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Article
A Model for The Prediction of Fracture Toughness Using Neural Network
نموذج لتنبؤ متانة الكسر باستخدام الشبكة العصبية

Authors: Aseel abdulbaky --- Dhafer Al-Fattal --- Harry Bhadeshia --- Talal Abdul Jabbar
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2012 Volume: 30 Issue: 5 Pages: 868-885
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The purpose of this research programme is to develop quantitative models for the prediction of mechanical properties (fracture toughness) using experimental data collected from the literature, together with a powerful computational technique known as neural network. Creating a truly general model requires a combination of available data and metallurgical knowledge. This model is proposed for martensitic and ordinary bainitic steels in addition to the more recent class of non-structural super-bainitic steels. Super-bainitic steels areattractive for many applications such as armour. The model of fracture toughness, based on chemical composition, heat treatment and mechanical properties is proposed. The predictions of fracture toughness are generally acceptable but the uncertaintiesare high and more input data need to be collected for super-bainitic steels when available in the future to improve the predictions of this model.


Article
An evaluation of the effects of different polishing materials and glazing techniques on the fracture toughness of dental porcelain

Authors: Ma’an R. Zakaria معن رشيد زكريا --- Saeed K. Shahwan سعيد شهوان
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2012 Volume: 24 Issue: 4 Pages: 29-33
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: As there is an increase in the importance of measuring the fracture toughness of dental porcelain,different methods and materials were supposed. The aim of this study was to compare the fracture toughness offeldspathic porcelain with different polishing materials and glazing techniques.Materials and methods: Forty-nine metal-ceramic discs (width =10 mm, height =5 mm) were fabricated andrandomly divided into seven groups (n = 7); group one was left intact and considered as a control group, othergroups’ surfaces were treated with autoglaze only, applied glaze only, polished with ceramic rubber wheel only,polished with Dentaurum universal polishing paste only, polished with paste then autoglazed, and polished withpaste followed by applied glaze respectively. Porcelain fracture toughness (KIc) for each specimen was measuredby a Micro-Vickers Hardness Tester then the mean KIc for each group was determined. The data were analyzed byusing analysis of variance (ANOVA) followed by Least Significant Difference (LSD).Results: Mean porcelain fracture toughness of all groups were 1.320, 0.665, 1.469, 1.319, 1.480, 1.108, 1.548 MN/m-3/2respectively. Very high significant differences were found between the groups (P<0.001). The highest mean of KIcvalue was recorded in group VII which represented the toughest group while the lowest mean value wasrepresented by group II.Conclusions: Surface treatment of feldspathic porcelain restorations with polishing paste and applied glaze showedhighly significant increase in fracture toughness. Polishing unglazed porcelain using ceramic rubber wheel andDentaurum universal polishing paste showed no significant differences compared with specimens treated withapplied glaze only.


Article
Study Some Physical and Mechanical Properties of Ceramic – Ceramic Fibers Composite

Author: Fadhil Attiya Chyad
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2011 Volume: 29 Issue: 9 Pages: 1631-1640
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

Zirconia fibers have been prepared by convertional method using cotton threadsimpregrated in zirconium oxychloride solution ( ZrOCl2. 8H2O ). X-raydiffraction shows the crystallinity of zirconia and optical microscopy shows thefibers fabrication. Differnet percentage ( 2 ,4 ,8 , 10 and 12 ) of prepared zirconiafibers mixed with ZnO powder.All the specmen sintered at 1250 °C for 2hrs. Physical properties (density andvolume shrinkage) were measured and Mechanicl properties (Vicker ̉shardness,fracture strength and fracture toughness by indentation method ) werecalculated, 10% of fiber content has the maximum values for these properties forthe composite.


Article
EFFECT OF THERMOMECHANICAL TREATMENTS ON AGING BEHAVIOR AND FRACTURE TOUGHNESS OF AL-CU-MG ALLOY PLATES USED IN AIRCRAFT STRUCTURE

Author: Dr. Alaa A. Ateia,
Journal: Iraqi journal of mechanical and material engineering المجلة العراقية للهندسة الميكانيكية وهندسة المواد ISSN: 20761819 Year: 2009 Volume: 9 Issue: 1 Pages: 53-67
Publisher: Babylon University جامعة بابل

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Abstract

The effects of variations in the thermomechanical treatments parameters on the microstructure and mechanical properties of Al-Cu-Mg alloy plates used in aircraft structure subjected to a post heat treatments have been conducted. It was confirmed that a large gain in fracture toughness combined with a good mechanical properties could be achieved by choice of the correct initial condition, amount and temperature of deformation, and the time temperature of the final age hardening sequence. In general, it was found that the material should be age hardened to the peak hardness conditions before deformation at an elevated temperature (warm rolling at 200°C) in order to prompt homogeneous slip. Room temperature deformation resulted in planar slip at the peak hardness conditions non uniform response on subsequent aging and give lower fracture toughness.

