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  1. 16 likes
    As an older engineer, I am rather dismayed by what I see as the results of engineering education today. I have seen most young engineers come out of their college degree programs with a modest familiarity with come CAD program and a related Finite Element program, and an almost complete lack of capability to analyze machine components without the use of FEA. Thus they are unfamilliar with basic design calculations relating shear stress in a shaft to the power being transmitted, the shaft sped and the shaft diameter. Instead, they want to create an FEA model and run the numbers that way which is simply not the way you make any progress in designing a machine. It is certainly true that FEA allows for a good detailed stress analysis of complex geometries, something that was not possible in general by the older methods. But the results obtained are highly dependent on the skill of the user in applying the correct boundary conditions, something that is a bit of an art in itself. I have observed a tendency to even want to use FEA to do kinematics, rather than using simple, rigid body kinematic relations. This seems like pure foolishness in almost all cases. Are we not developing a tendency to lean too heavily on the computer, rather than to learn to think as engineers? I would be happy to hear some comments and discussion from others on these matters.
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    Please reply Name Engineering college Location (City/ Country) Engineering Batch Engineering Company/ Dream company to work for Area of Interest Project undertaken Any other info you want to share
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    well in except that both of them are Dassault Systèmes's products . there is a little difference between them. Basically , Solidworks is a CAD (computer aided design) software - the best of it's kind i assume - Simple to manipulate , easy to learn and used by almost every single industry in the world . CATIA is A CAM software , indeed it's better than solidworks in some modules such as surfacing and kinematics. But the main idea is that in CATIA you can not only create a mechanism , but a factory in which it will be produced, the machining processes required, and even you can simulate ergonomics studies as well, like weather the current layout of a plant will be comfortable for workers to work or not. So you can simulate the whole thing within a virtual reality, including, and of course, rendering. However CATIA is almost exclusively used in Aviation and Automotive industries. So there is no doubt you need to learn them both ... because let's say if you want to create an airplane Use CATIA to create the surface and to simulate the manufacturing process and Solidworks would easily handle the engines
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    Saurabh, your comment about the quality of the English concerns me also. When you go to their web site, the English there is similar. These folks really need help in that respect. I am also concerned about the stated breadth of topics for this journal. It includes everything from history, to geology, to economics, and on to mathematics. I have reservations about how one journal can adequately cover such a broad scope. DrD
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    Ravi, I think you may be in over your head! What do you mean by the term "resting time"? Just a hint: Perpetual motion defies the second law of thermodynamics, and consequently cannot work. You are spinning your wheels (literally)! DrD
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    Quite a few interesting comments on reasons for design failure. Thank you JAG in particular. I would like to tell a story about a failure that I saw once long ago that was somewhat different. It involved a design that had been developed in a government laboratory, manufactured in very small quantities with tight controls for testing, and then put out to industry for mass production. In order to bring the unit price down, the government arbitrarily specified rather loose tolerances, far more loose than anything that had been allowed in the development phase. But then, the government added a performance specification, that the product must function according to design. The result was that the mass production companies were bidding, based on nothing more than the drawings and specifications. It was implicit in the drawing package that a product made according to the drawings was expected to meet the performance specifications, and this was the way the bids were developed. My company was unfortunate enough to win the bid. We found through bitter experience that it was entirely possible to build the product according to the drawings but still fail the performance test at the end. This resulted in massive amounts of rejected products. My job was to show mathematically that this was entirely possible, that the loosened tolerances allowed for performance failure. This was a failure driven by a desire to reduce costs to the purchaser. The result was the destruction of my employer; a company with over 100 years experience in the field was driven to bankruptcy. DrD
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    View this quiz Automobile Engineering Quiz 1 Questions on the concepts of automobile engineering. Submitter saurabhjain Time 5 minutes Type Graded Mode Submitted 04/20/2017 Category Automobile Engineering  
