Stiffness vs orientation angle

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#1

Hi,

I’m trying to approximate the stiffness of a tube taking into account the angle of the orientation of the fibres. Can anyone point me to a relevant equation that describes the relationship. I’m guessing it’s something like the stiffness is proportional to cosine (orientation angle). I’ve found some papers that have some complex maths that I need to wade through, I’m just hoping for a general rule of thumb in the meantime.

Thanks,

Owen.

#2

Here’s a good approximation according to the rule of mixtures, classical laminate theory and the hart-smith approximation. Does this help?

#3

Perfect, thank you

#4

I you don’t mind about torque strenght of a tube, just use the fibers at 0° and 90°.
The 90° ones are there just to support against the 0° fibres to collapse because of the ovalization of the section under flex.

#5

Hi, torque is an issue so there are angled layers. I’m building bike tubes. I heard that the stiffness drops off quickly as the angle increases and was just pondering how to quantify it.