Effects of Cryogenically Treated CFRP Composite on the Buckling Behavior in the Adhesively Bonded Beam

Carbon fiber reinforced plastic (CFRP) composite materials have favorable mechanical and physical properties such as low density, high strength-to-weight ratio, high fatigue resistance and high creep behavior, and high stiffness. Thanks to these unique properties, they produce aircraft parts such as outer flaps, carry-through structures, and center wing boxes and automotive parts such as body panels, engine components, and structure members. However, studies have been continuously performed on improving the properties of CFRP composite materials. Recently, investigation of the effects of cryogenic (LN2) cooling on the mechanical behavior and characteristic of these composite materials is getting a popular and important issue. In this sense, this study aims to examine the buckling behaviors of adhesively bonded beam-produced cryogenically treated carbon fiber reinforced plastic (Cryo-CFRP), CFRP, steel, and aluminum. Therefore, a new finite element model was adopted to evaluate the buckling capacity of Cryo-CFRP composite material in the adhesively bonded beam. The model is a supported adhesive beam subject to two opposite-edge compressions until the material buckles. The elastic, homogeneous adhesive was used in the assembly. Finite element models for the adhesively bonded beam having four different adherents (CRFP, Cryo-CFRP, steel, and aluminum) were established by ANSYS® software. The critical buckling loads of the adhesively bonded beam were predicted, and their mode shapes were presented for the first six modes. The effects of the usage of Cryo-CFRP on the critical buckling load were investigated. Among the adherents’ materials, the highest critical buckling load was determined for Cryo-CFRP/Steel adhesively bonded beam as 23.6 N. This value was obtained as 22.3 N for CFRP/Steel adherent samples. Thus, the critical buckling load was increased by 5.6 % when one adherent steel was constant and the other adherent material changed from CFRP to Cryo-CFRP. Also, the critical buckling load increased by 3.7 % when using a cryogenically treated Cryo-CFRP/Aluminum couple instead of a CFRP/Aluminum couple in the sandwich beam. The findings demonstrated that the cryogenic treatment positively affects the buckling behavior in the adhesively bonded beam.