Protection against corrosion of iron and steel in structures

Protection against corrosion of iron and steel in structures

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Effect of Bolted Joint Preload on Structural Damping

Effect of Bolted Joint Preload on Structural Damping                              Effect of Bolted Joint Preload on Structural Damping

Effect of Bolted Joint Preload on Structural Damping

Bolted joints are integral parts of mechanical systems, and bolt preload loss is one of the major failure modes for bolted joint structures. Understanding the damping and frequency response to a varying preload in a single-bolted lap-joint structure can be very helpful in predicting and analyzing more complicated structures connected by these joints.
In this thesis, the relationship between the bolt preload and the natural frequency, and the relationship between the bolt preload and the structural damping, have both been investigated through impact hammer testing on a single-bolted lap-joint structure. The test data revealed that the bolt preload has nonlinear effects on the structural damping and on the natural frequency of the structure. The damping ratios of the test structure were determined to increase with decreasing preload. An increase in structural damping is beneficial in most engineering circumstances, for it will reduce the vibrational response
and noise subjected to external excitations. It was also observed that the modal frequency increased with increasing preload, but remained approximately constant for preload larger than 30% in the bolt yield strength. One application for studying the preload effect is the detection for loose bolts in structures. The possibility of using impact testing for estimating preload loss has been confirmed, and the modal damping was determined to be a more sensitive indicator than the natural frequency in a single-bolted lap-joint structure

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New Optimization Techniques in Engineering

New Optimization Techniques in Engineering          New Optimization Techniques in Engineering

New Optimization

Techniques in Engineering

The process of producing a book is the outcome of the inputs of many people. We are grateful to all the contributors for their ideas and cooperation. Working together with such a number of contributors from remotely located distances is both challenging and interesting; there was such a speedy response from contributors, that they deserve to be acknowledged. On the publishers’ side, we want to thank
Thomas Ditzinger, Heather King and other colleagues at Springer-Verlag, Heidelberg, Germany for their enthusiasm and editorial hard work to get this book out to the readers.
BVB acknowledges the Director, Prof. S. Venkateswaran; Deputy Director
(Administration), Prof. K.E.Raman; Deputy Director (Academic), Prof. L.K.Maheshwari; and Deputy Director (Off-Campus Programmes), Prof. V.S.Rao of BITS-Pilani for continuous encouragement, support, and providing him with
the required infrastructure facilities in preparing this book. He thanks his colleagues and Ph.D. Students Mr. Rakesh Angira and Mr. Ashish Chaurasia for helping him in making some of the figures and proof reading.
Producing a book is not without the support and patience of some close people to the authors. In this regard, GCO thanks his wife, Ngozi and their children Chioma, Chineye, Chukujindu, Chinwe and Chinedu for their supporting-role and forbearance. In addition, the undergraduate and graduate students who worked under my supervision are acknowledged for their hardwork. BVB thanks his wife Shailaja for unconditional support and understanding, and his children Shruti and
Abhinav for understanding the importance and seriousness of this project contribution by not complaining on reaching home late nights. BVB also thanks his parents Shri Venkata Ramana and Mrs. Annapurna for making him what he is today.

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GUIDE OF MECHANICAL ENGINEER IN ARABIC

GUIDE OF MECHANICAL ENGINEER IN ARABIC                  GUIDE OF MECHANICAL ENGINEER IN ARABIC

GUIDE OF MECHANICAL ENGINEER IN ARABIC

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ASME B 18.24

ASME B 18.24                   ASME B 18.24                      ASME B 18.24                       ASME B 18.24

ASME B 18.24

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Fastener PowerPoint Video

Fastener PowerPoint Video                                                    Fastener PowerPoint Video

Determining Bolt Grade and Head Markings

Determining Bolt Grade and Head Markings                                         Determining Bolt Grade and Head Markings

Engineering Design Process

Engineering Design Process           Engineering Design Process         Engineering Design Process

