More Design for Impact

Back at the 1986 Marine Applications of Composites conference in Melbourne, FL, the chairman, Ron Reichard took some of us on an after-hours tour of the materials testing lab.
The most visually informative samples that he had were a series of cored panels of about 2′ by 2′ dimension. They all had the same laminate; probably two layers of 34 oz triaxial each face.  They all had the same thickness of core, 1″ as I recall. 

Each of these had a bowling ball dropped onto it from maybe 18 feet? 

The balsa one was made of contour core squares and had the little squares blasted out the far side of the panel.  The impact side was destroyed. 

The crosslinked PVC one (Divinycel)  had its core sheared apart but the face skins were mostly intact.

The linear PVC (Airex, and later would be like Corecel) had a slight delamination in a small impact spot, only on the impact face.

For me that was a powerful visual comparison.  As Prof. Thiel used to tell us, “Compare simultaneous alternatives.”

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