Software Development
Mechanics & Materials

The Mechanics and Materials Section has extensive experience in the development and application of advanced methods for component life prediction and probabilistic structural analysis. Many of these advanced methods are now available as licensable software tools with user-friendly graphical user interfaces. Major companies around the world are using these software tools to analyze material and structural integrity and reliability. Brief descriptions of these tools are provided below, along with links to more detailed web sites for each software product.

  • NESSUS® is a modular computer software system for performing probabilistic analysis of structural/mechanical components and systems. NESSUS combines state-of-the-art probabilistic algorithms with general-purpose numerical analysis methods to compute the probabilistic response and reliability of engineered systems. Uncertainty in loading, material properties, geometry, boundary conditions, and initial conditions can be simulated. Many deterministic modeling tools can be used such as finite element, boundary element, hydrocodes, and user-defined subroutines. NESSUS offers a wide range of capabilities, a graphical user interface, and is verified using hundreds of test problems.
  • NASGRO® is a suite of fracture mechanics and fatigue crack growth analysis computer programs that performs assessments of structural life, computes stress intensity factors, and processes and stores fatigue crack growth properties. The previous version NASGRO 3.0 has more than 2,000 users in the space, aircraft, rotorcraft, turbine engine, petrochemical, nuclear, and ground vehicle industries in more than 40 countries. NASGRO 4.0 has been jointly developed by SwRI and NASA Johnson Space Center under the terms of the Space Act Agreement.
  • DARWIN® integrates finite element stress analysis results, fracture-mechanics-based life assessment for low-cycle fatigue, material anomaly data, probability of anomaly detection, and inspection schedules to determine the probability of fracture of a rotor disk as a function of applied operating cycles. The program also indicates the regions of the disk most likely to fail and the risk reduction associated with single and multiple inspections. This software will be enhanced to handle anomalies in cast/wrought and powder nickel disks and manufacturing and maintenance-induced surface defects in all disk materials in the near future.

Related Terminology

NESSUS  •  mechanics and materials  •  structural integrity  •  reliability assessment  •  mechanical behavior  •  mechanical characterization, fatigue life characterization  •  crack growth  •  corrosion fatigue  •  probabilistic mechanics  •  uncertainty modeling  •  NASGRO  •  DARWIN  •  software development

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Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 9 technical divisions.