Fatigue Life Prediction of a Turbine Disc with Stress Gradient (original) (raw)

Case Study of Baji Gas Station unit one and Three for Performance Determination

Tikrit Journal of Engineering Sciences

Baiji thermal station supplied by heavy fuel HFO from Baiji refinery, while the gas station is operated by heavy fuel HFO and light fuel LFO, the first unit operates using LFO, the third unit operates using HFO. The results showed that the specific fuel consumption is reduced by rising the load, when the load is reduced to 20Mw s.f.c almost 0.765m3/Mw.hr this rate start to fall to become 0.35m3/Mw.hr when the unit operate near its maximum capacity for LFO, while the heavy fuel increases by 15% for the same number above. It’s correct that LFO is good but it is expensive which costs 1000$ per imported ton , in order to cover the load of 8000Mw for one year itcosts 1.92E+10$ for imported LFO ,9.6E+10$ for the local LFO, and 2.8E+9$ for HFO, the difference is obvious which is ten times the total cost. Also the studied performance of the gas units showed that the net is experience from a downturn of frequency along 24hr except in the let hours at night, while the allowed frequency is 50...

Finite element analysis of the cervical spine: a material property sensitivity study

Clinical Biomechanics, 1999

A 3D anatomically accurate finite element model of the human first cervical vertebra (atlas), including cortical and cancellous bones, was developed in ANSYS 9 based on CT-scan images. The main objective was to investigate the effect of cancellous bone on the value and distribution of maximum and average Von Mises stress in Atlas. The results showed that the material property of cancellous bone has no significant effect on the location of maximum stress and the pattern of average stress distribution in anterior arch, the junction of posterior arch and lateral mass and the groove of the posterior arch. Although the presence of cancellous bone in the model yielded higher values for the maximum and average stresses. The boundary condition had a considerable effect on this increase. Altering the material property of cancellous bone, under neutral and hyperextension loading configurations, affected the average stress only in cancellous bone in the lateral mass, but change in the material property of cortical bone resulted in average stress change both in the cortical and cancellous bones, and in the lateral displacement of the lateral mass as well. The interconnected effects of changing the material properties of these two bone tissues were also studied.

Study to modify the mechanical and chemical properties of building blocks (Thermostone)

Iraqi Journal of Civil Engineering

This study concern with a new technology to modified the compressive strength of the thermo brick which have a main role in construction field. This research using a new local cheap additives called (tar) which is available in Iraq (Kirkuk area). The experimental program have include three type of thermo brick available in local market (Iraqi, KSA, and Kuwaiti) and these type are common used in south area of Iraq especially Basrah City. The sample has exposed to the steam of tar in different temperature. Four affecting factor are studied carefully on compressive strength of brick including, tar , brick manufacture type, number of exposing faces of brick, and the age of brick after finishing expose of brick to the tar steam. The result shows maximum compressive strength conducted are 4.4 MPa when two faces expose to tar and two hours' time of exposing (one hour for each face) and the modified percentage was 62% compared with reference sample (KSA type). The improvement in compressive strength of Iraqi type and Kuwaiti were 27% and 45% respectively. Furthermore the improvement of compressive strength with same condition aforementioned but for one hour exposing time (half hour on each face) are 37.5%. The chemical properties also has conducted in this study.

اختبار استقرارية السلاسل الزمنية للبيانات المقطعية الخاصة بالمنشات الصناعية الكبيرة في العراق

Journal of Economics and Administrative Sciences, 2013

ملخص البحث مفهوم التكامل المشترك من المفاهيم المهمة في الاقتصاد الكلي التطبيقي. فكرة التكامل المشترك ترجع إلى جرانجر عام (1981)، وقام بشرحها بالتفصيل انجل وجرانجر في Econometrica عام (1987). إن إدخال التحليل بالتكامل المشترك في الاقتصاد القياسي في منتصف الثمانينات من القرن الماضي، يعتبر من أهم تطورات في المنهج التجريبي للنمذجة، ويمتاز ببساطة الحساب والاستخدام لأنه يحتاج فقط بالإلمام بالمربعات الصغرى العادية. التكامل المشترك ينظر إلى العلاقات التوازنية للسلاسل الزمنية في المدى الطويل، حتى وإن احتوت كل مسلسلة على اتجاه عام عشوائي (غير ساكنة، والمتغيرات متكاملة من درجة واحدة) فأنهم بالرغم من عدم السكون سيتحركون متقاربين عبر الزمن ويكون الفرق بينهم ساكناً هكذا فإن فكرة التكامل المشترك تحاكي وجود توازن في المدى الطويل يؤول إليه النظام الاقتصادي، ويتركّز السبب الرئيسي لعدم وجود التوازن في عدم مقدرة الوكلاء الاقتصاديين economic agents على التكيّف مع المعلومات لحظياً. اضافة الى ان هنالك تكلفة مقدّرة للتكيّف و التي تؤدى إلى تحديد قيمة المتغير التابع فقط...

تقدير تراكيز بعض المعادن الثقيلة في ألعاب الأطفال البلاستيكية المَبيعة في أسواق محافظة عدن – اليمن

المجلة العربية للبحث العلمي, 2020

This research is a first attempt to examine some heavy metals in plastic toys available in some of Aden Governorate markets-Yemen and to evaluate the toxicity effects on kids' health. To achieve this goal, we examined ten plastic toys as samples randomly. These toys were purchased from toy shops and stalls in Aden Governorate. The toys were assembled and classified by type, colour, and playing method: by mouth only, by hand only, or by both (which are the typical playing methods by children between 1-6 years old). The samples were prepared then analyzed at the National Research Center-Egypt. Toxicity Characteristic Leaching Procedure (TCLP) was used for the samples and then followed by the ICP-OES technique to determine heavy metals concentration namely: arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), Iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn). Using TCLP in this study showed that all heavy metals levels

Blades Vibration Response Study of a Bladed Disk System Connecting with Two Lacing Wires and Mistuning Effect

2019

In order to avoid flutter phenomena in blades of a turbine stage, the blades have not been made equal and they have some differences in their masses and stiffness. These small differences are called mistuning. In this study, the effect of the mistuning on vibration response of blades connecting with two lacing wires is studied. First, the system has modeled by mass-spring-damper and then the governing equations are derived. After that, the vibration response of the mistuned system is compared with the vibration response of the tuned system in the different type of blades numbers connection. The vibration response of the mistuned system is also investigated when all of the blades are connected. The results show that a small change in the stiffness of the tuned system causes the vibration amplitude of some of the blades of the system to change considerably in some of the blades connection arrangements. For example, it can be seen that the mistuning up to about 0.5 percent, in the case of connecting eight blades to each other in a row of turbine blades, increases about 11 percent the amplitude of vibration response of the system.

The effect of tools length on stable materials removal rate in high speed milling process

2015

High -speed milling is widely used in the manufacturing industry. This method is faster and more precise than the traditional milling. The feature of precision and speed in the method of manufacturing has made it suitable for manufacturing of bigger and high precision milling parts. This research studies the effect of tool length on stable materials removal rate in high speed milling processes. It is shown that the tools length is highly affected the natural frequency of the most flexible mode and the high material removal rate is obtained when the tools length in the stable region is accessible with the fastest speed. Furthermore, sometimes longer tools provide higher material removal rate