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  1. 5 points
    1. pressure represent intensity of external forces acting at a point. but stress represent intensity of internal resisting forces develop at a point.2. pressure is always acts normal to the surface. but but stress may also act either normal or parallel to the surface.3. magnitude of pressure at a point in all direction remain same. but magnitude of stress at a point in all the direction are unequal.4. pressure can be measure by using measuring device.like pressure gauge. but stress can't be measure directly by using any device.
  2. 3 points
    Selection of material is an important aspect for manufacturing industries . The quality of product is highly depends upon its material properties. These properties are used to distinguish materials from each other. For Example: A harder material is used to make tools.A ductile material is used to draw wires. So the knowledge of mechanical properties of material is desirable for any mechanical student or for any person belongs to mechanical industries. This post brings top 18 mechanical properties. Mechanical properties of material: There are mainly two types of materials. First one is metal and other one is non metals. Metals are classified into two types : Ferrous metals and Non-ferrous metals. Ferrous metals mainly consist iron with comparatively small addition of other materials. It includes iron and its alloy such as cast iron, steel, HSS etc. Ferrous metals are widely used in mechanical industries for its various advantages. Nonferrous metals contain little or no iron. It includes aluminum, magnesium, copper, zinc etc. Most Mechanical properties are associated with metals. These are #1. Strength: The ability of material to withstand load without failure is known as strength. If a material can bear more load, it means it has more strength. Strength of any material mainly depends on type of loading and deformation before fracture. According to loading types, strength can be classified into three types. a. Tensile strength: b. Compressive strength: 3. Shear strength: According to the deformation before fracture, strength can be classified into three types. a. Elastic strength: b. Yield strength: c. Ultimate strength: #2. Homogeneity: If a material has same properties throughout its geometry, known as homogeneous material and the property is known as homogeneity. It is an ideal situation but practically no material is homogeneous. #3. Isotropy: A material which has same elastic properties along its all loading direction known as isotropic material. #4. Anisotropy: A material which exhibits different elastic properties in different loading direction known as an-isotropic material. #5. Elasticity: If a material regain its original dimension after removal of load, it is known as elastic material and the property by virtue of which it regains its original shape is known as elasticity. Every material possess some elasticity. It is measure as the ratio of stress to strain under elastic limit. #6. Plasticity: The ability of material to undergo some degree of permanent deformation without failure after removal of load is known as plasticity. This property is used for shaping material by metal working. It is mainly depends on temperature and elastic strength of material. #7. Ductility: Ductility is a property by virtue of which metal can be drawn into wires. It can also define as a property which permits permanent deformation before fracture under tensile loading. The amount of permanent deformation (measure in percentage elongation) decides either the material is ductile or not. Percentage elongation = (Final Gauge Length – Original Gauge Length )*100/ Original Gauge Length If the percentage elongation is greater than 5% in a gauge length 50 mm, the material is ductile and if it less than 5% it is not. #8. Brittleness: Brittleness is a property by virtue of which, a material will fail under loading without significant change in dimension. Glass and cast iron are well known brittle materials. #9. Stiffness: The ability of material to resist elastic deformation or deflection during loading, known as stiffness. A material which offers small change in dimension during loading is more stiffer. For example steel is stiffer than aluminum. #10. Hardness: The property of a material to resist penetration is known as hardness. It is an ability to resist scratching, abrasion or cutting. It is also define as an ability to resist fracture under point loading. #11. Toughness: Toughness is defined as an ability to withstand with plastic or elastic deformation without failure. It is defined as the amount of energy absorbed before actual fracture. #12. Malleability: A property by virtue of which a metal can flatten into thin sheets, known as malleability. It is also define as a property which permits plastic deformation under compression loading. #13. Machinability: A property by virtue of which a material can be cut easily. #14. Damping: The ability of metal to dissipate the energy of vibration or cyclic stress is called damping. Cast iron has good damping property, that’s why most of machines body made by cast iron. #15. Creep: The slow and progressive change in dimension of a material under influence of its safe working stress for long time is known as creep. Creep is mainly depend on time and temperature. The maximum amount of stress under which a material withstand during infinite time is known as creep strength. #16. Resilience: The amount of energy absorb under elastic limit during loading is called resilience. The maximum amount of the energy absorb under elastic limit is called proof resilience. #17. Fatigue Strength: The failure of a work piece under cyclic load or repeated load below its ultimate limit is known as fatigue. The maximum amount of cyclic load which a work piece can bear for infinite number of cycle is called fatigue strength. Fatigue strength is also depend on work piece shape, geometry, surface finish etc. #18. Embrittlement: The loss of ductility of a metal caused by physical or chemical changes, which make it brittle, is called embrittlement.
  3. 2 points

