---
type: concept
title: "Abaqus Matrix-Based Model Definition"
complexity: advanced
domain: computational-mechanics
created: 2026-05-29
updated: 2026-05-29
address: c-000075
aliases:
  - Abaqus matrix input
  - matrix-based model definition
  - Abaqus matrix assembly
tags:
  - concept
  - finite-element-method
  - abaqus
  - matrix-assembly
status: current
related:
  - "[[Abaqus-Analysis-User-s-Guide-Volume-I|Abaqus Analysis User's Guide Volume I]]"
  - "[[Abaqus-Analysis-User-s-Guide-Volume-II|Abaqus Analysis User's Guide Volume II]]"
  - "[[Abaqus Matrix Generation and Reduced Models]]"
  - "[[Direct Stiffness Method]]"
  - "[[Static Equilibrium Equation Solvers]]"
  - "[[Direct Time Integration Methods]]"
  - "[[Finite Element Program Implementation]]"
sources:
  - "[[Abaqus-Analysis-User-s-Guide-Volume-I|Abaqus Analysis User's Guide Volume I]]"
  - "[[Abaqus-Analysis-User-s-Guide-Volume-II|Abaqus Analysis User's Guide Volume II]]"
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---

# Abaqus Matrix-Based Model Definition

## Definition

Abaqus matrix-based model definition is the use of directly supplied stiffness, mass, viscous damping, or structural damping matrices as part of an Abaqus/Standard model.

## How It Works

The guide describes named matrix input in text or SIM form. A matrix can be symmetric or unsymmetric, scaled, and assembled into the analysis model through shared nodes or explicit node remapping. Matrix-based components can represent a model part when the analyst already has a linearized matrix description from another source or from a previous analysis.

Matrix assembly connects matrix-represented regions to conventionally meshed regions. In nonlinear analyses, the supplied matrix contribution remains linear; the surrounding model can still undergo nonlinear material, contact, or geometric response depending on the procedure and connected elements.

Volume II adds the complementary generation workflow: Abaqus/Standard can generate stiffness, mass, damping, and load matrices in a linear perturbation step and write them to SIM or text files for later Abaqus input or external software.

## Why It Matters

Matrix input exposes the algebraic layer of finite element analysis. It connects production [[ABAQUS]] modeling to [[Direct Stiffness Method]] ideas: element or component contributions become matrices that are assembled into global static or dynamic equations.

## Connections

- [[Static Equilibrium Equation Solvers]] solve stiffness-based systems that matrix input can contribute to.
- [[Direct Time Integration Methods]] can use mass and damping matrices in transient dynamics.
- [[Finite Element Program Implementation]] explains the matrix assembly and global equation context behind this feature.
- [[Abaqus Matrix Generation and Reduced Models]] covers the export side of the same matrix-based workflow.

## Sources

- [[Abaqus-Analysis-User-s-Guide-Volume-I|Abaqus Analysis User's Guide Volume I]]
- [[Abaqus-Analysis-User-s-Guide-Volume-II|Abaqus Analysis User's Guide Volume II]]