Has anyone published or posted any data on determining the location of high stress points on a blank prior to the build.
If so where may this be located ?
I'd like to compare my findings with these to see if I'm viewing the same phenonema and placing the same degree of importance on it, prior to posting my procedure.
It seems like this knowledge would be relevant to guide placement in light of the previous post on the effects of guide location to rod loading under actual fishing pressures.
There may be good reason to make sure guides are not placed where they can contribute to rod failure under load.

Good fishing
Gene

Ah, \"previous posts\" have indicated that there is no problem with what you call high stress points on a blank either prior or after a good build.

Such a thing is not happening, nor will it happen, provided you employ a sufficient number of guides on the blank. The blank manufacturers are careful to provide products that are not inherently sensitive to such a problem provided some good common sense is utilized during the construction of the rod.

When a reasonable number of guides are used on a rod blank, there is no problem with rod breakage from high stress areas. If such a thing were happening, the manufacturers would certainly be aware of it and would include cautions and/or instructions along with their products.

............

"There may be good reason to make sure guides are not placed where they can contribute to rod failure under load"

If such areas existed on a blank I am sure the blank manufacturer would make a note NOT to place a guide there. The only stress points PRIOR to the build are going to be where the graphite pattern has been cut at sharp angles. But this does not seem to be causing any problem with breakage. St. Croix is using some sort of pattern design called ICP or something that does away with steep changes in the pattern. Whether this is a step forward or a smart marketing move I cannot really say. The blanks I use are not breaking due to stress problems.

But it is the area BETWEEN guide pairs where stress takes place and as others have stated many times as long as you do not have so few guides that they are many, many, many inches apart this is not going to be a problem.

"It seems like this knowledge would be relevant to guide placement in light of the previous post on the effects of guide location to rod loading under actual fishing pressures. "

In light of what post? One person's theory? The majority of the posts I have read where people have actually tried it show that rod loading is not affected much as long as you use enough guides. One per foot or thereabouts seems to be about right in most cases. Careful thought and attention to detail is a good trait, but going overboard can cause headaches over problems that do not really exist. With so many tens of thousands of people building rods and such a relatively small percentage of breakage for any reason it seems to me like your worries are not worth worrying over.

A bad blank design can appear on the market from time to time and they are quickly discovered. Warranty replacements require removal of that blank from availabilty if it does not bankrupt the manufacturer first. When excessive breakage starts I do not think many will attempt to place the blame on incorrect guide placement.

Quote

In light of what post? One person's theory?

"The earth is round!"

"Survival of the fittest" (Evolution of species)

"E=Mc2"

One person's theory.......


Personally, I applaud anyone who develops a theory and makes the investment in time and money to test it.
Moreover, it is accepted practice that such theories be presented for peer review. That too is to be applauded.
What follows is supposed to be acceptance or debunking of the theory(s) through debate of the principles.


I suspect that many rod blank manufacturers of yesteryear built the things "by the seat of their pants"
They did indeed run into stress point problems and they fixed them by making the blank big enough, thick enough or changing the taper until the problem went away.
Or they reduce these areas to achieve sensitivity or lightness until a problem arose.

NOTHING WRONG WITH THAT!
And it provided us with a very good tool for the job that serves a gret many of us so well that we have no need to seek much in the way of improvement, nor do we need to understand the scientific principles involved.
We know that with current manufacturing practices and materials then we only need to put roughly one guide per fott of blank and we'll have a pretty good tool.

But what if you want to develop NEW designs, or take advantage of new materials in order to make the tool stronger, lighter, more efficient in some area?
Then we either go back to trial and error, or we try to develop mechanical theories that allow us to accurately predict the results of a myriad of changes.

I don't believe blank manufacturers see a great need to invest millions in this sort of R&D.
In order to make money, they need to turn out maximum numbers of product from minimum numbers of tooling.

You really think that all those models are in fact completely unique?
You don't reckon that a model XYZ spinning blank is not the same exact blank as a model ABC casting rod that has identical specs?

I wonder how many of them have any sort of computerised R&D program?

Good ideas do not necessarily flourish just because they are good ideas.
Politics and money have lead to the advancement of a great many 2nd rate solutions or just to the maintenance of the status quo.
AC vs DC ring any bells?

I find the theories expounded here lately interesting but with no real impetus to make me change my building practices given my current understanding of the available materials for building a rod.
If my understanding, or the tools available change then well might my outlook on building a rod.

cheers,
Owen

Owen, Very good post!! Thanks

Mike (Southgate, MI)
If I don't want to, I don't have to and nobody can make me (except my wife) cuz I'm RETIRED!!