    Rocket Homework Problem

    Mechanics Corner A Journal of Applied Mechanics and Mathematics by DrD, #38 Machinery Dynamics Research, 2017 Rocket Homework Problem Introduction Most engineers find problems involving rockets to be exciting. There is something about a rocket that fires our imagination, whether we think of going to the moon or one of the planets, or simply of shooting down an incoming missile. The subject of this post involves a rocket on a mobile launcher. The rocket is intended to be transported in a horizontal position, but it must be elevated in order to be fired. Both positions are shown in the accompanying figure. Read the attached PDF for more on this problem. RocketHWProblem.pdf Addendum: One reader has posted a proposed solution for this problem as a comment. It was not my intent that solutions be posted in the comments at all. I only want solutions sent to me by the personal message system. DO NOT POST YOUR SOLUTION IN THE COMMENTS!! Regarding the solution that has been posted, let me say the following: 1. Some of the answers are correct, while others are not. Do not be misled into following this solution because there are errors therein. 2. Even where the results are correct, there are a number of methods that I would not recommend using. Thus again, I say to all other readers, do not follow this solution, but work it out for yourself. 3. Be sure to document your solution, so that if someone else were to ask how you obtained a particular result, you would be able to explain it in a clear and reasonable manner.
  4. 2 points


    One of the most interesting examples of automation that I have worked on is a paper cup making machine. Everyone has seen paper cups. They come in many different forms, from simply conical forms to more complex truncated cones with a flat bottom. The come in small, medium, and very large sizes. How do you make such things cheaply, cleanly, and fast? Starting with a long coiled sheet of paper, the pattern must be cut out, rolled up, a bottom added, and the whole thing sealed. This is quite a sequence of operations, and the machines that do this consist of a number of stations, each station performing one operation and then passing the work piece on to the next station. The machines that I worked on were all cam controlled, which is to say they were a form of hard automation. Cam driven systems are extremely repeatable, but they are fairly difficult modify for a different product. They are also capable of operating at incredible speeds. I saw machines making 1200 paper cups per minute. The literally come flying out the end to be caught and packaged for distribution. The machines are quite expensive, but the number of paper cups they can make is absolutely huge! DrD
  5. 2 points
    I can offer a few suggestions. 1. I would take your birth date off the resume. It really is not relevant, unless you want birthday cards. 2. I see several different type faces (not including headings). I would use the same for all (except headings), and surely do not use a smaller font for your experience. 3. In item #3 of your university projects, you did not calculate parameters. Parameters are things like the acceleration of gravity, the area of the parachute, the initial drop height, etc. You calculated results, not parameters. I'd re-word this section. 4. There is a misspelled word in one of your university projects. For goodness sake, use spell check!! 5. In item #4, I really doubt that you calculated anything at EVERY point on the beam. Much more likely you did this at many points. 6. Course titles like "Intro to Electrical Engineering" and "Analysis of Engineering Systems" do not tell the reader very much. Add some detail if you want this to count, something like "circuit theory" or "systems modeling" or "systems simulation" or whatever is appropriate. Go Mountaineers!! DrD
  6. 2 points
    I read somewhere that the Romans known for their great engineering feats used brute force to accomplish said feats. Human power was used when horses were available and domesticated. Even then there were worries about unemployment and labor unrest if the human labor was replaced (aka automation) with "high tech" methods. http://www.jagengrg.com/blog/-dump-trucks-vs-donkeys
  7. 2 points
    One of the problems with many of these software packages mentioned above is their expense. If you work for company "A" where you get very proficient in software X, what happens when you take a position with company "B" that uses software Y? Presumably the software packages X and Y do similar things, but in their own formats, and they are not compatible. Further, if you want to work on something on the side, for your own interest, will you be able to use the company's software for your personal work? Years ago (before the end of the Ice Age), engineers all used slide rules, but every engineer provided his own slide rule at work. There were many different brands (K&E, Dietzen, Post, etc.) but they all worked about the same (some small variations), and they gave the same results. You could use your slide rule at work and on your home projects; it was yours. For this reason, I encourage people to use public domain software, rather than proprietary software. Several folks above have mentioned MatLab, but no one has mentioned SciLab. SciLab is public, available for free, and works just about like MatLab. Why do so few use public software? This baffles me. There are other similar situations regarding other types of software. DrD
  8. 2 points
    Well, not really. Stress is a second order tensor while vectors are first order tensors. Confused enough? How about if we say that stress requires a square matrix for full representation, while a vector can be fully represented by a single column (or row) matrix. To JAG above ... Well, you're no fun at all. I want to play as well. DrD
  9. 2 points
    Sirazz92 has given a fairly good answer. Pressure usually refers to a distributed external load applied to a body. Stress is the distributed internal loading associated with displacement under load. DrD
  10. 2 points
    Pressure is the force acting upon the surface of an body.(Action) Stress is the resisting force developed in a body when an external force acts on a body.(Reaction)
  11. 1 point

