worked out when at least three natural frequencies are known. For crack identification of the cantilever beam under uncertain end conditions, the identified crack location of the proposed approach is more accurate than the Narkis’ method. Furthermore, the crack depth can also be obtained by the present method.

Response of Cracked Cantilever Beam Subjected to Traversing Mass

2015 ◽  
Author(s):  
Shakti P. Jena ◽  
Dayal R. Parhi ◽  
Devasis Mishra
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Dynamic Response ◽  
Numerical Method ◽  
Cantilever Beam ◽  
Crack Depth ◽  
Numerical Procedure ◽  
Element Analysis ◽  
Crack Location

The present work emphasizes the dynamic response of double cracked cantilever beam subjected to a traversing mass. The cracks are located at different positions of the beam with random crack depths. The response of the damaged structure has been evaluated employing a numerical procedure of Runge-Kuuta method. The effects of crack depth, traversing mass, traversing speed and crack location on the response of the structure are studied. Finite element analysis (FEA) using the commercial ANSYS 15 has been presented to validate the adopted numerical method.

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