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  1. Today
  2. Hi everyone, I've been stuck with this excercise for a while and would love an advice. So I have 3 beams with poles connected to them with a gap of delta 0 between them. Mt0 is the moment needed on beam 2 to close the gaps, 0.011 GJ/a by my calculations. after that, 3Mt0 is activated on beam 2 and I need to calculate the amount of moment created on beams 1 and 3 and the moment on beam 2 after the resistance of the 2 side beams to the shear force. The way I see it the shear stress*cosinus the angle created after closing the gap would transfer completly to the 2 beams and the central one would stop rotating but I doubt it. Thanks a lot.
  3. The new hard drives may have lost my automatic log in but I am in again. When I use any source I work through any example provided in step by step detail. If steps were skipped in the example, you may not notice the 2 in r/2 may have been dropped, just to mention one of many easy errors. I recall a professor who must have done the example in class countless times. He wrote 3x3 and came up with 12. Not that he did not know how to multiple, 12 was the incorrect answer, he just wrote down the wrong input but knew what the answer was. Proof readers can make the same error focusing on the answer and overlooking the input. If no example provided work out the units. And if possible do a simple estimate of the answer to get some idea if the refined answer is possible. I have briefly communicated with Dr D by email. In the attempt to demonstrate a basic concept the author may have concocted an impossible to build device.
  4. Yesterday
  5. Looks like I may have gotten it
  6. Applications:  Friction Losses calculations of piping network.  Irrigation piping.  Fire sprinklers system.  Water mist fire piping.  Domestic water pump estimation.  It is equipped with database engine.  You can store, edit and retrieve your data anytime.  You can Print reports.  It can transform your calculations to drawing and export it to AutoCAD.  It can export your calculations to Excel.  It equipped also with Lite CAD software.  It is equipped also with unit convertor software. https://youtu.be/Yh4dQbAfLGU Thanks Admins
  7. Last week
  8. the engine has a 90 degree V angle and the intake system will be between the cylinder banks and the firing order is 1-6-5-4-3-2. what will be the crank pins position in the V6 described above. Anyone willing to help would be much appreciated.
  9. Hi.! I am making Mechanism device animation by Siemens nx software. I want to share it to you. If you need the support to create a video by NX motion. Please, contact with me. Thank you! 1. This play list show robot gripper animation. https://www.youtube.com/watch?v=nB1VuR9j5zM&list=PLVTNqTfj-J8WK3WGSxZCeXtwc5Buz5X9b
  10. DrD

    A Bad Example #49

    Apparently I must write the dullest stuff found anywhere. As I write this, 290 folks have read this article, and not a single one has made a comment. I am really baffled. I had the (obviously mistaken) impression that this was significant, important information. It talks about a problem that is slightly out of the mainstream, a bit of an unusual challenge. It points to the fallibility of all people, even famous, highly successful authors. But no; not a single comment. I am baffled. DrD
  11. Timothy, Thanks for the reply. My goal is to produce a driving mechanism that will squeeze an ambu bag to create a ghetto ventilator. I am a former respiratory therapist and I am just trying to create a system made of common household items as a ventilator of last resorts. Any ideas are appreciated. Thanks, Jay
  12. I think it's impossible to convert constant RPM motion to constant velocity reciprocation. The only one I know that does have straight line constant velocity, a quarter of the cycle is way out of line. Chebyshev's lambda mechanism. I am confident you are not looking for that
  13. Engineers, Looking for solution to convert the rotary motion of a kitchenaid stand mixer to linear motion. The low speed on the mixer is about 60 rpms but I need it converted into around 10 to 12 linear strokes. Any suggestions? Thanks, Jay
  14. Hi there! Im currently a bit stuck on one section of a project I am currently undertaking. The project concerns a deployable panel system fitted to a 1U (10x10x10cm) cube satellite, orbiting at an altitude of 600km. I have calculated the effect of atmospheric drag on the satellite to be equal to 2.016*10^-8, so...my question is this, when the panels are collapsed (ie the shape is symmetrical), then the system is in equilibrium, if i were to open one panel on one side of the satellite (offsetting its centre of mass and therefore making the forces acting on the system unequal), am I correct in saying that the satellite will pivot? So as you can see from the diagram below, I have calculated the moments about the centre of the satellite to be: Ma = (0.05 * (2.016*10^-8)) - (0.1 (2.016*10^-8)) = -1.008*10^-9 Nm Is this correct? If so would it cause the satellite to pivot around the centre of mass? Lastly is there a way to work out the rate of its rotation? Thanks for any help anyone can offer! Im just a bit confused!! Sam :)
  15. Hi Baumi Seems like a classic thing many of us have experienced . Due to the not obvious way that stainless steel protects itself. Stainless steel actually protects itself with a very thin layer of chromium oxide that prevents further oxidation. Not by not forming an oxide as you may think. The oxide is very thin, a few microns , It Is not really visible, forms very quickly BUT is not very wear resistant. You are supposed to AVOID wearing on it. It will form again instantly. What you experienced will happen. Seemingly wear product emerging from nothing. The colour of the wear product will depend on what wears it of reasonably and present dirt etc. Black seems reasonable. What you are doing is very very slowly wearing on the stainless pulley. To prevent this you could use a material with hard surface oxide instead. Anodized aluminium should work well for that. https://www.schluter.co.uk/what-is-stainless-steel.aspx Mikael
  16. It depends a lot on the soil , If it is under ground water level it should be good conductivity. Then the heat transfer should depend on heat conductivity of the soaked soil. If it is above ground water level it may be worse. It may dry out around the pipe with airgaps etc. Some soils is not very heat conductive either. You should look for data on the soil type you have. Then apply the formulas that handle heat conducted through matter into a central pipe.. There are formulas for insulated pipes. Here the soil could be calculated as the "insulation". https://www.google.com/search?rlz=1C1AWFC_enSE748SE748&q=heat+conductivity+thick+pipe+wall&tbm=isch&source=univ&sa=X&ved=2ahUKEwj92tH47czoAhWgy8QBHfh1ApIQsAR6BAgJEAE&biw=1996&bih=994#imgrc=aR4X1vx7L2Ks0M Mikael
  17. Hello, the case concerns the operation of lamellas in the Pergola system. The slat is connected with the mechanisms run on screws. What companies offer this type of mechanisms that allow both to move the feathers in one direction, and on the other hand they are adapted to the axial rotation of the feathers? How do such mechanisms work? I am aware that such a mechanism is visible on individual YouTube videos, but I am interested in a bit more detailed information, maybe contacting some producer with whom I could discuss the details and order the mechanism for testing.🤔 Thanks for all the help PS. I can't add a photo to the text ... so please enter in youtube: Louvretec Super Roof Moving feathers to one side, Feather rotation with an open system
  18. I am working on a project and i need some assistance. How do i match a solar panel to a motor. My project requires i use scotch yoke mechanism (also known as a slotted link mechanism). I would need a 12 dc motor to make my component work. i am having challenges with choosing a preferred solar panel with an appropriate power rating to work perfectly with my motor. Any suggestion or measures i should put in place are also welcomed. Thanks.
  19. DrD