    ODE Solution --- Fail!!

    Mechanics Corner A Journal of Applied Mechanics and Mathematics by DrD, # 31 Machinery Dynamics Research, 2016 ODE Solution --- Fail!! Introduction Digital computation has become a major tool for engineers, and it is a great benefit. It can also lead to many pitfalls for the unwary. This note is about the latter, a potential pitfall that many engineers risk on a daily basis, most of them with little awareness of the danger. Early in the development of digital computation, every problem required that the user write a program specific to the problem at hand. If speed was a very important issue, the programs were written in machine language, so that they would execute as fast as possible. If speed was a little less critical, programs were written in so-called "high level languages." This included FORTRAN, BASIC, ALGOL, C, C++, and a host of other such names. But even with a high level language, there was the problem of generating a program for the solution of the specific problem at hand. As things have continued to evolve, it was soon evident that a lot of the work in writing each program was the same from one problem to the next. The major mathematical operations, such things as numerical integration, matrix operations and the solution of systems of linear equations, plotting, and many other steps were re-usable from one problem to the next. It was natural that this would eventually lead to the development of general purpose programs, able to solve broad classes of problems. This group includes programs like Mathematica, Maple, MatLab, SciLab, Maxima, TKSolver, and numerous others. Most of those just mentioned have built-in capability to solve ordinary differential equations, in some cases by analytical means, and in practically all cases, by numerical means. This has taken the sting out of working with differential equations from many engineering problems, and we must all be grateful for that. At the same time, we must also be somewhat skeptical about any general purpose solver when applied to a particular problem. How do we know that the solution generated is correct? How do we even know if it is reasonable? Most of the time, when engineers resort to numerical solutions, it is because there is no readily available analytical solution. Thus, when faced with a problem that cannot be solved in closed form, how can we know when to trust the numerical solution? This is a very serious question, one that all must consider. It you blindly trust a numerical solution, the old excuse, "The computer said it was OK" will not get you very far. The computer cannot be fined, fired, or (in extreme cases) possibly sent to prison, but all of these things can happen to an engineer! So, what can the engineer do when the differential equation has no known solution? Well, there are several options. (1) He can resort to any physical principles that apply to the situation. For example, if the system is such that energy should be conserved, then he can add code to calculate the total system energy at every instant. Just verifying that energy is conserved does not "prove" that the solution is correct, but if energy is not conserved when it should be, you can be sure there is an error in the solution. (2) He can try various approximations that may apply to see if they are in reasonable agreement with the computed solution. (3) He can verify the solution code by applying it to a similar problem for which there is a known solution. It is this last approach that I want to talk about in this post. ODE_Soln_Fail.pdf
  12. 1 point
    List of Seminar topics for Mechanical Engineers Hello 2 all engineers and Engineering students Every one look for good seminar topics lets make collection of good topics.. and latest intresting topics... Use Reply to add the topics u know.. keep updating it
  13. 1 point
    Pressure and stress are both force unit per area. Pressure applies to fluid (liquid or gas). It is a force per unit area applied perpendicular to a surface. Stress is more often used in solids, a force per unit area that can act parallel to a surface and/or perpendicular to it (vector).
  14. 1 point
    That was my best guess. Sometimes offering a solution to an ambiguous question, gets the questioner to realize how ambiguous the question is, and they can better form the question.
  15. 1 point

