A COMPUTATIONAL APPROACH FOR PREDICTING A- AND B-BASIS ALLOWABLES FOR POLYMER COMPOSITES

摘要

Accurate prediction of the A-basis and B-basis strength values is critical to reduce risk in structural design of composite aircraft structures. The calculation of polymer matrix composite allowables for aerospace applications is governed by FAA and Military Handbook 17-E standards and rules. The process is costly and time consuming as large numbers of coupon tests are inevitable. This paper describes an innovative computational approach to predict composite material allowables with minimum testing. The methodology combines multi-scale composite modeling with progressive failure and probabilistic analysis and minimum test data to determine A- and B-basis values. The scatter in material strength is determined by iterating on coefficient of variations of random variables from single or multiple sources of uncertainties (i.e. fundamental material properties and fabrication variables). The iterative process is necessary to replicate scatter in the strength value obtained from the test of one coupon of each material batch. The methodology is applicable to notched and un-notched coupons and structures and has the potential of reducing the coupon count for testing by over 60 percent.