The images below provide six different examples that can used to calculate the total deflection of the shaft and its slope. The Gerber criteria is another method that can be used to find the safety factor. The Trajectory Effect is a number we use that considers the effects of all the different elements (flex, torque, weight, etc.) Finally, it is used to control the geometry of their motion while they are rotating. The steeper landing angle led to slightly less roll-out, but the net gain was still significant. And if either Pureing or FLOing gives your customers more confidence that they will hit straighter shots, you have done the customer a good service. Next, let’s look at the 500lb weight. For a shaft that is supported on both ends you will need to create a moment diagram to find out where the greatest moment is. Figure 1: Shaft Trejectory Effect vs. Flex. The 500lb weight will always being push up on the wheel. In those cases the maximum stress will be on the surface of the shaft and is negligible at the centroid of the shaft. This paper presents a study conducted using a motion-capture system where participants hit drives with an R-flex driver shaft and a more rigid X-flex shaft. One way to measure torque is to clamp one end of the shaft and apply a constant couple-moment (turning force) to the other end. This tool will calculate the torque generated around an axis by a force applied at right angle to a lever arm of a specified length. a long pole or rod: Energy from the wheels turns the shafts and produces electricity. Others kept a similar handle lean, and did see higher delivered loft numbers with the R-flex shaft. There are different methods that can be used to solve for the safety factor, and each will produce a slightly different answer. The following article discusses in detail on how to find all of the values needed to find the endurance limit for the equation above. It is designed by Robin Arthur who crested the Grafalloy Blue all those many years ago. 1 The appearance of an overload failure depends on whether the shaft material is brittle or ductile. See Article History Work, in physics, measure of energy transfer that occurs when an object is moved over a distance by an external force at least part of which is applied in the direction of the displacement. Certainly other characteristics (accuracy, dispersion) can change as well, but 300 is decent estimate of the limit. The same thing can happen to a shaft after certain amount of cycles, normally ranging in the thousands to millions. For irons and drivers, the shaft type and its characteristics can have a significant effect on the sensation a player experiences during the swing and impact, while also influencing the launch and spin characteristics that can be achieved. If I use a shaft that is too whippy, my drives start out straight but then hook like crazy. Stiffness is related to the Young’s Modulus of the material, while strength is based off the yield strength and ultimate strength of the chosen material. As with most anything else in golf, the actual differential contribution of the shaft depends on the golfer, but for most it does have a direct influence on performance. $L$ = Length between the force and ground. Article Content Links: Shaft Materials, Shaft Layout, Torque Transmission, Calculating Static Stresses, Dynamic Stresses and Fatigue, Determining Critical Stress Locations, Deflection, Critical Speedeval(ez_write_tag([[728,90],'sbainvent_com-medrectangle-3','ezslot_0',118,'0','0'])); Generally, for most applications, steel is the most popular choice of material for shafts. With that said, low (lower, lowest) spin is a relative term and generally only relevant within a given manufacturer’s own lineup. This will allow for easier assembly of the chain or the belt. Than you need to determine what type of load the object will put on the shaft. Although shafts are typically categorized by an overall flex, there are many shaft parameters that influence the way a shaft feels and performs. To calculate the shear stress due to bending, also known as transverse shear, the following equation would be used. (Eq 16)  $\frac{nσ’_a}{S_e}+\left(\frac{nσ’_m}{S_{ut}}\right)^2=1$. MyGolfSpy, Inc. All Rights Reserved. It should be noted that this philosophy of leveraging swing characteristics is based on average behaviors across large samples of players. The second method could be to use Mohr’s Circle. The fire began in an elevator shaft and spread to the roof. Obviously you should go get fitted but a lot of the fitting carts don’t have all the particular shafts (or they have a lot of shafts, but not in all flexes) so you have to go off what a particular company thinks of the shaft. There are a number of reasons why shaft fitting is an important component of most any fitting, and something all players should consider before purchasing new equipment. Whether related to motors, pumps or any other types of industrial machinery, shaft failure analysis is frequently misunderstood, often being perceived as difficult and expensive. It is easy to see that a shaft will oscillate in a straight line in one orientation and wander all over when turned. In other words, the