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  1. Much of the answer depends on whether your system is static or dynamic. If it is static, alpha is zero, so that I*alpha is also zero. For a static system, you usually do not need to know I. If your system is dynamic, then you will need a value for I in many situations. DrD
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  2. I think you are asking what is the use for the mass moment of inertia (MMOI) in mechanical design. Any time you want to apply the rotational form of Newton's Second Law, T = I * alpha, you will need the MMOI calculation to provide the value for I. If you are asking specifically about the expression for a solid, homogeneous sphere, the I might suggest that you consider writing the T = I * alpha relation for a ball, such as a single ball in a ball bearing. DrD
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  3. i am 3rd yr m.e student, i have learnt autocad but as it has many designing restriction in 3D, i am trying to look for another but cant decide which one. i am unable to decide b/w pro e, solidworks & catia. please suggest. note- your answer should be based on designing power of the software not its UI or look. in reference to latest versions of all.
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  4. Explain Design for Assembly. How it is different from Design for manufacturing 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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  5. Mechanics Corner A Journal of Applied Mechanics and Mathematics by DrD © Machinery Dynamics Research, 2017 Last Post Time to Hang It Up This will be the final post of Mechanics Corner here on Mechanical Engineering Forums. It has run almost exactly two years, and there have been ups and downs along the way. In this final post, I want to reflect a bit on my original goals for the blog, and also on what has actually happened. When our host first proposed to me that I might write a blog for ME Forums, I was excited about it. About half of my career had been spent in engineering education, and I always loved working with students. It seemed like a way to get back to something that I had long enjoyed, and so I accepted his suggestion. A long time ago, back when I was about 14 or 15 years old, in Junior High School, my shop teacher mentioned, in an off-hand way in class, that various curves could be described mathematically. I’d never heard that before, but I thought immediately, “This has interesting possibilities.” Moving ahead a few years, I discovered that I wanted to study and build my career around was the area known as Applied Mechanics, although it was a time before I first heard that term. In my freshman physics class, I discovered the laws of motion, and thought to myself, “This is great stuff! I can use math to describe how things move!” All of that happened back in the 1950s, and I’m still doing the same thing today (some might say I am in a rut!). As a teacher, I taught mostly undergraduate engineering courses, although I taught my share of graduate courses as well. It was the undergraduate courses that I liked most, because I firmly believe that the economy of a nation is strongly dependent on the quality of the baccalaureate level engineers produced in that nation. Engineers with graduate degrees are valuable as well, but the vast majority of the national engineering workload falls to BS level engineers. Thus, I envisioned Mechanics Corner as a sort of continuation of the several undergraduate courses I most enjoyed teaching — kinematics, dynamics of machines, vibrations, and mechanics of materials. For the most part, I have stuck to the plan, so that most of the technical posts I have made have dealt with problems that I considered suitable for undergraduate engineering students, say perhaps, junior level. I have posted a few topics from my industrial experience, but those have been situations that baccalaureate level engineers would be expected to handle. Now I knew it would not be exactly like continuing to teach my classes. In particular, you would not have any homework or tests, and I would not have any grading to do – a win-win, or so I thought. I did hope, that even with no assigned homework, readers would take an interest in the problems discussed, even to the point of working through the details for themselves (I was terribly naive, apparently!). I knew from my own experience that the only way I ever really learned a new idea was to get in and work with it, work some problems, make some numbers, plot some curves, until I really understood what it was all about. I’ll venture to say that nobody ever learned any technical material simply by reading only. In actual fact, in the early days, I had one or two folks say that they would in fact work through the problems, so I was encouraged. What I was not prepared for, however, was the fact that the vast majority never seemed to even read very carefully, much less work through the problems! The questions that have come, and there have been a few, have largely been about matters totally unrelated to the posts. The most common question has been, “Suggest a topic for my final project,” which relates to not a single post. Needless to say, that aspect of my vision was totally unfulfilled. But there is another side. I ventured to write a few “philosophical” articles, items dealing with academic integrity and cheating, with how to ask for help, with how to write a report or a paper, and various other matters. I really thought all of this would be considered obvious and trivial, so I was completely unprepared for the excitement that some of these articles generated. There were, in some cases, many, many comments, and people seemed to really be interested. I’m left to wonder: why? Are these ideas foreign to the culture of India and SE Asia? Are these things not all taught at home and in the public schools? I don’t know, but there was a lot of interest in these matters. But Mechanics Corner was intended to be primarily a technical blog, and there, it just did not excite the interest of the readership. As time passed, there was less and less interest. First, the comments dropped off to just about zero, and later, there were fewer and fewer who even bothered to “like” the articles. Finally, the number of reads has dropped to almost nothing (there may be no one left to read this final note). Well, there could hardly be any more clear indication that it is time to stop. I asked for opinions about this from some of the administrators, and was told that the blog was just over the heads of the readership. That makes me sad; that was never the intent. If it is true, I do not see how engineering has a very bright future among this readership. Even so, I wish all of you the best for your careers. I hope that you are able to find rewarding and beneficial work in which you will be happy and make a real contribution to your societies. To use an old cowboy metaphor perhaps familiar to many of you from Bollywood, “It is time to hang up the bridle and saddle, and say, ‘Adios’ (Adios is literally, “to God”).
