Alot of Engineering Drawings in folder (Very goo Detail)
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A large triaxial investigation of the stress-path-dependent behavior of compacted rockfill
Ming Xu, Erxiang Song and Jinfeng Chen
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Preface
Engineering is not an exact science and, of the many disciplines within engineering,
welding is probably one of the most inexact – rather more of an
art than a science. Much of the decision-making is based on experience and
a ‘gut feel’ for what is or is not acceptable. When the difficulties of shop
floor or site control are taken into account and the occasional vagaries of
the welder and the sometimes inadequate knowledge of supervisory staff
are added, the problems of the practising shop floor engineer can appear
overwhelming. I hope that some of this uncertainty can be dispelled in this
book, which is aimed at those engineers with little or no knowledge of
metallurgy and perhaps only the briefest acquaintance with the welding
processes. It does not purport to be a metallurgical or processes textbook
and I make no apology for this. Having lectured fairly extensively on
welding technology, I have come to realise that most engineers think of
metals as being composed of a large number of small billiard balls held
together by some form of glue. I have attempted to describe the metallurgical
aspects of the aluminium alloys in these terms. I have therefore kept
the contents descriptive and qualitative and have avoided the use of
mathematical expressions to describe the effects of welding.
The book provides a basic understanding of the metallurgical principles
involved in how alloys achieve their strength and how welding can affect
these properties. I have included sections on parent metal storage and preparation
prior to welding and have also described the more frequently encountered
processes. There are recommendations on welding parameters that
may be used as a starting point for the development of a viable welding procedure.
Also included are what I hope will be useful hints and tips to avoid
some of the pitfalls of welding these sometimes problematic materials.
I would like to thank my colleagues at TWI, particularly Bob Spiller,
Derek Patten and Mike Gittos, for their help and encouragement during
the writing of this book – encouragement that mostly took the form of
‘Haven’t you finished it yet?’.Well, here it is. Any errors, inaccuracies or
omissions are mine and mine alone.
-----------------------------------
Contents:
1 Introduction to the welding of aluminium 1
1.1 Introduction 1
1.2 Characteristics of aluminium 4
1.3 Product forms 6
1.4 Welding: a few definitions 6
2 Welding metallurgy 10
2.1 Introduction 10
2.2 Strengthening mechanisms 10
2.3 Aluminium weldability problems 18
2.4 Strength loss due to welding 31
3 Material standards, designations and alloys 35
3.1 Designation criteria 35
3.2 Alloying elements 35
3.3 CEN designation system 36
3.4 Specific alloy metallurgy 40
3.5 Filler metal selection 46
4 Preparation for welding 51
4.1 Introduction 51
4.2 Storage and handling 51
4.3 Plasma-arc cutting 52
4.4 Laser beam cutting 58
4.5 Water jet cutting 63
4.6 Mechanical cutting 64
4.7 Cleaning and degreasing 66
v5 Welding design 69
5.1 Introduction 69
5.2 Access for welding 70
5.3 Welding speed 71
5.4 Welding position 72
5.5 Edge preparation and joint design 72
5.6 Distortion 84
5.7 Rectification of distortion 88
5.8 Fatigue strength of welded joints 89
6 TIG welding 97
6.1 Introduction 97
6.2 Process principles 97
6.3 Mechanised/automatic welding 114
6.4 TIG spot and plug welding 115
7 MIG welding 116
7.1 Introduction 116
7.2 Process principles 116
7.3 Welding consumables 130
7.4 Welding procedures and techniques 135
7.5 Mechanised and robotic welding 141
7.6 Mechanised electro-gas welding 143
7.7 MIG spot welding 144
8 Other welding processes 147
8.1 Introduction 147
8.2 Plasma-arc welding 147
8.3 Laser welding 150
8.4 Electron beam welding 155
8.5 Friction welding 160
9 Resistance welding processes 166
9.1 Introduction 166
9.2 Power sources 167
9.3 Surface condition and preparation 169
9.4 Spot welding 171
9.5 Seam welding 175
9.6 Flash butt welding 176
10 Welding procedure and welder approval 181
10.1 Introduction 181
10.2 Welding procedures 181
10.3 Welder approval 191
11 Weld defects and quality control 199
11.1 Introduction 199
11.2 Defects in arc welding 199
11.3 Non-destructive testing methods 205
Appendix A British and ISO standards related to
welding and aluminium 216
Appendix B Physical, mechanical and chemical
properties at 20°C 226
Appendix C Principal alloy designations: cast products 227
Appendix D Alloy designations: wrought products 228
