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Article
Load-deflection characteristics and force levels of coated nickel titanium orthodontic archwires

Authors: Hind Dawood Abaas هند داود عباس --- Akram Faisal Al-Huwaizi اكرم فيصل الحويزي
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2015 Volume: 27 Issue: 2 Pages: 154-157
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Coated archwires have been introduced to improve esthetics during orthodontic treatment. Theaim ofthe present study was to evaluate and compare the load–deflection characteristics and force levels of six brands ofcoated nickel titanium orthodontic archwires using palatal and gingival deflection.Materials and methods: Ten round wires (0.016 inch) and ten rectangular wires (0.019x0.025 inch) were obtained fromeach of six brands (G&H, Opal, Ortho Technology, Dany, Hubit and Astar Companies). The load-deflection propertiesof these archwires were evaluated by the modified bending test usinga readymade dental arch model in bothpalatal and gingival directions at 37°C temperature using a universal material testing machine. Forces generated atmaximum loading of 2mm and at unloading of 1.5mm were measured.Results: All the wires showed hysteresis and significant differences in their load deflection curves, but thesedifferences were more evident in round wires than in rectangular wires where G&H wires showed the widest loadingunloadingdeflection curves. The maximum loading force of round wires in gingival deflection were higher than bypalatal deflection. The force decline during unloading (plateau gap) ranged between 18 to 34% for round wires and17 to 37% for rectangular wires.Conclusion: Coated epoxy wires (G&H, Opal, Astar and Ortho Technology) produced lower forces compared topolymer (Dany) and Teflon (Hubit) coated round and rectangular archwire


Article
In-Vitro evaluation of load-deflection characteristics and force levels of nickel titanium orthodontic archwires

Authors: Riyadh Abdu Al-Hamza Ruwiaee --- Akram Faisal Al-Huwaizi اكرم فيصل الحويزي
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2015 Volume: 27 Issue: 3 Pages: 159-164
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Nickel-titanium (NiTi) archwires have become increasingly popular because of their ability to releaseconstant light forces, which are especially useful during initial alignment and leveling phase. The aim of the presentstudy was to investigate and compare the load–deflection characteristics of four commercially available NiTiarchwires.Materials and methods: 200 NiTi 0.014, 0.016, 0.018, 0.016x0.022 and 0.019x0.025-inch nickel–titanium archwires fromfour different manufacturers (3M, Ortho Technology, Jiscop and Astar) were tested. The load-deflection properties ofthese archwires were evaluated by a full arch bending test in both palatal and gingival directions at 37°Ctemperature using a universal material testing machine. Forces generated at maximum loading of 2mm and atunloading of 1.5mm were measured.Results: All the tested NiTi wires showed an increase in loading and unloading force with increased wire dimension.Generally, 3M gave the most flexible round wires and relatively stiff rectangular wires; with linear load deflectioncurves. Ortho Technology wires were flexible. Jiscop gave the stiffest round wires and the most flexible rectangularwires. Astar wires were stiff which gave the highest force levels during unloading.Conclusion: Force levels vary greatly from brand to brand and so NiTi wire brands must be selected withconsideration to their load-deflection characteristics and mechanical properties


Article
Influence of different recycling protocols on load deflection of nickel titanium orthodontic wire

Author: Dr. Mustafa M. Al-Khatieeb. B.D.S., M.Sc. * د. مصطفى الخطيب
Journal: MUSTANSIRIA DENTAL JOURNAL مجلة المستنصرية لطب الاسنان ISSN: 18138500 Year: 2008 Volume: 5 Issue: 1 Pages: 71-79
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

The purpose of this study was to investigate the changes in the load deflection of nickel titanium orthodontic wire after different recycling protocols. A spooled 0.014 inch nickel titanium wire was separated into 7 groups: as received condition (T0,control group),treated in artificial saliva for 4 weeks (T1), treated in artificial saliva and autoclaved (T2), treated in artificial saliva and dry heated (T3), treated in artificial saliva and disinfected by glutaraldehyde (T4), treated in artificial saliva and disinfected by iodophor (T5) and treated in artificial saliva and disinfected by chlorhexidine (T6).The changes in the load deflection were observed by special test apparatus based on 3-point bending mechanism, the findings of the current study showed that there was highly significant difference in mean load deflection of nickel titanium wire between all recycling protocols (P< 0.0001). The recycling by sterilization of the wire by heat autoclave or disinfection by chlorhexidine both seem to be the best recycling protocols because of lowest detrimental effect on the load deflection, while the disinfection by glutaraldehyde or iodophor shows intermediate detrimental effect on the load deflection, and the sterilization by dry heat seems to be the worst recycling protocol because it shows highest detrimental effect on the load deflection value.


