A two dimensional mixed boundary-value problem in a viscoelastic medium

Ataoglu, S. Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.32 No.3

A fundamental solution for the transient, quasi-static, plane problems of linear viscoelasticity is introduced for a specific material. An integral equation has been found for any problem as a result of dynamic reciprocal identity which is written between this fundamental solution and the problem to be solved. The formulation is valid for the first, second and mixed boundary-value problems. This integral equation has been solved by BEM and algorithm of the BEM solution is explained on a sample, mixed boundary-value problem. The forms of time-displacement curves coincide with literature while time-surface traction curves being quite different in the results. The formulation does not have any singularity. Generalized functions and the integrals of them are used in a different form.

A two dimensional mixed boundary-value problem in a viscoelastic medium

S. Ataoglu 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.32 No.3

A fundamental solution for the transient, quasi-static, plane problems of linear viscoelasticity is introduced for a specific material. An integral equation has been found for any problem as a result of dynamic reciprocal identity which is written between this fundamental solution and the problem to be solved. The formulation is valid for the first, second and mixed boundary-value problems. This integral equation has been solved by BEM and algorithm of the BEM solution is explained on a sample, mixed boundary-value problem. The forms of time-displacement curves coincide with literature while timesurface traction curves being quite different in the results. The formulation does not have any singularity. Generalized functions and the integrals of them are used in a different form.

Propagation of Axial Symmetric, Transient Waves from a Cylindrical Cavity

N. Kadioglu,S. Ataoglu 대한토목학회 2010 KSCE JOURNAL OF CIVIL ENGINEERING Vol.14 No.4

The aim is to determine the displacement and the stress fields for a cylindrical cavity under a transient pressure which is an arbitrary function of time. A fundamental solution, given by Kadioglu and Ataoglu, has been revised to be used in reciprocal theorem for the solutions of axially symmetric transient problems of elastodynamics. An integral equation, whose unknown is the radial displacement on the boundary, has been written, using this fundamental solution in reciprocal identity. The boundary values of two sample problems, have been determined by solving this integral equation. To calculate the propagation of the displacement field in the region for any axially symmetric problem, a second elastodynamic state has also been derived. This new elastodynamic state has been used in reciprocity theorem to compute the time-variations of the displacement and the stresses at any point in the region for both sample problems. Whole singularities arising in every stage of the formulation have been eliminated. The most interesting result of the presented solution is the representation of a propagating wave by two different two-dimensional integrals at any interior point. Each of these integrals is valid for a different time interval and these intervals are defined by the position of the mentioned interior point.

A BEM implementation for 2D problems in plane orthotropic elasticity

Kadioglu, N.,Ataoglu, S. Techno-Press 2007 Structural Engineering and Mechanics, An Int'l Jou Vol.26 No.5

An improvement is introduced to solve the plane problems of linear elasticity by reciprocal theorem for orthotropic materials. This method gives an integral equation with complex kernels which will be solved numerically. An artificial boundary is defined to eliminate the singularities and also an algorithm is introduced to calculate multi-valued complex functions which belonged to the kernels of the integral equation. The chosen sample problem is a plate, having a circular or elliptical hole, stretched by the forces parallel to one of the principal directions of the material. Results are compatible with the solutions given by Lekhnitskii for an infinite plane. Five different orthotropic materials are considered. Stress distributions have been calculated inside and on the boundary. There is no boundary layer effect. For comparison, some sample problems are also solved by finite element method and to check the accuracy of the presented method, two sample problems are also solved for infinite plate.