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    It is helpful to have specifications for the job that the design will accomplish to start with, it is then good to run FEA to validate the design. FEA can be a valuable tool if the proper and accurate data is entered into the program. I add a Factor of safety of at least 20% for my comfort but I frequently overbuild when I design production machines used in house where there is no issue with weight. A wise engineer once told me "You will be criticized for a design that fails long before being criticized for one that was too strong." When designing a product that has to be lightweight, I still overbuild at first and then find ways to lighten it as I refine the design. Personally I like to see multiple prototypes physically tested to extreme failure and the data collected, analysed and compared to customer requirements, I do not feel comfortable passing off a design that has not undergone a battery of testing. One of the reasons that I have seen designs fail is lack of experience.....education should include practical experience and application. Just because one has a degree from a university doesn't mean one is a competent engineer, I have worked with many green engineers who couldn't design their way out of a wet paper bag and were too proud to admit that they might not know something. In my opinion, engineers who ask more questions before designing a product, build better products in the end. Don't let your ego get the best of you! Also I believe it is extremely helpful to know as much as you can about the process or system that you are designing for, play production worker for a week if you can, you will gain valuable insight and gain allies on the production floor, both can be invaluable! Participating in design reviews can be a valuable resource. Remove yourself from your ego and listen to what your colleagues have to say and don't be so invested in your own ideas that you do not hear the other ideas in the room. Many heads have many ideas and combining ideas is a great way to make great designs. Lastly, dare greatly! Failure is part of life! Learning what doesn't work is how you work toward discovering what does! Do not let fear of failure inhibit your education, make your best design and try it, when it fails refine it, if it fails again, refine it again and try not to repeat the same mistakes. If you study the history of any great invention you will usually find a string of failed experiments that lead to a great discovery and a person who learned from their failures. Your failure will only define you if you let it.
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    During my Introduction to Engineering class the professor said many things that have stayed with me for 40 years. Two come to mind reading this conversation. Before you start a project research how everyone else has done it. "Everyone" was not to be taken literally but the point was to learn from others. He also emphasized details. For example we had to pick a project. Most wanted to design the next rocket to the moon. I picked a bolt. Started with selection of bar stock and learned from an old timer who ran the machine shop how to turn a bolt on a lathe including cutting the threads. The bolt, an item we take for granted has centuries of development (learning from others) and many minor features (details) that exist for reasons we don't think about. For that project I had to think about all of them and being very green, it was a big task. Why, for a given size bolt, is the flat to flat distance the dimension it is? Why is the head as thick as it is. What cutting tool arrangement is required if you want to cut a full thread vs partial. I'll never forget the professor asking why use steel and not soap. Sounded silly but it was to make us think and verbalize the reasons. Deciding on steel was easy. Which steel and for what application is critical in many applications. So when someone wants to know everything about anything be prepared to read!
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    Dear Marcus, It looks to me like you have five pulleys, not three, but that will not change things very much. Let R = D/2 be the large pulley radius (looks like this applies 3 times) and r = small idler pulley radius (two of these) Assume no belt slip or stretch, so the relations between belt and pulley speeds are v = R*Omega = r*omega where v = belt speed Omega = large pulley speed (rad/s) omega = small pulley speed (rad/s) Then the kinetic energy is T = (1/2)*[(I1 + I2 + I3)*(v/R)^2+(I4+I5)*(v/r)^2+M*v^2] where I1, I2, I3 are the large pulley Mass Moments of Inertia I4, I5 are the small pulley MMOI M = mass of belt and load on the belt Factoring out a v^2, the effective inertia is Meff = (I1+I2+I3)/R^2+(I4+I5)/r^2+M Be sure to understand that these are MASS values, not WEIGHTS.
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    Name : Azhar Irfan Gull Engineering college: SSM College Of Engineering And Technology Location (City/ Country) : Srinagar, KASHMIR Engineering: 2014-2018 Engineering Company/ Dream company to work for: CAT, TATA, HITACHI. Area of Interest- Designing Any other info you want to share: AutoCad, Solidworks, Ansys.
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    How about nature-inspired design of a system that you are interested in? Are you aware of biomimicry?