launch and spin from these two shafts, in general are inferred as almost identical. Copyright 2021. I’d highly recommend anyone who has been struggling with their game to get their shafts checked out to make sure they match your swing speed. Refer to the image below to see the difference between splines, keyways, pins, and set screws. Most of the loads on a shaft will be perpendicular to the shafts axis. There are so many variables, it’s really more art than science, but it’s way more important than anyone gives credit. A shaft is a mechanical part that normally has a circular cross-section. (Eq 15)  $\frac{σ’_a}{S_e}+\frac{σ’_m}{S_{ut}}=\frac{1}{n}$, $S_{ut}$ = the Ultimate Strength of the Materials. The difference being that the tip end is clamped and the load is applied to the butt end of the shaft. Now compare that to a loft change, where we see roughly a .8° change in launch angle for every degree of loft, which suggests it’s much easier to effect change though the head than with the shaft. Erik currently manages the Innovation and Fitting Science Department at PING Golf. This is a great instance of how different shafts can lead to significantly different results, even when the two shafts look similar and have similar flex codes. Safe answer is it depends on the fitter. Performance Results on Driver Shaft realignment are more significant & meaningful than a SST test on a #5 Iron. 3 a ray, beam, or streak, esp. The Flightscope launch monitor provides a shaft deflection reading that adds to the carry distance and shot dispersion data to help select the best shaft. Russ’s EI charts, similar to the one you show, are helpful when comparing shafts – bend points, overall stiffness, etc. These same players are also the only people good enough to see a difference and yes the shaft can make a big difference. A stress concentration is when the stress is amplified due to a change in the geometry. A shaft is a rotating machine element, usually circular in cross section, which is used to transmit power from one part to another, or from a machine which produces power to a machine which absorbs power. Either way though the part must pass the Langer Static criteria otherwise the part is predicted to fail statically. I am a PGA member and have played on tours in my country. It provides an axis of rotation for a variety of mechanical components fastened to it such as, sprockets, gears, pulleys, flywheels, and cams. Russ Ryden at Fit2Score/golfshaftreviews.info is routinely measuring the radial consistency of shafts from reputable manufacturers at over 99%. Take a look a bowling ball drilling layouts. He had a sense that one was performing a bit better than the other, but was not completely sure he wanted to switch from his current shaft (shaft A) to a new shaft (shaft B). A number of senior golfers just can not be made happy moving to a softer shaft even when the data is clear because “it doesn’t feel right.” Launch monitor science gives us a lot of help, but club fitting is still an art. Due to this fact you may not even need to consider that shear stress in your analysis. It is true, however, that making a shaft with lower torque can be more difficult, and as a result can lead to a more expensive shaft. I replaced my other driver head with the Adams head and made a slight weight distribution adjustment. As with anything else, fitting is key. Even though I have most of my life played to low single figures, I found as I got older and my swing speed slowed the stiff shafts were getting harder to hit consistently well. After having the player hit ten shots with each shaft while alternating clubs through the process, we spent some time looking at the results. Both metal wood and iron shafts can come in a range of weights and balance points. To meet the above criteria n must be greater than or equal to 1 if it is less than 1 then the part is predicted to fail. In the previous section, I described some of the elements that can characterize a shaft and how, IN GENERAL, varying these elements can influence ball flight. This first area that you should focus on is the outer surface of the shaft where the moment of the shaft is the greatest. The mass properties of the head (things like total mass and center-of-mass location) can change quite a bit from model to model. 2) The force component perpendicular to the radius is 8100 ∗ s i n ( 9 d e g r e e s) = 1270 N. 3) That force is at a radius of 300 mm = … Also, in the spirit of relativity, it depends on the rest of the shaft lineup. It can be viewed as the strength of a vehicle. Wonder how that affects ball flight. His club head speed was in the 95 mph range, and he hit both the Alta 55 Stiff shaft and the Tour 65 Regular shaft for comparison. The tighter impact dispersion and increased club head speed ultimately led to a decrease in dispersion landing area and greater carry distance, as seen in figures 7 and 8. Also, you should focus on areas of the shaft that have high stress concentrations that could amplify what might considered an insignificant stress into a stress that could cause failure. Very well thought out article. If two shafts have the same static flex, but one is significantly