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+---
+type: concept
+title: "Midas NFX Element Library"
+created: 2026-06-02
+updated: 2026-06-02
+address: c-000175
+aliases:
+  - NFX element library
+tags:
+  - concept
+  - finite-element-method
+  - midas-nfx
+  - elements
+status: current
+related:
+  - "[[Midas-NFX-Analysis-Manual|Midas NFX Analysis Manual]]"
+  - "[[midas NFX]]"
+  - "[[Isoparametric Finite Elements]]"
+  - "[[Abaqus Element Library]]"
+  - "[[Midas FEA Element Library]]"
+  - "[[Midas Civil Element Library and Section Stiffness]]"
+sources:
+  - "[[Midas-NFX-Analysis-Manual|Midas NFX Analysis Manual]]"
+---
+
+# Midas NFX Element Library
+
+## Definition
+
+The NFX element library is the collection of structural, field, rigid, interpolation, and joint element formulations documented in the [[Midas-NFX-Analysis-Manual|Midas NFX Analysis Manual]].
+
+## Structural Coverage
+
+The library includes scalar spring/mass/damper elements; one-dimensional rod, embedded rod, bar, embedded bar, pipe, cable, bush, and gap elements; two-dimensional membrane, shell, surface, plane strain, and axisymmetric solid elements; and three-dimensional solid, layered shell, and layered solid elements. The manual also covers geometric stiffness for rods, bars, pipes, membranes, shells, axisymmetric solids, solids, springs, bushes, rigid elements, and contact conditions.
+
+## Formulation Details
+
+The manual starts from variational finite element formulations and shape functions, then describes element-local coordinates, material/result coordinate systems, DOFs, stress/strain/result locations, integration choices, stabilization, reduced integration, assumed natural strain behavior, hybrid variants, drilling DOFs, offsets, and through-thickness integration. Shell elements are especially explicit: membrane forces, bending moments, transverse shear forces, top/bottom/center result locations, director vectors, and optional 5-DOF or 6-DOF behavior are treated as separate implementation choices.
+
+## Field Elements
+
+NFX thermal elements reuse the structural mesh topology but switch nodal DOFs to temperature and produce heat flux and thermal-gradient output. Joule heating adds electric potential as a coupled field, current-density results, electric potential gradients, and nonsymmetric coupled matrices.
+
+## Solver Development Use
+
+For a custom solver, this page separates element taxonomy from element implementation. Each element family should specify interpolation, DOF set, local coordinate system, integration rule, stiffness/mass/capacitance contributions, geometric stiffness availability, load conversion, result recovery, and nonlinear-state support.
+
+## Connections
+
+- [[Isoparametric Finite Elements]] gives the shared interpolation framework.
+- [[Abaqus Element Library]] provides a broad commercial element-family comparison.
+- [[Midas FEA Element Library]] and [[Midas Civil Element Library and Section Stiffness]] are sibling MIDAS element references.