    Catia 3D Design

    Version 1.1


  16. 1 point
  17. 1 point

    Simple Mechanical Analysis

    Thanks Henry!
  18. 1 point
    Ditto the last sentence. A membership card is expensive with little return on its own. Being active in a local chapter is very valuable.
  19. 1 point
    I thought I had written a post on professional societies some time ago in the Mechanics Corner, but I cannot find it now. Therefore, I'll address a few of these ideas now. I think the simple answer to your question is "yes," at least up to a point. If you see someone list a half dozen or more societies, you can be confident that they are not active in all of them, and most likely active in none. Therefore, I recommend that you join at least one and no more than three technical societies. The society I recommend most strongly for MEs is SAE (formerly the Society of Automotive Engineers, but now simply SAE). SAE is one of the most active societies in terms of holding conferences, publishing research and also standards, and aiding students. The definitely accept student members, and you should try to get a Student Chapter at your school if it does not already exist. The SAE mini-Baja race competitions, Formula 1 race competitions, etc. do a whole lot to build student interest and enthusiasm. I have been an SAE Faculty Adviser long ago, and I was really impressed with the way they supported student work. By the way, SAE is more than just automotive now. The describe themselves as the mobility society, so anything that moves is part of their interest area. Another well known (but not nearly as active) society is the American Society of Mechanical Engineers (ASME) and in the UK, the Institution of Mechanical Engineers (IMechE). There are dozens of special interest societies, such as these: American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) Society of Naval Architects and Marine Engineers (SNAME) American Institute of Aeronautics and Astronautics (AIAA) Japan Society of Mechanical Engineers (JSME) Institute of Electrical and Electronic Engineers (IEEE) There are literally hundreds of other societies, and as far as I know, they all take student members. I strongly recommend joining one or a few societies, and then take an active part. Attend meetings, serve on committees, make presentations, etc. You get out of the society what you put into it. DrD
  20. 1 point

    Plasma Arc Welding

    From the album Engineering images 10

    In plasma-arc welding (PAW), developed in the 1960s, a concentrated plasma arc is created and directed towards the weld area. The produced arc is stable and reaches temperatures around 33,000°C. Plasma is an ionized hot gas composed of nearly equal numbers of electrons and ions. The plasma is started between the tungsten electrode and the orifice by a low-current pilot arc. What creates plasma-arc welding unlike other processes is that the plasma arc is concentrated because it is forced through a relatively small orifice Plasma Arc Welding Torch Operating currents generally are below 100 A, but they can be superior for special applications. While a filler metal is used, it is fed into the arc, as is made in GTAW. Arc and weld-zone shielding is supplied by means of an outer-shielding ring and the use of gases like the following argon, helium, or mixtures.
  21. 1 point

    The New Way or the Old Way?

    Long, long ago, in a land far away, I was an undergraduate engineering student. I knew some of my fellow students who studied a course called "Kinematics," and that puzzled me. Kinematics had been one of the parts of my first course in dynamics, so I wondered what else there was to the matter; I really did not know much at all. I borrowed a textbook for the Kinematics course, and it looked interesting, particularly the aspect that seemed to deal with real machines. I liked that. But then I asked about the course and I learned that it was a lot like the drafting course that we were all required to take. Specifically, the solutions were all obtained by scale drawings. With that bit of information, my interest in Kinematics cooled completely. Now way back then, I was a pretty good draftsman, and I certainly was not put off by that in itself. I enjoyed drafting, and I had begun doing it for fun back in junior high school. But for kinematics, to major difficulties were immediately evident: (1) No matter how sharp you make your pencil point, drawn lines have width (without width, we could not see them). This very substantially limits the accuracy of a drawn solution. Jumping ahead some years, when I worked for Hamilton Watch Company, our draftsmen would make greatly oversized drawings to graphically check clearances, and other mechanism features. The common scale was 40:1, meaning that the drawing was 40 times the actual size. This was before CAD had really taken hold, so these huge drawings would be spread out on drafting tables and everything was carefully drawn to scale. (2) A single drawing can only show one mechanism position. Since most mechanisms operate through a considerable range of motion, the graphical analysis in one position was of little value for understanding velocities and accelerations in a second position. This could lead to the need to make many drawings, one for each position of interest. I was rapidly losing interst at the prospect of repeating essentially the same drawing, in slightly shifted positions, time and again! The long and short of it is that, I did not seriously study kinematics of machines until some 15 years after I finished my PhD. It happened when i was called upon to teach Theory of Machines at Texas A&M University. As I began reviewing textbooks in preparation for this course, I found that much had changed in the intervening time. There were still some books focused on the old graphical techniques. They claimed that this gave the student a feel for the motion, an intuitive understanding. It also gave him at most 3 digit accuracy. On the other hand, there were books out there that presented new methods, particularly based on the idea of a closed vector loop. While it is useful to have a sketch to identify the variables in this method, there are no graphical constructions involved in obtaining the results. It is all mathematical, and can be carried out to whatever level of precision the user wants. Usually 8 decimal digits is common, but 14 to 20 digits are readily available. No more worrying about how sharp your pencil point is!! I immediately adopted the mathematics based vector loop method for my own work and for teaching, and I have done so ever since that. The vector loop method has enabled me to answer many vexing questions that I would have never resolved by the graphical method. I went so far as to write a Theory of Machines textbook based on vector loop kinematics, and cannot imagine doing these problems any other way. An then, in the last few years, I have come to ME Forum, where I encounter folks who are still solving kinematics problems graphically. I know that they have access to computers; that is how I encounter them, at an Internet website. Thus I have to ask, Why are you still using graphical solutions? I simply do not understand. I hope that there will be some comments that will shed light on this question. DrD
  22. 1 point
    When are we going to see some action on the Kinematics Club? There is no mechanism that I can see for anyone to post an article, so until you, as "owner" act, it looks like the whole thing is dead. In the description, you said, " it also provides the tips to groom your personality." What is this about? New hair styles? Nail polish? Clothes? Stories to tell? Just what did you have in mind when you wrote this? Please get something started. We are all waiting. DrD
  23. 1 point
    I have been using autocad from two years. now i wish to learn a advanced software of designing. please suggest me which software to learn. as i am a mechanical engineering student for me which designing software will be important .
  24. 1 point
    Shalini Chakraborty


