Advanced experimental methods for the characterization of welded structures

Welding is one of the most prevalent techniques for mechanical fastening of metals. Recent developments in welding technology have led to welding techniques being more readily employed in safety-critical engineering structures. Since the existence of residual stresses and material property variation around welds affects the mechanical performance and thereby structural integrity, it is essential to improve our knowledge in understanding and modelling the mechanical response of the welded structures. The present work focuses on mechanical characterizations of such structures. This work can be broadly classified into two parts; the first part investigates the residual stress distribution in welded specimens of different metals and the second part presents investigations of mechanical properties in welded specimen using full field optical techniques. A newly invented destructive technique for residual stress measurement, the contour method, was used for the investigations of the residual stress in welded joints in this study. The principle of the contour method is based on a variation of Bueckner's superposition theory. By means of a single straight cut, the 2D residual stress component normal to the region of interest can be determined. In this work, first the numerical simulations of the contour method using two and three dimensional bodies have been demonstrated. The contour method was then applied to one-pass and three-pass groove weld specimens and the results obtained from the contour method were compared to those obtained by the neutron diffraction strain measurement technique. The capability of the contour method to measure multiple residual stress components was also investigated in this project. A recent development of the contour method of stress measurement, the multi-axial contour method, permits measurement of the 3D residual stress distribution in a body, based on the assumption that the residual stresses are due to an inelastic misfit strain (eigenstrain) that does not change when a sample containing residual stresses is sectioned. The eigenstrain is derived from measured displacements due to residual stress relaxation when the specimen is sectioned. By carrying out multiple cuts, the full residual stress tensor in a continuously processed body can then be determined. In this study, finite element simulations of the technique were carried out to verify the method numerically. The method was then used to determine the residual stresses in a VPP A-welded sample, and the results were validated by neutron diffraction measurements. As part of the characterization of the welded structures, a study was undertaken to develop a method of extracting local mechanical properties from weld metal by strain mapping using the digital image correlation (DIC) technique. The feasibility of determining local stress-strain behaviour in the weld zone of a 316H stainless steel pipe with a girth weld was investigated by tensile tests on miniature and standard tensile test specimens. In addition, electron speckle pattern interferometry (ESPI) was utilized to obtain the full-field strain maps of a standard tensile specimen during loading and compared to those obtained in the same specimen by digital image correlation in order to verify the DIC measurements

EXAMINING THE COMMUNICATION AND PROBLEM SOLVING SKILLS OF THE YOUTH CAMP PROGRAM SUPERVISORS

Purpose: The purpose of this study is to examine the communication and problem solving skills of the program supervisors who responsible for youth camps run by the Ministry of Youth and Sports in terms of several variables.Material and Method: The study group consisted of 103 participants 45 of whom were female and 58 of whom were male and who were in charge of the youth camps run by the Ministry of Youth and Sports in 2015-2016 period. The “Communication Skills Evaluation Scale (CSES)” was made use of in determining the communication skills of the people who were in charge of youth camps; and the “Problem Solving Inventory (PSI)” was made use of in determining the problem solving skills.The Findings: It was determined upon the analyses that there were no significant differences between the groups in the communication and problem solving skills of the people responsible for running the program in terms of gender, age, marital status, educational status and in-service training variables (p>0.05); however, it was also determined that there were significant differences between the groups in the communication skills according to the time at office variable as the responsible person (p=0.048), and in problem solving skills according to the occupational status variable. (p=0.042). Upon the analyses that were made to determine the origin of these significant differences, it was determined that the communication skills of the people responsible for the programs who worked for 1-2 years and 5 years and over 5 years were higher; and that the problem solving skills of the students were higher than the public employees.Result: According to the findings obtained in the scope of the study, it was determined that there was a decrease in the communication skills in the 3rd and 4th years according to the time at office variable; and it was also determined that the problem solving skills of the students were higher than the employees who were working in public institutions. As a conclusion, it was determined that the communication skills of the supervisors who were responsible for the program were high, and the problem solving skills were at the medium level.   Article visualizations

