Yazar "Saribay, Murat" seçeneğine göre listele

Listeleniyor 1 - 5 / 5
  • Küçük Resim Yok
    Öğe
    Effect of stress wave propagation phenomenon on the determination of strain energy density theory parameters and dynamic J-integral
    (Wiley, 2023) Saribay, Murat
    Dynamic loading for stationary cracks leads to results that are many times greater in magnitude than their static counterparts. If the dynamic loading is in the form of impact type, stress wave propagation effects become dominant. FRAC3D program comprises enriched element formulation which doesn't require excessive mesh refinement around crack tip for accuracy. Strain energy density (SED) theory parameters and dynamic J-integral are sought in this study to simulate and understand wave propagation phenomenon in detail. Structures under the effect of wave propagations yield more reliable J-integral values by taking the average of the results from multiple domain sizes. Governed by stress waves, space-time variations of minimum energy density locations strongly influence fracture characterization for straight and curved crack fronts. Details given in numerical examples section of this paper make a great contribution to understanding of the response for cracked structures subjected to sudden loading.
  • Küçük Resim Yok
    Öğe
    Finite Element Analysis of Evolut Transcatheter Heart Valves: Effects of Aortic Geometries and Valve Sizes on Post-TAVI Wall Stresses and Deformations
    (Mdpi, 2025) Mutlu, Onur; Mazhar, Noaman; Saribay, Murat; Yavuz, Mehmet Metin; Ozturk, Deniz; Ghareeb, Abdel Naser; Yalcin, Huseyin Cagatay
    Background/Objectives: For transcatheter aortic valve implantation (TAVI) therapy, a catheter-guided crimped valve is deployed into the aortic root. Valve types such as Edwards balloon-expandable valves and Medtronic self-expandable valves come in different sizes and are chosen based on patient-specific aortic anatomy, including aortic root diameter measurement. Complications may arise due to variations in anatomical characteristics and the implantation procedure, making pre-implantation assessment important for predicting complications. Methods: Computational modeling, particularly finite element analysis (FEA), has become popular for assessing wall stresses and deformations in TAVI. In this study, a finite element model including the aorta, native leaflets, and TAVI device was used to simulate procedures and assess patient-specific wall stresses and deformations. Results: Using the Medtronic Evolut R valve, we simulated TAVI for 14 patients to analyze the effects of geometrical variations on structural stresses. Virtual TAVIs with different valve sizes were also simulated to study the influence of TAV size on stresses. Our results show that variations in aortic wall geometries and TAV sizes significantly influence wall stresses and deformations. Conclusions: Our study is one of the first comprehensive FEA investigations of aortic geometrical variations and valve sizes on post-TAVI stresses, demonstrating the non-linear relationship between aortic dimensions, TAV sizes, and wall stresses.
  • Küçük Resim Yok
    Öğe
    Local and global energy densities associated with welding residual stresses of cracked structures
    (Elsevier, 2020) Saribay, Murat
    The residual stresses associated with fusion welding processes have recently become a popular issue considering the reliable design of structural components. In a welding problem, it is quite common that fracture is observed to initiate either directly from the welds or from fatigue cracks that develop in the weld's heat affected zone (HAZ). A recent study has investigated the effects of subsequent dynamic loading with stationary crack fronts, which assumes load being applied to the structure following the welding process. To analyze these types of problems, a computational procedure based on finite element methodology is developed to integrate the welding residual stresses with subsequent dynamic fracture behavior. The welding analysis is performed with a welding simulation program (SYSWELD). The inclusion of residual stresses and the determination of classical fracture parameters are handled with a specialized finite element program, called FRAC3D. The calculation of energy densities that are recently used in the analysis of cracked structures was shown to be an effective method for the solution of fracture problems. In this paper, a new methodology that is developed to determine local and global energy densities for the simulation of dynamic fracture behavior with initial welding residual stresses is presented.
  • Küçük Resim Yok
    Öğe
    Material modeling and recent findings in transcatheter aortic valve implantation simulations
    (Elsevier Ireland Ltd, 2024) Mutlu, Onur; Saribay, Murat; Yavuz, Mehmet Metin; Salman, Huseyin Enes; Al-Nabti, A. Rahman D. M. H.; Yalcin, Huseyin Cagatay
    Background and objective: Transcatheter aortic valve implantation (TAVI) has significantly transformed the management of aortic valve (AV) diseases, presenting a minimally invasive option compared to traditional surgical valve replacement. Computational simulations of TAVI become more popular and offer a detailed investigation by employing patient-specific models. On the other hand, employing accurate material modeling procedures and applying basic modeling steps are crucial to determining reliable numerical results. Therefore, this review aims to outline the basic modeling approaches for TAVI, focusing on material modeling and geometry extraction, as well as summarizing the important findings from recent computational studies to guide future research in the field. Methods: This paper explains the basic steps and important points in setting up and running TAVI simulations. The material properties of the leaflets, valves, stents, and tissues utilized in TAVI simulations are provided, along with a comprehensive explanation of the geometric extraction methods employed. The differences between the finite element analysis, computational fluid dynamics, and fluid-structure interaction approaches are pointed out and the important aspects of TAVI modeling are described by elucidating the recent computational studies. Results: The results of the recent findings on TAVI simulations are summarized to demonstrate its powerful potential. It is observed that the material properties of aortic tissues and components of implanted valves should be modeled realistically to determine accurate results. For patient-specific AV geometries, incorporating calcific deposits on the leaflets is essential for ensuring the accuracy of computational findings. The results of numerical TAVI simulations indicate the significance of the selection of optimal valves and precise deployment within the appropriate anatomical position. These factors collectively contribute to the effective functionality of the implanted valve. Conclusions: Recent studies in the literature have revealed the critical importance of patient-specific modeling, the selection of accurate material models, and bio-prosthetic valve diameters. Additionally, these studies emphasize the necessity of precise positioning of bio-prosthetic valves to achieve optimal performance in TAVI, characterized by an increased effective orifice area and minimal paravalvular leakage.
  • Küçük Resim Yok
    Öğe
    Multiprocessing implementations for time-dependent fracture analysis of an electronic packaging structure
    (Korean Soc Mechanical Engineers, 2023) Saribay, Murat
    Investigation of fracture mechanics problems with computational tools has always been a great challenge due to singularities present at the crack tip. FRAC3D is an effective finite element tool that benefits from enriched element methodology. The dynamic version of this code enables the analysis of structures with stationary cracks subjected to impact loading. Response of the components in these problems are highly influenced by stress wave propagation phenomenon. In this study, bimaterial interface cracking in an electronic packaging structure is analyzed considering transient behavior. Besides the complications associated with the finite element solution of such a problem, long computational times may also be an issue considering model sizes. Multiprocessing of finite element codes could save significant times if corresponding algorithms are restructured with parallel processing tools in an efficient form. Up to 75 % reductions in time for the given example were obtained by using newly implemented multiprocessing code.