## General Mechanical

#### Contact Tool Solution (Gap vs. Penetration)

• Diane
Subscriber

Hello,

I am working on a 2D model ( shown below) and I am using the Contact Tool Solution to detect the point at which 2 edges initially touch each other (space between two surfaces becomes zero at any location). The contact between the 2 edges is "Frictional" with a pinball radius allowing the initial contact status to be "Near Open".

• Govindan Nagappan
Ansys Employee
Hi @Diane nIn a Gap plot, a negative number represents gap and value 0 is displayed if there is penetration.nIn a Penetration plot, a positive number represents penetration and value 0 is displayed if there is gapn See help link: https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v202/en/ans_elem/Hlp_E_CONTA174.htmln In help section, for contact 174 element, check the Table 174.2: CONTA174 Element Output Definitions n nn
• Gary Stofan
Ansys Employee
Hi DianenLook up Contact Formulation Theory in the Ansys Mechanical Applications Help.nGap is geometric gap. Negative value is a wide gap. The value approaches 0 as the bodies become closer. It may not hit exactly 0. The contour plot might make this a bit more clear. nPenetration:The default Program Controlled contact type is Augmented Lagrange. As the gap approaches 0, penetration will begin to have a small positive value near where the initial contact is occurring. As long as the Penetration value is small or negligible, the result will be accurate.help/wb_sim/ds_contact_theory.htmlnA few tips:nNever use an artificially large pinball to bridge a large gap, as if modeling a geometry that isn't there. Large pinball can cause erroneous reaction forces.nIn your case above, it is not necessary to manually set a larger pinball. The contacts should detect properly with the default value.n
• Diane
Subscriber
Thank you Gary and ! This was very helpful. n