The interesting thing is that not one post in response to " / previous posts" has attempted to provide any critique of the physics involved.
intuitive judgements have been made in a number of posts that it doesn't make any difference.
That's everybody's right to make a judgment as to whether they use any particular tool or piece of information. The strength of that judgment is dependent whether the judgement is based on well founded assessment or meagre assessment.
Owen makes some very good points about the reality of the world we live in
"heretics" were burnt at the stake quite a few times for proposing that things were not as generally perceived at the time, some were madmen , some were wrong, some were right , but only recognised to be right or wrong in the fullness of time.

Eugene raises a point of some considerable significance.
three significant issues underlay engineering considerations in building blanks.
1.
multi modulus blanks
There are quite a few of these out there
- the ends of overlap Flags of high modulus material on lower modulus material a blank is made from, poses particular engineering considerations.
- from a stress management point of view ...............should guides be placed on those locations or placed in the middle of a span between guides.
or
who cares????
- Its a consideration where it is useful to have some numbers on which to base a decision.................and even identify whether a decision is warranted.............it might be "who cares", or it might not.

2. Blank mandrels and Blank flags.
Mandrels are damned expensive things to make. Blank manufacturers have a variety of mandrels that for sure, but they make maximum use of every mandrel they have in their kitbag and minimise mandrel types for cost reasons.
quite often a single mandrel taper is used to make a variety of blank actions by varying the flag design of the pre-preg layup.
( ever gone to the trouble of equating mandrel type inventory to blank inventory for a given manufacturer )
Materials change over time and blank flag layups evolve to maintain the desired 'action' using the new materials.................on that original mandrel.
Often this results in complex flag designs.
- what consideration should the rodbuilder using those blanks have for the intersection points of multiple overlapped flags in the blank design.
- Some ............none............how do you know ?????
3.
Ferrules in multi-piece rods pose particular issues too.........................where and why do you locate your guides relative to a ferrule.

Bill S makes the point that bad blank designs appear on the market from time to time ................. its not usually the mandrel that has changed , but a change in the material the blank flags are made from . or the blank flag design itself ( in an attempt to make a different action, or class of, blank on the same mandrel ).
Blank designs that fail to adequately cope with tip load deflection are easily and quickly identified. Word of mouth about the obvious issue sees them killed off pretty quick.
Other blank designs stagger along in the market place with some builders not having trouble with them, and others having failures. The reason for that is less obvious.............its guide train design pushing them over the brink....................... but as Bill points out nobody ever blames that................Heck, that guidetrain has been used for ' yonks' ...........its OK.
The rod fails at normal use angles and loads for a particular technique ...................but no..................the failure is assigned to highsticking..........or blank damage .
How do you know what you are dealing with as a rodbuilder.

I'm not going to attempt to answer Eugene's question in this thread................ the answer lays in "/previous posts"
Think about it, consider the validity, or otherwise, of the physics involved....................

I look forward to the responses to Eugene's thread...................an excellent and insightful question Eugene.



Edited 1 time(s). Last edit at 07/10/2009 09:20PM by Denis Brown.

Denis

Your address is to "Emory", do you mean "Eugene Moore" (the original poster of this thread), or did I miss something?

Interesting stuff.

Improper use and high sticking will normally result in one break in the upper 1/3 -

Designs that are not appropriate for the intended use may fail due to instaneous impulse shock overload during hook set. The loud sound at time of failure will be reported like a gun shot going off and typically results in more than one break occurring at the same time. Some of these occur on blanks that have utilized various fibers to reduce weight and increase stiffness - and these can be built on existing mandrels that produced trouble free blanks of lower modulus. When the problem is solved by today's manufacturer it is with blank alteration.



Edited 1 time(s). Last edit at 07/11/2009 09:56AM by Bill Stevens.

Bobby
OOOPS..............don't know where the mind was going with that ..............post edited to correct.
Thanks

You cannot look at a bare rod blank and tell where the pattern angles are. You cannot flex the rod blank and tell where they are. It would not appear that they matter one whit anyway.

The rod builder need not use any special consideration when considering where to locate guides on any well designed rod blank. The manufacturer has seen to it that there will not be a problem. If any special consideration was needed, the manufacturer would have specified such.

We are getting knee deep in gobledegook.

You cannot look at a bare rod blank and tell where the pattern angles are. You cannot flex the rod blank and tell where they are. It would not appear that they matter one whit anyway.

