Fibre buckling or constriction - Opinions Please

[Gary Prentice]

yes, its just matured, and your point?

 

I wouldn't personally class a thirty year birch as mature- having planted some that are about that age, but I suppose it could be termed as such. I'm not too sure how exactly these terms are applied or calculated.

 

Ignore me, I'm just over complicating things

[Gary Prentice]

 

I'm sorry if your tutor requires that you swallow all this simplified pseudoscience, then spit the appropriate quantity and quality back out. I agree; the state of the biomechanical arts is rather sorry. I tend to agree with Tony and Albert E. on this.

 

Not at all, I believe we're encouraged to research deeply enough to evaluate whatever peer reviewed research is available and to draw our own conclusions. Too often, the only conclusion I end up with is that there isn't enough info, creditable research or unmeasurable/incalculable factors to be applied to draw a definite conclusion.

 

There's more 'balance of probabilities ' than 'beyond reasonable doubt' in most answers.

[Tony Croft aka hamadryad]

Im going to stick to fibre buckle and leave you lot to pontificate!

[daltontrees]

Remember Einstein's words, remember them well, they will tell you when someones adding flannel to the equations!

 

" If an answer to a problem appears overly complex it is probably the wrong answer"

 

I think that Einstein was alluding to someting morespcifically known as Okkam's razor which say that that among competing hypotheses, the one with the fewest assumptions should be tested first, a presumption in favour not of simplicity but of scietific validity. Saying that you shouldn't look for complications if your theory can be proven without them.

 

This does nothing for the tree failure debate, we have only the fairly convincing body of evidence from Mattheck that failures increases dramatically in all species an all sizes after t/R falls below 0.3.

[Tony Croft aka hamadryad]

This does nothing for the tree failure debate, we have only the fairly convincing body of evidence from Mattheck that failures increases dramatically in all species an all sizes after t/R falls below 0.3.

 

indeed, Matthecks work (unlike the others) will stand the ages.

[daltontrees]

Jules, the buckling formulae is page 39, The body Language of Trees. But the function

σ - f(t/R) for the specific loading and tube geometry has still to be specified

 

FAILURE MODES FOR TREES AND RELATED CRITERIA C. Mattheck, K. Bethge, R. Kappel, P. Mueller, I. Tesari International Conference ‘Wind Effects on Trees’ September 16-18, 2003, University of Karlsruhe, Germany Provide some more mechanical formulas too

 

Well, quite. all he is saying is that buckling is a function of hollowing, with some vague allusion to a second derivative. Which is all I said in a different way about the cubed function. I fear some calculus will be needed to illustrate why the cubed function curve is not as steep as the curve on p.103.

 

I am obliged to you for bringing this to my atention. The M&B stuff in the book is scientifically and mathematically flawed, by the end of p.39 they have dug a hole for themselves and throw a few shovelfuls of dirt on at p.40 to complete the burial.

 

There is nothing wrong as I see it wth the evidence for a t/R ratio 0.3 for widespread failiure but I do not accept the arguments for the physics or mechanics that they put forward to explain it, because they don't. Their only mistake is pretending that they can.

[daltontrees]

indeed, Matthecks work (unlike the others) will stand the ages.

 

See most recent post by me, the t/R 0.3 observations useful but their theory to support it falls apart before ones very eyes.

[10 Bears]

See most recent post by me, the t/R 0.3 observations useful but their theory to support it falls apart before ones very eyes.

 

I presume you have all read the Bond paper? (Useful for the chap writing the essay)

 

http://www.urbanforestanalytics.com/sites/default/files/pdf/bond_tR.pdf

 

I agree with the comment above. The much cited t/R has been widely discredited on a number of points, but to summarise the key ones that affect the validity of the 'experimental' approach when Ozzy Osbourne/Matheck cam up with t/R questionable:

 

• The trees were all damaged in a single storm event
  
• They are not individual trees, but trees growing in a forest stand
  
• There are several trees below the 0.3 threshold - that did not fail in the storm event
  

 

t/R is over-hyped and misquoted and is not an absolute threshold. At best you could say rule of thumb which is what one or two of you have also suggested to be fair.

 

Also, Im interested - who was the picky tutor?

[daltontrees]

I presume you have all read the Bond paper? (Useful for the chap writing the essay)

 

http://www.urbanforestanalytics.com/sites/default/files/pdf/bond_tR.pdf

 

I agree with the comment above. The much cited t/R has been widely discredited on a number of points, but to summarise the key ones that affect the validity of the 'experimental' approach when Ozzy Osbourne/Matheck cam up with t/R questionable:

 

• The trees were all damaged in a single storm event
  
• They are not individual trees, but trees growing in a forest stand
  
• There are several trees below the 0.3 threshold - that did not fail in the storm event
  

 

t/R is over-hyped and misquoted and is not an absolute threshold. At best you could say rule of thumb which is what one or two of you have also suggested to be fair.

 

Also, Im interested - who was the picky tutor?

 

Thanks for the Bond article, looks good for a mid-morning tea-break read. I certainly am hoping to be able to reach a firm personal view on t/r ratios that I can bring to bear on my professional judgements, and this is all helpful. It is a principle I have had a pre-view on until now but the answer is becoming clearer ad clearer.

 

Poor Gary, bet he wishes he'd never asked....

 

But the best forms of education are the ones where you are not credited for getting the right answer but for showing that you understand why it's right, and its limitations.

[Gary Prentice]

All grist for the mill Jules, I followed this last night on my phone and will return this evening. I've twenty odd pdf's that I've read, including Bonds article. Kane et al -2001 & 2004 are particularly interesting. I'll post them up later.

 

I'll have to beg to differ with 10Bears, I think there may be some confusion in where data was collected. Smiley wrote mainly on Oaks after hurricane Hugo (I think) and Gruber based his work on two cultivated forest stands. Matthecks original work doesn't clarify whence the data came from but Fink states - refuting Gruber, that it was untouched virgin forests and I think it may have been over a number of countrys.

 

Later data was for over 1200 trees - Australia , N. America & Europe for the body language book.

 

 

 

I don't think, which is an issue, that Mattheck ever published all the collected data or the sources.

 

Please publish the calculus if you've done it, I've no shame admitting that I'm struggling on the understanding.