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Thread: Forced Energy Generator

  1. #1
    Associate Engineer
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    Smile Forced Energy Generator

    Hey guys, my apologies if this is posted in the wrong title forum, I'm kinda newbie engineer. But I'm working on a (still in theory) project about generating energy by force or impact so to speak. I could really need some pointers and directions to go to, if you would be so kind, interested or maybe even inspired by to do so.

    I'm not going to reveal my idea just yet, so I made up some kind of crypto example without revealing to much :-)

    But let's say that 6 guys meet up one night instead of soccerpractice, and they decide to get a good old 30 mins sledgehammer workout instead. You know these from the amusement parks:



    So let's say 6 guys take turns swinging their 20kg hammer with an average speed of 200kmph at impact into the receiver, hitting 1 time each per 10 seconds, that would equal 36 times/hits or impacts, per minute, and 1080 for the session (30 min). Without going to much into the actual convertionmedthods on how to extract the energy, I would rather ask if you have any idea, or way to make some kind of calculation on how much 'energy' - maybe in Watts (kwatts) - these 1080 blows would generate?

    I know it's a 'toughie', but any ideas, suggestions or gutfeelings are greately appreciated, and I will keep you posted.

    Cheers
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    Last edited by Kelly Bramble; 09-17-2015 at 06:48 PM.

  2. #2
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    Lol.. Thinking twice I'm not sure that a sledgehammer weigh 20kg

  3. #3
    Administrator Kelly Bramble's Avatar
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    See the following attachment...

    Hammer_Physics_web.pdf
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

  4. #4
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    Quote Originally Posted by Kelly Bramble View Post
    See the following attachment...

    Hammer_Physics_web.pdf
    Interesting, thank you. But how do I convert that knowledege into an actual equation? I understand that the range of motion is a factor, but if we just use an average or just a number, how many Watts would a single blow do? Peace

  5. #5
    Lead Engineer Cake of Doom's Avatar
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    Quote Originally Posted by KennyFerdinand View Post
    Interesting, thank you. But how do I convert that knowledege into an actual equation? I understand that the range of motion is a factor, but if we just use an average or just a number, how many Watts would a single blow do? Peace
    That'll mostly depend on the method you want to use to harvest the energy generated. Some ways will work better than others.

  6. #6
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    Make some assumptions and some number crunching and you will have your answer. An "average" here would be meaningless to you, because the braking distance is a major factor (consider a car stopping by hitting a brick wall and by coming to a standstill simply due to air resistance and friction)

    Now, in either case, the amount of *work* done is the same. If the moving body has a certain kinetic energy, measured in Joules, then you need to put in an equal amount of work in Joules (neglecting real world losses), to bring the kinetic energy down to zero. But what you are after, are watts. Power is the rate of doing work, in other words: watts=joules/seconds. That is- how fast the braking occurs (which is directly related to the braking distance and the deceleration).

    So in the end it comes down to this: assume some amount of kinetic energy for the hammer (considering it's mass and speed at the moment of impact). Then assume how long it will take for the hammer to come to a standstill (depends on distance of travel and deceleration, but I guess you could just pick a number at first, like 0,5 s or whatever). Divide energy by time and you have your watts.

    As you can see, the number of seconds it takes to stop the hammer plays a major role. The only way to rule out the guesswork and get a more precise answer is to actually think about and decide on what kind of braking system you will use.

    Also, remember than there will be a lot of wasted energy in your system (sound, heat, friction in the mechanical system and losses in the electrical system).

    Just out of curiosity, I'd like to take a guess about the system of your choice. I'm guessing you are either thinking about a coil and a magnet or some piezoelectric method ? I'd go for the solenoid. Did I get it right ?

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