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    I have been thinking for a couple of days about your request for some good books on design. On the one hand, this is an easy question, but on the other hand it is very difficult. First the easy answer. The machine design textbooks by Shigley (and usually a co-author) are very good, practical books. The same can be said of the books by Spotts. Both of these have put out a number of editions, and I could recommend any of them. The hard part is that, you really cannot learn design from a book. You learn design by doing design. Design is about making all of the many decisions, both large and small, that going into completely specifying how something is to be made. Let me give you a simple example; consider a door hings. Everyone has seen a door hinge, so the working concept should not require any explanation. But now, the boss has told you to design a door hinge. How big should the hinge be? He did not say, but you know it has to be big enough to do the job, but not so big as to waste a lot of material. How big is that? I don't know, but you as the designer must decide. How many screw holes should there be in each leaf? The boss did not say, but you as the designer must decide how many, and where, the screw holes go. What material is the hinge to be made from? The boss did not say, but you as the designer must decide. This will be based on the application and on the machines and tools available in your shop to make the hinge. How thick should the leaves be? The boss did not say, but you as the designer must decide and specify the material thickness. What is the heat treatment to be? You have to decide. Is the hinge pin to be hardened, and if so, to what hardness? You have to decide. This is only the beginning, and this is a super simple project. One of the things you will learn rather quickly is that it is a waste of time to try to optimize every aspect of the design. You may profitably spend some time trying to minimize manufacturing cost, or overall cost, but it is a waste to worry about maximizing fatigue life in this example. (In some other cases, maximizing fatigue life may be the most critical consideration.) Design is about making decisions, and you learn that by making decisions and observing the results of your decisions. DrD
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    hey bro i want to work on i.c engines........
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    It is certainly possible that links 2 and 4 have the same length. However, it is not necessary for this to be true. If L2 = L4, that is a special case. Whatever sort of project can you make from this super simple mechanism? DrD
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    Dr. D’s story reminded me of two related stories, then another and then another...but I will stop with two. The follow appeared in the Wall Street Journal 15-20 years ago. The happy ending was that the supplier finally won the court case against the US government. The unhappy part of the story, was that it cost the company much time and money. The article went on to say that a lot of companies go bankrupt from similar situations, but I digress. The government contracted with a commercial supplier to produce a device. The full-up device had a performance specification. The government was to provide the power supply that would be part of the final product. The government was never able to provide a power supply that met the government's own specifications, yet the government expected the supplier to provide an end item that was to specification, using an out of specification power supply. Only a government could keep a straight face and insist this made any sense. The other example can be found at the link below, titled What do you mean you made it as we told you to? https://www.linkedin.com/pulse/what-do-you-mean-made-we-told-joseph-a-gulino-pe?published=t At the above LinkedIn site you will find other articles by me.
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    For a journal bearing surface, it is obvious that a circular surface is essential; a square section in a square hole would not turn. A square section in a large round hole would have contact at 4 points at most, very little load bearing area. If we are going to use a circular section at a bearing, then there is no point at all to using a square section between the bearings. A square section would be heavier, and only a slight bit more stiff. The square section would require more material for no real benefit. Square or other polygon shapes are used for special situations, but only where the is an evident advantage in doing so. DrD
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    In the interest of being more accurate, I would ask more questions in regard to the question: Is there a specific application where designs are failing that you are referring to? As I have been thinking on this subject it occurred to me that some products are designed to fail as a means to create repeat business I.E. the auto industry is replete with examples of this where parts and material are selected to meet a predetermined somewhat predictable life cycle with cost constraints in place, #1 because wear is inevitable #2 materials that wear longer are generally more expensive and may price a product out of the market. Needless to say If your product never fails or wears out, you may eventually saturate your market, or your product may be too expensive to reach a broader customer base. In this respect product design is a balancing act between longevity, vs. price constraints vs. customer expectations vs. marketability etc. All of these things come into play as well as the fact that there is no way to control all of the outside factors that a product will be influenced by such as lack of maintenance, misuse and or abuse, adverse conditions etc. This brings to mind the questions: Is the product performing to the design intent? Is the product performing it's task for a reasonable life cycle? If the product fails due to lack of maintenance are you considering that a design failure? In my opinion if you can answer yes to the first two questions then you have met your design objective. Once a product is put on the market and into use you will inevitably discover that there are situations that arise that were not anticipated by the original design and a refinement must be implemented to meet the criteria of a new set of parameters, this is just a reality of engineering. The key is to develop short feedback cycles into your processes so that you can discover and solve problems quickly. I find it very effective to ask for customer feedback quickly and to respond to it quickly in order to develop an enduring relationship, and all customers are important whether it be your co-workers or end users, a satisfied customer is the ultimate test of any design!