    Industrial Automation is the new trend in the new millennium. There has been numerous technological advancement and researchers in the field of Industrial Automation. One can definitely realize that the world is easily transcending towards the philosophy of production in huge volumes with increased precision and quality with minimized human intervention. The PLCs have completely surged the market and with the advent of cheaper digital technologies, the implementation of them in different industries has been easier. The Internet of Things is one of the most prevalent topics discussed in the current global world. The ongoing developments have intensified with the aim of low cost, higher performance, and high valued industrial automation systems. Innovative industrial automation has taken one step further with systems using PLM, ERP, asset management, operation management and so on which has further enhanced the flexibility and efficiency of the manufacturing systems. The simultaneous development of Lean Automation Architecture, Smart Sensors, Cooperative Robots and what on!!!! The developments have been rampantly going on and on. Hence, companies and individuals who are thriving for change will sustain themselves easily by adapting the new global rules and services and we can together step up to discuss pros, cons, new innovations and amazing future possibilities yet to come.
  25. 1 point
    Hello Everyone, I from to TTP mechanical,Co.LTD in Vietnam. Our Company with specialization in all stainless steel Mechanical & Installation aspects. TTP is highly responsive in the Fabrication & nationwide installation company offering fast and best service with guaranteed quality. Today, TTP has constanly expanded its network of customer nationvide. TTP’s customer are Engineering as GEA, TETRA PAK, FRESCO, A&G … and End-user as VINAMILK, PEPSI, COCA-COLA, CALOFIC, URC… We provide full-package solutions from design, fabrication, assembly and installation of stainless steel products such as storage tank, pressure vessel, mixing tank, piping system, ect. Once again, we would like to thank you for making TTP able to introduce our business as well as bring our products closer to you. We look forward to receiving long-term cooperation with your company. Please find the Open Letter and bochre our TTP company as the attached file, If you have any questions or concerns in the product don't hesitate to let me know, Address contact : nguyendiep@ttpmechanical.com or info@ttpmechanical.com hotline: (+84) 650 363 0057 Website: www.ttpmechanical.com Thanks and best regards, open letter.pdf Brochure TTP.pdf
  26. 1 point
    JAG Engineering LLC

    The True Value of Certification

    I think some believe having a certificate is a magic item to hang on the wall. Others spend more time thinking about the place to hang the plaque, and placement on the their web page, than the purpose. They look at ISO or other certifications as an necessary evil to impress clients. They miss my point. What I identify sounds so ho hum. But people don't realise how many problems they have due to the issues I point out. Deming's work indicated 94% of the problems are in the system given to the workers vs the workers. Up to date through procedures are boring, so dismissed by many. I instituted a process which was driven by nothing more than a checklist that eliminated nearly all out repeat problems and avoided others. The check list started at order entry (which was outside my department and a major source of problems) through design release. I wrote about this a while back.http://www.jagengrg.com/blog/check-lists-simple-quality-control-tool
  27. 1 point