Engineering Design Process

Second Edition

Yousef Haik

University of North Carolina—Greensboro

Tamer Shahin

Kings College London,

This book is written as an introductory course in design. Students’ technical capabilities
are assumed to be at the level of college physics and calculus. For students with advanced
technical capabilities the analysis part in the design sequence could be emphasized.
This book consists of eleven chapters. Chapter 1 is an overview of the design steps
and serves as an introduction to the book. Chapter 2 presents a few design tools that
designers must master prior to the design process. Some of these tools serve as an introduction
to courses that students will encounter in future course work. Chapters 3 through
9 present the steps of the design process. The author is aware that the sequence of these
steps can be changed according to instructor preference. Instructors can alter the presentation
sequence without having to change the presentation material. Chapter 10 discusses
issues relating to the design cost. Chapter 11 presents a list of project descriptions that can
serve as an entry point to instructors’ assignments. In this second edition we have integrated
design labs with the chapters. The purpose of these labs is to create design activities
that help students, especially freshmen and sophomores, to adjust to working in teams.
The first few of these labs are geared toward team building. It is anticipated that instructors
may want to include other activities in their design classes.
The authors wish to thank all colleagues and students who helped in producing this
book, including Dr. Adnan Al-Bashir who provided Lab 5: Project Management. Students
are encouraged to submit their comments and suggestions to the authors. The authors also
wish to thank the following reviewers for their helpful suggestions: Thomas R. Grimm,
Michigan Technological University; Peter Jones, Auburn University; Peter Eliot Weiss,
University of Toronto; and Steven C. York, Virginia Tech

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Work and Energy

Work and Energy                             Work and Energy                           Work and Energy

Work, Energy and Power

Work, Energy and Power                                                                                                              Work, Energy and Power

Work, Energy and Power

Work
If a body moves as a result of a force being applied to it, the force is said to do work on the body. The amount of work done is the product of the applied force and the distance

work done = force× distance moved in the

                                direction of the force

The unit of work is the joule, J, which is defined as the amount of work done when a force of 1 newton acts for a distance of 1 m in the direction of the force. Thus, 1 J = 1 Nm
If a graph is plotted of experimental values of force (on the vertical axis) against distance moved (on the horizontal axis) a force/distance graph or work diagram is produced. The area under the graph represents the work done

work done=  force ×  distance

The work done by a variable force may be found by determining the area enclosed by the force/distance graph using an approximate method (such as the mid-ordinate rule)

Energy
Energy is the capacity, or ability, to do work. The unit of energy is the joule, the same as for work. Energy is expended when work is done. There are several forms of energy and these include:

(i) Mechanical energy
(ii) Heat or thermal energy
(iii) Electrical energy
(iv) Chemical energy
(v) Nuclear energy
(vi) Light energy
(vii) Sound energy






Energy may be converted from one form to another. The principle of conservation of energy states that the total amount of energy remains the same in such conversions, i.e. energy cannot be created or destroyed. Some examples of energy conversions include:
(i) Mechanical energy is converted to electrical energy by a generator
(ii) Electrical energy is converted to mechanical energy by a motor
(iii) Heat energy is converted to mechanical energy by a steam engine
(iv) Mechanical energy is converted to heat energy by friction
(v) Heat energy is converted to electrical energy by a solar cell
(vi) Electrical energy is converted to heat energy by an electric fire
(vii) Heat energy is converted to chemical energy by living plants
(viii) Chemical energy is converted to heat energy by burning fuels
(ix) Heat energy is converted to electrical energy by a thermocouple
(x) Chemical energy is converted to electrical energy by batteries
(xi) Electrical energy is converted to light energy by a light bulb
(xii) Sound energy is converted to electrical energy by a microphone.
(xiii) Electrical energy is converted to chemical energy by electrolysis.

Efficiency is defined as the ratio of the useful output energy to the input energy. The symbol for efficiency is 𝜂

efficiency,𝜂 = useful output energy / input energy

Efficiency has no units and is often stated as a percentage. A perfect machine would have an efficiency of 100%. However, all machines have an efficiency lower than this due to friction and other losses.

example, if a machine exerts a force of 200 N in lifting a mass through a height of 6 m, the efficiency of the machine if 2 kJ of energy are supplied to it is calculated as follows:
Work done in lifting mass =  force × distance moved
=  weight of body×  distance moved
=  200 N×  6 m =  1200 J
=  useful energy output
Energy input =  2 kJ =  2000 J
Efficiency, h =  useful output energy / input energy
=  1200 / 2000
=  0.6 or 60%

Power

Power is a measure of the rate at which work is done or at which energy is converted from one form to another.