heavier, the heavier shaft will have a slightly lower frequency measurement than the lighter one. Splines are similar to keys except instead of having one point of transmission into the shaft, there are multiple points where the torque can be transmitted into the shaft. Finally, the endurance limit can used to predict the fatigue stress in relation to a certain number of cycles by using the following equations. Typically, fitters will base an initial driver shaft recommendation on a player’s swing speed and/or distance. This a normal stress due to an axial force. Typically, the geometry of a shaft is a stepped cylinder. What we see with the example fitting is similar to what was seen in the study by MacKenzie. If the force is constant, work may be computed by multiplying the length of the path by the component of the force acting along the path. The amount the shaft bends corresponds to its stiffness. The fatigue strength fraction can be found by using the following graph. Sometimes this is measured in a very similar fashion as the static-flex measurement. As a result, a player may find that one shaft works really well in one model, but another shaft works best in another model. Once you’ve solved for the Von Mises Stress you will now need to determine what the endurance limit is by using the equation below. I have used the whole range of Xcaliber shafts over the past few years and really love the SWRD. You can however derive your own equations for unique situations by either using deflection by integration or by using the discontinuity functions. For example, a Matrix Black Tie can be expected to spin less than a Red Tie, but even that can very on an individual basis depending on how each of us loads and unloads the shaft. When analyzing shafts you do not need to analyze every point of a shaft, and from the above two sections you can see that this would be daunting task to do. Fig. Just a fraction of some of the very high priced items out there.It plays as well as any shaft you want to put up against it. The shaft-head combo is extremely important to optimizing ball flight. Privacy Policy | Terms & Conditions | Contact Us | Prepared by S. B. Amirault Founder of S.B.A. Sean, explain why I would hit a regular shafted driver to “the moon” while an X stiff is on a playable trajectory if the shaft does very little…. It would be interesting to know what shafts were used in the study Erik referenced. A fourth criteria that can used is the ASME-elliptic criteria which is represented by the equation below. I do FLOing as well. It doesn’t take long and demonstrates to the buyer how important it is. So a poor swing with the “right” shaft would be better than a “good” swing with any old shaft? It is best practice to rough cut the part first, heat treat it to remove the residual stresses, than perform a finish cut on the part to reach the desired dimensions. For most machine shafts, however, analysis should be relatively straightforward. These characteristics are pretty much the easiest to measure since all that is required is a scale and a knife edge (or 2 scales). Or .003% of the weight of the club. Finally, once you know what the endurance limit is, and what you know what the Von Mises stresses are, you can solve for the safety factor. Torque is the expression of a rotational or twisting force. Static Flex: There are two methods that are typically used to characterize the overall stiffness of a shaft. 1 A long, narrow part or section forming the handle of a tool or club, the body of a spear or arrow, or a similar implement. a weight hung from a stationary point in a way that allows it to swing freely back and forth So the weight of 1 paper clip made a difference? Even though this is the case, being fit for a shaft can be extremely fun and lead to improved performance on the course. The easiest types of deflection to calculate will be the deflection due axial loading and the deflection due to torsional loading. Comparing shafts in a fitting environment and examining actual performance data is still the best-case scenario since you may not always get the results you expect. Ongoing research looks to understand and predict how players react differently to inputs such as shaft stiffness. I’ve switched to a Taylor Made SLDR Mini Driver, 12 Degrees loft with SST Pured Shaft & I’m hitting tee shots in play. It is also referred to as the moment, moment of force, rotational force or turning effect, depending on the field of study.The concept originated with the studies by Archimedes of the usage of levers.Just as a linear force is a push or a pull, a torque can be thought of as a twist to an object around a specific axis. This will result in an alternating normal bending stress and an alternating transverse shear stress on the shaft. Also, remember if you are analyzing the shear stress due to the bending moment the maximum shear stress will be present at the centroid of the shaft, while it will be negligible on the surface of the shaft. The shaft IS the performance of the club. Pins however, are the better component to use if you want a failure to occur if you expect there is a change that torque levels could become too high.