    The True Value of Certification

    Good post, JAG. I must admit to being somewhat of an ISO 9000 skeptic, having seen very little value in it for places where I have worked. I do see your point about the value of requiring that everything be written down and looked at by many people. DrD
  28. 1 point


    I'd be inclined to start by trying to select appropriate tooth numbers for the gear pair. Do you want exactly 5:1, or simply something approximating that ratio? This is significant because of the wear problems associated with gear pairs that have a common factor in both tooth numbers. Moving past the tooth number matter, I'd look at the speed, lubrication, and power to be transmitted. Select a face width that will keep the tooth stresses low enough to give infinite life (unless this is a short term application), and consider the heat generated. DrD
  29. 1 point
    Success is the sum of small efforts repeated day in and day out. INTRODUCTION TO MECHANICAL ENGINEERING.docx
  30. 1 point
    I want this document in PDF for frequent use
  31. 1 point
    This came to me via e-mail. I am sure little of this is 100% correct. But just think if just 50% are 50% correct. The Exponential Age? Just a few things for us all to ponder, especially the younger ones amongst us. Did you think back in 1998 that 3 years later you would never take pictures on film again? In 1998 Kodak had 170,000 employees and sold 85 % photo paper worldwide. Within just a few years their business model disappeared and they went bankrupt. What happened to Kodak will happen in a lot of industries in the next 10 years and, most people won't see it coming. Yet digital cameras were invented in 1975. The first ones only had 10,000 pixels, but followed Moore's law. So as with all exponential technologies, it was a disappointment for a time, before it became way superior and became mainstream in only a few short years. It will now happen again with Artificial Intelligence, health, autonomous and electric cars, education, 3D printing, agriculture and jobs. Welcome to the 4th Industrial Revolution. Welcome to the Exponential Age. Software will disrupt most traditional industries in the next 5-10 years. Uber is just a software tool, they don't own any cars, and are now the biggest taxi company in the world. Airbnb is now the biggest hotel company in the world, although they don't own any properties. Artificial Intelligence: Computers become exponentially better in understanding the world. This year, a computer beat the best Go-player in the world, 10 years earlier than expected. In the US , young lawyers already don't get jobs. Because of IBM's Watson you can get legal advice (so far for more or less basic stuff) within seconds. With 90% accuracy compared with 70% accuracy when done by humans. So if you study law, stop immediately. There will be 90 % less lawyers in the future. Only specialists will remain. Watson already helps nurses diagnosing cancer, which is 4 times more accurate than human nurses. Facebook now has a pattern recognition software that can recognize faces better than humans. In 2030 computers will become more intelligent than humans. (NEVER says Albert) Autonomous cars: In 2018 the first self driving cars will appear for the public. Around 2020 the complete industry will start to be disrupted. You won't want to own a car anymore. You will call a car with your phone, it will show up at your location and drive you to your destination. You will not need to park it, you only pay for the driven distance and can be productive while being driven. Our kids will never need to get a driver's licence and will never own a car. It will change the cities, because we will need 90-95% less cars for that. We can transform former parking spaces into parks. 1.2 million people die each year in car accidents worldwide. We now have one accident every 60,000 miles ( 100,000 km), with autonomous driving that will drop to 1 accident in 6 million miles (10 million km). That will save a million lives each year. Most car companies will probably become bankrupt. Traditional car companies try the evolutionary approach and just build a better car, while tech companies like Tesla, Apple, Google will do the revolutionary approach and build a computer on wheels. Many engineers from Volkswagen and Audi are completely terrified of Tesla. Insurance companies will have massive trouble because without accidents, the insurance will become 100x cheaper. Their car insurance business model will disappear. Real Estate will change. Because if you can work while you commute, people will