A program is proposed that will extend (and build upon) the work already started by the Survivability Group of the Composites Affordability Initiative, Pervasive Team in developing methods for analyzing the effects of ballistic and hydrodynamic ram (HRAM) loading and damage in bonded/co-cured composite structures. Specifically, the objective will be to remedy a major shortcoming of current HRAM finite element codes, which are unable to accurately model the details that differentiate one joint design from another. The incorporation of stitching, z-pinning, co-curing, and bonding of the joints leads to different failure modes and paths. This is the area in which most work will be performed - in the proper selection of failure criteria within the joints as well as the entire model. Presently, the state-of-the-art is to use an elastic-plastic smeared properties technique in modeling the structure and "fuze elements" to model the joints. This program will greatly improve upon the current practices by developing cohesive elements, whose material properties can be determined by testing and incorporated into the HRAM finite element models.
Benefits: Commercialization of the herein proposed research and development activity is in an area where AdTech has demonstrated successes in the past; however, the technology area is broader in scope. Thus we envision commercialization of a software module that can be added to existing, general purpose, fluid structure codes. These would include such codes as: (1) LS Dyna by LSTC, Inc., (2) MSC Dytran, (3) ALE 3-D, (4) CALE, (5) the Sandia CTH code couled to the old Dyna 3-D code for buildings, and (6) the Allegra Code. Further, the Cohesive Element 2-D code is being developed into a 3-D code, and our module would be adaptable to that code as well. Some of the key people associated with several of these codes have already been contacted and have expressed interest. User companies of these established codes are already comfortable with them, have historical data based upon them, can make comparative assessments, and thus are oftentimes reluctant to change --- even though there may be a known better software product available to them. At the same time, they may be quite receptive to adding an enhancement module to an existing code in order to expand its usefulness.
Keywords: Finite Element Code Composites Hydrodynamic Failure Criteria Ballistic Survivability High Strain Rate
