Carbon fiber tube resistance for portaledge

[Annabelle]

Hi,

I am building a portaledge (hanging bed to sleep on a big wall when climbing) with a structure made of carbon fiber tubes and I'm trying to find out the least diameter so a 1,2m tube can resist to a 150kg mass in it's center. My main concern besides resistance its weight. I was thinking of 20x16mm.

Thanks for your help!

Annabelle 

[John Kimball]

4 hours ago, Annabelle said:

Hi,

I am building a portaledge (hanging bed to sleep on a big wall when climbing) with a structure made of carbon fiber tubes and I'm trying to find out the least diameter so a 1,2m tube can resist to a 150kg mass in it's center. My main concern besides resistance its weight. I was thinking of 20x16mm.

Thanks for your help!

Annabelle 

The basic response to this question is, The bigger the diameter and the thicker the wall, the stiffer the tube becomes. 150kg is not a light load, and loading only in the center makes is more difficult. Also assuming that the load will never be truly static as the person will be shifting weight and possibly bouncing a bit, the load could be more than that momentarily. If you have an aluminum tube that works, you can simply replicate it with carbon fiber and it will perform better and will be 2x lighter. As this a potentially life critical situation, we don't want to recommend or tell you what will work. We do recommend that you do some physical testing to ensure that the tube you choose will work in a dangerous situation. 

[Annabelle]

Hi, thanks for you answer. 

For information the braking of a tube would never be life threatening as the safety in assured by a harness at all times (I'm a climbing teacher). The existing portaledges are made  of 30x28mm aluminium tubes.  

[lo_0l]

On 3/25/2023 at 12:26 PM, Annabelle said:

Hi, thanks for you answer. 

For information the braking of a tube would never be life threatening as the safety in assured by a harness at all times (I'm a climbing teacher). The existing portaledges are made  of 30x28mm aluminium tubes.  

 

Good to know @Annabelle! We just want to keep everyone safe 🙂

When/if you do buy some carbon fiber please be sure to grab it somewhere reputable. Some of carbon fiber out there isn't the best quality.