move further away to live in a more beautiful neighbourhood. Electric cars will become mainstream about 2020. Cities will be less noisy because all new cars will run on electricity. Electricity will become incredibly cheap and clean. Solar production has been on an exponential curve for 30 years, but you can now see the burgeoning impact. Last year, more solar energy was installed worldwide than fossil. Energy companies are desperately trying to limit access to the grid to prevent competition from home solar installations, but that can't last. Technology will take care of that strategy. With cheap electricity comes cheap and abundant water. Desalination of salt water now only needs 2k Wh per cubic meter at 0.25 cents). We don't have scarce water in most places, we only have scarce drinking water. Imagine what will be possible if anyone can have as much clean water as he wants, for nearly no cost. Health: The Tricorder X price will be announced this year. There are companies who will build a medical device (called the " Tricorder " from Star Trek) that works with your phone, which takes your retina scan, your blood sample and you simply breath into it. It then analyses 54 bio-markers that will identify nearly any disease. It will be cheap, so in a few years everyone on this planet will have access to world class medical analysis, nearly for free. Goodbye medical establishments. 3 D printing: The price of the cheapest 3D printer came down from $18,000 to $400 within 10 years. In the same time, it became 100 times faster. All major shoe companies have already started 3D printing shoes. Some spare airplane parts are already 3D printed in remote airports. The space station now has a printer that eliminates the need for the large amount of spare parts they used to have in the past. At the end of this year, new smartphones will have 3D scanning possibilities. You can then 3D scan your feet and print your perfect shoe at home. In China they have already 3D printed and built a complete 6 storey office building. By 2027 10% of everything that's being produced will be 3D printed. Business Opportunities: If you think of a niche you want to go in, first ask yourself, "In the future, do I think we will have that?" If the answer is yes, how can you make that happen sooner? If it doesn't work with your phone, forget the idea. And any idea designed for success in the 20th century is doomed to failure in the 21st century. Work: 70-80 % of jobs will disappear in the next 20 years. There will be a lot of new jobs, but it is not clear if there will be enough new jobs in such a short time. This will require a rethink on wealth distribution. Agriculture: There will be a $100 agricultural robot in the future. Farmers in 3rd world countries can then become managers of their field instead of working all day on their fields. Aeroponics: Will need much less water. The first Petri dish produced veal, is now available and will be cheaper than cow produced veal in 2018. Right now, 30 % of all agricultural surfaces is used for cows. Imagine if we don't need that space anymore. The Times They Are A Changing!
  32. 1 point
    I would like to add a story here. There are a limited number of units in this world. Different properties share the same units and combination of units though the meanings are VERY different, as DrD and sirazz92 explained. Two values that are very related are stress and modulus of elasticity (MoE). Both have the units of pounds per square inch. I once witnessed a complete misunderstanding of the relationship. The engineer, a very proficient ProE user when it came to building models, ran an FEA routine. He was under the mistaken belief that as long as the stress was below the MoE the load was ok. Dr D is now holding his head. The MoE for steels are usually taken as 30,000,000 psi. This is good enough for classroom work. When you are doing real world work you will find values vary, but not by large percentages. Some steels are very strong but I am not aware of any that yield or fail at 30,000,000 psi. On a somewhat related topic a group of us were discussing a stress issue and a question came up that also showed a lack of understanding the basics. I too had to stop and think for a while. Though I was long past confusing MoE with the strength of a material, a basic understanding had grown stale. QUESTION: If all steels have about 30,000,000 psi for MoE, how can they have different strengths? I would like to see answers from students and recent graduates. Dr D knows the answers all too well so he is not allowed to answer.
  33. 1 point

