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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.


Article
Estimation of Stator Winding Temperature of a Three-Phase Induction Motor

Authors: Amer Mejbel Ali --- Afrah Thamer Abdullah
Journal: IRAQI JOURNAL OF COMPUTERS,COMMUNICATION AND CONTROL & SYSTEMS ENGINEERING المجلة العراقية لهندسة الحاسبات والاتصالات والسيطرة والنظم ISSN: 18119212 Year: 2019 Volume: 19 Issue: 2 Pages: 9-17
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This paper adopted a thermal network method (TNM) based on Motor-CADwith MATLAB/Simulink software, and finite element method (FEM) based on Motor-CAD with Flux2D software, to estimate the stator winding temperature of a totallyenclosed fan-cooled (TEFC), squirrel cage, three-phase induction motor. The threesoftware packages were adopted successfully with a good agreement among their resultsresulting in preferring using Motor-CAD in obtaining results, and using Flux2D withMATLAB to validate these results. The success of triple-software methodology will givethe induction motor designer a well-validated tool in attaining a safe motor operationwithout exceeding the maximum allowable stator winding temperature rise, and withoutusing an experimental test based on an expensive manufacturing motor.

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