RamboRich wrote:I am a structural engineer for an aircraft company. I use FEA and hand analysis methods for the design of wing structure. Here are my thoughts: The flex rating is a measure of the linear stiffness of the pole (beam). It is calculated by the use of classical beam bending theory (Mc/I). It is a very simplified approximation of a beam. This method is only valid for linear behavior, or in other words it assumes linear behavior. The method will be very good provided that the deflections of the pole are very small. This is not the case with a pole vault pole. This is one reason why poles of the same flex rating can feel different. The large pole deformations experienced coupled with a time dependent loading function cause pole dynamics to be very difficult to simulate with any analysis method including FEA.
I would argue that the best and most economic solution for rating the stiffness of poles is test data. I believe that some of the pole manufacturers bend each pole tip-to-tip dynamically.
Analysis of a bending pole tip to tip would not emulate the bending of the pole by a vaulter! So you are correct the info you get here is really worthless. see this page for how we bend and test poles! http://www.xlogicsports.com/home/ Then select sport staff
RamboRich wrote: These large deformation tests provide the most realistic and useful data. Now provided that test data is collected, it is possible to establish an analysis method that correlates to the test data. Once this correlation model is made, all subsequent pole stiffness could be predicted very accurately. However, if the composite layup is modified (sail pattern changed, or ply angle changed) then the model is no longer valid. This is why it is very difficult to compare the pole performance between two manufacturers. One could get a great comparison if a manufacturer wanted to spend the time and money to purchase and test other brands. This would provide a common standard for comparison. Some reverse engineering may also have to be used to determine the layup of the tested poles. Testing is also very good because it will include any variation in the manufacturing process which is very important with composite materials.
You are correct again and frankly I was never interested in reverse engineering others poles and spend over $200,000 to copy others ideas that for years seem to hold athletes back! For years one company led you to believe that their pole came back faster than any other pole out there! They had a machine to show you in demos and company tours their device lifted a 100lbs weight and threw it hight in the aaaaaaaair faster than my pole! They were telling the truth their pole did come back fast, too fast, and for years you saw vaulters clear heights by 2-3 feet over the bar and they come down on the bar! As a result you opened the door to cheating with vol-zing and moving the bar out of the way and steadying it to clear the bar til it was banned.
You will feel the ESSX pole lift you over the bar with penetration to clear the bar and you will not get the action of too much return common in improperly made CARBON POLES! Using Carbon to stiffen the pole and reduce some weight is wonderful but to use the CARBON to make the pole return fast destroys the concept of the double Pendulum needed to jump very high!
If one maintains consistency in the formulas such as distance between short side of sail and butt is correlated throughout the line as a comparable and relative to the length of the pole. Your response confirms what I am trying to say all perimeters must be mathmatically consistant and changing the process will change the line unless it is part of the structure of the line's concept!
And that the sail wraps are set to be the same wraps of hoop and body wraps combined, then you will have a line that has been formulated and the vaulting process has been maintained throughout the whole line (10'8" the exception) Then adding a carbon stiffness that has specific width and gaps measured mathematically and determined by the diameter of the manderel and the relative to the poles stiffness position, wraps, types of glass, then again you have knowledge input and knowledge of the vaulting process, the pole making process, the stiffness of the pole relativity process, and engineering! FEA software if used properly, not just a tool to find stiffness but properties up and down the pole inside the pole and its reaction to stress, tensile strength, and modular compression.
Other words something no one else has, a properly engineered pole!
RamboRich wrote:"FEA Finite Element Analysis allows one to build computer model of a pole and calculate the strands needed every 0.001mm one could if you had the time measure in nanometer. This finite structure can be built for function and performance without failure and best when you have the program model made by an engineer who understand the pole vault , and a World record holder and myself who has studied the pole vault for many years all calculating the needs for the vaulters."
In my opinion FEA (no matter who the user is) will not solve the issues of designing poles and assigning flex ratings that compare with different manufacturers. This is because an analysis is only as good as its assumptions. In my mind the only way to see how 'stiff' a pole really is.. is to jump on it. IMO
Yes you are correct if you do not know anything about pole making, carbon, or vaulting! But I had two engineers one in carbon composites the other from NASA, Earl Bell, and myself all establishing the input properties and formulas needed to form a complete line starting over not using any thing I had seen or learned in pole patterns before. (nanometers can be established within math equations, that is why it is called finite and often rounded up grin)
So for the third time in the post I will again agree with you
the only way to see how 'stiff' a pole really is.. is to jump on it.
Call it radical, call me the RENEGADE POLE DESIGNER but this system works really well and you will never know unless you try the poles.