Deceleration - Slide Hammer
Deceleration - Slide Hammer
(OP)
I have a scenario that is quite similar to that of a slide hammer (thought not a slide hammer), whereas an object is dropped about a foot, then collides with a forged body. I was asked to compute the force on the forging at the moment of collision. I used conservation of energy principles to calculate a velocity and estimated several scenarios of deceleration (0.05s, 0.1s, and 1s). Is there some guideline or the deceleration of metal to metal impact?
Alternately, I provided the party asking the question with total energy absorbed, but I wanted to find out if I was reasonable in providing forces based on those types of "instantaneous" decelerations.
I realize I'm leaving out details involving the scenario, but I'm looking for general, rather than specific suggestions.
Alternately, I provided the party asking the question with total energy absorbed, but I wanted to find out if I was reasonable in providing forces based on those types of "instantaneous" decelerations.
I realize I'm leaving out details involving the scenario, but I'm looking for general, rather than specific suggestions.





RE: Deceleration - Slide Hammer
this is one of the hits when I ran the search:
thread404-272070: Equivalent force on impact
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RE: Deceleration - Slide Hammer
http://www.eng-tips.com/viewthread.cfm?qid=110558
RE: Deceleration - Slide Hammer
Likewise, in the thread I posted, the solution is to use the strain energy to effective determine a spring constant, from which you can determine the energy stored into the spring, hence its deflection, hence the maximum force applied.
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RE: Deceleration - Slide Hammer
RE: Deceleration - Slide Hammer
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RE: Deceleration - Slide Hammer
A "great answer" without "guessing" or "chasing your tail on this one," would be to apply some good educated engineering judgement; pick a few stopping times and stopping distances to start to bracket the magnitude of the forces involved. Then educated the people who asked you for this info., explaining essential what IRstuff has told you, and what you should know and brush up on a bit, by reading your physics and dynamics text books, before you respond. This is not a question which lends itself to a single, exact, answer; and you have just brushed the surface on what happens with all the energy; but you can look all the better by educating them on this matter. It is an approximation, but maybe graph how the force changes with time or distance, and let them determine if the want to spend another million dollars to halve the time or distance, or double the force. And, quit using the word "guess," at least try using terms like 'educated assumptions' or 'approximations based on experience.'
Nice response and direction IRstuff.
RE: Deceleration - Slide Hammer
Good suggestions, and I did what you suggested and gave a range or bracket of magnitudes based on variation in variables and my educated approximation.
Maybe using the word guess isn't appropriate in your eyes, and clarifying it as an "educated" guess is better. They aren't approximations based on experience...I DON'T have any experience in this area, so I think it's also inappropriate for us as engineers to call it otherwise. It's an approximation based on what I consider to be reasonable assumptions, but not much more. And in that regard, what I deem reasonable is subject to argument.
This is a very helpful forum. I had stumbled upon this a few years back, but had forgotten it until this issue was presented.
Thank you to everyone for your feedback.
RE: Deceleration - Slide Hammer
Cheers
Greg Locock
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RE: Deceleration - Slide Hammer
RE: Deceleration - Slide Hammer
RE: Deceleration - Slide Hammer
Too simplistic?
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada
RE: Deceleration - Slide Hammer
RE: Deceleration - Slide Hammer
Conservation of Momentum is always 100%.
With energy who knows what the "efficiency" is.
RE: Deceleration - Slide Hammer
Engineering is the art of creating things you need, from things you can get.
RE: Deceleration - Slide Hammer
Who knows, could be a full feature movie some day? LOL, give the artsies a run for their money!
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada
RE: Deceleration - Slide Hammer
RE: Deceleration - Slide Hammer
Or ultrasonic measuring tape.
Ted
RE: Deceleration - Slide Hammer
http://c
Alternately, you might just try gluing an accel on the hammer and see what you get: http://ww
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RE: Deceleration - Slide Hammer
http
They're probably still inadequate for a hammer strike. If you want to actually measure the shock, you'll probably need to build or buy something more appropriate, i.e., something that will read out at least 500 g
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