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  6. This is a standard Turbocharger, the compressors is a centrifugal compressor where the blades are arranged to pull air in and as the air travels up the conical vane face of the rotor it is compressed and blown out through the discharge pipe into a plenum chamber, this type of compressor is derived from an early gas turbine engine (DeHaviland Goblin as designed by Sir Frank Whittle in the late 1930s ), in fact you can run a turbocharger as a gas turbine, All Centrifugal turbines work this way whether just as a compressor or a jet turbine. as a jet turbine they have a far lower power output as this compressor is limited to the volume of air it can force through which is why modern turbines are axial flow as the air follows a straighter path. Turbochargers were first used in high altitude Boeing B29 bombers. Just to add to my comments, I have currently 2 turbocharged vehicles (Mercedes Van and a Volvo car) also in my younger days I have turbocharged a couple of motorcycle engines for motorcycle drag racing.
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  7. The efficiency of diesel engine cycle increases with.. 1. You can answer this question 2. You can like the best answer 3. You can share the question...
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  8. This is one important point missing in the two previous answers. The "cc rating" of an engine is a volume measure, as previously stated, but it is not the actual cylinder volume. Rather, it is the swept volume of the cylinder, also called the "displacement" of the cylinder. The actual cylinder volume is always somewhat greater than this value because the piston at TDC does not leave zero cylinder volume. The small volume remaining at TDC is called the "clearance volume," the volume available for the early stage of combustion. DrD
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  9. 1016.05 kg =1ton 1000kg=1tonne cooling effect produce by 1000 kg ice in a day is called tonne of refrigeration. cooling effect produce by 1016.05 kg ice in a day is called ton of refrigeration.
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  10. 1. What are the differences between true stress, engineering stress, proof stress. 2. What do you men by factor of safety and what is its significance 3. What do you mean by Young’s modulus, modulus of rigidity and bulk modulus. 4. What do you mean by resilience. 5. What is pure torsion and what do you mean by flexural igidity. 6. What is the difference between endurance limit stree and endurance strength. 7. What do you understand by efficiency of riveted joint. 8. What is caulking and fullering in riveted joint. 9. What do you mean by stress conc. Factor and what are the methods to reduce stress conc. 10. Why stress conc. Is more serious in brittle materials. 11. What do you mean by fatigue . 12. Springs are subjected to which type of streses. 13. What are the difference between through bolt, tap bolt and stud. 14. What is check nut and what is the function of washer. 15. Cotter and knuckle joints take which type of load and where they are used. 16. What are the difference types of couplings and what is their function. 17. What is the function of key and which type of stress they are subjected to? 18. Generally shafts are subjected to which type of stress. 19. What are the difference types of mechanical drives and which is the best for different situations. 20. What is the function of a bush why it is phosphor bronze. 21. What are difference types of threads and which threads are used for power transmission and why. 22. Why the pulley arms are elliptical in cross section and it is made up of cast iron. 23. Why it is required to change the all V belt if one of them is broken. 24. Why V belts transmit more power than flat belts. 25. What is the meaning of 6*37 or 6*7 in a rope drive. 26. What do you mean by pinion sprocket and wheel sprocket and which one is used for driving shaft. 27. What is the function of flywheel and why its material is cast iron. 28. Why the leaf springs are laminated as reducing length. 29. What is the function of clutch and is the difference between uniform wear and uniform pressure. 30. Now a days which type of clutches are used in automobiles. 31. Why disc brake is more efficient than mechanical brake. 32. What is the function of bearings and what are the different types. 33. What is bearing characteristics number and bearing modulus. 34. What is the significance of the digits of a rolling contact bearing number 6304? 35. Which type of gear drive is used for perpendicular transmission of power? 36. Why helical gears transmit more power than spur gears. 37. What do you mean by different terms like back lash, pressure angle, circular pitch in a gear drive. 38. Why involute tooth profile is better than cycloid tooth profile? 39. What is interference in gear drive and how to avoid it? 40. What do you mean by law of gearing
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  11. This is wrong. A diesel engine utilizes the diesel cycle, whereas a petrol engine utilizes the otto cycle. The main difference between these two cycles, which are both non-ideal versions of the Carnot cycle, is their method of ignition. In the otto cycle, the combustion process is catalyzed by a spark. In the diesel cycle, the combustion process instantaneously begins when the air-fuel mixture temperature reaches the ignition temperature of the diesel fuel. A petrol engine cannot have a compression ratio as a large as a diesel engine. This is because it begins the combustion process pressure by sparking the petrol-air mixture to initiate ignition, rather than building up more pressure until ignition is initiated by reaching the ignition temperature of the petrol fuel. Thermal efficiency, which is a function of an engine's compression ratio, increases as the compression ratio increases. Though, when operating with the same compression ratio, a petrol engine is more efficient than a diesel engine, a diesel engine can have a higher efficiency than a petrol engine because it can utilize a much higher compression ratio that a petrol engine cannot possibly achieve. This is why, generally, diesel engines are more efficient than petrol engines.