The rod builder need not use any special consideration when considering where to locate guides on any well designed rod blank. The manufacturer has seen to it that there will not be a problem. If any special consideration was needed, the manufacturer would have specified such.

We are getting knee deep in gobledegook.

Good rod blanks are designed so that high stress points do not occur to the extent that the blank would be put in danger during the intended use. And yes, computer stress modeling software is used in the design of most modern blanks. For this reason, it is a non-issue for the custom rod builder.

Poor designs fail quickly and are either removed from the market or redesigned.

No amount of careful guide location will prevent an inherently bad blank from failure nor will anything short of terribly poor guide number and location cause a well designed blank to fail.

.............

Absolutely right Bill
The stress management in those cases is by manufacturers choice of material to better handle the stress involved.
Its a significant point in highlighting the issue of stress and its cause in Carbon fibre blanks with high modulus which comes at the compromise of lower compression capabilities.
Kudos to those manufacturers who are not chasing the bandwaggon of marketing hype in high modulus materials for every application...............its horses for courses.
The anglers ( and custom rodbuilders ) of course have to recognise the right blank & material it is made from to make the correct choice for the particular application.
Some do and some don't.
a lot get sold on the hype of light weight & high modulus without an understanding of the risk involved.

As a result of its very nature carbon fibre always fails with a sound like a gunshot............... it rarely splinters it catastrophically & instantly fails under excess stress.
The indicator of shock loads is typically a break in multiple places as you rightly point out.
A single break is typically an indicator of something else in stress management.

I recently did an analysis of a very highend blank that failed , but not from misuse , a single break between stripper and the next guide forward, not the place you normally see breaks, the images of the break was a good example of the mechanism of fracture in C/F blanks.
He He..................this was a heavy wall blank.................the 'gunshot' was very, very, very loud............ He He.

St Croix has a nice little flash "virtual tour" of their factory.
I see some 3D modelling and some dynamic repetitive stress testing, but no mention of CAE or FEA for predicting stress etc as a tool in the actual design process. Likewise no mention of any such method on batson, loomis etc.
Personally I think such a program would be largely a waste of time and a massive expense which ultimately requires you go build a blank and test the thing the "old fashioned way"
It would cost far less to build a prototype and manually test it that to model it electronically.
Some time back I was tasked with designing a test procedure for determining the effect of fitting bullbars on vehicles and their interaction with the vehicle airbag system.
We looked at the various FEA options and determined that when you added it up the cost of the product plus the cost of the engineers and computer techs to run it, it was cheaper to build the thing and smash it with a huge pendulum. Which is exactly what we would have to do in order to prove any theoretical design anyway.
I know that there are lots of reasons why manufacturers would be coy about revealing their methods, but technological advantages are usually exploited by marketing to the fullest extent, regardless of their real world benefits.
It would be really great to hear from a couple of the blank manufacturers if the cost vs benefits of FEA for non linear structures has indeed progressed to the point that it is a viable solution.

I reckon with current production techniques and materials it seems like using a sledge hammer to crack a nut.


Found this information that may interest some.

[books.google.com.au]



Edited 1 time(s). Last edit at 07/10/2009 10:52PM by Owen Dare.

Further searching has revealed that E21 carrot stix did use FEA in the design process. They claim it to be a first (but don't say if it's an industry first, or a first for them).

Great stuff Owen
the bit that really interested me was the subject of the preceeding paper to the one you linked to. i have a meeting in a month critiquing a Resource MSE ( Management of Sustainability Evaluation) tool here in Oz for species managed by an AFMA MAC ( Resource assessment Group Review ).
Lucky post for me...............appreciated................. I have saved the link to read that article in depth next week................ might be useful, might not............... I have a reasonable understanding of the parameters involved, but always willing to learn.

In regards to the article link you provided
The classical deflection diagram in 2.1 is a large part of the reason the paper is so complicated as they have to resolve the parameters they have described to try to get to the real force parameters, this affects their estimation of the actual bending moment parameters and calculation.
Fig 3.1 is a ripper..........explains the key elements of sensitivity in rod elevation and their effect on deflection .............if you know what you are looking at.
the concept of 3.17 is interesting............. other authors of similar stuff suggest a different power ratio of sensitivity, if I interpret the different approaches correctly.
the density concept in 3.23 is somewhat negligible in a fishing rod ( but understand why they went there in their model ).

