The document summarizes concepts related to fatigue in welded steel structures. It discusses the mechanism of fatigue failure, factors influencing fatigue behavior, effects of fatigue loading on structural members and weld connections, fatigue analysis methods including the S-N approach and fracture mechanics approach, Indian standard practices, techniques to improve fatigue strength, and conclusions.
Mumbai University.
Mechanical Engineering
SEM III
Material Technology
Module 2.2
Fatigue Failure:
Definition of fatigue and significance of cyclic stress, Mechanism of fatigue and theories of fatigue failure, Fatigue testing, Test data presentation and statistical evolution, S-N Curve and its interpretation, Influence of important factors on fatigue, Notch effect, surface effect, Effect of pre-stressing, corrosion fatigue, Thermal fatigue.
Mumbai University.
Mechanical Engineering
SEM III
Material Technology
Module 2.2
Fatigue Failure:
Definition of fatigue and significance of cyclic stress, Mechanism of fatigue and theories of fatigue failure, Fatigue testing, Test data presentation and statistical evolution, S-N Curve and its interpretation, Influence of important factors on fatigue, Notch effect, surface effect, Effect of pre-stressing, corrosion fatigue, Thermal fatigue.
The fundamentals of welding arc, mechanisms of electron
emission, different zones in welding arc, electrical aspects related with welding arc, arc forces.
and their significance in welding.
Rolling mills are used to reduce the width and increase the hardness of the metal. They are often used in steel industries. It is an energy efficient / energy saving process that produces more uniform, lower fines and larger particles for product quality.
Mumbai University.
Mechanical Engineering
SEM III
Material Technology
Module 2.3
Creep:
Definition and significance of creep, Effect of temperature and creep on mechanical behaviours of materials, Creep testing and data presentation and analysis, Mechanism and types of creep, Analysis of classical creep curve and use of creep rate in designing of products for load-bearing applications, Creep Resistant materials
Recrystallization is the process in which deformed grains of the crystal structure are replaced by a new set of stress-free grains that nucleate and grow until all the original grains have been consumed. The process is accomplished by heating the material to temperatures above that of crystallization.
This Presentation covers the basic concepts of EBW in a easy version. For more information, please refer the books mentioned in the references slide.... Thank you
The fundamentals of welding arc, mechanisms of electron
emission, different zones in welding arc, electrical aspects related with welding arc, arc forces.
and their significance in welding.
Rolling mills are used to reduce the width and increase the hardness of the metal. They are often used in steel industries. It is an energy efficient / energy saving process that produces more uniform, lower fines and larger particles for product quality.
Mumbai University.
Mechanical Engineering
SEM III
Material Technology
Module 2.3
Creep:
Definition and significance of creep, Effect of temperature and creep on mechanical behaviours of materials, Creep testing and data presentation and analysis, Mechanism and types of creep, Analysis of classical creep curve and use of creep rate in designing of products for load-bearing applications, Creep Resistant materials
Recrystallization is the process in which deformed grains of the crystal structure are replaced by a new set of stress-free grains that nucleate and grow until all the original grains have been consumed. The process is accomplished by heating the material to temperatures above that of crystallization.
This Presentation covers the basic concepts of EBW in a easy version. For more information, please refer the books mentioned in the references slide.... Thank you
Seismic behavior of elevated water tankeSAT Journals
Abstract Hydrodynamic analysis of elevated water tank is a complex procedure involving fluid structure interaction. The elevated tank supports large water mass at the top of slender staging. In case of elevated tank the resistance against lateral forces exerted by earthquake is largely dependent of supporting system. Staging is considered to be a critical element as far as lateral resistance is concern. Satisfactory performance of staging during strong ground shaking is crucial. In this paper seismic behavior of elevated water tank in view point of their supporting system is evaluated using finite element software ETABS. The main objective is to evaluate a performance of different staging system for elevated water tank using finite element software ETABS. The spring mass model consisting of impulsive and convective masses as per IS 1893:2002 Part 2 has been used for the analysis. The parametric study is performed on mathematical model with different staging system to evaluate their performance with regard to lateral stiffness, displacement, time period, seismic base shear, overturning moment, flexure etc. Keywords: Hydrodynamic analysis, Staging Performance, spring mass model, ETABS
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In this you will find some of the basic thing regarding the elevated water tank and this is our one of the team project work in college. Hope you will enjoy it....
The presentation summarizes the project work done on "Seismic Analysis of Elevated Water Tank". Elevated water tanks are important structures that serve the function of supplying municipal water to the civil community. The stability of such structure is highly uncertain in the eve of earthquake. This project analyses the performance of such a structure in the eve of earthquake.
The project is done as a course requirement for undergraduate degree in May 2013. The degree in pursuit was "Bachelor of Technology in Civil Engineering" in National Institute of Technology in Tiruchirappalli (INDIA). The authors were in final year of the study during the making of the project.