    Pump Handbook



    The handbook is divided into 5 chapters which deal with different phases when designing pump systems. Chapter 1 Design of pumps and motors Chapter 2 Installation and performance reading Chapter 3 System hydraulics Chapter 4 Performance adjustment of pumps. Chapter 5 Life cycle costs calculation
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    Name :G. Vu Engineering college: University of Civil Engineering Location (City/ Country): HN/Vietnam/Japan Engineering Batch: 2008 Engineering Company/ Dream company to work for: Oil drilling industry Area of Interest: Vibration/ Reliability for maintenance Project undertaken: Environment & maintenance dept. Any other info you want to share
  35. 1 point
    Habib Hussain

    Difference between Pipes and Tubes?

    Tubes are used for both HEAT&MASS Transfer. Pipes are used for only MASS Transfer.
  36. 1 point
    Alaa Ghazalah

    Difference between Pipes and Tubes?

    All pipes are tubes. However not all tubes are pipes!
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    Following are the reasonable points that conclude the high torque and efficiency of diesel engine. Diesel engine uses simple mechanism for combustion unlike in gasoline engine. Removal of ignition system not only makes the mechanism simpler but also reduces the risk of improper combustion due to damage in ignition system. In short burning of the fuel is easy and always accessible. This results in higher efficiency diesel engine. Diesel fuel is a heavier hydrocarbon in which carbon and hydrogen are strongly bonded with each other. And when energy is supplied in form of heat it gets explode releasing much higher energy then gasoline. In short diesel fuel has higher energy density then gasoline which results in huge explosion. One more factor for higher efficiency in diesel engine is its property of lubrication. Although all fuel has property of lubrication but diesel fuel has much higher lubrication then gasoline fuel. The compression ratio is much higher in diesel as compared to gasoline because in diesel engine air is alone compressed inside the cylinder and it’s a known fact that gas easily compresses then liquid. This is not so in gasoline engine because air-fuel mixture is compressed inside the cylinder. This higher compression gives higher heat and simultaneously higher torque. We can’t use Carnot cycle to get 100% efficiency but can use its principle to attain maximize efficiency. In diesel engine heat is added at constant pressure which results in higher utilization of heat energy to get maximize work output. These were the advantageous features of diesel engine but it has some demerits as well like it releases highly toxic gases, noisy, higher maintenance cost and starting problem (now starting problem is eliminated by using a bulb nearby to the cylinder) to heat the engine before ignition. And it is costlierthan gasoline engine but with optimum operation and good maintenance resolve all these problems.
  39. 1 point

    Version 1.1.0


    A COMPLETE INSTRUCTOR AND STUDENT SUPPLEMENT PACKAGE - Continued These ppts are set of instructor and student supplements. . A FOCUS ON DIAGNOSIS AND PROBLEM SOLVING The primary focus of these ppts is to satisfy the need for problem diagnosis. Time and again, the author has heard that technicians need more training in diagnostic procedures and skill development. To meet this need and to help illustrate how real problems are solved, diagnostic stories are included throughout. Each new topic covers the parts involved as well as their purpose, function, and operation, and how to test and diagnose each system.
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    Difference between Pipes and Tubes?

    A pipe is measured by Nominal Pipe Size (NPS) per Inch and Schedule number ( Thickness of pipe ) and tube is measures by Outside Diameter (OD) and BWG number ( Thickness of Tube) . The common Pipes size as ANSI are produced from size 1/8" to 48". Pipes are used for mass. fluid and gas transfer in different industrial. Tubes are manufactured from size 1/32" to 12". Tubes are used for heat transfer in Heat exchanges,boilers,vessels and also in fire burners ( size 2" and more) and as instruments tubes and also accessories tools in Turbines and Compressors.
  42. 1 point
    A right hand helical gear is being cut on a milling machine. What changes in machine setting have to be made to cut a left hand helical gear of same pitch and number of teeth ? You can answer this question. You can like the best answer. You can share the question You can get updates of new questions on Facebook linkedin twitter & google plus
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    In casting we change the shape of material by changing it in molten form whereas in forging the work piece is heated and then hammered to change the shape.Forging is only for simple designs but casting can be used for complicated design.
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    Casting is a process in which the metal is melted at high temperatures and then poured into a mould to give it the desired shape. There are many casting methods: Sand Casting, DIe Casting, Lost Wax casting. In casting process the newly formed shape sometimes needs extra machining to get the desired surface finish. The cast parts can also incorporate defects because of air bubbles and internal stresses. Casting have some issues with metal selection. All the metals are not suitable for casting. It is sometimes associated with blow, scar, scab etc. errors. Forging is also very old method. Blacksmiths used to do forging with the hammer and anvil from an ancient time. It is the process where metal is heated in different temperature ranges and then hammered to get the desired shape. Depending on the temperature forging can hot, cold or warm. While forging there is a change in the grain structure of the metal which consequently makes it more tough and wear resistant. There are very less porosity and shrinkage defects.
  47. 1 point



    Collections of useful excel sheets for engineers.
  48. 1 point
    Forging is stronger for a number of reasons, not least due to the internal stresses of the forged material bolsterring the crystaline structure and running along the shape of the forged item - effectively work hardening. Cast items are generally more brittle (due to high carbon steel being used predominantly to aid the liquid metal flow) and also the precipitation of the Carbon along the crystal walls in the material structure. (I cannot remember the correct nomenclature off hand (I recall "martensitic is in there somewhere), so, with regret, that's the best i can do on this at the moment!!!)
  49. 1 point
    The Difference Between Casting & Forging Casting is the process where metal is heated until molten. While in the molten or liquid state it is poured into a mold or vessel to create a desired shape. Forging is the application of thermal and mechanical energy to steel billets or ingots to cause the material to change shape while in a solid state.
  50. 1 point



    Example of Use for mechanical engineering students Source : ASME