Table 3.1 is a beauty and has relevance to vertical displacement concepts of CCS and their sensitivity.............enables one to understand the sensitivity of things like ERN
and the necessary concepts needed to relate things like the real power difference for rods of significantly different tapers, rather than directly relating them from ERN...... but it still only gives a part of the story as the ERN is related to a fixed comparative deflection and table 3.1 is a fixed force and variable deflection.
Again the modeler would have been simpler in his table if "r" was not defined in such a complex way.

Another good background paper is the Team 5 Report to the 2006 International Conference on Engineering Modeling.................which reports on fishing rods too..............very heavy on the integration maths.

Two problems with this stuff for rodbuilders
- the ability to understand the language
- recognition whether the objective of the report or issues it contains are relevant to the object of the quest of the rodbuilder interrogator.

20 pages or so of integration formulae development condense to my first diagram in my post on tip load bending moments, which is a simple way to look at it...............and a much simpler integration formula into the bargain............( that formula has been validated against a real fishing rod to 2% accuracy, too , its not just maths theory manipulations)
Compare the approach taken at 2.1 to the diagram and parameters for tip load bending moment with the approach taken in my equivalent diagram
From memory the validation error in bending moment using (l-i ) was greater than 10% , whereas with the the effective lever length and load angle approach the validation error is 2%
This is the sort of stuff modelers live or die over....................this paper was in trouble from its first parameter identification.

NONE of any of the reports I have read on fishing rod deflection relate to deflection forces from line tension on the guides .............they use pure beam theory unaffected by guides and line in their approach........... nor do they recognise in a real rod that whilst the deflection is cumulative the stress forces between guide pairs is not cumulative outside those pairs.
That issue kind of screws up the use of a single integration formulae for stress interrogation for a fishing rod.and results in a complex integration string to do the job properly.

Note the authors closing comment that " their NEXT work is applying their theory to fishing rods "................ at least the Team 5 stuff provided a validation of their model to a real rod blank and enabled the assessment of their correlation errors & why that might have been the case.

Nice Post Owen...........keep up the good work.

Have seen the reference to the FEA application in the Carrot Stix publicity info a while back.....................now that would be a really interesting report to review in relation to the carrot fibre content and the core of those blanks......................... probably commercial 'in Confidence' info never to see the light of day...................... maybe yes or maybe no. If the FEA Analysis information was available publicly , I for one, would be very interested in reviewing it.



Edited 1 time(s). Last edit at 07/11/2009 08:18AM by Denis Brown.

This is just a continuance of the quest to build a better rod.
My problem is I've no first hand knowledge of rod breakage. Just been lucy for 55 years.
The math for absolute values is daunting and I would not attempt a full analysis on every blank I build. I've done 3-D modeling and FEA on simple rod blanks, both straight taper and polynomial but the assumptions made by the meshing engines is not up to the task IMO. I'm not proposing these tools, as they are not at the required maturity level, yet. They do show trends which can be applied.

I'm somewhat shocked that people would consider rod manufacturers as behind in engineering technology. To produce this volume of product at the price and quality levels they achieve speaks well of their engineering prowess. I believe they have done enough destructive analysis to know exactly where the high stress points in their products exist. They rate their blanks below these levels but can not eliminate their existance. St Croix's adoption of IPC (Integrated Polynomial Curve) is an excellent tool for minimizing and distributing stress. ART (Advanced Reinforcement Technology) is another tool to add material selectively to high stress areas. These high stress areas are still present but material has been added to raise the failure point above blank rating.
I also believe their guide selection and placement is not random but placed to work with these known weaknesses.

We start our build with their product and should attempt to make it better for our customers. We can add, subtract or change location of guides. We can change hardware components to match our customers requests. This in itself does not mean we improved it by just the "laying of hands".

Owen
Good leads. Thanks.

Denis
"NONE of any of the reports I have read on fishing rod deflection relate to deflection forces from line tension on the guides .............they use pure beam theory unaffected by guides and line in their approach........... nor do they recognise in a real rod that whilst the deflection is cumulative the stress forces between guide pairs is not cumulative outside those pairs.
That issue kind of screws up the use of a single integration formulae for stress interrogation for a fishing rod.and results in a complex integration string to do the job properly. "

Relavent observation and entirely correct


My only purpose is to find a quick and relatively easy to locate these "mines". Given the choice to walk around the mine field by arbritarily placing additional guides and using the law of averages and the blank manufacturers safety factor is not progressing, but defeatist. I've several more blanks to check before submission of data.

There is only one way to prevent stressing a rod blank - don't bend it.

Rod blanks are designed and constructed to handle the stress that results from using it in a normal fishing situation. If you use an adequate number of guides spaced reasonably well, you will not undermine the design nor construction of the blank.

............