Over the past thirty-two years, we have carried out a number of studies dealing with damage assessment and structural vulnerability, involving both nuclear and conventional high explosive blast effects as well as the effects of vapor cloud explosions. In all these studies the emphasis has been on the development of efficient blast simulation models, suitable for execution on microcomputers. As part of these studies we have served as an explosive safety consultant to a number of organizations. A number of technical papers have been published dealing with our work in this area.

Initial efforts involved a Company-funded study which was designed to construct and operate a computer simulation model to study the effects of a nuclear air burst on multiple target structures. This software, the Nuclear Damage Assessment Model (NDAM) was designed for an Apple III microcomputer and included both overpressure and dynamic pressure effects, and also a simple shielding algorithm to make allowance for one structure shielding another.

Based on NDAM, under a three-year contract with the Strategic Defense Command, we developed the Enhanced Nuclear Damage Assessment Model (ENDAM) for operation on an HP 9816 system. ENDAM was designed as an engineering tool for making blast damage assessments for a collection of structures resulting from a nuclear burst. Vulnerability data, based on the VN-system, for a total of 178 different types of structures and equipment were included.

Based on ENDAM, under a series of contracts with the Army Corps of Engineers Huntsville Division, over a period of three years, we developed three successive versions of the High Explosive Damage Assessment Model (HEXDAM). The last version, HEXDAM-III, was designed for operation on an IBM-PC XT-AT.

HEXDAM-III produces tabulated damage assessment data for each structure (building, ship, plane, storage tank, etc.) being processed. It also generates: (1) graphs of damage incurred versus structure distance form the burst point; (2) before-damage graphical display illustrating plan views of structure locations in relation to the burst point; (3) contour plots of overpressure, dynamic pressure, and structural damage.

Under subcontract with the Southwest Research Institute (SRI), we carried out research efforts to verify the HEXDAM damage algorithm and to correlate results with SRI dimensionless pressure-impulse plots. As part of the study, a procedure was developed, based on the SRI Pressure-Impulse plots, to permit calculation of the vulnerability parameters, based on the VN-system, which are used as inputs by HEXDAM. This work proved to be the foundation for the VASDIP concept.

The military version of HEXDAM (HEXDAM-III) software has been widely distributed throughout the Department of Defense for use in both safety analysis and physical security evaluation. Six industrial versions (HEXDAM-A, B, C, D, 5.0 and 5.2) are currently in use by private U.S. and foreign industries, and also foreign government agencies. The latest industrial versions of HEXDAM make extensive use of both two-dimensional and three-dimensional graphical displays.

Working with two of the world's largest petrochemical companies, we have developed the Vapor Cloud Explosion Damage Assessment Model (VEXDAM). Four industrial versions of VEXDAM have been developed (VEXDAM+, VEXDAM 5.0, VEXDAM 5.1 and VEXDAM 5.2).

With a combination of HEXDAM (or VEXDAM) and VASDIP, the user can design individual structural components to satisfy specific blast requirements for an unlimited number of different scenarios, involving either safety or physical security.

Most of the users of HEXDAM and VEXDAM are concerned with personnel safety and the effects of an explosion on the human body. For that reason we have developed the HEXDAM Man software for use with HEXDAM and the VEXDAM Man software for use with VEXDAM.

Prediction of personnel casualties due to fragmentation effects are also a major concern.  For that reason we have developed new software dealing with fragmentation effects.

We have entered into a working agreement with Trinity Consultants, leading to the development of HEXDAM 6.0 and 7.0, VEXDAM 6.0 and 7.0 and VASDIP 4.0 versions of our explosive safety software.

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