Kevlar creep

[Muzialis]

Hi All,

I was wondering if anybody could help with regards to the following matter.
Assuming experimental data (static load vs time to failure) for a kevlar fibre are available is there any evidence / research suggesting the possibility of a cumulative calculation in the fashion of Milner's rule?

In more detail, if the time spent under each load is known (discretely using load intervals or in form of a continuos distribution), the idea is as follows:
- per each load, calculate time effectively spent under the load / time to failure ( similarly to what is done for damage in a fatigue calculation for a metallic component)
- sum all the partial contributions and should the sum be < 1 this would support the capability of the cord to resist the loading history.

I am rather optimist as modelling the fiber with linear viscoelasticity gives good correlations and this somehow builds confidence, but a paper or an opinion from a more experienced polymerfem-er would be greatly appreciated.

All the best

Muzialis

[Jorgen]

I am curious, are you interested in single Kevlar fibers, or fibers in a resin matrix?

I think that your approach is also likely suitable for polymers - at least to first order. I suggest that you give it a try and let us know how it goes.

- Jorgen

[Muzialis]

Jorgen,

thanks for your interest.

The idea refers to single Kevlar fibers, with the intent of trasferring it later to the composite.

We are very likely to try it and I would certainly let you know.

Have a very fine weekend

Muzialis