Moisture effects on the bending fatigue of laminated composites

Abstract

This paper investigated the effect of moisture ingress on the bending fatigue of laminated composites. An accelerated testing method was developed to investigate the correlation between composite fatigue and moisture diffusion effects. Unidirectional and cross-ply laminated CFRP composites were manufactured in autoclave, and then submerged in both fresh and seawater for various periods until moisture saturation. Quasi-static and cyclic tests were carried out in both air and wet environment, and the failure mechanisms were investigated using visual and microscopic methods. Additionally, a robust 2D Finite Element model (FEA) was developed to simulate the fatigue crack propagation based on Virtual Crack Closure Technique (VCCT), while a 3D FEA model was developed to investigate the edge effect on fatigue crack propagation. The experimental observations gave a good agreement with the FEA models. The study showed that the bending fatigue failure was due to the so-called buckling-driven delamination, and the fatigue life was reduced significantly owing to the combination of edge effect and capillary effect. The fatigue test indicated that the fatigue resistance was degraded one stress level due to the water ingress. Therefore, a 4-step fatigue failure theory was proposed to explain the moisture effects on the crack propagation under bending fatigue

Perilaku Tarik Komposit Laminat Serat Kulit Waru-Aluminium

“…Fiber metal laminates (FMLs) merupakan struktur komposit hybrid yang terbentuk dari kombinasi lapisan-lapisan atau lembaran logam dengan berat ringan seperti aluminium atau titanium dan lapisan polimer yang diperkuat dengan serat dengan rasio berat terhadap kekuatan yang tinggi [2,3]. Meng, et al (2016) [4] telah melaporkan bahwa Laminat serat-logam (FMLs) memiliki sifat mekanik yang baik, ketahanan lelah yang tinggi, kapasitas dalam menyerap energi dan ketahanan impak yang tinggi, tahan terhadap korosi dibandingkan dengan laminat komposit konvensional. FMLs dari serat sintesis seperti Aramid fibre aluminium laminate (ARALL), glass laminate aluminium reinforced epoxy (GLARE) dan carbon reinforced aluminium laminates (CARAL) telah banyak digunakan mulai dari bidang industry pesawat terbang, marinir, otomotif, olahraga dan biomedis [5,6].…”

Report of Committee III.2: Fatigue and fracture

“…The advanced numerical modelling techniques of composite tidal turbine blades demonstrate the development of numerical techniques for modelling the growth of interfacial cracks (Harper & Hallett, 2015). The effect of moisture ingress on the bending fatigue of laminated composites was investigated in (Meng et al, 2016). A 2D Finite Element model (FEA) was developed to simulate the fatigue crack propagation based on virtual crack closure technique, while a 3D FEA model was developed to investigate the edge effect on fatigue crack propagation.…”

Novel method for improving fatigue behaviour of laminated glass

“…Marcon et al have reported that microcracks in the windshield (produced due to the impact of a foreign object) propagate due to the chemical reaction between humidity and SiO 2 in the glass not by cyclic fatigue. The conclusions of Marcon et al are supported by Meng et al; however, the conclusions of Marcon et al and Meng et al are not directly implied on structural applications of LG; fracture mode mixity may lead to a different conclusion under cyclic fatigue loading spatially at nanolevel . Fatigue fracture mechanics of laminated composites is discussed widely; however, fibre‐reinforced plastic composites are the prime consideration in those studies.…”