Broken Blade Analysis

Discussion in 'Fencing Discussion' started by Rabid Monk, Dec 13, 2018.

  1. Rabid Monk

    Rabid Monk DE Bracket

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    Hi all. Longtime no see. Been busy. Got into triathlon and ran an Ironman. I'm here because I need some assistance.

    Short version:
    I need information on broken epees and foils.

    Long version:
    A couple of years back, we had an incident where a blad broke and went through a fencer's sleeve (foil). Fencer was fine; it missed their arm. Jacket was was old and worn, and promptly destroyed.
    The incident piqued my curiousity into blade forces on hits. I was able to find two studies evaluating hitting force.
    1) "Impact Forces of the Blade in Fencing Movements", Rodano, 1991, available online at: https://ojs.ub.uni-konstanz.de/cpa/article/view/2632/2473
    2) "Foil target Impact Forces during the fencing lunge", Klinger & Adrian, 1983, not available online (I had to spend $0.50 for the book it's in and $7.00 for shipping)
    Neither of the studies took into account the force of a broken blade. A broken blade will be short, and therefore less flexible, than a full blade. Which will increase impact force.
    I plan to do a study to evaluate hit forces in foil and epee, comparing intact and broken blades. I am not looking at sabre due to the relative rarity of point hits.
    In order to do this study, I need to establish a broken blade baseline. I have been running around at local training camps and competitions to measure blades when they break. I've also been getting assistance from other local clubs. But I need a wider net to get more data (the past 18 months has gotten me less than 20 data points).

    This is where you come in.

    If you or your club has any broken blades, or you break any, please add the information to this thread.


    What I need:
    - measurement (in centimeters to one decimal place) from the shoulder (the guard, if assembled) to the break
    - blade size (0, 2, 5)
    - FIE or non-FIE
    - how the blade broke (on a hit, being flexed in the hand, etc; if you don't know, just put "unk").

    What I don't need:
    - if a blade breaks right at the hilt, I don't need it
    - if a blade breaks inside the barrel, I don't need it (I figure that's equivalent to a full-size blade)
    - if a blade breaks into 3 or more pieces, I don't need it
    - if it's a sabre, I don't need it

    And remember, this is for posterity. So be honest.

    Thanks in advance,
    Rabid (Ironman) Monk
     
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  2. K O'N

    K O'N Podium

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    I have a stack of broken epees at the club, maybe 20 or 30. I can measure them for you in the next week or so. No data on how they broke, sorry, though the vast majority of them will have been while fencing.
     
  3. Mergs

    Mergs Podium

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    I have a few at the club, but cause will be 'unk'. Will try to get the info to you next week. Are you trying to look at this from a column buckling standpoint, ie some of the energy is dissipated due to the blade flexing on impact? I think you can make the assumption that the impact force would be basically the same for either case, since the impact force appears to be dependent on the speed and mass of the fencer.

    I'd be curious to see if your analysis would support the FIE homologation test specs for material of 6 m/sec travel speed of the probe (Appendix A, 2.1.2) as being representative of broken blade hitting a uniform.
     
  4. Rabid Monk

    Rabid Monk DE Bracket

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    Thanks.

    I'm not sure it would be the same from a column buckling standpoint, for two reasons. First, the blade ("column") is now shorter. Second, the distal and profile tapers of the blades mean the end of the blade is the most flexible segment, so the cross section of the broken blade is larger. I'm planning on comparing the numbers, and seeing if there's a reasonable adaptation that can make the calculation give a rough approximation. I may have to break out my old engineering texts and, god forbid, do some calculus. But it would change the amount of energy dissipated by buckling.

    And yes, I will be looking to see how (if) it relates to the testing specs of a uniform. Still not sure why they rate that as a force. I would think a pressure value would be more appropriate. But that's a gut reaction. I haven't read their specs in too much detail; only the methodology for testing.
     
  5. Inquartata

    Inquartata Podium

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    I am going to do this in excruciating detail for about 100 broken blades I have lying around.

    They are all sabre blades.

    And I am going to send it to you! :D
     
  6. Grey Sabreur

    Grey Sabreur DE Bracket

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    Are they in the shape of a throne?
     
  7. Inquartata

    Inquartata Podium

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    LOL, no, I just use swords, I don't shape them. :D
     
  8. Mergs

    Mergs Podium

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    Rabid - How do you want data formatted? Can you send us an email where we can send a spreadsheet?
     
  9. dcchew

    dcchew Podium

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    My suggestion would be to contact Dan Dechaine who was the US representative on the FIE SEMI committee during the time period of development of the changeover to maraging steel blades. You may be able to get his contact information thru US SEMI.

    He would have all the history and background to the testing, etc.
     
  10. Rabid Monk

    Rabid Monk DE Bracket

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    Mergs:
    I have a spreadsheet I'm tracking the info on. Doesn't take me long to enter it. A couple of examples of the way I write my short notes (for later entry) are
    "Foil, FIE, size 5, 64.5 cm from shoulder, broke on hit", or
    "Epee, non-FIE, size 5, 77.3 com from shoulder, broke in hand"
    (if you only have the button end of the blade, write the measurement from the button or from the tip, and I'll work out the math)

    I can forward my email address to anyone who would like it, but I'd prefer not to openly post it on a forum. I may make a dedicated temporary email address for it.

    dcchew:
    Thanks for the tip. I'll look him up.
     
  11. Mergs

    Mergs Podium

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    So here is my data in a CSV format. I used your data from above. Measurements are from the shoulder to the break.

    Epee,Non-FIE,5,87.1,UNK
    Epee,Non-FIE,5,72.5,UNK
    Epee,Non-FIE,5,65.0,UNK
    Epee,Non-FIE,5,76.0,UNK
    Epee,Non-FIE,5,78.5,UNK
    Epee,Non-FIE,5,76.5,UNK
    Epee,Non-FIE,5,63.4,UNK
     
  12. K O'N

    K O'N Podium

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    Here you go. These are all epees. I dump all my broken blades into a tube behind my workbench, for some reason, so this is ten years or so worth. The two columns on the right are the only broken center sections I found; I presume they go with the shortest Vniti and LP broken blades, but of course I'm not sure. Most of these will have broken while fencing, a few while straightening the blade.Measurements are from the shoulder to the break. I only had a tape measure in inches, so I measured that way then converted to cm.

    https://drive.google.com/open?id=13Du1ZrqereZXCjJNMmMpDsNsM68IaU9Swci7zJ_aScQ
     
    Last edited: Dec 22, 2018
  13. Zebra

    Zebra Podium

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    Do all blades have a manufacturing date stamped or engraved on them? That might be a relevant covariate.
     
  14. Rabid Monk

    Rabid Monk DE Bracket

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    Thanks everybody for the data so for (except Inq; always except Inq).

    Zebra: I thought about including the manufacturing info, but that adds a lot more complexity than I want to get into. I also thought about including fencer size and experience. But at a certain point, i have to ask myself if it helps the overall project, or it I'm just making a data mine to hunt for correlation in.
     
  15. TraverseCut

    TraverseCut Rookie

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    Epee,FIE,5,78.4,received beat/hard parry
    Epee,Non-FIE,5,71.9,UNK
     

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