Power P = energy used / time take  or

 P = work done / time taken

The unit of power is the watt, W, where 1 watt is equal to 1 joule per second. The watt is a small unit for many purposes and a larger unit called the kilowatt, kW, is used, where 1 kW D 1000 W

Since work done =  force×  distance, then

power = work don/time taken= (force × distance) / time taken

 = force × (distance / time taken)

However, distance / time taken  = velocity

Hence        power = force × velocity

ANALYSIS OF BOILER TUBE FAILURES

ANALYSIS OF BOILER TUBE FAILURES                                     ANALYSIS OF BOILER TUBE FAILURES

ANALYSIS OF BOILER TUBE FAILURES

AN INTRODUCTION TO HYDROGEN DAMAGE

AN INTRODUCTION  TO  HYDROGEN DAMAGE                        AN INTRODUCTION  TO  HYDROGEN DAMAGE  

                                                 

AN INTRODUCTION  TO  HYDROGEN DAMAGE  

General Description
Hydrogen damage may occur where corrosion reactions result in the production of atomic hydrogen. Damage may result from a high-pH corrosion reaction or from a low-pH corrosion reaction. Damage resulting from a high-pH corrosion reaction is simply caustic corrosion
This form of deterioration is a direct result of electrochemical corrosion reactions in which hydrogen in the atomic form is liberated.* It is typically confined to internal surfaces of water-carrying tubes that are actively corroding.

Generally, hydrogen damage is confined to water-cooled tubes. Damage usually occurs in regions of high heat flux; beneath heavy deposits; in slanted or horizontal tubes; and in heat-transfer regions at or adjacent to backing rings at welds, or near other devices that disrupt flow. Experience
has shown that hydrogen damage rarely occurs in boilers operating below 1000 psi (6.9 MPa).
Concentrated sodium hydroxide dissolves the magnetic iron oxide according
to the following reaction:

4NaOH + Fe₃O₄ ↦ 2NaFeO₂ + Na₂FeO₂ + 2H₂O

With the protective covering destroyed, water is then able to react directly with iron to evolve atomic hydrogen:

3Fe + 4H2O↦Fe₃O₄ + 8H ↑

The sodium hydroxide itself may also react with the iron to produce hydrogen:

Fe + 2NaOH↦ Na₂FeO₂+ 2H ↑

If atomic hydrogen is liberated, it is capable of diffusing into the steel. Some of this diffused atomic hydrogen will combine at grain boundaries or inclusions in the metal to produce molecular hydrogen, or will react with iron carbides in the metal to produce methane.

Fe₃C + 4H -» CH₄ + 3Fe

Since neither molecular hydrogen nor methane is capable of diffusing through the steel, these gases accumulate, primarily at grain boundaries.
Eventually, gas pressures will cause separation of the metal at its grain boundaries, producing discontinuous intergranular microcracks (Fig. 1). As microcracks accumulate, tube strength diminishes until stresses imposed by boiler pressure exceed the tensile strength of the remaining,
intact metal. At this point a thick-walled, longitudinal burst may occur (Fig. 2). Depending on the extent of hydrogen damage, a large, rectangular section of the wall frequently will be blown out, producing a gaping hole (Fig. 3).

FIG 1 

FIG 2

FIG 3

Hydrogen damage may also result from a low-pH corrosion reaction in an operating boiler.
Atomic hydrogen may be liberated during corrosion resulting from local low-pH conditions. Atomic hydrogen is capable of diffusing into the metal and reacting to form molecular hydrogen or methane, as described above. Hydrogen damage resulting from exposure to low-pH conditions is mechanistically and physically identical to that resulting from high-pH conditions. The difference is merely the source of the atomic hydrogen.

