How to include damping effect in a complex eigenvalue extration??

[cyteoh09]

Hi everyone, i am doing on brake squeal using Abaqus/Standard 6.8.1 (CAE). Anyone how to include friction induced-damping in the system? I tick on "include friction induced-damping" in step complex frequency. The analysis completed without error. But the 'effective damping ratio' and 'real part' in the result is zero for all the modes.. Mean that it not included any damping in the system.. How to solve this problem without adding any material damping to the system.. waiting for help... Thanks. Regards, Cyteoh