---
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]]"
source_refs:
  - source: "[[Midas-NFX-Analysis-Manual|Midas NFX Analysis Manual]]"
    raw_path: ".raw/MidasNFXAnalysisManual/"
    raw_files:
      - "MidasNFXAnalysisManual_001.md"
    md_indices:
      - 1
    match: "heuristic-heading-keyword"
    confidence: low
---

# 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.