Critical Factors
The critical factors governing hydrogen damage resulting from high-pH corrosion
The critical factors governing hydrogen damage resulting from low-pH corrosion

Identification
It is generally not possible to visually identify hydrogen damage prior to failure. In boilers operating at more than 1000 psi (6.9 MPa), areas that have sustained either high-pH or low-pH corrosion should be considered suspect.
Generally, hydrogen damage is difficult to detect by nondestructive means, although sophisticated ultrasonic techniques have been developed to reveal hydrogen-damaged metal. Ultrasonic thickness checks may disclose corroded areas that should be considered suspect.
Gouging and hydrogen damage resulting from low-pH conditions may be distinguished from damage resulting from high-pH conditions by a consideration of the boiler-water chemistry and the chemistry of the probable sources of contamination. For example, a common source of contamination of boiler water is condenser in-leakage. The source of the cooling water determines whether the in-leakage is acid-producing or base-producing.
Fresh water from lakes and rivers usually provides dissolved solids that hydrolyze in the boiler-water environment to form a high-pH substance, such as sodium hydroxide. In contrast, seawater and water from recirculating cooling-water systems incorporating cooling towers may contain dissolved solids that hydrolyze to form acidic solutions.


Elimination
Two critical factors govern susceptibility to hydrogen damage. These are the availability of high- or low-pH substances, and a mechanism of concentration. Both must be present simultaneously for hydrogen damage to  occur.
To eliminate the availability of high- or low-pH substances, the following steps should be taken:
1- Reduce the amount of available free sodium hydroxide. This can be done in the case of hydrogen damage caused by high pH.
2- Prevent inadvertent release of regeneration chemicals from makeup-water demineralizers.
3- Prevent condenser in-leakage. Because of the powerful concentration mechanisms that may operate in a boiler, in-leakage of only a few parts per million of contaminants may be sufficient to cause localized corrosion and hydrogen damage.

4- Prevent contamination of steam and condensate by process streams.  Preventing localized concentration of corrosive substances is the most effective means of avoiding hydrogen damage. It is also the most difficult to achieve. 
5 - Preventing departure from nucleate boiling (DNB), excessive water-side deposition, and the creation of waterlines in tubes may help prevent localized concentration of corrosive substances.
Prevent departure from nucleate boiling. Preventing DNB usually requires the elimination of hot spots, which is accomplished by controlling the boiler's operating parameters. Hot spots may be caused by excessive overfiring or underfiring, misadjusted burners, change of fuel, gas channeling,
and excessive blow down.

6- Prevent excessive water-side depositions. To prevent excessive water-side deposition, tube sampling on a periodic basis (usually annually) may be performed to measure relative thickness and amount of deposit buildup on tubes. Tube-sampling practices are outlined in ASTM D887-82. Consult boiler manufacturers' recommendations for acid cleaning.
7- Prevent waterline formation. Slanted and horizontal tubes are especially susceptible to the formation of waterlines. Boiler operation at excessively
low water levels or excessive blowdown rates may create waterlines. Waterlines may also be created by excessive load reduction when pressure remains constant. When load is reduced and pressure remains constant, water velocity in boiler tubes is reduced to a fraction of its full-load value. If
it becomes low enough, steam/water stratification occurs and creates stable or metastable waterlines.

Cautions
Hydrogen damage typically produces thick-walled ruptures. Other failure mechanisms producing thick-walled ruptures include stress-corrosion cracking, corrosion fatigue, stress rupture, and, in some rare cases, severe overheating. It may be difficult to visually distinguish ruptures caused by
hydrogen damage from other ruptures, although certain features may serve as an aid

Limitz - Program

Limitz - Program                          Limitz - Program                               Limitz - Program      

 Limitz - Program

Introduction:
This program calculates shaft and hole dimensions and tolerances in accordance with ISO286-1 & ISO286-2 1988 (AS1654.1 & 2 1995).
Square and rectangular parallel keyways are in accordance with BS4235 Part1 1972.
Selected fits are in accordance with AS 1654 - 1974.
If a greater depth of understanding is required the user should refer to these standards.