تم في هذا ألبحث دراسة ألتأثيرات ألناجمة من تغيير بعض معاملات ألتعامل ألحراري-ألميكانيكي على استجابة سبيكة ألألمنيوم-نحاس-مغنيسيوم ألمستخدمة في هياكل ألطائرات للتقادم ألاصطناعي أللاحق ومتانة ألكسر. وقد ثبت بأن من ألممكن ألحصول على استجابة جيدة ومتانة كسر عالية عن طريق ألاختيار ألصحيح للظروف ألابتدائية كدرجة حرارة وزمن ألتقادم ألأولي،نسبة ودرجة حرارة ألتشويه بالدرفلة وكذلك درجة حرارة وزمن ألتقادم أللاحق. وبصورة عامة فقد وجد بأن ألواح هذه ألسبيكة يجب أن تصلد حتى ألوصول ألىأعلى صلادة ممكنة قبل أن تدرفل بدرجة حرارة (٢٠٠°م) وذلك لتشجيع حصول عملية انزلاق منتظمة لكل ألبنية ألمجهرية. و ثبت أيضا بأن ألعينات ألمدرفلة بدرجة حرارة ألغرفة في ظروف قمة ألصلادة لاتستجيب جيدا لعملية ألتقادم أللاحق وتعطي متانة كسر منخفضة.


Article
Study of Transverse and Longitudinal Crack Propagation in Human Bone Using the Finite Element Method with MATLAB
دراسة نمو الشق الطولي والعرضي لعظم الانسان باستخدام طريقة العناصر المحدودة بوساطة الماثلاب

Author: Abdullah Dhayea Assi عبدالله ضايع عاصي
Journal: Al-Khwarizmi Engineering Journal مجلة الخوارزمي الهندسية ISSN: 18181171 23120789 Year: 2019 Volume: 15 Issue: 2 Pages: 44-49
Publisher: Baghdad University جامعة بغداد

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Abstract

A finite element is a study that is capable of predicting crack initiation and simulating crack propagation of human bone. The material model is implemented in MATLAB finite element package, which allows extension to any geometry and any load configuration. The fracture mechanics parameters for transverse and longitudinal crack propagation in human bone are analyzed. A fracture toughness as well as stress and strain contour are generated and thoroughly evaluated. Discussion is given on how this knowledge needs to be extended to allow prediction of whole bone fracture from external loading to aid the design of protective systems.

ان اي دراسة باستخدام طريقة العناصر المحدودة قادرة على توقع نمو الشق ومحاكاة توليد الشق ونشأته في العظم الانساني. ان النموذج المادي مطبق في رزمة من برنامج الماثلاب بوساطة طريقة العناصر المحدودة التي تسمح للامتداد الى اي شكل هندسي واي ترتيبه حمل مما يمكن عوامل ميكانيك الكسر من تحليل توليد الشق الطولي والمستعرض في العظم الانساني .ان صلابة الكسر فضلاً عن مخطط الاجهاد والانفعال يولدان ويقيمان كليا. ان المناقشة اعطت كمَاً من المعرفة الضرورية التي تمدد للسماح لتنبؤ بالكسر العظمي الكامل من التحميل الخارجي لمساعدة تصميم الانظمة الوقائية.


Article
Influence of Temperature on Fracture Toughness of Jute Fiber Reinforced Unsaturated Polyester Resin
تأثير درجة الحراره على متانه التكسير النوعيه لمتراكب راتنج البولي أستر غير المشبع المقواة بالياف الجوت

Author: Akram R. Jabur
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2010 Volume: 28 Issue: 17 Pages: 5481-5494
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

Jute fiber reinforced unsaturated polyester resin composites (J/UP) weresubjected to low velocity impact tests in several Temperatures degree in order to study the effects of temperature variance on the intrinsic fracture toughness Gc impact properties. An investigation was conducted onto the effects of temperatures on impact resistance of jute fiber-reinforced unsaturated polyester resin composite. Impact tests were performed on the specimens at different temperatures. The temperatures were 27, 50, 75 and 100 Cº. The results reflect the influence of ambient temperature on impact toughness measurements. The resultsindicate an obvious correlation between the ambient temperatures and impact load, total absorbed energy and fracture toughness. The prepared specimens exhibited brittle fracture behavior with a lower peak load, lower impact energy and less time to fail compared with results at temperature higher Tg. The impact test results show that the total energy absorbed at 100 C° have higher energy when the composite behavior changed from brittle to ductilebehavior. The intrinsicfracture toughness is higher for specimens tested in 100 Cº and 75 Cº and shows ductile behavior; while specimens tested with temperature lower than Tg show brittle fracture and lower Gc.