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  12. 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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  14. 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.
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  16. Work done by pump= specific volume*dP to give an idea of specific volume- at 7 kpa(40 c saturation tempreture) specific volume of steam =20.531 m3/kg. where as of water at 7 kpa= 0.001 m3/kg SO AS WE KNOW specific volume of steam is far more than water. so your pump would consume a lot of power than rather you would save by eliminating condensor. Main purpose of condensor is to convert steam in to water so we can save pumping power. To pump steam you would need compressor.When steam is rejected from turbine it has around 12% wetness. so water droplet present in steam would damage blade of compressor. Main purpose of condensor is to convert steam in to water so we can save pumping power.
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  17. I want to know the latest trends and technologies in CAD. If someone have any ideas, do share.
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  18. Hello all, I have used autocad in the past for 2d design but its limited performance for 3d design made me look for sth else. I want to try solidworks anyone know where to download ? link
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  19. Computer-aided design is used in many fields. Its use in designing electronic systems is known as electronic design automation, or EDA.
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  20. You can choose CATIA or UG NX , both softwares are best only.
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  21. DFM: financial success of any organisation is depends on the how much profit margin earned by selling each parts, if the cost of manufacturing is low with producing good quality product, automatically profit is more. and this is the aim of the DFM. to achive this goal DFM (development team) reduce the cost of 1. cost of components 2.cost of assembly 3.cost of overhead and DFA is the sub set of the DFM. uses some guidelines to keep the assembly cost as low as possible.
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  22. Screw Jack :- Is a mechanical device used in applications where linear motion is required. Lifting of any load, pushing or pulling of mechanical equipment, adjusting of tight clearances of mechanical parts can be done by screw jacks. Mechanical capacity of screw jacks is between 5kN and 2000kN. Jack screws can be used as linear motors, linear actuators, or mechanical lifts depending on type of motio
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  23. Solidworks!You can try it.It is a very good alternative of Autocad. Thanks
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  24. @ pramit sir, thnx for your suggestions, it really has cleared my view as i totally am willing for pursue my career as a designer in automotive fields as major, by that i have decided to go for CATIA, thnx for your support. just can't get 1 thing clear in your point no.-4, why have you suggested to use Creo for 2/3 wheeler & CATIA for 4 wheelers.(its just for clearification).
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  25. Thanks all, I think i've gained a lot from everyone's contribution especially Pramit Senapati. This has opened me up to some bothering questions on CAD softwares Regards 'Sola
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  26. I am 2nd year student and You could opt for Solidworks .. is very interesting and covers many aspects regarding mechanical
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  27. thnx @milos i think then i should go for CATIA or CREO
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  28. It meant, that Im not aware of any kind of free licence for students when it comes to Solid Works.
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  29. thnx everybody for your suggestions, @Bryan, i was unable to get your last line about campatibility in case of catia. @Milos i ant get your reason regarding license file, did it meant you were not able to use SW due to license issues or are there any other problems with it too.
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  30. I can recommend latest Creo 2.0. which is based on ProE, it has quite fast FEM analysis module among many others, with many linked solvers - ANSYS/MSC MARC and what ive seen there will be soon link to Comsol as well. Wish I could try Solid Works, but it seems I cant get to any student licence file, yet.
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  31. @raunak, Its depend on you, as what i think.. all 3 differ in platform but have same ideology n methodology behind d design.. Most of the industries using Solidworks... But Catia is More user friendly and there are a lot of moduls compare both... n problem regarding to older version so u can change the file in step or iges file and import it in any sw.
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  32. You can prefer catia...its best to design in that...
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  33. I use ug nx 7.5. Its a very powerful program and the synchronous modeling functions are a lifesaver for manipulating STEP files and bodies that don't have feature dialogues. It doesn't seem terribly common in the US but very popular in EU. I would steer clear of Catia just because it doesn't have backward compatibility with older version files.
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  34. you should opt for catia or ug nx these two are latest 3d modelling software.. and pro e and others are somehow little older softwares.
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