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fits,hole basis system, shaft basis system

fits,hole basis system, shaft basis system                            fits,hole basis system, shaft basis system

Preferred Limits and Fits for Cylindrical Parts B4.1-1967

Preferred Limits and Fits for Cylindrical Parts B4.1-1967               Preferred Limits and Fits for Cylindrical Parts B4.1-1967

Preferred Limits and Fits for Cylindrical Parts B4.1-1967

This standard presents definitions of terms applying to fits between plain (non-threaded)
cylindrical parts and makes recommendations on preferred sizes, allowances, tolerances, and fits
for u s e wherever they are applicable. The standard through 20 in. diameter i s in accord with the
recommendations of American-British-Canadian Conferences. Experimental work i s being carried
on and when results are available, agreement in the range above 20 in. will be sought. It represents
the combined thinking and experience of groups who have been interested in standards in this field, and it should have application for a wide range of products. The recommendations, therefore, are presented for guidance and for use where they might serve to improve and simplify products, practices, and facilities.

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Handbook of Reliability Engineering

Handbook of Reliability Engineering                             Handbook of Reliability Engineering

Handbook of Reliability Engineering

Hoang Pham, Editor

This Handbook of Reliability Engineering, altogether 35 chapters, aims to provide a comprehensive state-of-the-art reference volume that covers both fundamental and theoretical work in the areas of reliability including optimization, multi-state system, life testing, burn-in, software reliability, system redundancy, component reliability, system reliability, combinatorial optimization, network reliability,
consecutive-systems, stochastic dependence and aging, change-point modeling, characteristics of life distributions, warranty, maintenance, calibration modeling, step-stress life testing, human reliability, risk assessment, dependability and safety, fault tolerant systems, system performability, and engineering management.
The Handbook consists of five parts. Part I of the Handbook contains five papers, deals with different aspects of System Reliability and Optimization.

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ROLLER BEARING TYPES

ROLLER BEARING TYPES                                                                                                                                               ROLLER BEARING TYPES             

ROLLER BEARING TYPES 

DRAG FORCES

DRAG FORCES                                 DRAG FORCES                              DRAG FORCES

Drag force Case study

Drag force study                                                                                                                                                                   Drag force study                                          
                           Drag force Case study 

A body moving through the air experiences resistance and a stationary body in an air stream experiences wind force. The forces are due to the shearing action which is produced when the air flows over a surface and are generally known as drag forces. 
Motor vehicle and aeronautical engineers are continually seeking to reduce these forces in a quest for improved efficiency. Architects and structural engineers must also take account of wind force in the design of buildings and bridges. Aerodynamics is the study of air flow and its effects, in which the wind tunnel testing of models plays a major role.


Drag force

Drag is the aerodynamic force that opposes an aircraft's motion through the air. The total drag force acting on a body in a fluid stream is made up of two components. They are known as form drag and skin friction drag. On streamlined objects, the form drag and skin friction drag are roughly of the same magnitude. Skin friction drag is the viscous resistance caused by the shearing action which takes place across the boundary layer adjacent to the surface of a body. It is dependant on the surface area and the surface texture. The magnitude of skin friction drag is extremely difficult to predict except on the most simple shapes. It can, however, be kept to a minimum by making surfaces as smooth as possible.

FIG 1 

Form drag depends on the projected area which a body presents to the fluid stream. With an irregularly shaped or bluff body, the form drag will be high and with a streamlined body it
will be comparatively low. Figure 1 shows a bluff body in a fluid stream. Station (1) is in the free stream where the velocity is 𝓥₁and the pressure is 𝓟₁. It is assumed that the pressure behind the body is also 𝓟₁. Station (2) is on the front surface of the body where stagnation conditions are assumed to exist, i.e. where the fluid has been brought to rest. The pressure,  𝓟₂ will thus be greater than 𝓟₁. Applying Bernoulli’s equation to stations (1) and (2), we obtain