    A Bad Example #49

    117 views, and yet no comments! Does no one have any reaction to this? Do you think Rao had it right in the first place? Do you think he got it wrong, but that getting it wrong does not matter, its only an example problem? Or did you read it at all? DrD
  20. 3D CAD modeling helps you in increasing design flexibility and improve the quality of the design and end product. Errors can be discovered and resolve easily during the early design development stage. It removes inefficiencies and establishes a streamlined workflow between design and fabrication needs for assemblies and sub-assemblies.
  21. Earlier
  22. Hi everyone; I am a fresh graduated mechanical engineer. Right now I am part of a entrepreneur program with my project called pipeline network design. I passed the first step and right now in order to past second step I need to prepare a business plan. I finished most of it but the most importentpart is letter of intent and only potential customers for my product can fill it. Below you can see summary of my project and an example of letter of intent. (I know it is long and I want to keep it short but this is the shortest way to express my project ) “summery of my project” Today, the need to speed up the calculations made in the design of district central heating and mechanical installation systems with the support of a software and to draw large distribution lines with the help of computers has been an important research topic. While the dimensioning of the distribution pipes, the pressure and heat losses to be formed in the pipes are made manually, especially the need to speed them up with the help of computers has arisen. At this stage, performing the iteration manually is tiring and at the same time creating a manual network layout for large networks is complicated and time consuming. One way to improve this process is to automate it. With the developing district heating systems, the design and sizing of distribution networks has become complicated. With the support of computer software, it is possible to design the distribution and speed up the sizing calculations. In the distribution line design, the critical point can be easily determined and the type of pipe in accordance with the industry standards can be selected according to the calculated pipe diameter. Developing a program that calculates the flow and diameter of pipe distribution networks with the routes and parameters entered in the interface using Python and pyqt5. In this context, it is planned to first search the literature required for calculations and then integrate the algorithms that will perform these calculations in the developed interface. It is aimed that the developed program will push the pipe diameters and flow rates until the desired recommendation range. In this way, the design and sizing of the pipe distribution networks will be automated, not manually, time consuming. When the program reaches the desired level, it will be in a position to provide the following services. - For regional central heating systems, the lines of round-trip and side streets of pipe distribution networks can be designed. In this way, it is provided to enter the necessary parameters for entering the routes of the pipes to be laid on the map and for the window calculations opened. – - It is provided to calculate the pipe diameter and flow rate by using the data obtained from geographical information systems not in the literature and the hardy - cross method. In summary, thanks to the parameters entered by the user, pipe pressure drop values and losses are calculated with iterations and the results are presented to the user again in a schematic way. – - Pipes and pumps are selected according to the need. The program calculates the losses and chooses the pipes and pumps with the required capacity, thus reducing the cost by not selecting the excess product. – - Designing distribution networks outside the regional central heating systems at the designed 2 and 3-dimensional interface. With the help of drag and drop option in the developed interface, pipes will be laid by hand and a pipe network will be created. The program, which has reached a level that can provide these services, is aimed to be sold as a subscription to consultancy companies providing regional central heating and mechanical installation design services, academicians or organizations that develop projects or provide analysis services in academic terms. It was aimed that this program would be able to optimize flow and diameter by iterative means on a map in the short term and to design a pipe network in a CAD interface in the long term. “letter of intent” In small size water distrubition network it is easy to calculate their parameters. But large size networks it is almost impossible to design pipelines and calculate their parameters. This project can easily do pipe diameter and flow rate calculations and pipeline design by entering routes in a map thanks to mouse click events. There are different programs that can do that but no one do flow rate optimization by using hardy - cross method and hazen - williams equations. Moreover geographical information system and CAD options on this program is advantage in this way program can be use both district heating systems and pipeline installation sectors. I see commercialization potential in this project due to these. If you read all this boring stuff and come here I want you one last thing. Can you fill a letter of intent for me, If not can you forward this to related persons. userinterface.pdf
  23. Hi guys, this is the first design , V6 ntake manifold, I have a question how i align the pin into the hole? cause it says it will break other mates? any feedack thanks in advance
  24. Hai all, i need to get to know how a Gear pair teeth numbers are selected.Details : Power = 300KW, N1=2950, N2=816.5 , i=3.62, Helix angle = 35deg, Pressure angle = 20deg.I need to know how to select a Gear pair teeth for this input?Knowing a gear set should have common Module to transmit velocity.Is there any method to select Gear teeth w.r.t power to be transmitted?Thanks.
  25. Diesel engine is more efficient than patrol engine because in diesel engine, there is high compression ratio as compared to petrol engine: this gives high power output as a result of high pressure and temperature. Also, diesel is made of very Long hydrocarbon chains as compared to petrol hence after the power stroke stage high power is liberated to do more work than petrol. Even though there is ingnition delay in diesel engine but the maximum mechanical efficiency is from diesel engine
  26. DrD