عرضت عينات من راتنج البولي أستر غير المشبع المقواة بالياف الجوت لاختبارتالصدمه بسرعه واطئه في درجات حراريه مختلفه لغرض دراسة تأثير تغاير درجات الحراره البحث يتعرض لتأثير درجات الحراره × Gc على مواصفات متانه التكسر النوعيه بالصدمه أنجزت × على مقاومة الصدمه لمتراكبات راتنج البولي أستر غير المشبع المقوى بالياف الجوت درجات الحراره التي أجريت بها × فحوص الصدم على العينات بدرجات حراره مختلفه أن النتائج المستحصله تعكس تأثير درجه حرارة المحيط × 100 م° , 75 ,50, الفحوص هي 27 عرضت عينات من راتنج البولي أستر غير المشبع المقواة بالياف × على قياسات متانة الصدمالجوت لاختبارت الصدمه بسرعه واطئه في درجات حراريه مختلفه لغرض دراسة تأثير تغاير البحث يتعرض لتأثير × Gc درجات الحراره على مواصفات متانه التكسر النوعيه بالصدمه درجات الحراره على مقاومة الصدمه لمتراكبات راتنج البولي أستر غير المشبع المقوى بالياف درجات الحراره التي × أنجزت فحوص الصدم على العينات بدرجات حراره مختلفه × الجوت أن النتائج المستحصله تعكس تأثير درجه × 100 م° , 75 ,50, أجريت بها الفحوص هي 27 تتشير النتائج الى أرتباط وِاضحِ بين درجات × حرارة البيئيه على قياسات متانة الصدمالطاقه الممتصه الكلي ومتانة التكسير. أن العينات التي حضرت , الحرارة البيئيه وتحميل الصدم تبدي سلوك تكسير قصيفا" يرافقه قمم تحميل واطئه وطاقة صدم واطئه وتستغرق زمنا" أقل Tg للانهيار مقارنة" مع النتائج الحاصله للعينات في درجات حراريه أعلى من أن نتائج فحوص الصدم بينت أن الطاقه الكليه الممتصه بالفحص بدرجة حراره 100 م تستلزم طاقه أعلى عندما يتغاير سلوك المتراكب من القصيف الى المطيلي . أن متانة التكسير النوعيه تكون للعينات المفحوصه بدرجة حراره 100 و 75 م تكون أعلى وتظهر تظهر سلوكا" قصيفا" في Tg سلوكا" مطيليا" بينما العينات المفحوصه بدرجات حراره أقل من. Gc التكسر وأقل قيمه ل


Article
Effect of nano and micro SiO2 weight percent on interlaminar fracture toughness of woven roving/ epoxy composites
دراسة تأثير النسب الوزنية لجزيئات السليكا المايكروية والنانوية على متانة الكسر الطبقية لمتراكبات الايبوكسي المدعمة بالالياف نوع المنتظم

Authors: Zainab R.Muslem زينب رحيم مسلم --- Harith I. Jaafer حارث ابراهيم جعفر
Journal: Iraqi Journal of Physics المجلة العراقية للفيزياء ISSN: 20704003 Year: 2012 Volume: 10 Issue: 18 Pages: 117-121
Publisher: Baghdad University جامعة بغداد

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Abstract

Effect of nano and micro SiO2 particles with different weight percent (2,4,6,8 and 10) %wt on the Interlaminar fracture toughness (GIc) of 16-plies of woven roving glass fiber /epoxy composites prepared by hand lay – up technique were investigated. The specimens were tested using DCB test (mode I). Area method was used to compute the interlaminar fracture toughness. The results show that, GIc would increase with the increasing in the filler content, the main failure in microcomposites and nanocomposites was delamination in the layers, the delamination reduced with increasing in the filler content.

تم في هذا البحث دراسة تاثير اضافة نسب وزنية مختلفة من جزيئات السليكا المايكروية والنانوية على متانة الكسر الطبقية لمتراكبات الايبوكسي المدعمة بالالياف نوع المنتظم المحضرة بتقنية التشكيل اليدوي وبنسب 2 و4 و6 و8 و 10 %. فحصت العينات باستخدام نموذج العتلة المزدوج (النمط الاول) واستخدمت طريقة المساحة لحساب متانة الكسر الطبقية. اظهرت النتائج ان متانة الكسر الطبقية تزداد بزيادة نسبة الجزيئات المضافة وان السبب الرئيسي للفشل في المتراكبا ت المايكروية والنانوية هو التوسعات الطبقية والتي لوحظ انها تقل بزيادة نسب الجزيئات المضافة.


