Dear Chun

I understand your problem in defining a material with different young’s modules(E). As seen in the attached figure, the E value is changed as the strain value reaches 0.25. First of all, make sure that the value of strain reaches 0.25 in your loading condition. I suggest to define a material with E=7.5, and run your analysis.Then check whether the value of strain reaches to 0.25 or not. Unless the amount of strain is less than 0.25 in the final increment, you have to use a "user subroutine" which is usually coded using a "Fortran compiler". You could find useful information about subroutines in Abaqus documentation.

As a useful guide, you can see a sample of subroutine which addresses the same issue in the following:

https://www.researchgate.net/post/How_to_update_Youngs_modulus_according_to_change_in_total_strain

If using a subroutine seems a difficult way, you can try to find different data about your sample. I guess that capsular ligament can be considered as a hyperelastic material. If it is the case, you can define your material as a hyperelastic material:

property>create material>mechanical>elasticity>hyper elastic

However, for defining a hyper elastic material you need to have extra data, and I hope you would find them in other sources.

With best regards

Use concrete material and adjust ist properties e.g. concrete Damage plasticity. May be helps

Check paper

https://link.springer.com/article/10.1007%2Fs10439-011-0315-4

and references cited there.

This document might also be helpful

http://www.mate.tue.nl/~piet/inf/trc/pdf/infmamo1d.pdf

Hyperelastic material type is probably what you will use

Dear Khar,

I didn't model material with two modulus of elasticity, but I suppose that you havevto define usef subroutine in which you have to get strain, compare it to your value (25%) and change modulus of elastivity if strain is higher. Using subroutines isn't easy especilly for new abaqus user. Try to find papers or thesis to learn if someone successfully modeled similar problem of yours.