But 𝓥₂ = 0 and 𝓩₁ =𝓩₂. Eliminating these, we get

where

𝝆    is density  kgm ⁻³
𝓥₁  is the velocity of the free stream  ms⁻ ¹ 
𝓟₁  is the pressure behind the body  kg m⁻² 
𝓟₂  is the pressure on the front of body kg m⁻² 
This is known as the dynamic pressure acting on the body as a result of the fluid being brought to rest. It is assumed to act uniformly over the whole projected area A(a) which the body presents to the fluid stream. The theoretical form drag is thus given by

theoretical drag = dynamic pressure × projected area

Dynamic pressure is the pressure increase that results when a fluid is brought to rest on a surface in a fluid stream.
the dynamic pressure does not act uniformly over the projected area and in addition to the pressure build-up in front of the body, there is often a pressure decrease in the wake behind it. There is also skin friction drag present. Nevertheless, the above theoretical drag force is used as a standard against which the actual measured drag force can be compared. The actual drag force is obtained from exhaustive wind tunnel tests where it is measured on sensitive balances. The theoretical and measured drag forces can then be used to calculate the drag coefficient C𝘋 for the body.

drag coefficient = measured drag force / theoretical drag force

where 𝓥 is the free stream velocity. (𝓥₁)
The value of  C𝘋 for a flat plat is around 1.15 and for a cylindrical object it is around 0.9. For modern cars it is around 0.3 and for a fully streamlined teardrop shape it is around 0.05.
The drag coefficient gives a comparison of the measured drag force on a body and the theoretical drag force that is calculated from The dynamic pressure.

Bentley WaterCAD CONNECT

Bentley WaterCAD CONNECT                                                                                                                           Bentley WaterCAD CONNECT

Bentley WaterCAD CONNECT

This app helps you to correctly map water distribution system and network design, planning and management. All this increases the capacity of the service, providing quality design with lowest cost and the possibility of change and transition convenient water system at any time.
Features and WaterCad:
Plumbing system analysis and critical control points
To optimize the system for protection against heat flows
Ability to create and manage hydraulic models
Full design water distribution network
Possible to plan for the development of flushing
The ability to detect water leaks
Energy Management
And…

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Password: www.downloadly.ir

CHARPY AND IZOD TEST

CHARPY AND IZOD TEST        CHARPY AND IZOD TEST               CHARPY AND IZOD TEST                       CHARPY AND IZOD TEST 

CHARPY AND IZOD TEST 

 LEARN AND GROW

Belt drives- ISO 5287

Belt drives- ISO 5287                                                                                                                                                                                      Belt drives- ISO 5287

Belt drives — Narrow V-belts for the

automotive industry — Fatigue test

ISO 5287

This International Standard specifies a fatigue test for the quality control of narrow V-belts (sections AV 10 and AV 13) intended for driving the auxiliaries of internal combustion engines used for automotive purposes.

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Mechanical Engineer’s Reference Book

Mechanical Engineer’s Reference Book                                                                                                                                      Mechanical Engineer’s Reference Book

Mechanical Engineer’s Reference Book

Mechanical Engineer’s Reference Book Twelfth edition Edited by FI Mech E Head of Computing Services, University of Central Lancashire With specialist contributors
To see this book in print is a considerable personal http://zipansion.com/xCGRachievement, but I could not have done this without the help of others. First, I would like to thank all the authors for their tremendous hard work. It is a major task to prepare information for a hook of this type, and they have all done a magnificent
job. At Butterworth-Heinemam, Duncan Enright and Deena Burgess have been a great help, and Dal Koshal of the University of Brighton provided considerable support. At the University of Central Lancashire, Gill Cooke and Sue Wright ensured that the administration ran smoothly. I hope you find the book useful

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CNC الفريزة تشغيل وبرمجة ماكينة

تشغيل وبرمجة ماكينة

CNC الفريزة

التحميل

centrifugal clutch ASSEMBLY (Grass Cutter Machine)

centrifugal clutch ASSEMBLY (Grass Cutter Machine)                                      centrifugal clutch ASSEMBLY (Grass Cutter Machine)

    centrifugal clutch ASSEMBLY

 (Grass Cutter Machine)