Writing VUMAT/UMAT

Hi all,

I was wondering if anyone could provide some guidance on writing the following VUMAT /UMAT or have anything similar that I can modify;

I would like to define a material for ABAQUS that has the following properties; the material is elastic and isotropic and does not have any inelasticity performance;

1. Elastic properties to be defined are; Modulus of elasticity (E), Poisson’s ratio (v) and an ultimate TENSION strain value.
2. The material is isotropic and elastic. Under any state of applied loading, any finite element that reaches the specified ultimate tensile strain value must be considered failed.
3. At this stage, ABAQUS is expected to continue the analysis without the element that has failed but with the consideration that there is a geometrical change in the structure modelled (meaning the element does not strain further or take any stress. It is not accepted to set the modulus of elasticity to zero only). The analysis continues in search of another element that would reach the tension strain value and remove it.
4. This process continues until the modelled structure fails or cannot take any more loading.

I have attached a stress-strain relation of the material. 

Any help would be very much appreciated.

Many thanks

Hussam