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in creator/contributor: "HARSTAD, E. N."  
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Differential Sensitivity Theory applied to the MESA code for high pressure interactions

Description: A technique called Differential Sensitivity Theory (DST) is applied to the system of equations solved by the MESA hydrocode. DST uses adjoint techniques to determine exact sensitivity derivatives, i.e., if R is a calculational result of interest (response R) and {alpha}{sub i} is a calculational input (parameter {alpha}{sub i}), then {partial_derivative}R/{partial_derivative}{alpha}{sub i} is defined as the sensitivity. The advantage of using DST is that for an n-parameter problem all n sensiti… more
Date: July 1, 1993
Creator: Maudlin, P. J.; Henninger, R. J. & Harstad, E. N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Differential sensitivity theory applied to the MESA2D code for multi-material problems

Description: The technique called Differential Sensitivity Theory (DST) is extended to the multi-component system of equations solved by the MESA2D hydrocode. DST uses adjoint techniques to determine exact sensitivity derivatives, i.e., if R is a calculation result of interest (response R) and {alpha}{sub i} is a calculation input (parameter {alpha}{sub i}), then {partial_derivative}R/{partial_derivative}{alpha}{sub i} is defined as the sensitivity. The advantage of using DST is that for an n-parameter prob… more
Date: September 1995
Creator: Henninger, R. J.; Maudlin, P. J. & Harstad, E. N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Single chain stochastic polymer modeling at high strain rates.

Description: Our goal is to develop constitutive relations for the behavior of a solid polymer during high-strain-rate deformations. In contrast to the classic thermodynamic techniques for deriving stress-strain response in static (equilibrium) circumstances, we employ a statistical-mechanics approach, in which we evolve a probability distribution function (PDF) for the velocity fluctuations of the repeating units of the chain. We use a Langevin description for the dynamics of a single repeating unit and a … more
Date: January 1, 2001
Creator: Harstad, E. N. (Eric N.); Harlow, Francis Harvey, & Schreyer, H. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Analysis of strain wave propagation in polymeric materials

Description: Polymeric materials used as binders in energetic materials exhibit interesting and unique material behavior. These include full geometrical recovery after deformation and a rate dependent stress strain relationship which can be categorized as viscoelastic. Taylor Cylinder Impact Tests have been conducted for adiprene-100 polyurethane. These produce time resolved cylinder profiles from which deformation wave speed can be extracted as a function of strain and strain-rate. Using this information a… more
Date: July 1, 1996
Creator: Harstad, E.N.; Foster, J.C., Jr; Wilson, L.L.: Maudlin, P.J. & Schreyer, H.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Viscoelastic models for explosive binder materials

Description: An improved model of the mechanical properties of the explosive contained in conventional munitions is needed to accurately simulate performance and accident scenarios in weapons storage facilities. A specific class of explosives can he idealized as a mixture of two components: energetic crystals randomly suspended in a polymeric matrix (binder). Strength characteristics of each component material are important in the macroscopic behavior of the composite (explosive). Of interest here is the de… more
Date: July 1997
Creator: Bardenhagen, S. G.; Harstad, E. N.; Maudlin, P. J.; Gray, G. T. & Foster, J. C., Jr.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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