Suggested modifications of the ASTM D2344-16 short-beam shear test method to be applied to fiber metal laminates

Abstract

ASTM D2344/D2344M-16, Standard Test Method for Short-Beam Strength of Polymer Matrix Composite Materials and Their Laminates, is used to test fiber-metal laminates (FMLs), although its scope is limited to high-modulus fiber-reinforced composite materials. These two groups of materials have differences in their mechanical behavior, and it is possible that this standard cannot be employed in FMLs in its current status. To verify this, short-beam shear (SBS) tests were performed in aramid aluminum laminate (ARALL) 3 4/3 specimens employing two sets of rollers diameters. One set was in accordance with ASTM D2344/D2344M-16, whereas the other made use of smaller diameters. The options to stop the tests presented in the standard were not adequate for the ARALL specimens using the normalized rollers diameters. Modifications to the standard in order to include FML specimens are suggested as follows: to include a test rig with reduced roller diameters, to observe of delamination at one side of a specimen as a new option to stop the test, and to define the short-beam strengths (Fsbs) as that corresponding to the maximum load value observed previous to a total load drop-off of 30 %. The difference between the means of Fsbs obtained with both set of rollers was not significant when using these modifications.