Approved for public release; distribution is unlimited.ii
REPORT DOCUMENTATION PAGE
Form Approved OMB No. 0704-0188Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.
PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.
REPORT DATE (DD-MM-YYYY)September 2012
SPONSOR/MONITOR'S REPORT NUMBER(S) 12. DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution is unlimited.
SUPPLEMENTARY NOTES
ABSTRACTMaterial nonlinearity and progressive ply failure are important considerations in the finite element modeling of thick-section composite structures. LAMPATNL uses a method to model the material nonlinearity and progressive ply failure of composite laminates using finite element software without explicitly simulating individual plies. Improvements to LAMPATNL are documented and discussed in this report. Also, LAMPATNL is validated against both the linear and nonlinear material point models. In this work, a standardized process for designing composite structures with LAMPATNL using newly formulated output parameters, stiffness ratios, to analyze the nonlinear response and progressive failure of the composite structure is developed. These new parameters greatly improve the visualization of critical design information of the structure. Two case studies, an open-hole sample under multi-axial loading and a compressive shear sample, are evaluated using the design methodology. Coupling LAMPATNL with a design methodology and new stiffness ratio parameters demonstrates the utility of progressive failure and nonlinear analysis when applied to composite structures. The straightforward visualization of critical design information creates a unique approach to analyzing the design of thick section composites. This methodology represents a unique contribution to the modeling of composite structures that is not matched by any current composite model. iii