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    i have to say in any branch of knowledge practice is very important that only sharpens - see as lawyers we use incisive questions besides again revisit with further interagations why, then only you can do real research on the problems - in law we ask too many questions even our own clients, to get at the heart of the issue, that is what we call sensible designing to progress further to ensure whether our client can really convince his stand with the judges....that is also called dynamic designing,
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    In most of the products made as per design need some modifications after the product has been practically tried and this can not be termed as failed design Also,a perfectly designed machine may fail during use due to number of other related factor such as operational parameters like pressure,temperature,environment,load,speed.Also,it must be ensured that the personnel operating the machine have got necessary technical skills. In short,before declaring a failed design,thorough analysis must be carried out to pin point the cause of failure.
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    I think every engineering firm is behind completing projects on given deadline. But as Engineer every Drawing, Calculations need to be Sanity checked at least three times. This is time spending activity which costs money. Other reason, Sometimes engineers are made limited to work only in office rather than exploring the site or company whose products they design. Knowing the how things are manufactured is most important as each feature cost money to make. There might some compromises made which could lead to failure as well. Visit manufacturer should be regular thing to see and ask how its made.
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    These two concepts are not related the way you evidently think that they are. An aircraft is in accelerated flight when it flies a horizontal circle. That does not cause any increase in lift at all. If you think in terms of straight line flight, then yes, flying faster will produce more lift. If you want to go faster but no higher, you adjust the trim tabs, modifying the airfoil to reduce the increased lift. DrD
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    Which book he needs depends in part on the purpose for which he is learning this material. Does he want to be a boiler designer? Or does he want to drive a steam locomotive? Or perhaps he wants to be an operating engineer in a steam power plant? Each of these needs to know different aspects of boiler operation, but it is unlikely that any of them know it all. He should go to the library and start researching this topic. DrD
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    If you can survive on $15/hr x 15hr per week do so and finish your education. A friend tried the full time work and part time BSME and dropped after a short time. The level of difficulty multiplied by the extended duration many times kills plan. I knew a few who could do full time work and full time school. I think they were also able to leap tall buildings in a single bound. I did work full time and attend graduate school which was a killer. The MSME program required 45 credits and most classes met once per week for 2 credits. I could not handle more that 4 credits at a time and on occasion had to take only two, due to that quarter's offerings. I had a growing family and going full time would have been a double hit - no salary and no company to pay for the education. Get it done!
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    Paulo gave a very good answer. Make an estimate about how long it will take you to finish your degree if you work full time. Then figure how much you would make during that time at the higher salary. Then estimate how much time it will take if you move ahead full toward a degree while making $15 per hour. Then assume you will get a good position (use Paulo's $65k per year figure as an average value), how much will you have made by the time you reach the age for the slow route. The difference is what it cost you. I am pretty sure you will find that it is to your advantage to move most rapidly towards a degree, and that anything that slows you down costs you money in the long run. The slow route also increases your insecurity, due to a longer time without a degree to aid you if things get difficult. Good luck with this choice. DrD
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    There are many factors to consider here; 1) Why are you studying to become a Mechanical Engineer, is it the money, the challenge that engineers face, or whatever? The average college graduate mechanical engineer coming right out of school will make on an average of about 65k per year depending on what part of the country you are living in. Some may make more, some a little less. Based on that amount of money, you do the math and see how much it is costing you every year that you do not graduate and weigh that against the current job you are doing at $15.00/hr. The 40k that your boss is tempting you with is a carrot. Obviously you are a good worker, otherwise he would not be making this offer to you. In the end, it is your decision what is best for you. Remember, the easy road is well traveled. The more difficult path usually pays bigger dividends but is way less traveled. Good luck in your future endeavors!
