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Balsa cores are a little tricky because the stiffness/weight ratio is high and the mass is low. Right now i'm only analyzing 5 ply all wood blades, and getting good results, but if i introduce composites then the problem gets more complex. Also, there are stiffer glues then others, and sometimes...

Ok, forget the frequency. Frequency is just the way i have to find the Young Modulus of the existing blades. Without knowing their composition all i have left it's the measured frequency, thickness and mass. With that i can calculate the approximate stiffness of the homogenized section based on...

Funny, i found kiri in 1, 1.5, 2.0, 2.5, 3, 4 and 5 mm easily and cheap but haven't found Ayous. I also bought WRC but only in 3.5 and 4 mm which is a little much for my needs. I have to get it to the right thickness but i don't have access to a thickness sander or planer. I was thinking of...

That is commom sense and i have already explained a few times along the topic: Stiffer=higher bounce=faster

How do you guy deal with the different thickness for the plies? Do you source the material in the dimensions you want or do you use a thickness sander or other tools?

Thanks Tropical. Yes, i saw that thread, in fact it's what gave me the idea to try my own analysis. For those who doubt, or don't understand, that there is a correlation between the bounce test, frequency and blade speed i suggest a couple of papers...

You are still missing the point. I'm not correlating the model to speed ratings, i'm correlating the model to existing blades which have established speed ratings and stating if they are faster or slower. And it's not a challenge, it's presented in the table above.

Ok, i have another approach. First let me remind whoever is reading that this is just an attempt to create a simple way of comparing blade speed. It's not meant to be exact and definitive. Blade speed is not a number, it's a range, it varies depending on several factors, too many to be...

Because of that i had to go buy a rubber last minute to play a tournament on saturday. On another note, i tried the B2 on the blade i made and totally changed my opinion about the rubber. It's great and it's gonna stay on the FH.

The handle on the first blade came out much better, in the second the angle is indeed steep and i forgot to account for the thickness of the rubbers. It's not uncomfortable because i mostly rest the thumb on the rubber but it could be better and it will be improved in the future. I had to use...

I think i used copydex wich is similar to tear mender. I've read somewhere that the bond as a tendecy to get stronger over time and maybe that's what happened. I didn't have problems removing the rubber on the side that was already sealed.

I think you are missing the point, the natural modes and their frequency only tell you the properties of the blade. If you excite the blade with that frequency, it will start vibrating in the shape of the corresponding mode, just like a bridge in the wind. I'm not calculating the speed, i'm just...

You might be right but i'm only looking for a simple way to predict the speed of a blade before i build it. And to understand what will happen if i increase the core thickness and reduce the other layers, things like that. So far i have modeled one blade i built and a few that i know the...

I suppose it would work, and I really doubt that it would harden the wood. First, shellac is soft, second, if applied by the "boneca" method goes in very thin layers. I just don't know if it would be very durable.

These rubbers are very fragile, especially the blue. I was removing the rubber from the DHS301 and i haven't sealed the blade yet, the rubber just disintegrated! So my advice is to seal the blade before you glue this rubber.

In a lab study you would need an external excitation to measure the natural response. In FEA the program excites the system "virtually". Also, i'm not getting in to the ball-blade interaction. I'm just calculating the fundamental modes of the blade and estimating the speed by looking at the 6th...

I have made some progress on this. I refined the mesh and sorted out the weird results i was getting with balsa cores. Just a few notes about the modelling assumptions: I'm using isotropic materials. I have found that the perpendicular stiffness is almost negligible, and using orthotropic...

I order some materials but they haven't arrived yet, so i had to use some stuff from another projects. These were mainly experiments but didn't turn out too bad, in fact the second one managed to overthrow the DHS301. I weight all the materials and calculate the density so i can calibrate the...

Yogi_bear, there a simple test you can make, just google "table tennis blade frequency". Basically you download a spectrum analyzer app, bounce the ball on the blade and see the frequency peak. There is a list of recorded frequencies for many blades. I'm basing my ratings on those findings...

I will try that. I used layered elements first because i wanted a simple way to change the parameters, with solid elements is a little bit more time consuming but i think the results will be better.