Article
Reliability of the Installation and Operation of Pipeline Systems

Author: S. M. Beden
Journal: Basrah Journal for Engineering Science مجلة البصرة للعلوم الهندسية ISSN: Print: 18146120; Online: 23118385 Year: 2016 Volume: 16 Issue: 2 Pages: 108-118
Publisher: Basrah University جامعة البصرة

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Abstract

Pipelines are one of the most convenient and effectiveways of transporting petrol over a long distance. The environmentapplies, beyond extremely high external pressures, lowtemperatures and intensive corrosive process, the occurrence ofdefects on the pipe body, which compromises the structuralintegrity of pipelines leading to catastrophic failures. The mainmodifications concern the mechanical resistance, toughness at lowtemperatures weld ability and resistance to embrittlement relatedto hydrogen. Among mechanical characteristics, the fracturetoughness is very important for pipeline steels in design and safeassessment. Aiming to enhance the reliability and operation ofcomplex pipelines system, a study based on the mechanics of theelastoplastic fracture in order to determine better prediction of thefatigue life. The materials tested here are API 5L X42 and X52micro alloyed steels, as well as to evidence the toughness resistanceof these materials. Results indicated that both X42 and X52 steelbehave in a similar way and in all cases a slight increase of thetransition temperature was found. The characteristic toughnessvalue shows an evident loss in mechanical performances ifcompared to the uncharged one.


Article
STUDYING THE EFFECT OF CHEMICAL TREATMENT AND ORIENTATION ON FRACTURE TOUGHNESS OF KENAF FIBRE EPOXY COMPOSITES

Author: Mushtaq Albdiry,
Journal: Al-Qadisiyah Journal for Engineering Sciences مجلة القادسية للعلوم الهندسية ISSN: 19984456 Year: 2017 Volume: 10 Issue: 4 Pages: 505-515
Publisher: Al-Qadisiyah University جامعة القادسية

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Abstract

In this paper, the effect of surface modification and fibre arrangements of kenaf fibers on fracture toughness of epoxy composite was investigated. The chemical treatment of kenaf fibers (KFs) with 6 % NaOH was achieved, and composites with two different fibre arrangements (X and Y) directions were fabricated. Values of fracture toughness (KIc) measured of the compact tension (CT) specimens for both untreated kenaf fibre-reinforced epoxy (ut-KFRE) composites and treated kenaf fibre-reinforced epoxy (treated-KFRE) were much better than the neat epoxy. The KIc value of the treated-KFRE composite in Y-fibre direction was the highest of 2.74 MPa.m1/2 while it was 1.45 MPa.m1/2 for the neat epoxy. Different toughening mechanisms were noticed in the fracture surfaces of the composites in relation to the fibre reinforcement planar, they are shear yielding and fibre splaying with the X-direction and broken fibers, fibre pullout and fibre delamination with the Y-fibre orientation.


Article
Fracture Toughness of Two Types of All-ceramic Restoration after Repeated Firing

Authors: Sabiha Mahdi Kanaan --- Ruaa Mohammed Zghair
Journal: Journal of Oral and Dental Research مجلة طب الفم والاسنان ISSN: 23106417 Year: 2019 Volume: 6 Issue: 1 Pages: 29-39
Publisher: Iraqi Association for Oral Research الجمعية العراقية لبحوث طب الفم

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Abstract

Background The ability to measure and describe changes in the mechanical properties of ceramics due to various thermal handling protocols will provide a better understanding of the mechanical performance and application of dental ceramic materials. Objectives To evaluate and compare the fracture toughness of two types of all-ceramic restoration (Zirconia and IPS e. max (Lithium disilicate) CAD) after repeated firing.Materials and Methods Sixty all ceramic samples (in final dimensions of 18 mm Length, 4 mm Width, and 3 mm Thickness) were prepared and divided into two main groups according to the used materials; Group (Z) for Zirconia and Group (E) for IPS e. max CAD. Each main group subdivided into three subgroups according to firing cycles. The (Z) group subdivided into ZF3, ZF5 and ZF7; And group (E ) also subdivided into EF3, EF5 and EF7 for three, five and seven firing cycles respectively. Then, the samples were subjected to the indentation strength using a Micro-Vickers Hardness Tester device. After completing of the firing process, the samples were subjected to the fracture toughness test for each specimen. Scanning electron microscope (SEM) images were taken for one random specimen for each subgroup. Results The data showed the highest fracture toughness were obtained with EF5 and the lowest fracture toughness with ZF7 and the P-value of (P≤ 0.05). LSD test done and revealed a highly significant difference between the groups. Conclusion generally, E. Max. CAD material may verify best results of fracture toughness test compared with Zirconia material after repeated firing cycles.

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