THE EXPERIENCES OF TURKEY IN BRANCH TEACHER TRAINING AND SUSTAINABLE NEW MODEL APPROACHES

1970li yıllarda ülkemizde yaşanan siyası, sosyal olaylar sonucunda öğretmen yetiştirme görevi, 1981 yılında yüksek öğretim kanunu (YÖK) ile Milli Eğitim Bakanlığından (MEB ) üniversitelere verilmiştir. Bu nedenle bu çalışmada öğretmen yetiştirme modeli YÖK öncesi ve sorası olarak ele alınmıştır. YÖK öncesinin en önemli modeli olan Yüksek Öğretmen Okulları ve bu okullarda zaman içinde yapılan gelişmeler açıklandıktan sonra YÖK'le başlayan süreç ayrıntılı olarak incelenmiştir. Burada Eğitim Fakültesi modeli ve 1998 yılında onun yeniden yapılandırılması ile oluşturulan "Tezsiz Yüksek Lisans Modeli (TYL )"açıklanmıştır. TYL modelinin eğitim Fakültelerinde 3,5+1,5 yıl olarak bütünleşmiş yüksek lisans, fen-edebiyat fakülteleri içinde 4+1,5 yıl olarak TYL şeklinde uygulanması irdelenmiştir. 2010 yılında TYL modelinin uygulamadan kaldırılması, yerine "Öğretmenlik Sertifika Programı"nın getirilmesi ve daha önce de uygulanan bu sertifika programının olumsuz yönleri vurgulanmıştır. Son olarak Dünya da ki uygulamalara örnekler verilmiştir. Tüm bu deneyimler ışığında Türkiye için sürdürülebilir öğretmen yetiştirme modelleri önerilmiştir \r\n\r\n ABSTRACT: As a result of social-political events of 1970's in Turkey, the mission of teacher training passed from ministry of education to universities with the Law of Higher Education (LHE) in 1981. For this reason, in this study, the model of teacher training has been discussed as before and after LHE. After explaining the Higher Teacher's Training Schools and modification of them, which is the most important model before the LHE, the process starting with the LHE has been investigated in detail. The model of the education faculty, and reconstruction of it with the "postgraduate master program of 1.5 years" in 1998 has been explained and its application as integrated master program of 3.5+1.5 years in education faculties and postgraduate master program of 4+1.5 yeas for science and art faculties have been discussed. In 2010, by removing the postgraduate master program of 4+1.5 yeas in application and substitution it with "pedagogic formation certificate program", and aspects of disadvantages of this model, applied earlier, for undergraduate students of science faculties, have been emphasized. Finally, examples of the teacher training models of the world have been given. In the light of these experiences, sustainable teacher training models for Turkey have been proposed

The influence of pulsed laser powder bed fusion process parameters on Inconel 718 material properties

Funding This publication was made possible by the sponsorship and support of Lloyd's Register Foundation, United Kingdom. The work was enabled through, and undertaken at, the National Structural Integrity Research Centre (NSIRC) United Kingdom, a postgraduate engineering facility for industry-led research into structural integrity established and managed by TWI through a network of both national and international Universities. Lloyd’s Register Foundation helps to protect life and property by supporting engineering-related education, public engagement and the application of research. Data availability The raw data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study. The processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.Peer reviewedPostprin

DETERMINATION OF MISCONCEPTIONS REGARDING "COMPOUNDS'' CHAPTER IN SECONDARY EDUCATION 9th GRADE BY TWO-TIER CONCEPTUAL UNDERSTANDING TEST

Bu çalışmada ortaöğretim 9. sınıf öğrencilerinin kimya dersi "Bileşikler" ünitesi ile ilgili kavram yanılgılarına sahip olup olmadıklarını ve sahip oldukları kavram yanılgıları varsa bu yanılgıların derecesini tespit edebilmek için iki aşamalı kavramsal anlama testini geliştirmek amaçlanmıştır. Çalışmada ayrıca geliştirilen bu test yoluyla öğrencilerin kavram yanılgılarının belirlenmesi hedeflenmiştir. Toplam 34 maddeden oluşan test İzmir ilinde bulunan ortaöğretim kurumlarında öğrenim görmekte olan ve konuyu bilen toplam 175 öğrenciye uygulanmıştır. Yapılan madde analizleri sonucunda testin güvenirliği, maddelerin güçlük ve ayırt edicilik indeksleri ve çeldirici fonksiyonları elde edilmiştir. Madde analizlerinin sonucunda iki aşamalı kavramsal anlama testinden 10 madde çıkarılmıştır. Testin güvenirlik katsayısı (Cronbach Alfa) 0.80 olarak bulunmuştur. Testin madde güçlük indeksleri 0.24-0.90 aralığında, ayırt edicilik indeksleri ise 0.22-0.50 aralığında bulunmuştur. Testte her bir maddeye verilen yanıtların incelenmesi sonucunda, ünite ile ilgili öğrencilerin bazı kavram yanılgılarına sahip oldukları belirlenmiştir. The aim of this study is to determine whether 9th grade students in secondary schools have misconceptions regarding ‘'compounds'' chapter and to develope a two-tier conceptual understanding test to be able to determine the degree of the misconceptions if there are any. Furthermore; this study aims determining the the misconceptions of the students by means of this test. The test, consisting of a total of 34 items, was carried out with 175 students familiar with the subject and receiving education in secondary schools in Izmir. As a result of item analyses made, the reliability of the test, the difficulty and distinctiveness indices and the distractor functions of the items were acquired. As a result of the analysis item two-tier conceptual understanding test 10 items were removed.The relaibility coefficient of the test (Cronbach Alfa) was found as 0.796. As a result of item analyses, the item difficulty indices were found to be between 0.24-0.90 and the item discrimination index were between 0.20-0.50. Some misconceptions about compounds chapter were determined after the analysis of the items in the tes