Article
Behavior of Hybrid Deep Beams Containing Ultra High Performance and Conventional Concretes
سلوك العتبات العميقة الهجينة المتكونة من الخرسانة فائقة الاداء و الخرسانة التقليدية

Author: Hassan Falah Hassan
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2015 Volume: 33 Issue: 1 Part (A) Engineering Pages: 30-50
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This paper presents an experimental investigation consisting of casting and testing twelve rectangular simply supported reinforced concrete deep beams. Three of the tested beams are made with conventional concrete (CC), three with ultra-high performance concrete (UHPC) and six as hybrid beams of the two concrete (UHPC &CC). UHPC is used in compression in the hybrid beams. The effect of these parameters on the behavior of the test beams included deflection, failure mode, and ultimate loads is investigated. Experimental results generally show that stiffer load-deflection behavior is obtained with the increase of UHPC layer thickness (hR/h) and steel fibers volumetric ratio (Vf) for hybrid beams with UHPC in compression.

يقدم هذا البحث تحريا مختبريا يتضمن الصب و الفحص لأثنى عشر عتبة خرسانية مسلحة مستطيلة عميقة المقطع و بسيطة الاسناد. ثلاث عتبات كانت مصنوعة من الخرسانة التقليدية و ثلاث من الخرسانة فائقة الاداءة وست كعتبات هجينة من نوعي الخرسانة (فائقة الاداء و التقليدية). استخدمت الخرسانة فائقة الاداءة في منطقة الانضغاط في العتبات الهجينة. وتم ايضا دراسة تاثير هذه المتغيرات مع تصرف عتبات الاختبار الذي شمل الهطول ،نوع الفشل والحمل الاقصى لها. اظهرت النتائج المختبرية عموماً انه تم الحصول على سلوك الحمل-الهطول اكثر صلادة عند زيادة سمك طبقة الخرسانة فائقة الاداء و نسبة الياف الحديد للعتبات الهجينة ذات الخرسانة فائقة الاداء في منطقة الانضغاط.


Article
Effect of Different Fluoride Agents on the Load Deflection Characteristics of Heat Activated Nickel Titanium Arch Wires (An in Vitro Study)

Authors: Rawaa SaadoonHashim رواء سعدون هاشم --- Sami K. Al-Joubori سامي كاظم الجبوري
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2017 Volume: 29 Issue: 1 Pages: 160-164
Publisher: Baghdad University جامعة بغداد

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Abstract

Background:Hydrogen absorption and related degradation in the mechanical properties of Ni-Ti based orthodontic wires has been demonstrated following exposure to fluoride prophylactic agents. This study was designed to investigate the effects of three fluoride containing agents on the load deflection characteristics of heat activated nickel titanium arch wires during unloading phase.Material and method: Eighty specimens of heat activated nickel titanium arch wires were obtained from Ortho Technology Company, half of which had a 0.016 inch round and 0.019x0.025 rectangular. Ten specimens from both wire size were immersed in one of the tested fluoride prophylactic agents (neutral sodium fluoride gel, stannous fluoride gel or phos-flur mouth rinse) or in the controlled medium “normal saline”, and incubated at 37˚C for sixty minutes.A Wp 300 universal material testing machine was modified and used to perform a three point bending test in a water path at 37˚C ±1˚C.The statistical difference between the different agents were analyzed using ANOVA and LSD tests.Results: The unloading forces at 0.5, 1.0, and 1.5 mm where significantly reduced especially in neutral sodium fluoride treated specimens.Conclusion: Based on the results founded in th study it might be preferred to use prophylactic agent with the least fluoride ions concentration.It can be concluded that the tested agents have only a limited effect on the load deflection behavior of the heat activated Ni-Ti wires, in a way that they do not have a clinically significant effect on the mechanical behavior of these wires.