    A Bad Example #49

    Mechanics Corner A Journal of Applied Mechanics & Mathematics, #49 A Bad Example Most of us are inclined to trust an established textbook. We assume (1) the author knows what he is talking about, (2) the book has been carefully vetted by several editors and reviewers, and finally (3) the fact that it is well established in the market means that thousands of other readers have tacitly endorsed it as well. While these assumptions are usually true, they are no guarantee, and they can and do fail us at times. The topic of this post is one such failure. Beware!! The format of engineering textbooks is fairly uniform, consisting of alternating sections of Theory and Examples. For a student encountering the material for the first time, the Theory is often simply too much, and blows right over the head of the student. The starting student relies heavily on the Examples to comprehend, even if incompletely, what the material is about. The Theory is most useful when the material is studied a second or third time in some depth. Because many will only study the material a single time while in college, it is critically important that the Examples be correct and in no way misleading. Sadly, both of these problems exist in the book discussed here. The book in question here is Mechanical Vibrations by S.S. Rao, where both the book and the author are well known. The book was published early by Addison-Wesley; I have a 2nd edition dated 1990. It has been re-published more recently by Pearson in a 6th edition with a 2018 copyright date. The problem shown in the Figure is used in both of these, with only very minor changes. The same errors exist in both versions, indicating that in 28 years, Rao has learned nothing about this simple statics problem. I encourage all readers to examine carefully the discussion in t he attached paper. It demonstrates clearly that even the experts go badly astray at times. RaoCrane.pdf
  27. as Offtake stations are located on ground level that number of pipes exposure in open area is huge. Dirty dust and moss always stick on pipe surface which may damage pipe surface coating and obstruct inspection process during maintenance. The removal of stains requires huge amount of human resources and time, which is time-consuming and cost-wasting.The diameter of pipe varies around 450-600mm and there are obstacle along the pipe likes flange or support base. The orientation of pipe is restricted by API 5L specification of pipe. The surface of pipe is covered by a specific paint coating and then a layer of stains. Main goals of the device are to clean stain along a pipe (both vertical and horizontal), which contains 3 special features-a curved length, a flange and a supporting base. How can I design a robot to clean this huge pipe?? It is a big challenge. There are two main area to be focused.1. How to adhere the robot to the pipe2. How to clean the stains effectivelyOf course, building an robot adhering to the pipe is not a only way. We may build a robot car jetting pressurized water for cleaning or build a frameworks-and-slider system around pipe to avoid obstacle while cleaning. Focus on adhesive method, there are few restrictions.1. Magnetic cannot be applied as the magnetization may affect function of electronic components near the pipe.2. Vacuum may not be applied since the curved area of pipe. Also, the removal of stains requiring either brushing it with huge force or washing it by pressurized water. If water is involved, vacuum may not work properly. There are also restrictions in this project.1. Robot should be ease to install/handle (light weight and easy operation)2. Budget < USD1250
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