Hello Devorshi Bhattacharjee ,

After you import the whole orphan mesh (including yarn and matrix together) to Abaqus, you can separate 'yarn' and 'matrix' by defining different sets and assigning different materials for them. Thus, you won't need to define any contact between 'yarn' and 'matrix'.

Best regards

Devorshi Bhattacharjee , how did you separate yarn and matrix before? You can do it in the same way. By looking these parts, you can select the related elements and create a set in Abaqus. Then, you can assign the related material property for the set.