Article
Compressive and Tensile Strength of Fibrous Clayey Soil Stabilized with Lime
مقاومة الانضغاط والشد للتربة الطينية الحاوية على الألياف والمثبتة بالنورة

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Abstract

AbstractThis investigation was conducted to assess the efficacy of the glass, hay and polypropylene fibers for enhancing the unconfined compressive and tensile strengths of clayey soil stabilized with lime. Lime was mixed with the clayey soil in different proportions. Based on the optimum value obtained for lime (according to the unconfined compressive strength values), the compressive and tensile strength characteristics, stress – strain and load – deflection behaviors of lime stabilized samples mixed with different percents of glass, hay and polypropylene fibers were investigated. Fibers were added to the soil at range of (0.5 – 1.5 %). All stabilized samples were cured for 7 days at 250 C.Results indicate that the inclusion of fibers does not meaningfully improve the compressive strength, but significantly enhances the tensile strength, stress – strain and load – deflection behaviors. Also, it was found that the stress – strain and load deflection curves can be utilized to evaluate the performance of a fiber – reinforced stabilized soil for geotechnical and pavement applications.Keywords: Lime stabilization, fibers, tensile strength, stress – strain behavior, load – deflection behavior.

الخلاصةيهدف هذا البحث إلى دراسة تأثير إضافة كل من الألياف الزجاجية وألياف التبن والبولي بروبلين على خصائص مقاومة الانضغاط والشد للتربة الطينية المثبتة بالنورة. تم إضافة نسب مختلفة من النورة إلى التربة وتم ايجاد نسبة النورة المثلى بالاعتماد على نتائج فحص الانضغاط غير المحصور. تم إضافة نسب مختلفة من ألياف الزجاج, التبن والبولي بروبلين إلى نماذج التربة المثبتة بنسبة النورة المثلى, اذ تراوحت هذه النسب بين (0.5 – 1.5%) وتم إنضاج النماذج المثبتة لمدة 7 أيام بدرجة حرارة 25 درجة مئوية. بعدها تم إيجاد خصائص مقاومة الانضغاط والشد, كذلك تم ايجاد كل من منحنيات الإجهاد – الانفعال ومنحنيات الحمل – الأود.أظهرت النتائج حصول زيادة في كل من مقاومة الانضغاط ومقاومة الشد, وكان مقدار التحسن في مقاومة الشد أكثر منه في مقاومة الانضغاط لنماذج التربة المضاف إليها الألياف. أيضا بينت النتائج أنه يمكن الاستفادة من منحنيات الإجهاد – الانفعال ومنحنيات الحمل – الأود في تقييم أداء الطرق المثبتة والمضاف إليها الألياف.


Article
Mechanical Properties of Reactive Powder Concrete (RPC) with Various Steel Fiber and Silica Fume Contents
الخواص المیكانیكیة لخرسانة المساحیق الفعالة ذات محتویات مختلفة من الالیاف الفولاذیة وابخرة السلیكا المكثفة

Authors: Lubna S. Danha --- Wasan Ismail Khalil --- Hisham M. Al-Hassani
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2013 Volume: 31 Issue: 16 Part (A) Engineering Pages: 3090-3108
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

An experimental work was carried out to investigate some mechanical propertiesof Reactive Powder Concrete (RPC) which are particularly required as input data forstructural design. These properties include compressive strength, tensile strength(direct, splitting and flexural), flexural toughness, load-deflection capacity and staticmodulus of elasticity. The effects of three variable parameters on these properties werecarefully studied which are, the silica fume content SF (0%, 10%, 15%, 20%, 25%, and30%) as a partial replacement by weight of cement, hooked macro steel fibers volumefraction Vf (0%, 1%, 2% and 3%) and superplasticizertype(Sikament®-163N andPC200).The diameter of the steel fiber is 0.5mm and its length is 30mm with aspectratio 60.The experimental results showed that as the silica fume content (SF) increasesfrom 0% to 30% the compressive strength significantly increases, while the increase intensile strength is relatively lower. The inclusion of steel fibers leads to a considerableincrease intensile strength, while the addition of steel fibers causes a slight increase incompressive strength of RPC as fiber volume fraction increases from 0% to 3%.Theincrease in the steel fibers volume fraction and silica fume content improved the loaddeflectionbehavior and consequently gave higher ductility and fracture toughness ofRPC.


