SYMPOSIA PAPER Published: 01 January 2002

Qualification Using a Nested Experimental Design


The general aviation approach was taken in these material qualifications, where it is assumed that a large portion of composite material property batch-to-batch variability can be reproduced in the laboratory through independent layup and cure of panels, termed a process lot. A nested experimental design was used to quantify the actual sources of variability for hot/wet tension and compression strengths, and dry and wet glass transition temperatures. Two large crossplied panels, each representing a process lot, were independently made from each of three qualification batches. Two subpanels, each representing a machine lot, were cut from each process lot panel, then independently machined into coupons, moisture conditioned, and tested. With these three nested experimental levels the batch-to-batch variability can be partitioned into true batch variability, laminate fabrication, coupon test, and within sample variability. Results indicate that true batch variability was a relatively minor contributor to material property variability as a whole.

Author Information

Ruffner, D
The Boeing Company, Mesa, AZ
Jouin, P
The Boeing Company, Mesa, AZ
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Developed by Committee: D30
Pages: 85–98
DOI: 10.1520/STP10632S
ISBN-EB: 978-0-8031-5464-3
ISBN-13: 978-0-8031-2893-4