STUDENTS' OPINIONS ABOUT WEB ASSISTED COLLABORATIVE LEARNING IN ANORGANIC CHEMISTRY

Bu çalışmadaki amaç; anorganik kimya dersinde koordinasyon kimyası konusunun öğretiminde web destekli işbirlikli öğrenmeye (WDİÖ) yönelik öğrencilerin görüşlerini belirlemektir. Bu amaçla, araştırmada nitel bir araştırma modeli olan durum çalışması yöntemi kullanılmıştır. Araştırmanın çalışma grubunu Dokuz Eylül Üniversitesi 2. sınıf kimya öğretmen adayları oluşturmuştur (n=18). Öğrencilerin öğrenme sürecine yönelik görüşlerini belirlemek için Web Destekli İşbirlikli Öğrenmeye Yönelik Görüş Anketi (WDİÖG), Görüşme Formu (GF), Web Sayfası Forum Etkinliği (WFE) kullanılmıştır. Elde edilen veriler içerik analizi ve betimsel olarak analiz edilmiştir. Öğrenciler genel olarak öğrenme sürecine yönelik olumlu görüş belirtmişlerdir. Derslerin tamamen web üzerinden yapılmamasını, mutlaka bir öğretmenin öğretim sürecinde yer almasını, işbirlikli çalışmalarda bazı grup üyelerinin pasif olabildiğini, öğretmenin web ortamında daha fazla geri bildirim vermesi gerektiğini ifade etmişlerdir. Araştırmada elde edilen bulgular web destekli işbirlikli öğrenme ortamlarının tasarlanmasında önemli bir yol gösterici olacaktır. \r\n\r\nABSTRACT: Aim of this study is to define students‘ opinions related to web assisted collaborative learning (WACL) approach in coordination chemistry topic in anorganic chemistry course. In accordance with this aim, it was used case study which is a qualitative research method. Working group in the study are second class chemistry teacher candidates (n=18) in second semester of 2009-2010 educational year in Dokuz Eylül University. The Questionnaire About Students‘ Opinions Related the Learning Approach (QASO), Interview Form (IF), Web Page Forum Activity (WPA) as qualitative data collection tools were used in the study. The findings show that they have commonly positive opinions related to this learning approach. The students declaired that they wanted not to be delivered the courses completely via web, a lecturer to whom they would consult must be throughout learning process, they wanted to be gived more feedback by the lecturer. Also, they stated that if any member of group was sensitive and not experienced, it was not compatible with collaboration. The findings will be guide for researchers to design and plan web assisted learning approach

Investigation of Novel Post-Thermal Treatments of Alloy 718 Fabricated by Modulated Laser Powder Bed Fusion

Acknowledgements This publication was made possible by the sponsorship and support of Lloyd’s Register Foundation The work was enabled through, and undertaken at, the National Structural Integrity Research Centre (NSIRC), a postgraduate engineering facility for industry-led research into structural integrity established and managed by TWI through a network of both national and international Universities. Lloyd’s Register Foundation helps to protect life and property by supporting engineering-related education, public engagement, and the application of research.Peer reviewedPublisher PD

A CPFEM based study to understand the void growth in high strength dual-phase Titanium alloy (Ti-10V-2Fe-3Al)

Author is thankful to University of Aberdeen for the award of Elphinstone Scholarship which covers the tuition fee of PhD study of author. Thanks are also due to Professor R.M. McMeeking for useful discussions.Peer reviewedPostprin