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    Questions I would ask of you to better advise you: 1. Do you absolutely love your current job? Do you enjoy your time and does the time fly by when you are working? 2. Is your current employer making the world a better place? Would you consider working for them for the rest of your life? In my opinion experience is as valuable as formal education. Learning is a continual and necessary exercise of life. The opportunity in front of you could turn into a rewarding career. If you have a boss that is willing to mentor you and invest in your education that could be far more valuable than a degree. $40k is a great start for a 20 year old and you still have plenty of time to work on your degree. I can recommend 4 books that I have read recently that have had a huge impact on my life: Essentialism: The Disciplined Pursuit of Less Book by Greg McKeown Multipliers: How the Best Leaders Make Everyone Smarter Book by Liz Wiseman How to Win Friends and Influence People Book by Dale Carnegie The 17 Indisputable Laws of Teamwork: Embrace Them and Empower Your Team Book by John C. Maxwell These 4 books will teach you lessons that if mastered and applied will take you farther than any college degree. My mantra is "Love what you do, do what you love!" Find your native talents, magnify them and follow you dreams, you and you alone can determine where life takes you. Make the most of it!
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    Can you write any equilibrium equations for this system? Think of the concrete as a spring in compression while the cables are springs in tension. DrD
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    Stay where you are and lead the way making it a better place to live and work. DrD
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    Thank you JAG and Saurabh. No, I have never heard of BS3, BS4, euro3, or euro4. All of this is pretty industry specific to the automotive engine industry. For those of us not currently involved with the standards in that area, it is simply Greek. I wonder how many, if any, outside of India know that Bharat is another name for India? I certainly did not. Perhaps this site should be restricted to Indians only, those in the know. DrD
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    This is country specific standards .. BS3 Bharat Stage 3 Bharat is another name of India As you must have heard of euro3 and euro 4 based on emission standards, the BS3 engines & BS4 enginers are classified.... however the difference in technology is still to be checked upon... it may very from company to company......
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    Whatever in the world does "bs4" and "bs3" mean? I've never heard such terminology, after many years of working with engines of many sorts. DrD
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    A filter is just a trap. When traps fill up they must be emptied or flow will be restricted. Time to do some research. Self Cleaning Filters Eliminate Particles - Orival Filternox Automatic Self-Cleaning Water Filters Filtration 101 - Automatic, self-cleaning water filter and water filtration.
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    Name: Yap, Chor Yen Nanyang Technological University, Singapore Current location: Los Angeles, California, USA Graduation years: Aug 2012 (Bach. Eng.), Aug 2016 (PhD) Current employer: Divergent Technologies, Inc Areas of Interest: Metal additive manufacturing, aerodynamics, aircraft design Projects undertaken: Morphing airfoil via MFC actuators, additive manufacturing of aluminium alloy for aircraft and automotive applications, additive manufacturing of steel, nickel and titanium alloy, material studies on various additively manufactured metals
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    use same poles of rare earth magnets. instead of spring . reply if work
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    you need to reduce temperature of exhaust and a little more fuel so it can burn. it may environment friendly but would increase weight to power ratio. i think.!!!
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    Dear All, Please explain about ASR and BSR. Also explain what is required to do before fill welding or after root weld???
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    Welcome on the board... We encourage knowledge sharing however adverting is not allowed You can start the discussions in relevant forums ME Basics https://mechanical-engg.com/forums/forum/34-mechanical-engineering-basics/ ME applications https://mechanical-engg.com/forums/forum/32-mechanical-engineering-applications/ You can even start your own blog section... Videos from youtube can be directly added on the site....
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    Name : Ranganath Engineering college: avr & svr engg college Location (City/ Country): Kurnool Engineering Batch: 2010-2014 Engineering Company/ Dream company to work for : Automobile Area of Interest: Design Project undertaken: CArR Any other info you want to share:No.
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    This is a very poor English for a publication representative
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    What are the appropriate topics for a paper? Are there publication fees? Is it open access? Where is this journal published and who sponsors it? Here is is nearly the end of July and you are asking for papers for an August edition? How does that work? Is there peer review? There are a lot of unanswered questions that you need to address. DrD
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    This may not be relevant to your field, or helpful. But a college student just asked for someone to invent toothpaste that does not come in metal tubes. He wants to buy dissolvable single use balls like " Tide " detergent balls come in I have been trying to design a low cost, simple crane to lift objects approximately the weight of a person. I do not want to use hydraulics because that drives the price, and complexity up. But my cantilever, couterweighted cranes cannot drop the load quickly, because the boom and rigging recoil violently, any ideas?
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