## General Mechanical

Topics relate to Mechanical Enterprise, Motion, Additive Print and more

#### friction forumulation in ansys: Exponential friction decay

• Pranshu Kharbanda
Subscriber

Hi,

Based on ansys contact technology guide (section 3.9.5), I understand that the friction formulation in ansys is based on Columb friction. In transient analysis, only one coefficient of friction can be defined (unlike explicit dynamics). So, I created a transient analysis linked to explicit dynamics workbench as shown below. allowing me to input the friction coefficient for dynamic and static, decay coefficient.

As I wanted to simply test this friction formulation, i tried to simulate a block sliding example. However, I got the following graph for friction stress vs relative velocity.

I am unable to see the friction decay, as I was expecting to see based on Figure 3.12 in contact technology guide.

If anyone has any insight regarding this, it would be really helpful. Kindly advise what could be the error here.

Thanks.

• Akshay Maniyar
Ansys Employee

Hi Pranshu,

A command snippet needs to be added in the contact definition to define a frictional contact with both Static and Dynamic frictional coefficients. We need to specify the two Real constants FACT (Static/dynamic ratio) and DC (Exponential decay coefficient) with APDL commands. Please check the below knowledge material for more details.

Example of Static and Dynamic friction coefficient definition in Workbench. - Ansys Knowledge

Thank you,

Akshay Maniyar

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• Pranshu Kharbanda
Subscriber

Hi Akshay,

thanks a lot for this information. it worked :)

any chance you would also happen to have insight about further modifying this snippet such that the friction coefficient can be defined as function of relative velocity after the decay from static to dynamic, as shown below. That is, the viscous friction part where coefficient u = K*Vrelative

Thank you.

• Akshay Maniyar
Ansys Employee

Hi Pranshu,

Glad to know that it worked for you.

Can you please check the below knowledge material and see if it helps you in your follow-up query?

How to define frictional coefficient as a function of relative sliding velocity - Ansys Knowledge

Thank you,

Akshay Maniyar

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• Pranshu Kharbanda
Subscriber

Hi Akshay,

My apologies for the delayed response, I was trying the earlier snippet.

Thanks for this, I will embed and try this one too. Let you know how it goes! Thnks again