Crack Detection through the Change in the Normalized Frequency Shape

Dahak, Mustapha; Touat, Noureddine; Benkedjouh, Tarak

doi:10.3390/vibration1010005

Cited by 8 publications

(7 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Here, d x and d y are the diameters of the primary and secondary axes of the air holes. This proposed design was simulated by varying the value of d x while maintaining the constants D core , d x and total radius of the fiber = Core/A [17]. A is the area.…”

Section: Device Structure and Designmentioning

confidence: 99%

Cyclic Olefin Copolymer Based Photonic Crystal Fiber as Single Mode THz Waveguide

Tun Naziba,

Tun Nafisa,

Nasir Uddin

2024

IJCDS

View full text Add to dashboard Cite

Photonic Crystal Fiber Technology (PCF) based terahertz (THz) communication is widely considered the key component of future generation high capacity communication and biomedical engineering. The most difficult aspect of employing this technology is minimizing material losses and dispersion over longer distances. In PCF modeling, a wide variety of materials are considered (Zeonex, Silica, Cyclic Olefin Copolymer, etc.). The Cyclic Olefin Copolymer (COC) stands out as a highly flexible material that is both easily fabricable and inexpensive. This study proposed hexagonal porous cladding and core using the Finite Element Method (FEM). A fiber with an optimal core diameter of 300 µm, a low Effective Material Loss (EML) of 0.039456 cm -1 , a low Confinement Loss (CL) of 2.264 × 10 -5 dBcm -1 , dispersion of 0.8594 psTHz -1 cm -1 and V-parameter of 1.42 are obtained for 1 THz operating frequency. The suggested fiber's propagation parameters have been diligently analyzed and obtained promising values. A significant porosity of 65% and power fraction of 29.88% was recorded.

show abstract

Section: Device Structure and Designmentioning

confidence: 99%

Cyclic Olefin Copolymer Based Photonic Crystal Fiber as Single Mode THz Waveguide

Tun Naziba,

Tun Nafisa,

Nasir Uddin

2024

IJCDS

View full text Add to dashboard Cite

show abstract

“…Incorporating the assumed modes of Equation ( 3) into (11) and following the procedure outlined previously results in the boundary penalty stiffness matrix of the system. The symmetric penalty stiffness matrix is given by…”

Section: Boundary Penalty Functionsmentioning

confidence: 99%

“…A simply supported and a fixed-fixed beam were considered for the study of the proposed model. Dahak et al [11] presented a method to identify and quantify of cracks in beams using natural frequencies. The stiffness matrix was calculated by the theory of fracture mechanics, by inverting the flexibility matrix.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Characteristics of a Beam with a Shallow Crack Using Alternative Admissible Functions

Kateel

Baddour

2022

Symmetry

View full text Add to dashboard Cite

The presence of a crack in a beam leads to changes in its dynamic characteristics and hence changes in its natural frequencies and mode shapes. In this paper, Alternative Admissible Functions (AAF) with penalties for extracting the dynamic characteristics of a Euler–Bernoulli Beam with a shallow crack is proposed and validated. The proposed method has two key advantages. First, the alternative admissible function choice is independent of the boundary conditions, which are modelled via boundary penalty terms. Second, the crack is treated as a penalty function to account for the local stiffness reduction while ensuring beam continuity. The approach is validated with different crack depth ratios and locations. The mass, stiffness, and penalty function matrices for Simply Supported (SS), Clamped–Clamped (CC), and Clamped–Free (CF) are developed and are used in the analysis of a beam with a shallow crack. The proposed method demonstrates results in good agreement with published literature for shallow cracks. A significant advantage of the proposed method is the ease of applicability, eliminating the need for remodeling with changes in boundary conditions or crack parameters. The results show that the crack introduces asymmetry to the beam and may require changing the boundary penalty values, depending on the location and depth of the crack.

show abstract

“…Khalkar and Ramachandran [31] have performed modal analysis by using ANSYS software for identifying the natural observations of different rectangular shape and v-shape subjects of a cantilever cracked beam. Dahak et al [32] used the standard observations for quantifying and localizing beams' cracks. Hanif et al [33] have addressed the challenges in vibration modeling on concrete modeling by implementing nonlinear behavior.…”

Section: Related Workmentioning

confidence: 99%

Simulation and Analysis with Wavelet Transform Technique and the Vibration Characteristics for Early Revealing of Cracks in Structures

Abu‐Hamdeh

Daqrouq

Mebarek‐Oudina

2021

Mathematical Problems in Engineering

View full text Add to dashboard Cite

Implementation of improved instruments is used to detect damage in an accurate manner and fully analyze its characteristics. An aluminum beam has been used in this work to identify cracks by using a vibration technique. The simulation of frequency response feature was conducted using a finite element model to provide average measures of intensities of vibration. Two forms of wavelet packet transform (WPT) entropies Shannon and log energy were applied to identify the position, width, and size of the crack. The results showed that with an increase in crack depth, the amplitude also increased at certain crack sizes and for all crack positions. For two crack depths of 1.6 mm and 0.16 mm having the same crack size and position 12 mm and 60 mm, respectively, a 4.5% increase in amplitude was observed at a crack depth of 1.6 mm. Moreover, the amplitude varied inversely with the position. A 12.6% increase in amplitude was observed at a crack depth of 1.6 mm rather than 0.16 mm, while both depths occurred at the same crack position (75 mm) and size (20 mm). Experimental validation was performed on a cantilever beam with one crack. The maximum absolute error found was 7.5% for the crack position and 9.1% for the crack size. With the increase in crack depth, the obtained results decrease the stiffness of a beam in a single crack case.

show abstract

Crack Detection through the Change in the Normalized Frequency Shape

Cited by 8 publications

References 31 publications

Cyclic Olefin Copolymer Based Photonic Crystal Fiber as Single Mode THz Waveguide

Cyclic Olefin Copolymer Based Photonic Crystal Fiber as Single Mode THz Waveguide

Dynamic Characteristics of a Beam with a Shallow Crack Using Alternative Admissible Functions

Simulation and Analysis with Wavelet Transform Technique and the Vibration Characteristics for Early Revealing of Cracks in Structures

Contact Info

Product

Resources

About