The counselling process; Stages of the counselling processSunil Krishnan
The counselling process:
Stages of the counselling process
Stage 1: Initial Disclosure
Stage 2: In-depth Exploration
Stage 3: Commitment to action
Three stages of Counselling in Perspective
Counselling …………………………………………………………………
Counselling and Psychotherapy………………………………………
The Role of the Counsellor……………………………………………
Counselling Skills ……………………………………………………
Stages of the counselling process: …………………………………………
Some Misconceptions About Counselling ……………………………
The Counselling Process ………………………………………………
Stage 1: Relationship Building - Initial Disclosure ………………………
Stage 2: In-Depth Exploration - Problem Assessment ………………….
Stage 3: Goal Setting - Commitment to Action ………………………….…
Guidelines for Selecting and Defining Goals ………………………..
Summary ………………………………………………………………
Three stages of Counselling in Perspective …………………………………
Psychoanalytic theory ……………………………………………..…
Benefits and limitations of Psychoanalytic theory ……………
Psychodynamic Approach to Counselling …………………………
Id, Ego and Superego …………………………………………
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Client Centred/Non Directive Counselling……………………
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Humanistic Approach to Counselling …………………………………
Behaviour Theory …………………………………………………
Behavioural Approach to Counselling …………………………
Cognitive Theory …………………………………………………
Effect of V Notch Shape on Fatigue Life in Steel Beam Made of High Carbon St...IJMER
The present work includes study effect of V notch shape with various angle orientation and
depths on fatigue life behavior in steel beam made of High Carbon Steel alloy AISI 1078 which has a wide
application in industry. Fatigue life of notched specimens is calculated using the fatigue life obtained from
the experiments for smooth specimens (reference) and by use Numerical method (FEA).The fatigue
experiments were carried out at room temperature, applying a fully reversed cyclic load with the
frequency of 50 Hz and mean stress equal to zero (R= -1), on a cantilever rotating-bending fatigue testing
machine. The stress ratio was kept constant throughout the experiment. Different instruments have been
used in this investigation like Chemical composition analyzer , Tensile universal testing machine
,Hardness tester , Fatigue testing machine and Scanning Electron Microscope (SEM).The results show
that there is acceptable error between experimental and numerical works
Similar to Concept of ‘fatigue’ in welded steel (20)
Student information management system project report ii.pdfKamal Acharya
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Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
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Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
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Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
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Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
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• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
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Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
1. Concept of ‘FATIGUE’ in WELDED
STEEL STRUCTURES
Under the guidance of
M H Prashanth
Assistant Professor
NITK
Submitted by
B Harish
16ST05F
2. Overview
• Introduction
• Mechanism and Factors influencing Fatigue
• Effect of fatigue loading on Structural members
and Weld connection
• Fatigue Analysis...S-N approach
...Fracture Mechanics approach
• Indian Standard Practice
• Improvements of Fatigue Strength techniques
• Conclusions and References
3. Introduction
• DEF: A Fatigue failure can be defined as
“the number of cycles (or) the time taken to attain a pre-
defined failure criterion.”
• Fatigue phenomenon is experienced by structures, which are
subjected to moving loads(such as bridges and crane girders)
or structures subjected to cyclic loads .
4. • Fatigue Failure Proceeds in 3 distinct stages:
crack initiation in the areas of stress concentration (near
stress raisers)
incremental crack propagation
final catastrophic failure.
• In most of the welded steel structures the crack initiation
phase does not exist as crack–like weld defects are invariably
present in them.
• In the case of fatigue fracture of engineering structures, the
following are the two main types of fatigue loading.
a) High–cycle fatigue
b) Low–cycle fatigue
5. Mechanism of Fatigue Failure
• At Present 4 mechanisms are proposed for fatigue failure:
1)Orowan’s theory:
Metals contain small,weak regions for
-- orientation of slip (or) areas of stress concentration
results in notch formation
-- if total plastic strain > critical value, crack is formed
6. 2) Mott theory :
cross slip of screw locations part of metal is extruded from
surface cavity is left in the interior of crystal source of
fatigue crack.
3)Wood’s theory :
fine slip movement static slip bands back & forth of fine
slip bands formation of notches or ridges a fatigue crack
4)Cottrell & Hull theory :
two different slip systems when work with different directions
produce slip at surface forming intrusions and
extrusions
7. Factors influencing Fatigue Behavior
1. Stress concentration: Points where stress distribution
is different from that adopted ---
a)relative deformations
b)Macroscopic stress concentration`
c)Local geometric stress concentration
2. Frequency of cyclic loading : indicates the number of
fatigue load cycles per second
no influence on fatigue strength if low stress range
and low frequency of loading
3.Size effect :
small members- more fatigue resistance- max size
effect
8. 4.Residual Stress :
compressive residual stress
tensile residual stress
5.Material :
Tests have shown that under ideal conditions, fatigue limit is
approximately 50% of ultimate stress.
However, other factors may considerably alter this fatigue
limit.
The general relation between fatigue limit and ultimate stress
is given below
F1 = 140+0.25 Fu
F1 = fatigue limit for zero to maximum tensile loading in Mpa
9. Effect of fatigue loading
• In structural members:
Compressive members will not generally produce fatigue failure
The fatigue behavior of tensile members is generally decided
by their connections
• In Weld Connections :
Residual stresses of yield stress level are always present in
the vicinity of welds.