Clinical evaluation of efficacy of transcortical anesthesia for the extraction of impacted mandibular third molars: a randomized controlled trial

Demir, Esin,Ataoglu, Hanife The Korean Dental Society of Anesthsiology 2020 Journal of Dental Anesthesia and Pain Medicine Vol.20 No.1

Background: This study aimed to compare the pain levels during anesthesia and the efficacy of the QuickSleeper intraosseous (IO) injection system and conventional inferior alveolar nerve block (IANB) in impacted mandibular third molar surgery. Methods: This prospective randomized clinical trial included 30 patients (16 women, 14 men) with bilateral symmetrical impacted mandibular third molars. Thirty subjects randomly received either the IO injection or conventional IANB at two successive appointments. A split-mouth design was used in which each patient underwent treatment of a tooth with one of the techniques and treatment of the homologous contralateral tooth with the other technique. The subjects received 1.8 mL of 2% articaine. Subjects' demographic data, pain levels during anesthesia induction, tooth extractions, and mouth opening on postoperative first, third, and seventh days were recorded. Pain assessment ratings were recorded using the 100-mm visual analog scale. The latency and duration of the anesthetic effect, complications, and operation duration were also analyzed in this study. The duration of anesthetic effect was considered using an electric pulp test and by probing the soft tissue with an explorer. Results: Thirty patients aged between 18 and 47 years (mean age, 25 years) were included in this study. The IO injection was significantly less painful with lesser soft tissue numbness and quicker onset of anesthesia and lingual mucosa anesthesia with single needle penetration than conventional IANB. Moreover, 19 out of 30 patients (63%) preferred transcortical anesthesia. Mouth opening on postoperative first day was significantly better with intraosseous injection than with conventional IANB (P = 0.013). Conclusion: The IO anesthetic system is a good alternative to IANB for extraction of the third molar with less pain during anesthesia induction and sufficient depth of anesthesia for the surgical procedure.

Absolute effective elastic constants of composite materials

Osman Bulut,Necla Kadioglu,Senol Ataoglu 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.57 No.5

The objective is to determine the mechanical properties of the composites formed in two types, theoretically. The first composite includes micro-particles in a matrix while the second involves long, thin fibers. A fictitious, homogeneous, linear-elastic and isotropic single material named as effective material is considered during calculation which is based on the equality of the strain energies of the composite and effective material under the same loading conditions. The procedure is carried out with volume integrals considering a unique strain energy in a body. Particularly, the effective elastic shear modulus has been calculated exactly for small-particle composites by the same procedure in order to determine of bulk modulus thereof. Additionally, the transverse shear modulus of fiber reinforced composites has been obtained through a simple approach leading to the practical equation. The results have been compared not only with the outcomes in the literature obtained by different method but also with those of finite element analysis performed in this study.

Periodontitis as a Risk Factor for Preterm Low Birth Weight

Ismail Marakoglu,Ulvi Kahraman Gursoy,Kamile Marakoglu,Hulya Cakmak,Tamer Ataoglu 연세대학교의과대학 2008 Yonsei medical journal Vol.49 No.2

Purpose: There is growing evidence showing that a number of complex human diseases are caused or are at least influenced by periodontal diseases. Such diseases include cardiovascular diseases, respiratory diseases, diabetes mellitus and osteoporosis. The aim of study was to evaluate periodontal diseases as a risk factor for a preterm low birth weight. Materials and Methods: A total of 48 mothers, 20 of who had a preterm low birth weight delivery, were examined in the Clinics of Periodontology, Faculty of Dentistry, Cumhuriyet University. The periodontal exams consisted of a full mouth pocket depth, a Loe and Sillness Gingival index score measurements, and a panoramic radiograph analysis. Information on any other factors that may cause a preterm low birth weight was obtained from the family physician. Results: The study results indicated that periodontitis (OR: 3.6 95% CI: 1.06- 12.18) together with bacterial vaginosis (OR: 11.57 95% CI: 1.26-105.7) were independent risk factors of a preterm low birth weight. According to the data obtained from this study, the paternal age, tobacco use and the mothers' height were not significant risk factors for a preterm low birth weight. Conclusion: Within the limits of this study, it is concluded that a poor periodontal health status of the mother may be a potential risk factor for a preterm low birth weight.