Effect of carbon nanofibre orientation on fatigue properties of carbon fibre-reinforced polymers

Abstract

Nano-reinforcements in carbon fibre-reinforced polymer (CFRP) have proven to enhance the mechanical properties considering quasi-static, as well as fatigue load and, are a promising option with regard to CFRP performance optimisation. While general knowledge about the nanofiller content and its influence in CFRP is well documented, the use of alignment techniques for a specific orientation of the nano-reinforcements is still insufficiently studied. In this work, the influence of oriented carbon nanofibres (CNF) on the mechanical properties of bidirectional CFRP is investigated. CFRP was produced CNF-reinforced with and without orientation using a hot press, where an electric field was applied during curing. The laminates were characterised with respect to dispersion quality, pore volume, quasi-static properties (tensile and bending tests) and dynamic properties (fatigue tests). Electrical resistance measurement was applied together with digital image correlation and in situ computed tomography to generate knowledge about the fatigue-related damage evolution and evaluate the sensors for viable use of condition monitoring. Results show that the orientation of CNF has a significant impact on both quasi-static and fatigue properties, increasing the strength while reducing and slowing down the introduced damage. Orientation of nanofillers thus shows large optimization potential of mechanical properties of CFRP components.

Fatigue condition monitoring of notched thermoplastic-based hybrid fiber metal laminates using electrical resistance measurement and digital image correlation

“…The detected crack structure in the central aluminum sheet is comparable to the outer aluminum layers, which indicates that the crack development is similar in all aluminum layers and therefore the used methodology is applicable to the investigated structures. With regard to condition monitoring and lifetime prediction, precise investigation of the damage evolution should be possible using intermittent in situ CT testing methods 42 to determine the damage states at e.g., defined crack lengths.

Figure 18.Computed tomography scan cross-section images of the constant amplitude tested 3/2 (GC) MB DH5 specimen’s (maximum stress of 200 MPa, after 24.5 × 10 5 cycles, and 250 MPa after 24.6 × 10 5 cycles) front, rear, and center aluminum sheets. DIC deformation images showing the maximum strain overlaid for front and rear to illustrate the detectability of the cracks.

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“…The detected crack structure in the central aluminum sheet is comparable to the outer aluminum layers, which indicates that the crack development is similar in all aluminum layers and therefore the used methodology is applicable to the investigated structures. With regard to condition monitoring and lifetime prediction, precise investigation of the damage evolution should be possible using intermittent in situ CT testing methods 42 to determine the damage states at e.g., defined crack lengths.…”

Nanotechnology-enhanced fiber-reinforced polymer composites: Recent advancements on processing techniques and applications

“…They determined that the oriented CNFs influenced the fiber-matrix interface by strengthening it and reducing delamination. Tensile properties, flexural properties, and interlaminar shear strength (ILSS) improved by incorporating CNF in CFRP [ 62 ]. Applications of CNFs include the implementation of branched carbon nanotube/carbon nanofiber composites as supercapacitors for electrode materials [ 63 ] and CNF structures in developing anode materials for sodium-ion batteries [ 64 ].…”

“…Various methods exist for adding nanofibers into a composite material. Nanofibers can be dispersed in the matrix before fabricating the composite [ 62 , 66 ]. Another method includes coating fibers with nanofibers to improve the characteristics of the composite.…”

In situ and offline mapping analyses of fatigue behavior in carbon-fiber-reinforced polymers by small- and wide-angle X-ray scattering

“…Carbon-fiber (CF) -reinforced polymers (CFRPs), which have received considerable attention as composite materials owing to their excellent mechanical properties, have been applied in various fields, such as the automotive industry, architecture, and the aerospace sector. 3,4 However, further investigation is needed to expand their applications toward sustainable development goals. For instance, fatigue tests, in which destructive phenomena are induced by repeated stimulation over a long period, are crucial because they closely replicate application conditions.…”