Page 2 of 4 FirstFirst 1234 LastLast
Results 11 to 20 of 31

Thread: Hole in the garage?

  1. #11
    Havasu Hangin'
    Originally posted by gstark:
    As a mechanical/structural engineer with a strong background in design and stress analysis...The words "cumulative fatigue damage" come to mind...
    As a non-engineer, the words "duct tape" come to mind. http://www.goldenplasma.f2s.com/foru...es/happy09.gif
    Originally posted by RiverDave2:
    GStark, I'm not an engineer of any sort, but ...
    Why is the prop on the back of the outdrive? http://www.goldenplasma.f2s.com/foru...confused27.gif
    -Havasssssu Hangin'
    http://www.websitemonster.com/images/pimp.gif

  2. #12
    gstark
    RiverDave2:
    Cumulative fatigue is a stress analysis method (also known as Miners Law) based upon a known (or estimated) fatigue spectra with the intent of determining how close something is to failure. Every metal has what is known as an endurance limit, which is the stress level where infinite fatigue life exists. Therefore, cumulative fatigue damage can be applied to aluminum, carbon steels, alloy steels, titanium (comm. pure and alloy), nickel-based super alloys, etc. The technique has no dependency on the metal.
    The hinge pin arrangement shown sets up a complex load and stress distribution in the attaching structure. That is what I am trying to get across. This arrangement also forms a weak link. Think of the trailer as a series of springs. The tab/pin arrangement acts as a spring. When trailering, high bending loads exist due to road accelerations (up/down motions). These bending loads are carried thru these "springs". Loads accumulate with time yielding fatigue. It may well be that the stress levels that result are below the endurance limit of plain carbon steel. If so, great. If not, sooner or later we'll see this in a courtroom as a product liability action.
    Sorry, not on my trailer, carrying my boat with $$$ invested, attached to my tow rig ($$$) carrying my grandkids (priceless).

  3. #13
    jroos
    gstark, it sounds as if you are a metallurgical engineer. just curious.

  4. #14
    Jetmugg
    I am a metallurgical engineer. Steels have fatigue limits, aluminum alloys generally do not. This means that for steels, when cyclic stresses are applied at a level under this fatigue limit, failure will not occur. For aluminum alloys, cyclic stresses at any level will eventually cause fatigue failure (even though it may take millions of cycles).
    On a practical level, I have had trailers with both removable (telescoping as described), and swing away. Both systems have worked well, although the telescoping is quicker to operate.
    STeve.

  5. #15
    mister460
    I say convince the wife that you now HAVE to build a bigger garage/shop. It's the only way to be sure. If she says no, feed her the line about "cumulative fatigue" and those girls at Hooters need the money for college. Trust me, it'll work!

  6. #16
    jroos
    Tried that 460, now boat is in driveway and I`m in the garage!

  7. #17
    LS7
    lol

  8. #18
    gstark
    jroos:
    I am a CA registered mechanical engineer, spent some time in met labs.
    I work in aerospace and have been involved in the structural design of a whole bunch of really bitchen stuff that goes really fast and turns really hard. Jet boats, jets....
    99% of my design background is Inconel and titanium based, so I am pretty weak in the subject of aluminum (Jetmug). All of my activity is fatigue-based by definition. It can be very surprising how fast fatigue cycles can add up, so while a million cycles may sound like a lot, that may represent several hours or several years of accumulation, depending on the load magnitude and frequency. That is why I am sensitive to a design such as the swing-away tongue. Fatigue design rules are one reason why most airplanes don't fall out of the sky, wings don't fail, horiz stabs stay intact, wing boxes carry their loads. For most of the stuff I am involved in, aluminum would fail in a heatbeat (temps greater than 800F).

  9. #19
    Jetmugg
    I love to see a good engineering discussion of just about anything. It's good to see a level of discussion above how many strippers will fit on any given jetboat, or how much beer someone can drink and still race his boat.
    I have a particular interest in materials selection for all kinds of applications. There are available materials which would be better for jet drive manufacturing than those currently used. In particular, I would like to see someone make impellers from materials which are easier to cast, fabricate, and machine than the current crop of 300 series stainless steels. (I know of a few) Not only could we see an improvement in performance, but also lower cost.
    Gstark is correct about the slip-in removable tongue being a more robust design. However, for some reason, the trailer manufacturers seem to have taken more of a liking to the swing-away design. Maybe they figure that we would lose the tongues if they were totally removable. LOL.
    Steve.

  10. #20
    rivercrazy
    I have one of these slide in removable tongues with a quick brake line release. I've put tons of miles on the rig without any problems. For that reason I like the setup.
    However, its a real pain in the rear to remove compared to the swingaway type. Also, when you disconnect the brake line, it always leaks a few drop of brake fluid. I believe it also introduces a very small amount of air in the brakes lines every time its disconnected. This requires bleeding the system from time to time.

Page 2 of 4 FirstFirst 1234 LastLast

Similar Threads

  1. are you an a$$hole?
    By whiteworks in forum Sandbar
    Replies: 61
    Last Post: 06-10-2007, 05:58 PM
  2. Am I an a$$hole?
    By adjones419 in forum Sandbar
    Replies: 82
    Last Post: 06-07-2007, 02:08 PM
  3. So some A-Hole
    By UnionJack in forum Sandbar
    Replies: 15
    Last Post: 01-05-2007, 06:05 PM
  4. hole?
    By jetboat in forum Jet Boats
    Replies: 24
    Last Post: 05-11-2006, 05:34 AM
  5. What an A**HOLE!
    By OGShocker in forum Political Phetoric
    Replies: 6
    Last Post: 06-16-2005, 07:44 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •