FALCON v1.0.0 - GUI-based Framework for Isogeometric Analysis

FALCON was developed as a tool for the Indian Space Research Organisation (ISRO - VSSC), in strategic collaboration with Avkalan Labs.

The primary objective of FALCON v 1.0.0 is to bridge the gap between high-fidelity CAD modeling and complex numerical simulations, providing a seamless workflow for aerospace and structural engineers.

1. Motivation

While IGA offers superior accuracy by using exact CAD geometry, its practical application has historically been limited by the complexity of script-based workflows. FALCON addresses this by:

  • Removing the need for manual coding of analysis scripts for end-users.
  • Providing an intuitive, “what-you-see-is-what-you-get” (WYSIWYG) environment.
  • Enabling engineers to focus on structural behavior rather than mathematical implementation.

2. Implementation & Backend Development

The strength of FALCON lies in its modular subroutine architecture. Unlike standard black-box FEA tools, FALCON is built on a custom-coded Python backend that manages the heavy mathematical lifting of spline theory.

Core Subroutine Development

  • Spline Engine: Custom subroutines were developed to handle NURBS basis function evaluation, knot insertion, and degree elevation across multiple dimensions.
  • Integration Modules: Specialized Gauss quadrature subroutines ensure precise numerical integration over the physical domain, maintaining the “exact geometry” advantage of IGA.
  • Assembly Logic: The framework uses an optimized global stiffness matrix assembly routine that accounts for the high-order continuity (C^p-1) inherent in splines.
  • Python Integration: The backend is implemented in Python, utilizing libraries like NumPy and SciPy for high-performance linear algebra, while the frontend is built using robust GUI libraries to ensure cross-platform stability.

3. Software Capabilities

FALCON v1.0.0 is designed for versatility, supporting a wide range of structural configurations and analysis types.

Modeling Domains

  • 2D Analysis: Plane stress and plane strain configurations.
  • 3D Analysis: Solid modeling for complex aerospace components.
  • Plate Modeling: High-order continuity in IGA makes it exceptionally efficient for thin-walled structures, avoiding the “locking” issues found in traditional FEA.

Analysis Modules

  • Linear Static Analysis: For predicting displacements and stresses under constant loads.
  • Eigenvalue Analysis: To determine natural frequencies and mode shapes, ensuring structural stability during launch conditions.

4. The GUI Workflow

The FALCON interface is divided into three functional zones: Pre-processing, Solver, and Post-processing.

Pre-processing & Visualization

Users can visually define the simulation environment:

  • NURBS Geometry: Import or create geometries directly within the interface.
  • Visual BCs & Loading: Boundary conditions (fixed supports, rollers) and loads (point loads, pressures) are applied via a mouse-driven interface directly on the spline patches.

Post-processing

Results are rendered in a dedicated visualizer that supports:

  • Displacement Contours: High-resolution mapping of structural deformation.
  • Mode Shapes: For eigenvalue analysis, users can animate natural frequency vibrations.
  • Stress Distributions: Visualizing Von Mises and principal stresses across the exact NURBS surface.

6. Key Contributions

  • Early Implementation: One of the few GUI-based IGA frameworks developed specifically for the Indian aerospace sector.
  • CAD-Analysis Unification: Eliminates the “meshing” phase by performing analysis directly on the geometry.
  • Research & Teaching: A modular architecture that allows for the easy addition of new subroutines (e.g., non-linear analysis or thermal modules).
  • IGA subroutines in Python: A python-based backend code, that works independently of the GUI, running on isogeometric formulatios. The physical-parametric-parent spaces of IGA is accurately captured with respect to spline basis functions.