NASA names co-winners for Software of the Year

NASA Tech Briefs, Oct 2003

A software program that has advanced aircraft structural integrity and safety, and a program that processes and displays satellite data have been selected as co-winners of the 2003 NASA Software of the Year Award. The NASGRO(R) fracture control analysis software developed at Johnson Space Center, Houston, TX, and the SeaWiFS Data Analysis System (SeaDAS) from Goddard Space Flight Center, Greenbelt, MD, have both been adopted by other government agencies, private industry, and academia.

Making Mechanical Structures Safer

NASGRO(R) is NASA's standard software package used by all NASA centers and many NASA contractors for fracture control analysis of space hardware and safety-critical ground systems. Developed by Royce G. Forman of Johnson Space Center (JSG) and his team, NASGRO 3.0 was released to the public from a NASA/JSC Web site beginning in 1999. Since that time, more than 1,700 different users have downloaded the software, including more than 600 different companies. About 25% of these users represent space applications, while other users come from civilian aircraft and rotorcraft, U.S. military applications, universities, and other industries including railroad, petrochemical, turbine engines, automotive, nuclear, and pipeline applications.

NASGRO is actively supported by the Federal Aviation Administration to assure the safety of an aging fleet of civilian aircraft. NASGRO users also include many other government agencies and four Department of Energy national laboratories. A significant new use of NASGRO is by biomechanical engineers engaged in life calculations of components designed for human use such as valves for artificial hearts and hip-joint prostheses.

The newest version - NASGRO 4.0 - features analytic capabilities for performing crack propagation analysis on fracture-critical hardware. It is the standard software used for meeting fracture control analysis requirements on the Space Shuttle, the International Space Station, and their payloads. Use of NASGRO is important in resolving crack-like anomalies in structural components or hardware equipment that can possibly cause a catastrophic accident. In addition to space flight hardware analysis, the software is important for fracture control analysis of safety critical ground systems. The impact of NASGRO on NASA's mission has been a significant improvement in fracture control analysis that has resulted in a higher level of safety and mission success.

The NASGRO fracture mechanics analysis code simulates crack growth and failure in engineering structures. Fracture is the primary threat to the integrity, safety, and performance of nearly all highly stressed mechanical structures. Failures due to fracture can have major negative consequences, including serious injury or loss of life, and severe environmental damage. NASGRO enables designers and operators to develop and maintain fracture control plans that substantially reduce the risk of structural failure. Therefore, the software is used for optimal design of fractureresistant structures and specification of fracture control plans to avoid failure within a specified lifetime. Designers use NASGRO to determine safe stresses for a specified life, safe lifetime for a specified design, or required inspection intervals to maintain safety. Operators use NASGRO to determine safe remaining life (if any) or required inspection intervals after damage is discovered in the field.

NASGRO contains a massive database of material properties for fatigue crack growth and fracture: 476 different metallic materials, 3,000 sets of fatigue crack growth data, 6,000 fracture toughness data points, and statistically-derived crack growth equations for all 476 materials. It runs on all PC systems and on several UNIX operating systems.

The software has been downloaded by 183 universities as a tool for teaching and advanced research. The commercialization and distribution of NASGRO 4.0 outside NASA is guided by a Space Act Agreement (SAA) between NASA/ JSC and Southwest Research Institute (SwRI). NASA/JSC and SwRI now collaborate as joint developers of NASGRO. SwRI has recently released the software for commercial licensing.

Royce G. Forman's research team includes Leonard Williams of GB Tech, and Joachim Beek, Sambi Mettu, Venkataraman Shivakumar, and Feng Yeh of Lockheed Martin.

Bringing Satellite Data Down to Earth

The Sea-viewing Wide Field of view Sensor (SeaWiFS) mission is part of NASA's Earth Science Enterprise, which looks at Earth from space to better understand it as a system in both behavior and evolution. The SeaWiFS Project provides quantitative data on global ocean bio-optical properties to the Earth science community. The project operates a research data system that processes, calibrates, validates, archives, and distributes data received from an Earth-orbiting ocean color sensor.

For NASA to maximize its investment in Earth remote sensing, users must have the tools to work with the data. The SeaWiFS Data Analysis System (SeaDAS) is the answer to this requirement of data display, processing, and analysis support. SeaDAS is provided as a packaged executable software and source code. The software runs on commonly used desktop systems - Silicon Graphics, Sun Microsystems UNIX workstations, and PC Linux systems - and features an easy-touse graphical user interface (GUI), which greatly expands the user base, especially overseas.