Bibliography 230
Index 235
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Welding Robots - Technology, System Issues and Applications
Author: J. Norberto Pires, Altino Loureiro and Gunnar Bölmsjo | Size: 2.44 MB | Format:PDF | Quality:Original preprint | Publisher: Springer-Verlag | Year: 2006 | pages: 192 | ISBN: 1-85233-953-5/978-1-85233-953-1
Industrial robots are essential components of today’s factory and even more of the factory of the future. The demand for the use of robots stems from the potential for flexible, intelligent machines that can perform tasks in a repetitive manner at acceptable cost and quality levels. The most active industry in the application of robots is the automobile industry and there is great interest in applying robots to weld and assembly operations, and material handling.
For the sake of competitiveness in modern industries, manual welding must be limited to shorter periods of time because of the required setup time, operator discomfort, safety considerations and cost. Thus, robotic welding is critical to welding automation in many industries. It is estimated as much as 25% of all industrial robots are being used for welding tasks.
Robotic welding is being initiated to satisfy a perceived need for high-quality welds in shorter cycle times. The first generation of robotic welding system was a two-pass weld system, where the first pass is dedicated to learning the seam geometry followed by the actual tracking and welding in the second pass. The second generation of welding systems, on the other hand, track the seam in realtime, performing simultaneously the learning and the seam tracking phases. The third generation of welding systems not only operates in real-time but also learns the rapid changing in seam geometries while operating within unstructured environments. Flexibility was achieved with this third generation of welding systems but at the expenses of a considerable amount of programming work of high skilled people in system’s integration directed to specific applications.
However, availability and agility are additional key issues in modern manufacturing industries, demanding new welding systems incorporating these features as well, revealing in this way the flexibility of the system to the normal operator without the need of extra skills from him.
This book covers up-to-date and relevant work in the area of third generation of robotic welding systems with availability and agility features. The principalwelding processes are reviewed from the point of view of their automation. A distributed system’s approach is followed for the integration of the different components and software of the welding cell and its integration within the global production system. Particular emphasis is given to the availability and agility to the end user. Application examples demonstrating step-by-step the system’s integration design clarify the relevant aspects to the interested reader.
The authors have made a strong-minded effort to set their work in the context of international robotic arc welding research. The mix of specific research issues and the review of broader research approaches make this a particularly welcome contribution.
This book is directed towards readers who are interested in developing robotic welding applications, and in particular to perform system integration. Although this work is presented in the context of arc welding, the issues related to system integration are general in nature and apply to other robotic applications as well.
This book constitutes a valuable source of the kind of information on robotic welding that result of years of experience, making it suitable as well for the decision maker, the application engineer, the researcher, the technician, and the student.
----------------------
Preface
Modern manufacturing faces two main challenges: more quality at lower prices and the need to improve productivity. Those are the requirements to keep manufacturing plants in developed countries, facing competition from the low salary regions of the world. Other very important characteristics of the manufacturing systems are flexibility and agility of the manufacturing process,
since companies need to respond to a very dynamic market with products exhibiting very short life-cycles due to fashion tendencies and worldwide competition. Consequently, manufacturing companies need to respond to market requirements efficiently, keeping their products competitive. This requires a very efficient and controlled manufacturing process, where focus is on automation, computers and software. The final objective is to achieve semi-autonomous systems, i.e., highly automated systems that work requiring only minor operator intervention.
