Dan Trowbridge Email and Phone Number

Performed contracted engineering tasks for NASA Glenn Research Center.Code development for enhancements to NASA's Numerical Propulsion and System Simulator (NPSS). This work required development of computer code enhancements to generate three dimensional parametric geometry definitions from aircraft engine cycle analysis results. A gradient based method was developed to obtain optimized geometry of engine disk components, minimizing weight while insuring a positive margin of safety. Implemented a transfer matrix solution method for quick structural assessment of engine disk components.Generated NASTRAN finite element models and performed analyses for multiple design iterations for the CONNECT space experiment which is to be mounted external to the International Space Station. Performed static, modal and random vibration analyses. Reported results and suggested design changes as needed. As part of the ARES I and the ORION program's Integrated Vehicle Ground Vibration Test (IVGVT), analyzed and evaluated the vibrational characteristics of the ARES I launch vehicle at different stages of the flight profile. Performing static, modal, cross-orthogonality and transient analyses with differential stiffness using NASTRAN and FEMAP. Wrote many supporting computer programs (C++, Python, and Java) to automate the parametric analyses performed on the ARES 1 vehicle.

Development of software for programmatically accessing material property database via sockets communications. Uncertainty quantification analysis code development and neural network modeling of uncertainty predictions. Software development to automate thermo-mechanical modeling and analysis of tires.

Work in software engineering as applied to NURBS-based airfoil modeling and preliminary design of engine structures.Development of the SABER (Structural Airfoil and Blade Engineering Routines) code under contract with NASA Glenn Research Center (see www.ap-solutions.com/Structures/saber_index.htm and work experience below). Developed an integrated finite element solver based on the transfer matrix analysis method and utilizing automatic mesh generation and refinement. The solver allows for the automated sizing optimization of engine flow surface structures, providing mass audits of engine components and stress values to be used in the preliminary design of the rotating machinery. The solver can analyze rotating and non-rotating axisymmetric flow surfaces and can consider pressure loads, temperature loads, and temperature dependent material properties.

Work in software engineering as applied to NURBS-based airfoil modeling, finite element analysis, material constitutive modeling, and symbolic computations.Under funding from the U. S. Army through the Cleveland Clinic Foundation, developed methodology to describe hyperviscoelastic material properties for biological tissues with any number of tissue fibers for any or all elements in an ABAQUS finite element model. Development of the SABER code under a grant from NASA Glenn Research Center. Added many significant improvements to the code including the ability to model multiple airfoils using shell and solid finite elements, HTML log file output, and its own scripting language (SCL, Saber Command Language). The SCL is complete with mathematical expression parser, looping constructs, if-then-else conditionals, and array variables that dynamically "grow" in size as needed.Developed GUI for the COMPARE code using the Tcl/Tk scripting language.Under funding from the Ohio Department of Transportation, developed methods to optimize pavement thicknesses by programmatically adjusting ABAQUS finite element models that describe various pavement layers.Developed methodology for automatic finite element input deck submission to ABAQUS to minimize overhead encountered in transient analyses with large number of cyclic loadings.Developed multiple computer programs to view in-house finite element code results using MFC/OpenGL/C++. These codes allow the viewing of finite element meshes with surface color shading and vector display of analytical data in a virtual 3D environment using fitting and displaying of NURB surfaces where appropriate. Implemented the stand-alone MAC (Micromechanics Analysis Code) computer program as a user material subroutine from within the ABAQUS finite element code.Developed MACSYMA routines for symbolic evaluation of a generalized Ogden-type hyperelastic constitutive model.

The emphasis of the work experience at Analex was in static and transient finite element analysis, numerical methods, research in impact dynamics, composite materials, software engineering and development, as well as classical structural analyses.Technical lead of the CATS (Coupled Aero-Thermal-Structural) software development team and primary author of the SABER (Structural Airfoil and Blade Engineering Routines) computer program. Responsible for code development and evaluation, assigning tasks to team members, and team member selection and appraisal. SABER is a C++ NURBS-based airfoil modeler and automatic finite element mesh generator that allows analysis data to be mapped onto the parametrically defined geometric surface of an airfoil and a displaced airfoil to be generated based on finite element results.Structural analysis team member for the SAMPIE (Solar Array Module Plasma Interaction Experiment) space experiment, performing finite element analyses on the major structural components comprising the experiment. The SAMPIE experiment was designed to investigate the interaction of high voltage space power systems with ionospheric plasma and was successfully flown on March 4, 1994 aboard space shuttle flight STS-62.Structural analysis team member for the Space Station Freedom FASTMast test and analysis effort. Performed substructured finite element analyses for various structural damage scenarios. Wrote the software (LOADEM, written in C) for real-time control of the load cell that applied the loads to the FASTMast structure during testing.As part of the U. S. Navy's Insensitive Munitions program, developed a procedure to model the impact of composite rocket motor casings using the NASTRAN finite element code. A paper describing this procedure was published in the International Journal of Computers and Structures, and was awarded "Most Outstanding Paper" at the 1990 NASTRAN User's Colloquium. (This work required

the Graduate Research Fellowship program at the University of Akron. Evaluated the effects of various failure modes on the structural performance of advanced metal matrix composites and performed detailed substructured finite element analysis using NASTRAN. Published thesis entitled "Superelement Methods in High Temperature Metal Matrix Composites".

Analyzed existing structures and provided designs to increase their structural capacity. Developed cost estimates on proposed work while serving in the Corporate Engineering Department.