CompositesWorld
Issue link: https://cw.epubxp.com/i/830100
JUNE 2017 26 CompositesWorld Accelerating materials insertion: Where do virtual allowables fit? In the quest to reduce the time and cost for aerocom- posite design allowables development, will conven- tional physical testing and virtual testing go head-to- head or work side-by-side? ยป ere is an important, ongoing debate in aerospace composites. Critics of the "building block approach" (BBA) used to generate design allowables claim that the required testing of thousands of physical coupons at the materials level (Fig. 1, this page) wastes time and balloons costs to the point that new materials insertion in aerospace programs is overly burdensome. ese same critics assert that today's simulation software is sophisticated enough to virtually duplicate the conditions in physical coupon testing and, therefore, ought to be considered, in some cases, a sufficient substitute for physical testing. is could, at a minimum, abbreviate coupon testing. Opponents contend that the majority of BBA cost is not in coupon testing but, instead, in component and full-scale tests, and that these levels are where the progressive damage analysis (PDA) that undergirds virtual allow- ables (VA) offers more benefits. Further, they argue that physical testing is, in any case, currently an aircraft certification process requirement. At CAMX 2015, two presentations in the Accelerated Materials Insertion track took up these opposing views. Roger Assaker, president of software By Ginger Gardiner / Senior Editor COUPONS ELEMENTS DETAILS FIG. 1 The building block pyramid: Original cost- saver The building block approach (BBA) was originally developed to minimize cost by reducing the number of large-scale tests (top) required for design substantiation. However, the trade-off is that thousands of physical coupons are required at the materials level (bottom). Source | MIL-HDBK-17-1F (open source) Non-Generic Specimens Generic Specimens Structural Features Data Base SUB-COMPONENTS Half the Cost of Test Program FULL-SCALE TEST ARTICLES