Article
EXPERIMENTAL STUDY FOR BEHAVIOR OF (WASTE CONCRETE FILLED STEEL TUBULER) COLUMNS SUBJECTED TO A STATIC AXIAL LOADS

Author: Zaid Ali Kadhim Alzaidi
Journal: Al-Qadisiyah Journal for Engineering Sciences مجلة القادسية للعلوم الهندسية ISSN: 19984456 Year: 2017 Volume: 10 Issue: 3 Pages: 291-298
Publisher: Al-Qadisiyah University جامعة القادسية

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Abstract

In this study, composite columns have been tested under axial load. The steel tubes were filled with waste concrete to perform the composite action. The specimens divided into two groups; square and circular columns. The diameter of the circular hallow columns was 7.5 cm with 2mm thickness, while the dimension of the square hallow columns was (7.5 cm × 7.5 cm) with 2mm thickness. For each group a column without waste concrete filled steel tubular (W.C.F.S.T) was tested to act as a reference column. Load-deflection curves were constructed for all specimens. The results indicate that the waste concrete filled steel tube has more capacity due to the composite action. The pattern of failure in circular sections was different from the failure pattern of the square ones.


Article
Experimental Study on Doweled Expansion Joints on Behavior for Plain Concrete Pavement System
دراسة تجريبية في مفاصل التمدد الموتّدة على سلوك التبليط الخرساني غير المسلح

Authors: Zainab Ahmed Al-kaissi زينب أحمد القيسي --- Mohammed Hashim Mohammed محمد هاشم محمد --- Nabaa Sattar Kareem نبأ ستار كريم
Journal: Al-Khwarizmi Engineering Journal مجلة الخوارزمي الهندسية ISSN: 18181171 23120789 Year: 2018 Volume: 14 Issue: 3 Pages: 68-80
Publisher: Baghdad University جامعة بغداد

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Abstract

This paper deals with load-deflection behavior the jointed plain concrete pavement system using steel dowel bars as a mechanism to transmit load across the expansion joints. Experimentally, four models of the jointed plain concrete pavement system were made, each model consists of two slabs of plain concrete that connected together across expansion by two dowel bars and the concrete slab were supported by the subgrade soil. Two variables were dealt with, the first is diameter of dowel bar (12, 16 and 20 mm) and the second is type of the subgrade soil, two types of soil were used which classified according to the (AASHTO): Type I (A-6) and type II (A-7-6). Experimental results showed that increasing dowel bar diameter from 12 mm to 20 mm has a little effect on load-deflection behavior of the tested specimens with only 5% increase in failure load. This may be attributed to that the failure (caused by flexural crack) depends mainly on concrete strength. Results also showed that decreasing CBR value of subgrade soil from 7% to 5% decreases failure load by about 33%.

