CFRP thin-ply fibre metal laminates : influences of ply thickness and metal layers on open hole tension and compression properties

Thin-ply laminates exhibit a higher degree of freedom in design and altered failure behaviour, and therefore, an increased strength for unnotched laminates in comparison to thick-ply laminates. For notched laminates, the static strength is strongly decreased; this is caused by a lack of stress relaxation through damage, which leads to a higher stress concentration and premature, brittle failure. To overcome this behaviour and to use the advantage of thin-ply laminates in areas with high stress concentrations, we have investigated thin-ply hybrid laminates with different metal volume fractions. Open hole tensile (OHT) and open hole compression (OHC) tests were performed with quasi-isotropic carbon fibre reinforced plastic (CFRP) specimens. In the area of stress concentration, 90° layers were locally substituted by stainless steel layers of differing volume fractions, from 12.5% to 25%. The strain field on the specimen surface was evaluated in-situ using a digital image correlation (DIC) system. The embedding of stainless steel foils in thin-ply samples increases the OHT strength up to 60.44% compared to unmodified thin-ply laminates. The density specific OHT strength is increased by 33%. Thick-ply specimens achieve an OHC strength increase up to 45.7%, which corresponds to an increase in density specific strength of 32.4%.

Subjects

stainless steel foil

stress distribution

hybrid material

non-destructive testing

digital image correlation

DDC Class

600: Technik

620: Ingenieurwissenschaften

Funding(s)

Publikationsfonds 2020

Lizenz

https://creativecommons.org/licenses/by/4.0/

Name

materials-13-00910-v2.pdf

Size

39.76 MB

Format

Adobe PDF

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CFRP thin-ply fibre metal laminates : influences of ply thickness and metal layers on open hole tension and compression properties