The volumetric method to calculate the permeability is verified by Nettles [22]. The

study is to investigate the effect on permeability test of laminated composites after

experiencing impact loads. Moreover, the study investigated the possible cases of testing

condition which influence the permeability results. When the glass capillary tube is

mounted vertically or horizontally, the variation of permeability results is insignificant.

The permeability tests were performed using various types of liquid indicators in a

capillary tube. The variation of permeability results was found to be insignificant. Also,

the length of liquid indicator does not affect the permeability results. However, the glass

capillary tube with inner diameter 0.4 mm underestimated permeability than the capillary

tubes with 1.2 mm and 3 mm diameters.

 The permeability test on laminated composites and bonding materials were

performed by Nettles [23]. The permeability results before and after cryogenic cycles

were compared. The composite specimens of both type of prepreg materials and layup

configuration have low permeation results after 4 and 12 cryogenic cycles. Glass et al.

investigated the permeability for core materials of a composite sandwich when it is

subjected to shear loads [24]. The Hexcel HRP honeycomb and the Dupont Korex

honeycomb were chosen for core materials. The composite sandwich specimens were

fabricated and air inlet holes were drilled through a facesheet. The permeability is

calculated by measuring the flow rate of upstream air.

 In this study, the permeability was estimated for various composite material

systems as the composite laminates undergo cryogenic cycling. An optical microscope

was used to understand the nature of microcrack propagation after cryogenic cycling. The

permeability increased rapidly and became constant as the number of cryogenic cycles