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MMCD Developers

APTEK personnel are highly trained and each hold advanced engineering/computer science degrees.  The two key developers of the MMCD are Yvonne Murray and Carolyn (Carrie) Yeager.

Yvonne Murray

Program Manager, Principal Calculator, and Material Model Developer

  • Program manager and developer of the Mixed Mode Constitutive Driver and Composite Retrofit Programs.
  • Primary developer and implementer of the Continuous Surface Cap Model (MAT_159) and Wood Model (MAT_143) in the LS-DYNA finite element code.

Ms. Murray joined APTEK in 1986 after five years employment at SRI International. She has over 22 years experience in performing finite element analyses of dynamically loaded structures, with emphasis on the LLNL DYNA and LS-DYNA codes. She has 20 years experience with material model evaluation and development, with emphasis on progressive damage and cap plasticity models for concrete, rock, and soil, and transversely isotropic constitutive models for wood and fibrous composites.

Ms. Murray is the Program Manager responsible for continued development of the Mixed Mode Constitutive Driver. This project began as a joint commercial-university venture which blossomed into a Phase I and II SBIR with the Federal Highway Administration. Ms. Murray was also the Program Manager/Principal Investigator on two contracts with the Federal Highway Administration responsible for developing and validating LS-DYNA concrete, wood, and soil material models to analyze roadside structures impacted by vehicles.

Ms. Murray was the Program Manager/Principal Calculator of the Composite Retrofit Techniques Phase I and II SBIR with DTRA. She supervised the development of a fast-running building component survivability/vulnerability assessment tool (Composite Retrofit Program) which uses engineering models derived from data supplemented with high fidelity DYNA3D calculations. The calculations simulate the response of blast-loaded reinforced concrete columns, beams, and masonry walls, with and without bonded composite retrofits, for with comparison with traditional techniques like steel jackets and shotcret strengthening.

Other efforts include program management or computational support on projects involving model development and calculation of buried tunnel deformations to ground shock; buried and aboveground concrete structures to internal and external detonations; ballistic penetration of fibrous-composite laminates; penetration of steel vessels; case damage and propellant spall of composite motor cases from laser loading.

Education:

  • Master of Science, Mechanical Engineering; University of California (Berkeley), 1981
  • Bachelor of Arts, Applied Mechanics, University of California (San Diego), 1979

Carolyn (Carrie) Yeager

Staff Scientist, Senior Architect/Software Developer
  • Lead software architect and developer of the Mixed Mode Constitutive Driver.
  • Lead software architect and developer of the Composite Retrofit Program which is a web-based program for predicting and simulating building component vulnerability and retrofit selection.

Ms. Yeager has extensive software development experience in user interface, database, graphics, and engineering analysis code integration. Ms. Yeager is the lead architect and developer of the Mixed Mode Constitutive Driver (MMCD).  She was also the lead architect on several other related projects including the Composite Retrofit Program developed for DTRA. This program predicts component vulnerability against a given threat. The CRP is a web based application that provides user interfaces for defining structures (beams, columns, and walls), defining threats, performing a vulnerability analysis, applying retrofits and graphically displaying the results.

Ms. Yeager is currently developing a custom graphics display program for displaying 2-D and 3-D engineering results. 
In 1999 Ms. Yeager was awarded a patent for her innovative work on the Training Hardware Management System developed for NASA to manage space station inventory.

For the Air Force Ms. Yeager designed and developed a real time 3-D trajectory viewer (TrajView).  TrajView is used to display and animate in real time the trajectories of multi-body defense systems or multi-trajectory predictions and their associated data. 

Areas of expertise include Oracle, SQL Server, C#,  Scalar Vector Graphics, Active Server Pages, Expression Web, HTML, C, C++, Java, Basic and Perl.

Education:
  • Master of Science, Computer Science, 1989, University of Colorado, Colorado
  • Bachelor of Science, Biochemistry, 1982, University of Wisconsin, Wisconsin


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