김경종
76 lines
3.2 KiB
Markdown
76 lines
3.2 KiB
Markdown
---
|
|
type: concept
|
|
title: "Abaqus User-Defined Material Behavior"
|
|
complexity: advanced
|
|
domain: computational-mechanics
|
|
created: 2026-06-01
|
|
updated: 2026-06-01
|
|
address: c-000103
|
|
aliases:
|
|
- Abaqus UMAT
|
|
- Abaqus VUMAT
|
|
- Abaqus UMATHT
|
|
- Abaqus user material
|
|
- Abaqus user-defined material
|
|
tags:
|
|
- concept
|
|
- finite-element-method
|
|
- abaqus
|
|
- user-subroutines
|
|
- materials
|
|
- implementation
|
|
status: current
|
|
related:
|
|
- "[[Abaqus-Analysis-User-s-Guide-Volume-III|Abaqus Analysis User's Guide Volume III]]"
|
|
- "[[Abaqus User Subroutines and Utility Routines]]"
|
|
- "[[Abaqus Constitutive Integration]]"
|
|
- "[[Abaqus Material Library and Data Definition]]"
|
|
- "[[Finite Element Program Implementation]]"
|
|
sources:
|
|
- "[[Abaqus-Analysis-User-s-Guide-Volume-III|Abaqus Analysis User's Guide Volume III]]"
|
|
source_refs:
|
|
- source: "[[Abaqus-Analysis-User-s-Guide-Volume-III|Abaqus Analysis User's Guide Volume III]]"
|
|
raw_path: ".raw/AbaqusAnalysisUserGuide3/"
|
|
raw_files:
|
|
- "AbaqusAnalysisUserGuide3_071.md"
|
|
- "AbaqusAnalysisUserGuide3_070.md"
|
|
- "AbaqusAnalysisUserGuide3_005.md"
|
|
- "AbaqusAnalysisUserGuide3_004.md"
|
|
md_indices:
|
|
- 71
|
|
- 70
|
|
- 5
|
|
- 4
|
|
match: "heuristic-heading-keyword"
|
|
confidence: high
|
|
---
|
|
|
|
# Abaqus User-Defined Material Behavior
|
|
|
|
## Definition
|
|
|
|
Abaqus user-defined material behavior lets analysts implement mechanical or thermal constitutive laws through material subroutines when built-in material models are insufficient.
|
|
|
|
## How It Works
|
|
|
|
For mechanical behavior, Abaqus/Standard calls `UMAT` at material points during each iteration and requires updated stresses, solution-dependent state variables, and the material Jacobian matrix. The Jacobian quality strongly influences Newton convergence and computational efficiency. Abaqus/Explicit calls `VUMAT` on blocks of material points and passes information suited to explicit vectorized updates.
|
|
|
|
For thermal behavior, `UMATHT` defines constitutive thermal response. User materials can allocate state variables, output them through SDV identifiers, and use state variables to control element deletion. In Abaqus/Explicit, deleted material points remain in the subroutine block but receive zero stresses and strain increments after deletion.
|
|
|
|
The guide also describes practical combinations and limitations. User-defined mechanical materials can often be combined with density, thermal expansion, permeability, and heat-transfer properties, while stiffness-proportional damping must be handled through the user material in some cases.
|
|
|
|
## Why It Matters
|
|
|
|
User materials are the most direct bridge from finite element theory to production implementation. They offer maximum constitutive flexibility but move correctness burdens onto the analyst: stress update, state evolution, tangent consistency, deletion logic, heat generation, and compatibility with elements and procedures.
|
|
|
|
## Connections
|
|
|
|
- [[Abaqus User Subroutines and Utility Routines]] is the broader compiled-extension workflow.
|
|
- [[Abaqus Constitutive Integration]] explains why stress updates and material tangents matter.
|
|
- [[Finite Element Program Implementation]] provides the general FE code architecture context.
|
|
|
|
## Sources
|
|
|
|
- [[Abaqus-Analysis-User-s-Guide-Volume-III|Abaqus Analysis User's Guide Volume III]]
|
|
|