In addition to the geo-material modeling experience of Dr. Schwer described above, Dr. Schwer has extensive experience with many of the other DYNA3D material models, especially composite material modeling. As part of the Strategic Defense Initiative (Star Wars Defense) in the early 1990’s, Dr. Schwer led a team comprising analysts from APTEK, Professors Simo and Chang from Stanford University and Dr. John Hallquist to develop and implement a laminated composite shell element with damage and failure in DYNA3D for the analysis of solid rocket motor cases under impulsive loading. This work is partially documented in the peer reviewed publication:

Murray, Y.D. and L.E. Schwer, “Verification of a General Purpose Laminated Composite Shell Element Implementation: Comparisons with Analytical and Experimental Results,” Finite Elements in Analysis and Design, Vol. 12, pp. 1-16, 1993.

Very recently, Dr. Schwer developed and implemented a novel resultant shell constitutive model in DYNA3D for the analysis of 3D woven textile composite panels subjected to high speed impacts simulating bird strike on aircraft components. This peer reviewed work has been accepted for publication and will appear as:

Schwer, L.E. and R.G. Whirley, “Impact of a 3D Woven Textile Composite Panel: Damage and Failure,” accepted for publication Mechanics of Composite Materials and Structures, July 1998.

Dr. Schwer will also be a presenter at the LS-DYNA User’s Conference, 21-22 Sept 98, of a manuscript, to be included in the proceedings, entitled;

“Modification of LS-DYNA Discrete Beam Material Type 68 to Include Axial Force Dependence of the Input Parameters”

which describes a major modification of the existing LS-DYNA Material Model 68 (*MAT_NONLINEAR_PLASTIC_DISCRETE_BEAM) provides for a zero-length beam element, i.e. a discrete element, that includes general, nonlinear elasto-plastic, linear viscoplastic, and failure modeling response. For this work, LSTC granted Dr. Schwer access to this LS-DYNA subroutine and it’s associated input and output routines, in part because of the close working relation that exists between LSCT and Dr. Schwer.

As part of his material modeling work with DYNA3D, Dr. Schwer has always made an effort to document and explain the various complex material models he has used over the years in numerous applications. Perhaps the best example of this is an unpublished work entitled:

“A Primer on the DYNA/NIKE Linear Viscoelastic Material Model”

which explains the theory, numerical implementation and model fitting to material characterization data for the linear viscoelastic model used in DYNA3D, DYNA2D, NIKE3D, NIKE2D, LS-DYNA and LS-NIKE. Although not published, the manuscript is available by request from LSTC and LLNL.