김경종
54 lines
2.5 KiB
Markdown
54 lines
2.5 KiB
Markdown
---
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type: concept
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title: "Midas NFX Contact Analysis"
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created: 2026-06-02
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updated: 2026-06-02
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address: c-000180
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aliases:
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- NFX contact analysis
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- NFX penalty contact
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tags:
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- concept
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- finite-element-method
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- midas-nfx
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- contact
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- nonlinear-analysis
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status: current
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related:
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- "[[Midas-NFX-Analysis-Manual|Midas NFX Analysis Manual]]"
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- "[[midas NFX]]"
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- "[[Finite Element Contact Formulation]]"
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- "[[Abaqus Contact Formulations and Enforcement]]"
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- "[[Midas FEA Static Contact Analysis]]"
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sources:
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- "[[Midas-NFX-Analysis-Manual|Midas NFX Analysis Manual]]"
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---
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# Midas NFX Contact Analysis
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## Definition
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NFX contact analysis enforces non-penetration and optional tangential behavior between bodies. The manual covers general contact, rough contact, welded contact, sliding contact, breaking-weld contact, node-to-surface, surface-to-surface, single-surface, and mortar contact.
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## Contact Search and Discretization
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The source distinguishes global contact search from local projection. Contact can be detected through slave node to master segment projection, surface-to-surface integration, or mortar segment integration. It notes the usual tradeoff: node-to-surface contact is cheaper, while surface-to-surface contact is generally more accurate for contact pressure distribution.
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## Penalty Enforcement
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Normal contact force is enforced with a penalty relation based on the normal gap, with contact active when the gap becomes negative. NFX automatically computes penalty stiffness from element/material scale quantities and smooths the contact-force transition to reduce oscillation near contact onset.
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## Friction and Breaking Weld
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Tangential behavior uses a penalty relation coupled to normal contact force. The manual gives a friction yield-like condition based on tangential force norm and `mu f_C`. Breaking-weld contact maintains welded relative motion until combined normal and tangential contact force measures exceed a failure envelope.
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## Solver Development Use
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For a custom solver, this page separates contact into five testable pieces: search/projection, active set detection, normal penalty force, tangential/friction update, and tangent contribution. Each needs reference-model checks because contact errors can look like element or nonlinear-solver failures.
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## Connections
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- [[Finite Element Contact Formulation]] gives the shared FE contact formulation context.
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- [[Abaqus Contact Formulations and Enforcement]] is a commercial contact enforcement comparison.
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- [[Midas FEA Static Contact Analysis]] is the sibling MIDAS static contact reference.
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