# How to use gridap topology optimization while using 2 governing equations

**URL:** <https://discourse.julialang.org/t/how-to-use-gridap-topology-optimization-while-using-2-governing-equations/99017>\
**Category:** General Usage\
**Tags:** question, package, diffeq\
**Created:** [May 17, 2023, 9:08pm UTC](https://discourse.julialang.org/t/how-to-use-gridap-topology-optimization-while-using-2-governing-equations/99017 "2023-05-17T21:08:22Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![mary](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mary/32/53139_2.png) [@mary](https://discourse.julialang.org/u/mary)\
**Post date:** [May 17, 2023, 9:08pm UTC](https://discourse.julialang.org/t/how-to-use-gridap-topology-optimization-while-using-2-governing-equations/99017/1 "2023-05-17T21:08:22Z")

</div>

I want to use gridap topology optimization for fracture optimization. so there is two governing equations one is for stress strain relation and the other is about fracture energy. how can i use gridap in this case? as i shoulf define matrix A and other matrices in tutorial 18 gridap.