Coupled Loads Analysis

graphRapidly Predict Critical Loads

Coupled loads analysis (CLA) is a critical process for many high-technology systems including launch vehicles and satellites. CLA predicts responses caused by major dynamic and quasistatic loading events such as liftoff, gust, buffet, and engine startup and shutdown. CLA helps to minimize risk and maximize the probability of mission success.

Advanced CLA Methods

shuttle_2Quartus Engineering has a wide range of capabilities for rapidly and accurately performing coupled loads analysis. Specific features include:

  • Modal synthesis methods including Craig-Bampton, Rubin-MacNeal residual flexibility, and others
  • Superelement and substructure software for model processing and assembly
  • Damping synthesis algorithms including Hruda-Benfield, triple matrix product, and energy participation methods
  • Efficient modal transient analysis for systems with diagonal or coupled damping matrices
  • Residual vector and mode acceleration methods for accurate data recovery
  • Hydroelastic analysis software for slosh and coupled fluid/structure modes of liquid propellant launch vehicles and satellite tanks

Extensive CLA Experience

Quartus engineers have performed coupled loads for a wide range of launch vehicles and satellites including:

Launch Vehicles

  • Space Shuttle
  • Titan IV/Centaur
  • Titan 34D
  • Atlas
  • Taurus
  • Pegasus
  • Next generation


  • Cassini
  • Galileo
  • MilStar
  • Tethered Satellite
  • ACTS
  • Intelsat VI
  • TOMS

LV and SV Model Processing

Quartus has extensive experience in processing launch vehicle and spacecraft models. Special capabilities include:

  • Craig-Bampton and bulk data model formats
  • Model checking procedures to examine numerical grounding, rigid body mass, and effective mass
  • Data recovery matrix (DRM) generation, checking, and processing
  • Results postprocessing and visualization
  • Pretest analysis, test-analysis correlation, and model updating for modal survey tests

Software Tools


Quartus has an extensive array of software programs and custom tools for performing coupled loads analysis. Commercial software includes MSC/NASTRAN, NX NASTRAN, and Matlab. Quartus also has a library of custom software including C and FORTRAN programs, DMAP alters, and Matlab scripts to assist in CLA model and data processing.

Technology Transfer and Outsourcing

Quartus can work with clients in a variety of methods including:

  • Technology transfer of advanced methods to improve capabilities and productivity
  • Complimenting in-house resources to accelerate schedules and handle peak workloads
  • Performing CLA on an outsourcing basis
  • Providing independent verification and validation (IV&V) of methods, models, and results