Fatigue crack growth and delamination mechanisms of Ti/CFRP fibre metal laminates at high temperatures

Abstract

Ti/CFRP (titanium/carbon fibre reinforced polymer) fibre metal laminates (FMLs) are composed of titanium sheets and carbon fibres reinforced PMR (polymerization of monomeric reactants) type polyimide resin. Due to the outstanding heat resistance of the material, it can be used in hypersonic aircraft applications. Fatigue cracks in the metal layer and delamination at metal/fibre interface may occur in long-term high-temperature use processes. However, the behaviour of the fatigue failure at high temperatures has not been investigated. A temperature-dependent equation has not been presented to predict the crack growth behaviour at high temperatures. In this study, to investigate the crack propagation and delamination behaviours, fatigue crack growth rate tests using tension-tension loads at 25 C, 80 C, 120 C, and 150 C were conducted in accordance with ASTM E647-15e1. The results indicated that the variation in fatigue crack growth rate could be described by a modified temperature-dependent Paris equation. Interfacial strength and tensile strength may influence fatigue failure at high temperatures. Hence, these strength values were also obtained to analyse the mechanism of fatigue behaviour. The delamination area increased exponentially with temperature due to the weakening of the Ti/CFRP interface, and delamination was invariably generated on the microcracks of the titanium layers. K E Y W O R D S delamination, fatigue crack growth, fibre metal laminates, thermal effect

Analysis of the Deceleration Methods of Fatigue Crack Growth Rates under Mode I Loading Type in Pearlitic Rail Steel

“…Carbon fiber-reinforced polymer (CFRP) patches are still of particular interest in various applications in civil engineering [9][10][11][12]. However, there are not many papers devoted to degradation problems in a real operational environment [13][14][15]. Thus, in some cases, the historic stop-hole technique is still attractive based on simple crack "blunting" and re-initiation period [16][17][18].…”

A new phenomenological creep residual strength model for the life prediction of the laminated composites

“…The mentioned advantages make the residual strength models suitable to be used in progressive fatigue damage modeling. [24][25][26] Since cyclic loading occurs in most applications, the majority of the models available in the literature are related to cyclic loading, [27][28][29][30] while the life and damage prediction under sustained load is less addressed. However, the fatigue cycles could be transformed into loading time with the relation t = f  N, where f is loading frequency and N is the number of cycles.…”

Temperature-Dependent Fatigue Failure of Flexible Poly(9,9-dioctylfluorene-alt-benzothiadiazole) (PFBT)–ZnO Nanoparticle Hybrid Resistive Switching Memory Devices

“…Similarly, Jin et al found that the fatigue crack growth rate in Ti/CFRP nanocomposite was temperature-dependent. The delamination region expanded exponentially with increasing temperature from 20 to 150 °C due to the weakening of the bonding force at the Ti/CFRP interface at high temperatures . For polymer/NPs hybrid nanomaterials, Tsang et al showed that the epoxy polymer embeded with silica NPs was more susceptible to fatigue damage at −40 °C .…”

“…The delamination region expanded exponentially with increasing temperature from 20 to 150 °C due to the weakening of the bonding force at the Ti/CFRP interface at high temperatures. 20 For polymer/NPs hybrid nanomaterials, Tsang et al showed that the epoxy polymer embeded with silica NPs was more susceptible to fatigue damage at −40 °C. 21 Clearly, temperature has a great influence on the fatigue endurance of flexible devices, but the underlying physics of how the temperature affects the fatigue endurance is rarely studied, especially for polymer−inorganic NP hybrid devices at low temperatures.…”