Advanced Residual Strength Degradation Rate Modeling For Advanced Composite Structures

This report presents the results of the first task of the last two tasks of a three-task program focusing on the study of relationship between damage propagation and residual strength of graphite/epoxy laminates. Specimens of two laminate types, a 32-ply quasi-isotropic and 24-ply 67%-0, containing a centered poorly drilled hole were evaluated in this study. Baseline static tension and compression tests were conducted at high and low strain rates and at elevated temperature.

This report presents the results of the first task of the last two tasks of a three-task program focusing on the study of relationship between damage propagation and residual strength of graphite/epoxy laminates. Specimens of two laminate types, a 32-ply quasi-isotropic and 24-ply 67%-0, containing a centered poorly drilled hole were evaluated in this study. Baseline static tension and compression tests were conducted at high and low strain rates and at elevated temperature.

This report presents the results of the first task of a three task program directed at the study of relationship between damage propagation and residual static strength of composite laminates. In Task 1: Preliminary screening, two laminates a 24-Ply 67% 0 deg. fiber and a 32-Ply quasi-isotropic laminate of T300/5208 graphite epoxy material were selected for study. Two damage types were studied, a low velocity impact condition (i.e., simulated tool drop) and a badly drilled hole. An initial study was conducted for each damage type to determine the detailed damage introduction parameters resulting in the selection of one set of impact and one set of poor drilling conditions. Baseline static tension and static compression tests were conducted on each of the four damage/laminate conditions. Stress vs life (S-N) fatigue data were then generated at range ratio R=-1 for each of the four conditions. The damage growth characteristics were monitored on each fatigue specimen using a modified Holscan ultrasonic unit. A subset of the damaged hole specimens was also evaluated in static compression and fatigue (R = -1) using TBE enhanced X-ray methods to monitor damage growth and to assess any detrimental effect of TBE on subsequent behavior of the damage. The results indicate significant reduction in initial static tension and compression strengths for the damaged hole condition in both laminates.

This report presents the results of the first task of the last two tasks of a three-task program focusing on the study of relationship between damage propagation and residual strength of graphite/epoxy laminates. Specimens of two laminate types, a 32-ply quasi-isotropic and 24-ply 67%-0, containing a centered poorly drilled hole were evaluated in this study. Baseline static tension and compression tests were conducted at high and low strain rates and at elevated temperature.

This standardization handbook has been developed and is being maintained as a joint effort of the Department of Defense and the Federal Aviation Administration. It provides guidelines and material properties for polymer (organic) and metal matrix composite materials. This handbook aims to provide a standard source of statistically-based mechanical property data, procedures, and overall materials guidelines for characterization of composite material systems. This volume provides methodologies and lessons learned for the design, manufacture, and analysis of composite structures and for utilization of the material data provided in Volume II consistent with the guidance provided in Volume I. It covers processes and effects of variability; quality control of production materials; design and analysis; structural behavior of joints and reliability; thick section composites; and supportability.

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