---
type: concept
title: "Abaqus Prescribed Conditions and Amplitudes"
complexity: intermediate
domain: computational-mechanics
created: 2026-06-01
updated: 2026-06-01
address: c-000117
aliases:
  - Abaqus prescribed conditions
  - Abaqus amplitude curves
  - Abaqus time-dependent loads
tags:
  - concept
  - finite-element-method
  - abaqus
  - prescribed-conditions
  - amplitudes
status: current
related:
  - "[[Abaqus-Analysis-User-s-Guide-Volume-V|Abaqus Analysis User's Guide Volume V]]"
  - "[[Abaqus Initial and Boundary Conditions]]"
  - "[[Abaqus Loads and Predefined Fields]]"
  - "[[Abaqus Input File Syntax]]"
  - "[[Abaqus General and Linear Perturbation Steps]]"
  - "[[Abaqus Nonlinear Solution Control]]"
sources:
  - "[[Abaqus-Analysis-User-s-Guide-Volume-V|Abaqus Analysis User's Guide Volume V]]"
---

# Abaqus Prescribed Conditions and Amplitudes

## Definition

Abaqus prescribed conditions are externally imposed model quantities such as initial conditions, boundary conditions, loads, assembly loads, connector motions, and predefined fields. Amplitudes define their time or frequency variation.

## How It Works

A prescribed condition can be applied as model data or history data depending on the feature. Boundary conditions, loads, and predefined fields can refer to named amplitude curves. Without an explicit amplitude, Abaqus applies default ramp or step behavior depending on the product, procedure, and condition type.

Amplitude definitions can be tabular, equally spaced, periodic, modulated, smooth step, exponential, solution-dependent, user-defined, or imported from alternate files. They can use step time or total time and can be shared by many conditions.

In Abaqus/Standard, removing a displacement or rotation boundary condition in a stress/displacement analysis converts it to an applied conjugate flux that is then ramped or stepped to zero. This makes condition removal part of the load history rather than a purely symbolic edit.

## Why It Matters

The same nominal load or boundary value can produce very different nonlinear and dynamic results depending on its amplitude history. Prescribed conditions are therefore part of the analysis strategy, not just input decoration.

## Connections

- [[Abaqus Initial and Boundary Conditions]] covers the boundary-condition subset.
- [[Abaqus Loads and Predefined Fields]] covers load and field definitions.
- [[Abaqus General and Linear Perturbation Steps]] determines how step context changes condition interpretation.
- [[Abaqus Nonlinear Solution Control]] is sensitive to abrupt prescribed-condition changes.

## Sources

- [[Abaqus-Analysis-User-s-Guide-Volume-V|Abaqus Analysis User's Guide Volume V]]