Robotic welding is one of the most successful applications of industrial robot manipulators. In fact, a huge number of products require welding operations in their assembly processes. Despite all the interest, industrial robotic welding evolved only slightly and is far from being a solved technological process, at least in a general way. The welding process is complex, difficult to parameterize and to monitor and control effectively. In fact, most of the welding techniques are not fully understood, namely the effects on the welding joints, and are used based on empirical models obtained by experience under specific conditions. The effects of the welding process on the welded surfaces are currently not fully known. Welding can in most cases impose extremely high temperatures concentrated in small zones.
Physically, that makes the material experience extremely high and localized thermal expansion and contraction cycles, which introduce changes in the materials that may affect its mechanical behavior along with plastic deformation. Those changes must be well understood in order to minimize the effects. The majority of industrial welding applications benefit from the introduction of
robot manipulators, since most of the deficiencies attributed to the human factor is removed with advantages when robots are introduced. This should lead to cheaper products since productivity and quality can be increased, and production costs and manpower can be decreased. Nevertheless, when a robot is added to a welding setup the problems increase in number and in complexity. Robots are still difficult to use and program by regular operators, have limited remote facilities and programming environments, and are controlled using closed systems and limited
software interfaces.
The present book gives a detailed overview of Robotic Welding at the beginning of the twenty-first century. The evolution of robotic welding is presented, showing to the reader what were the biggest steps and developments observed in the last few years. This is presented with the objective of establishing the current state-of-theart in terms of technologies, welding systems, software and sensors. The remaining issues, i.e., the issues that remain open are stated clearly, as a way to motivate the readers to follow the rest of the book which will make contributions to clarify most
of them and help to solve a few.
To do that, a good chapter on “Welding Technology” is presented, describing the most important welding techniques and their potential and requirements for automation using robot manipulators. This chapter includes recent results on robotic welding processes, which can constitute a good source of information and practical examples for readers.
A good revision with current research results on “Sensors for Welding Robots” used on robotic welding is also presented. This includes sensors for seam tracking, quality control and supervision. This chapter includes all system requirements necessary to use those sensors and sensing techniques with actual robot control systems. Hardware and software interfaces are also covered in detail.
A good revision on available welding systems, including hardware and software, clarifying their advantages, and drawbacks is also necessary to give to the reader a clear picture of the area. The book includes a chapter on “Welding Robots: System Issues”, which covers recent state-of-the-art of industrial robotic welding systems currently available in industry and university laboratories.
Finally, a few industrial applications using the presented techniques and systems is presented. The present book includes a chapter on “Robotic Welding: Application Examples”, where a few selected applications are described in detail including aspects related to software, hardware, system integration and industrial exploitation. This chapter uses actual robots, but it is presented in a general way so that the interested reader can easily explore his interests.
Conclusions stating what was presented and what are the next challenges, guiding the reader to what are the next required developments, is presented at the end of the book. A good collection of references is also presented, to enable the reader to explore further from the literature.
J. Norberto Pires, Coimbra, 2005
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Ambraseys, N.N. (1962). “Data for Investigation of Seismic Sea Waves in the Eastern
Mediterranean”, Bulletin of the Seismological Society of America, Vol. 52, No. 4, pp. 895-913.
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National Geographic: London's Olympic Stadium (2012) PDTV XviD AC3 English | 00:44:56 | XviD | 720x400 | 25.00fps 2184 Kbps | AC3 128 Kbps 48.0khz | 698.9MB Genre: Documentary The eyes of the world will be watching when Jessica Ennis, Mo Farah, Usain Bolt and Co.’ go for gold’ at the London 2012 Olympic Games. But for some, the real star of the show won’t be on the track – it will be the athletics stadium itself. In the UK premiere of London’s Olympic Stadium take your seat inside the 80,000 capacity, ?486 million arena that’s helped to transform the previously unfancied area of East London. Those lucky enough to have a ticket will enter a truly world-class sports venue that will form a fitting destination for the greatest show on Earth. And that’s not all: with London aiming to host the greenest Games ever, the eco-engineered stadium has been designed to be downsized afterwards, leaving behind a customised 25,000-seat athletics arena. Find out how some 5,000 workers battled freak weather conditions, a derelict site and the global financial crash to realise their very own Olympic dream.
