ansys formula for initial surface-to-surface contact stiffness

RD
Robert Dillworth
Mon, Jul 15, 2024 5:56 PM

Does anyone know the formula that ANSYS uses for its initial choice of surface-to-surface contact stiffness?  I know the program changes contact stiffness as a solution advances, but there's some choice made to start out with, and I don't remember the formula for calculating it.  I have a written documentation at the office (could be an old xansys post), but I'm working remotely all week, so I can't look in my file cabinet.  As I recall, it involved both the depth of the particular contact pair (calculated by ANSYS) and Young's modulus of the material on which the contact elements reside, but I don't remember whether there might be a nondimensional factor.

Anyone?

Robert Dillworth, PE
Principal Engineer
T.: +1 212 233 2737 x966
Robert.Dillworth@socotec.us
SOCOTEC Engineering, Inc
151 W 42nd Street, 24th Floor
New York
, NY 10036
www.socotec.us

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Does anyone know the formula that ANSYS uses for its initial choice of surface-to-surface contact stiffness? I know the program changes contact stiffness as a solution advances, but there's some choice made to start out with, and I don't remember the formula for calculating it. I have a written documentation at the office (could be an old xansys post), but I'm working remotely all week, so I can't look in my file cabinet. As I recall, it involved both the depth of the particular contact pair (calculated by ANSYS) and Young's modulus of the material on which the contact elements reside, but I don't remember whether there might be a nondimensional factor. Anyone? Robert Dillworth, PE Principal Engineer T.: +1 212 233 2737 x966 Robert.Dillworth@socotec.us SOCOTEC Engineering, Inc 151 W 42nd Street, 24th Floor New York , NY 10036 www.socotec.us ​ Consider the environment before printing this email This e-mail may contain confidential, copyright or privileged information. If you are not the intended recipient or if you have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden. ​ SOCOTEC cannot guarantee the integrity of this communication. As the Internet is not a guaranteed secure environment, SOCOTEC cannot ensure that an e-mail is not interfered with during transmission, as such will not be held responsible for any damage from e-mail transmission.
JM
Joe Metrisin
Mon, Jul 15, 2024 6:04 PM

Hi Robert,

Here's an Email from 2008 by Rod Scholl.

-----Original Message-----
From: xansys-bounces@xansys.org [mailto:xansys-bounces@xansys.org] On Behalf Of Rod Scholl
Sent: Friday, September 19, 2008 9:08 AM
To: 'ANSYS User Discussion List'
Subject: Re: [Xansys] what value for FKN?

Jerome,

I guess I meant to do a focus blurb on this, but forgot:


Contact stiffness = FKN * E / (Thickness/20)

So its E divided by 1/20th the element depth.  Remember that the presense of plasticity reduces this by a factor of 100.

It doesn't depend on element area (which makes sense given the units of psi).


I have a test script used in this investigation: below

Rod Scholl
Specialist Engineer, Analysis
Phoenix Analysis & Design Technologies
612-605-6894
602-218-5391 (AZ Toll Free)
Rod.Scholl@padtinc.com
http://www.padtinc.com

Joseph T Metrisin
Structures Lead

Florida Turbine Technologies, Inc a KRATOS Company
1701 Military Tr. Suite 110 | Jupiter, FL 33458 USA
+1 (561) 427-6346 Office | +1 (772) 834-4156 Mobile
Joe.Metrisin@kratosdefense.com

We are hiring; Join the FTT Team in Jupiter, Florida
Visit our website: https://kratosdefense.com

Confidentiality Note:
The information contained in this transmission and any attachments are proprietary and may be privileged, intended only for the use of the individual or entity named above. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited.  If you received this communication in error, please delete the message and immediately notify the sender via the contact information listed above.

-----Original Message-----
From: Robert Dillworth via Xansys xansys-temp@list.xansys.org
Sent: Monday, July 15, 2024 1:57 PM
To: XANSYS Mailing List Home xansys-temp@list.xansys.org
Cc: Robert Dillworth Robert.Dillworth@socotec.us
Subject: [External] - [Xansys] ansys formula for initial surface-to-surface contact stiffness

CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.

Does anyone know the formula that ANSYS uses for its initial choice of surface-to-surface contact stiffness?  I know the program changes contact stiffness as a solution advances, but there's some choice made to start out with, and I don't remember the formula for calculating it.  I have a written documentation at the office (could be an old xansys post), but I'm working remotely all week, so I can't look in my file cabinet.  As I recall, it involved both the depth of the particular contact pair (calculated by ANSYS) and Young's modulus of the material on which the contact elements reside, but I don't remember whether there might be a nondimensional factor.