Fatigue resistance of welded joint is the geometry and
the resulting stress concentration effects.
Fatigue life varies with the type of weld details due to the varying
nature of the defects in the different details
10. • Fatigue failure at a welded joint may occur in
any one or combination of the following
Failure in the line of fusion, due to lack of proper fusion or
microscopic cracks.
Failure in the heat affected zone due to crystalline change in
the base metal.
Failure at the toe edge of the weld, which is a stress
concentrated point due to the joint design, weld contour
undercut, etc.
11. Fatigue Analysis
• Fatigue analysis involves :
1) determination of nominal stresses in structural members
2)stress concentration factors at critical points
3)safe number of stress reversals before the onset of failure.
• Fatigue life determination
S-N approach : Constant amplitude
Variable amplitude
Fracture mechanics approach
14. In order to determine the fatigue strength of a welded
joint configuration, under a given load condition, it is
necessary to test a series of similar specimens.
Each of the specimens is subjected to constant
amplitude loading and the number of loading cycles
required to produce failure in each specimen is
recorded.
The relationship between the applied stress , S and the
number of cycles to failure, N, is obtained.
Logarithmic scales are commonly used for both axes,
namely, LogS – LogN
15. • In constant amplitude loading, one cycle equals two reversals.
R = -1 is called the fully reversed condition since Smin= -Smax
R = 0, where Smin = 0, is called pulsating tension.
Example of constant amplitude
loading S-N curve (Log-Log)
16. • For welded joints the relationship between fatigue life
and applied stress range is linear over a wide range of
stress and takes the form
N = number of cycles to failure,
= applied stress range
m, = depending upon the joint type.
18. Palmgren-Miner’s rule
• C= part of life decreased due to applied stress ranges
(generally C=1)
C<1 failure occurs if high to low cycle testing
C>1 failure occurs if low to high cycle testing
20. An important parameter K which is defined as stress at the tip of
crack and is known as stress intensity factor(K)
K=Yσ
Y= geometric correction factor(depends on crack
size,shape,loading)
σ = nominal stress
a = crack length
21. Fatigue life assessment by fracture mechanics is based on the
observed relationship between the stress intensity factor range
and rate of growth of fatigue cracks da /dN
= crack extension per cycle
C,m = crack growth constants can be determined by
conducting tests on materials
22. In welded connections, the stress intensity factor and
fatigue strength is given by following equations with initial and final
crack depth ai and af respectively
23. IS code of Practice
• IS: 1024 – 1999 “Code of Practice for Use of Welding in Bridges and
Structures Subjected to Dynamic Loading” covers the use of metal arc
welding in bridges and structures subjected to fatigue loading.
• Welding details-7
Class A
Class B
Class C
Class D
Class E
Class F
Class G
24. • For each of the stress ranges, the maximum allowable number
of cycles N1, N2 ……Nn
should be determined from the tables given in
the IS Code 1024 - 1999.
• Considering the expected number of cycles for each stress
level as n1, n2 ……nn,
the element should be so designed such that
n1 / N1+ n2 / N2+ n3 / N3+-------------------+ nn / Nn >1.0
25. Permissible stress in Welds
Butt Welds
• Butt welds shall be treated as parent metal with a thickness
equal to throat thickness, and the stresses shall not exceed
those in the parent metal.
• In structures subjected to dynamic loading, tensile (or) shear
stresses in butt welds shall not exceed 66 percent of the
permissible stresses.
26. Fillet Welds
• The basic permissible stress in fillet welds based on a
thickness equal to the throat thickness shall be 100 N/mm2.
• Load carrying fillet welds in dynamically loaded structures
shall be designed so that the secondary bending stresses are
not introduced
• The permissible stresses for field welds of structural members
shall be reduced to 80 percent of those specified in Field
welds .
27. • For combined shear and bending stresses, the equivalent
stress fe is given as
(or)
• The equivalent stress should not exceed 0.9Fy where Fy is
the yield strength of the steel.
)
28. Improvements of Fatigue Strength
techniques
• Crack initiation life can be extended by
Reducing the stress concentration of the weld.
Removing crack-like defects at the weld toe.
Reducing tensile welding residual stress or introducing
compressive stresses.
• The various methods of improvements can be classified
into:
Weld geometry improvement by grinding, weld dressing
Residual stress reduction by peening and thermal stress
relief
29. Conclusions
• various factors affecting fatigue behavior of welded
connections are explained.
• The nature of fatigue in welded connections and its critical
importance are showed.
• Methods of evaluating fatigue lives of welded connections
are described.
• Techniques for improvement in fatigue performance are
presented
30. References
• Fatigue analysis of welded joints:state of development by
Wolfgang Fricke.
• Study of effect of welding joint location on fatigue strength
and fatigue life for steel weldment by Dr. Ali Sadiq Yasir.
• Estimating the fatigue behavior of welded joints by
M.D.Chapetti.
• Owens G.W. and Cheal B.D., ‘Structural Steelwork
Connections’, Butterworths,London, 1989-chapter 6.
• IS:1024-1999, ‘Code of Practice for Use of Welding in Bridges
and Structures Subjected to Dynamic Loading’, Bureau of
Indian Standards.