Matthew E. Melis

Full-field dynamic deformation and strain measurements using high-speed digital cameras

Digital cameras are rapidly supplanting film, even for very high speed and ultra high-speed applications. The benefits of these cameras, particularly CMOS versions, are well appreciated. This paper describes how a pair of synchronized digital high-speed cameras can provide full-field dynamic deformation, shape and strain information, through a process known as 3D image correlation photogrammetry. The data is equivalent to thousands of non-contact x-y-z extensometers and strain rosettes, as well as instant non-contact CMM shape measurement. A typical data acquisition rate is 27,000 frames per second, with displacement accuracy on the order of 25-50 microns, and strain accuracy of 250-500 microstrain. High-speed 3D image correlation is being used extensively at the NASA Glenn Ballistic Impact Research Lab, in support of Return to Flight activities. This leading edge work is playing an important role in validating and iterating LS-DYNA models of foam impact on reinforced carbon-carbon, including orbiter wing panel tests. The technique has also been applied to air blast effect studies and Kevlar ballistic impact testing. In these cases, full-field and time history analysis revealed the complexity of the dynamic buckling, including multiple lobes of out-of-plane and in-plane displacements, strain maxima shifts, and damping over time.

Dynamic Impact Testing and Model Development in Support of NASA's Advanced Composites Program

This paper presents an overview of the High Energy Dynamic Impact element of NASA’s Advanced Composites Project (ACP). The paper summarizes the work done for the ACP to advance our understanding of the behavior of composite materials during high energy impact events and to advance the ability of analytical tools to provide predictive simulations. The experimental program carried out at the NASA Glenn Research Center is summarized and a status on the current development state of an advanced computational composite impact model will be provided. Future work will be discussed as the effort transitions from fundamental analysis and testing to investigating sub-component structural concept response to impact events.

A summary of the NASA Glenn Ballistic Impact Lab contributions to the Columbia accident investigation

On February 1, 2003, the Space Shuttle Columbia broke apart during reentry resulting in the loss of 7 crewmembers and craft. For the next several months an extensive investigation of the accident ensued involving a nationwide team of experts from NASA, industry, and academia, spanning dozens of technical disciplines. The Columbia accident investigation board (CAIB), a group of experts assembled to conduct an investigation independent of NASA, concluded in August, 2003 that the cause of the loss of Columbia and its crew was a breach in the left wing leading edge reinforced carbon-carbon (RCC) thermal protection system initiated by the impact of thermal insulating foam that had separated from the orbiters external fuel tank 81 seconds into that missions launch. During reentry, this breach allowed superheated air to penetrate behind the leading edge and erode the aluminum structure of left wing which ultimately led to the breakup of the orbiter. Supporting the findings of the CAIB numerous ballistic impact testing programs were conducted to investigate and quantify the physics of external tank foam impact on the RCC wing leading edge material. These tests ranged from fundamental material characterization tests to full-scale Orbiter wing leading edge tests. Following the accident investigation, NASA turned its focus to returning the Shuttle safely to flight. Supporting this effort are many test programs to evaluate impact threats from various debris sources during ascent that must be completed for certifying the Shuttle system safe for flight. Researchers at the NASA Glenn Ballistic Impact Laboratory have conducted several of the impact test programs supporting the accident investigation and return-to-flight efforts. This paper summarizes those activities and highlights the significant accomplishments made by this group.

A summary of the Space Shuttle Columbia tragedy and the use of digital high-speed photography in the accident investigation and NASA's return-to-flight effort

On February 1, 2003, the Space Shuttle Columbia broke apart during reentry resulting in loss of seven crewmembers and craft. For the next several months an extensive investigation of the accident ensued involving a nationwide team of experts from NASA, industry, and academia, spanning dozens of technical disciplines. The Columbia Accident Investigation Board (CAIB), a group of experts assembled to conduct an investigation independent of NASA concluded in August, 2003 that the cause of the loss of Columbia and its crew was a breach in the left wing leading edge Reinforced Carbon-Carbon (RCC) thermal protection system initiated by the impact of thermal insulating foam that had separated from the orbiters external fuel tank 81 seconds into that missions launch. During reentry, this breach allowed superheated air to penetrate behind the leading edge and erode the aluminum structure of the left wing which ultimately led to the breakup of the orbiter. Supporting the findings of the CAIB, were numerous ballistic impact testing programs conducted to investigate and quantify the physics of External Tank Foam impact on the RCC wing leading edge material. These tests ranged from fundamental material characterization tests to full-scale Orbiter Wing Leading Edge tests. Following the accident investigation, NASA turned its focus to returning the Shuttle safely to flight. Supporting this effort are many test programs to evaluate impact threats from various debris sources during ascent that must be completed for certifying the Shuttle system safe for flight. Digital high-speed cameras were used extensively to document these tests as significant advances in recent years have nearly eliminated the use of film in many areas of testing. Researchers at the NASA Glenn Ballistic Impact Laboratory have participated in several of the impact test programs supporting the Accident Investigation and Return-to-Flight efforts. This paper summarizes the Columbia Accident and the nearly seven month long investigation that followed. Highlights of the NASA Glenn contributions to the impact testing are presented with emphasis on the use of high speed digital photography to document theses tests.

Multiphysics Simulation of Active Hypersonic Lip Cooling

This article describes the application of the Multidisciplinary Analysis (MDA) solver, Spectrum, in analyzing a hydrogen-cooled hypersonic cowl leading-edge structure. Spectrum, a multiphysics simulation code based on the finite element method, addresses compressible and incompressible fluid flow, structural, and thermal modeling, as well as the interactions between these disciplines. Fluid-solid-thermal interactions in a hydrogen impingement-cooled leading edge are predicted using Spectrum. Two- and semi-three-dimensional models are considered for a leading edge impingement coolant, concept under either specified external heat flux or aerothermodynamic heating from a Mach 5 external flow interaction. The solution accuracy is demonstrated from mesh refinement analysis. With active cooling, the leading edge surface temperature is drastically reduced from 1807 K of the adiabatic condition to 418 K. The internal coolant temperature profile exhibits a sharp gradient near channel/solid interface. Results from two different cooling channel configurations are also presented to illustrate the different behavior of alternative active cooling schemes.