تتناول هذه الدراسة سلوك الحمل- الهطول في مفاصل التمدد للتبليط الخرساني غير المسلح باستخدام قضبان الحديد كآلية لنقل الحمل عبر مفاصل التمدد. عملياَ, تم أنشاء اربع موديلات لنظام التبليط الخرساني المحلي كل موديل يتكون من بلاطتين من الخرسانة المحلية كل بلاطة بطول (600 ملم) وعرض (600 ملم) وسمك (125 ملم) ويتم ربط البلاطتين عبر مفصل تمدد عرضه (10 ملم ) بوساطة اثنين من قضبان الحديد الاملس (Dowel Bars) ويستند الموديل الخرساني على مكون بذلك موديل لنظام التبليط الجاسئ المحلي, مختبرياَ تم تناول متغيرين , المتغير الاول قطر قضبان الحديد الاملس (Dowel Bars) ولثلاث قياسات ( 20, 16, 12ملم) والمتغير الثاني نوع التربة وهما نوعان بحسب تصنيف (AASHTO): النوع الاول (A-6) والنوع الثاني (A-7-5). وأظهرت النتائج التجريبية أن زيادة القطر الحديد الاملس (Dowel bar) من 12 ملم الى 20 ملم له تأثير قليل على سلوك الحمل-الهطول حيث لوحظ من نتائج تحليل العينات زيادة 5٪ فقط في حمل الفشل. ويمكن أن يعزى هذا إلى أن الفشل ناجم عن (flexural crack) يعتمد بشكل رئيس على قوة مقاومة الخرسانة. وأظهرت النتائج أيضا أن نقصان قيمة CBR للتربة التحتية من 7٪ إلى 5٪ يؤدي الى نقصان حمل الفشل بنحو 33٪.


Article
Study of the Flexural Behavior of Ferrocement Element Subjected to Heating Conditions by High Degrees of Temperature
دراسة سلوك الانثناء لمركب السمنت الحديدي (الفيروسمنت) المعرض لظروف تسخين بدرجات حرارة عالية

Author: د. ميسر محمد جمعة، مدرس
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2013 Volume: 20 Issue: 2 Pages: 27-39
Publisher: Tikrit University جامعة تكريت

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Abstract

The research study has performed to investigate the ferrocement beam element which is subjected to rise of temperature under different flexural loads. The experimental program includes a ferrocement beams fabricated of cement mortar contained varying number of layers (or variable volume fraction ratio) of steel welded wire mesh of square openings (4, 6, and 8 layers). Four groups of beams were studied ; all beams have the same dimensions, and exposed to three temperature rates namely (300 °C, 450 °C and 600°C) and compared to the control ferrocement beams (reference group) without exposing to temperature rate. The main three parameters of the ferrocement beams (mix ratio, number of steel wire mesh layers and rising of temperature degree) as a structural performance parameters used for comparing ultimate flexure failure load and load-deflection relations . Throughout this study, the properties of ferrocement elements subjected to heating conditions are very important for structural stability, structural behavior and durability.

ان الهدف الرئيسي من البحث هو دراسة كفاءة مركب السمنت الحديدي المعرض الى درجات حرارة مختلفة تصاعديا" وتحت تأثير أحمال أنثناء مختلفة. تضمن البرنامج العملي لهذا البحث أعداد نماذج عتبات من مركب الأسمنت الحديدي (الفيروسمنت) ferrocement والمتكون من مونة السمنت مع المشبكات الحديدية السلكية ذات الفتحات المربعة و بنسبة كسر حجمي مختلفة (variable volume fraction ratio) وتعريض هذه العتبات الى درجات حرارة متفاوتة باستخدام فرن التسخين , ودراسة تأثير ارتفاع درجة حرارة التسخين على سلوكية الانثناء, أذ اعتمدت عدة حالات لعدد طبقات المشبكات السلكية في مقطع العتبة وكانت (4 , 6 , 8 طبقات), وتم تعريض نماذج العتبات إلى مستويات تسخين تراوحت من( °C300-°C600) وبواقع ثلاث مراحل تسخين وبفرق مقداره (150°C) بين مرحلة وأخرى, بعد أن عرضت العينات للتسخين تم قياس الهطولات الحاصلة ومقارنتها من الناحية العملية مع الدراسات السابقة. أظهرت نتائج الفحص ألمختبري عدة محددات من خلال المعاملات الثلاثة المؤثرة والتي هي (نسبة الخلط , عدد طبقات المشبك السلكي , درجة حرارة التسخين ) لكل عتبة, ممثلا" ذلك بمنحنيات (الحمل – الأود). تأتي دراسة الخواص الحرارية للفيروسمنت كخطوة مهمة في هذا البحث لإمكانية تحديد درجة الحرارة التي من الممكن ان يتعرض لها هذا المركب مع محافظته على الحد الأدنى من الخصائص الإنشائية المهمة لثباتية واستقرار الهيكل الانشائي.

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