İnşaat Mühendisliği Bölümü
https://hdl.handle.net/11494/1796
2024-03-29T00:39:01Z
2024-03-29T00:39:01Z
Implementation of finite element and artificial neural network methods to analyze the contact problem of a functionally graded layer containing crack
Yaylacı, Murat
Uzun Yaylacı, Ecren
Özdemir, Mehmet Emin
Ay, Sevil
Özturk, Sevval
https://hdl.handle.net/11494/4718
2023-02-23T09:11:35Z
2022-01-01T00:00:00Z
Implementation of finite element and artificial neural network methods to analyze the contact problem of a functionally graded layer containing crack
Yaylacı, Murat; Uzun Yaylacı, Ecren; Özdemir, Mehmet Emin; Ay, Sevil; Özturk, Sevval
In this study, a two-dimensional model of the contact problem has been examined using the finite element method (FEM) based software ANSYS and based on the multilayer perceptron (MLP), an artificial neural network (ANN). For this purpose, a functionally graded (FG) half-infinite layer (HIL) with a crack pressed by means of two rigid blocks has been solved using FEM. Mass forces and friction are neglected in the solution. Since the problem is analyzed for the plane state, the thickness along the z-axis direction is taken as a unit. To check the accuracy of the contact problem model the results are compared with a study in the literature. In addition, ANSYS and MLP results are compared using Root Mean Square Error (RMSE) and coefficient of determination (R2), and good agreement is found. Numerical solutions are made by considering different values of external load, the width of blocks, crack depth, and material properties. The stresses on the contact surfaces between the blocks and the FG HIL are examined for these values, and the results are presented. Consequently, it is concluded that the considered non-dimensional quantities have a noteworthy influence on the contact stress distributions, and also, FEM and ANN can be efficient alternative methods to time-consuming analytical solutions if used correctly.
2022-01-01T00:00:00Z
Biomechanical analysis of odontoid and transverse atlantal ligament in humans with ponticulus posticus variation under different loading conditions: finite element study
Güvercin, Yılmaz
Yaylacı, Murat
Dizdar, Ayberk
Kanat, Ayhan
Uzun Yaylacı, Ecren
Ay, Sevil
Abdioğlu, Ahmet Atilla
Şen, Ahmet
https://hdl.handle.net/11494/4336
2022-12-27T08:17:02Z
2022-01-01T00:00:00Z
Biomechanical analysis of odontoid and transverse atlantal ligament in humans with ponticulus posticus variation under different loading conditions: finite element study
Güvercin, Yılmaz; Yaylacı, Murat; Dizdar, Ayberk; Kanat, Ayhan; Uzun Yaylacı, Ecren; Ay, Sevil; Abdioğlu, Ahmet Atilla; Şen, Ahmet
Purpose: Ponticulus posticus (PP) is a variation of the bone bridge that appears in the first cervical vertebra and through which the vertebral artery passes. Odontoid fractures are common spinal bone fractures in older people. This study aims to investigate the effect of neck movements on the odontoid and transverse atlantal ligament (TAL) of people with PP variation from a biomechanical view. Method: C1, C2, and C3 vertebrae of the occipital bone were analyzed using the finite element method (FEM). In this study, solid models were created with the help of normal (N), incomplete (IC), and asymmetric complete (AC) PP tomography images. The necessary elements for the models were assigned, and the material properties were defined for the elements. As boundary conditions, models were fixed from the C3 vertebra, and 74 N loading was applied from the occipital bone. Stress and deformation values in the odontoid and transverse atlantal ligament were obtained by applying 1.8 Nm moment in flexion, extension, bending, and axial rotation directions. Results: The stress and deformation values of all three models in odontoid and TAL were obtained, and numerical results were evaluated. In all models, stress and deformation values were obtained in decreasing order in rotation, bending, extension, and flexion movements. The highest stress and strain values were obtained in AC and the lowest values were obtained in N. In all movements of the three models, the stress and deformation values obtained in the TAL were lower than in the odontoid. Conclusion: The greatest stresses and deformations obtained in spines (AC) with PP were found in the odontoid. This may help explain the pathogenesis of odontoid fractures in older people. First, this study explains the mechanism of the formation of neck trauma in people with PP and the need for a more careful evaluation of the direction of impact. Secondly, the study reveals that the rotational motion of the neck independent of PP has more negative effects on the odontoid.
2022-01-01T00:00:00Z
Extraction of road lane markings from mobile LiDAR data
Zeybek, Mustafa
https://hdl.handle.net/11494/3317
2021-08-10T08:12:48Z
2021-01-01T00:00:00Z
Extraction of road lane markings from mobile LiDAR data
Zeybek, Mustafa
This study presents a method for automatic extraction of road lane markings from mobile light detection and ranging
(LiDAR) data. Road lanes and traffic signs on the road surface provide safe driving for drivers and aid traffic flow movement
along the highway and street. Mobile LiDAR systems acquire massive datasets very quickly in a short time. To simplify the
data structure and feature extraction, it is essential for traffic management personnel to apply the right methods. Road lanes
must be visible and are a major factor in road safety for drivers. In this study, a methodology is devised and implemented for
the extraction of features such as dashed lines, continuous lanes, and direction arrows on the pavement from point clouds.
Point cloud data was collected from the Riegl VMX-450 mobile LiDAR system. The alpha shape algorithm is implemented on
a point cloud and compared with the widespread use of edge detection techniques applied for intensity-based raster images.
The proposed methodology directly extracts three-dimensional and two-dimensional road features to control the quality of
road markings and spatial positions with the obtained marking boundaries. State-of-the-art results are obtained and compared with manually digitized reference markings. The standard deviations were evaluated and acquired for intensity imagebased and direct point cloud-based extractions, at 1.2 cm and 1.7 cm, respectively
2021-01-01T00:00:00Z
Effect of size and slenderness on the axial-compressive behavior of basalt FRP-confined predamaged concrete
Ma, Gao
Chen, Xiaohuang
Biçici, Erkan
Hou, Chunxu
Sezen, Halil
https://hdl.handle.net/11494/2721
2022-02-24T08:11:03Z
2021-01-01T00:00:00Z
Effect of size and slenderness on the axial-compressive behavior of basalt FRP-confined predamaged concrete
Ma, Gao; Chen, Xiaohuang; Biçici, Erkan; Hou, Chunxu; Sezen, Halil
To investigate the size and slenderness effect on the axial-compressive behavior of basalt fiber-reinforced polymer (BFRP)-confined predamaged concrete, five groups of concrete cylinders with different sizes and slenderness ratios were designed and tested. The cylinders were axially preloaded to three predamage levels, then repaired using BFRP, and reloaded. The results showed that the concrete predamage had an adverse effect on the ultimate strength and initial elastic modulus of BFRP-confined concrete. Except for the smallest specimens affected by the wall effect, the initial analysis found that the ultimate strength of BFRP-confined concrete decreased with an increase in size and slenderness ratio, and the size and slenderness effect decreased with an increase in BFRP confining pressure, while these increased with the severity of concrete predamage. However, there was no obvious size or slenderness effect on the ultimate strain of BFRP-confined concrete. Through multifactorial analysis, it was confirmed that the ultimate strength of BFRP-confined undamaged and predamaged concrete was influenced by the slenderness. Considering the effect of size, slenderness, and predamage, monotonic and cyclic models were developed for BFRP-confined concrete. Finally, a uniaxial material object was added into OpenSees to provide an effective numerical material model for theoretical analyses and engineering applications. © 2021 American Society of Civil Engineers.
2021-01-01T00:00:00Z