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My colleague has partecipated at this congress about Mechanized Tunnelling in Urban Areas, which took place in Rome, Italy, in April 2012.
Topics:
- Mechanized tunnelling in soft soil. General aspects & history of the machine’s development, Rick LOVAT
- Face pressure design in mechanized tunnelling, George ANAGNOSTOU
- Slurry Shield tunnelling design, Markus THEWES
- EPB Tunnelling design. Investigations, soil conditioning and backfilling technology, Daniele PEILA & Sebastiano PELIZZA
- Segment lining design, Fritz GRUEBL
- Use of fibers in segment lining and structural design, Giovanni PLIZZARI
- Geological & geotechnical issues related to the design of ‘Martina’, the world’s largest EPB TBM (15.62 m in diameter) Giuseppe LUNARDI
- Surface settlements. Design theory, Giulia VIGGIANI
- Metro Roma case history. Settlement study and analysis of stability of buildings, Andrea SCIOTTI
- Bologna underground railway by-pass case history. Description of the work and use of compensation grouting, Robert MAIR
- Risk management and real time monitoring of settlements. Application to relevant case histories, Piergiorgio GRASSO
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The Tallest Tower: Building The Shard (2012) PDTV XviD AC3 English | 00:47:05 | XviD | 720x400 | 25.00fps 2084 Kbps | AC3 128 Kbps 48.0khz | 699.4MB Genre: Documentary The story of The Shard - the colossal glass skyscraper that has transformed London's skyline. Built against a backdrop of massive public opposition and one of the worst recessions in history, this feat of architectural engineering in the heart of the capital will stand at over 1000 feet - the tallest tower in Western Europe. Love it or hate it, The Shard is destined to become one of London's most dominant landmarks. The film lifts the lid on the challenges and achievements of an enormous engineering project in a densely populated area of London. The demanding construction schedule required builders to add a new floor every seven days, and has used 100,000 tonnes of concrete, 11,468 glass panels, a spire made of 500 tonnes of steel and the UK's tallest crane. On completion, this 1016 foot 'vertical town' will include office space, the highest residential apartments in the UK, a five-star hotel, restaurants and public viewing galleries. Its construction is the dream of property developer Irvine Sellar, a former fashion-store owner, who appointed world-renowned architect Renzo Piano, who's famous for landmark buildings including Paris's Pompidou Centre and the home of the New York Times. Filmed over four years, The Tallest Tower: Building the Shard provides exclusive behind-the-scenes access to this architectural journey, and the story of one man's desire to leave a lasting mark on the capital.
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This publication contains the papers originally presented in a symposium on the topic of thin reinforced cementitious products organized by ACI Committee 549, Thin Reinforced Cementitious Products and Ferrocement, during the ACI 2003 Spring Convention held in Vancouver, British Columbia, Canada. The symposium explored current state-of-the-art and recent advances in material science, manufacturing methods, and practical applications of thin reinforced cementitious products.
The topics covered in this publication include material science of textile reinforced concrete, use of textile reinforced concrete for integrated formwork and exterior cladding panels, prestressed thin-sheet concrete products, ultra-high-performance thin precast concrete products, production of concrete tubes by centrifugation method, freezing-and-thawing durability of commercial fiber-reinforced cement boards, structural evaluation of cement-skin sandwich building systems, microwave accelerated curing method for producing precast cementitious products, history of glass fiber-reinforced concrete (GFRC) products, and modeling of cement-based laminate composites.
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