Anyone?

Robert Dillworth, PE
Principal Engineer
T.: +1 212 233 2737 x966
Robert.Dillworth@socotec.us
SOCOTEC Engineering, Inc
151 W 42nd Street, 24th Floor
New York
, NY 10036
https://urldefense.com/v3/http://www.socotec.us;!!KM6X6ZXWXVtZMQ!aJiYxAmoUQSrh-BYBb7laYdvyh0jsZOJQb3ktV2NkRIuQGdDRGgY_FpNrbSver3fBDfqrzDBwxBDow_eGB47yHrGzQ$

Consider the environment before printing this email This e-mail may contain confidential, copyright or privileged information. If you are not the intended recipient or if you have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden.

SOCOTEC cannot guarantee the integrity of this communication. As the Internet is not a guaranteed secure environment, SOCOTEC cannot ensure that an e-mail is not interfered with during transmission, as such will not be held responsible for any damage from e-mail transmission.

Hi Robert, Here's an Email from 2008 by Rod Scholl. -----Original Message----- From: xansys-bounces@xansys.org [mailto:xansys-bounces@xansys.org] On Behalf Of Rod Scholl Sent: Friday, September 19, 2008 9:08 AM To: 'ANSYS User Discussion List' Subject: Re: [Xansys] what value for FKN? Jerome, I guess I meant to do a focus blurb on this, but forgot: **** Contact stiffness = FKN * E / (Thickness/20) So its E divided by 1/20th the element depth. Remember that the presense of plasticity reduces this by a factor of 100. It doesn't depend on element area (which makes sense given the units of psi). **** I have a test script used in this investigation: below Rod Scholl Specialist Engineer, Analysis Phoenix Analysis & Design Technologies 612-605-6894 602-218-5391 (AZ Toll Free) Rod.Scholl@padtinc.com http://www.padtinc.com Joseph T Metrisin Structures Lead Florida Turbine Technologies, Inc a KRATOS Company 1701 Military Tr. Suite 110 | Jupiter, FL 33458 USA +1 (561) 427-6346 Office | +1 (772) 834-4156 Mobile Joe.Metrisin@kratosdefense.com We are hiring; Join the FTT Team in Jupiter, Florida Visit our website: https://kratosdefense.com Confidentiality Note: The information contained in this transmission and any attachments are proprietary and may be privileged, intended only for the use of the individual or entity named above. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited. If you received this communication in error, please delete the message and immediately notify the sender via the contact information listed above. -----Original Message----- From: Robert Dillworth via Xansys <xansys-temp@list.xansys.org> Sent: Monday, July 15, 2024 1:57 PM To: XANSYS Mailing List Home <xansys-temp@list.xansys.org> Cc: Robert Dillworth <Robert.Dillworth@socotec.us> Subject: [External] - [Xansys] ansys formula for initial surface-to-surface contact stiffness CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe. Does anyone know the formula that ANSYS uses for its initial choice of surface-to-surface contact stiffness? I know the program changes contact stiffness as a solution advances, but there's some choice made to start out with, and I don't remember the formula for calculating it. I have a written documentation at the office (could be an old xansys post), but I'm working remotely all week, so I can't look in my file cabinet. As I recall, it involved both the depth of the particular contact pair (calculated by ANSYS) and Young's modulus of the material on which the contact elements reside, but I don't remember whether there might be a nondimensional factor. Anyone? Robert Dillworth, PE Principal Engineer T.: +1 212 233 2737 x966 Robert.Dillworth@socotec.us SOCOTEC Engineering, Inc 151 W 42nd Street, 24th Floor New York , NY 10036 https://urldefense.com/v3/__http://www.socotec.us__;!!KM6X6ZXWXVtZMQ!aJiYxAmoUQSrh-BYBb7laYdvyh0jsZOJQb3ktV2NkRIuQGdDRGgY_FpNrbSver3fBDfqrzDBwxBDow_eGB47yHrGzQ$ ​ Consider the environment before printing this email This e-mail may contain confidential, copyright or privileged information. If you are not the intended recipient or if you have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden. ​ SOCOTEC cannot guarantee the integrity of this communication. As the Internet is not a guaranteed secure environment, SOCOTEC cannot ensure that an e-mail is not interfered with during transmission, as such will not be held responsible for any damage from e-mail transmission.