PSI - Issue 43

Wilfried Becker et al. / Procedia Structural Integrity 43 (2023) 77–82 Author name / Structural Integrity Procedia 00 (2022) 000 – 000

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1. Introduction Nowadays, nanoclay-reinforced polymers are one of the most widely used nanocomposites due to their high aspect ratio, higher contact area and their unique properties. These composites are used in a number of industrial applications, such as construction (building sections and structural panels), automotive (gas tanks, bumpers, interior and exterior panels), chemical processes (catalysts), pharmaceutical (as carriers of drugs and penetrants), aerospace (flame retardant panels and high performance components), food packaging and textiles, (Guo et al., 2018). In recent years the range of research on this type of nanocomposite has considerably increased and shows that more than two phases appear in it. For the proper design and safe application of the latter, it is necessary to study their properties in order to predict the occurrence of delamination in them. For this purpose, a lot of experimental and numerical methods have been developed (Heydari-Meybodi et al., 2015). Some of them are based of application of finite element methods for modeling of elastic modulus or stiffness of the interphase layer with emphasising on the role of inclusion/matrix interphase (Saber ‐ Samandari and Afaghi ‐ Khatibi, 2007). The latter has been applied to determine either the probability of debonding at the interface (Heydari-Meybodi et al., 2015) or for investigation of the effect of various geometrical parameters, such as the change of the nanoclay contact area, the nanoclay angle in the planes, etc. on the elastic modulus of the polymer nanocomposite reinforced with nanoclay (Heydari-Meybodi et al., 2016). There have been developed other methods such as this one of Halpin-Tsai and Mori-Tanaka (Fornes and Paul, 2003) for estimation of the reinforcement in layered aluminosilicates and glass fibers using the composite theories or 3D voxel based model for determination of the damage in nanocomposites with intercalated structures (Mishnaevsky, 2012). The lack of methods in the available literature for investigation of the effect of the interphase properties of considered nanocomposites on the interphase shear stress (ISS) and interphase peel stress (IPS) in them is noteworthy. Тhis study has implemented the two -dimensional stress-function method of Petrova et al. (2022) to obtain the analytical solutions for ISS and IPS in nanoclay/polymer nanocomposite structure, subjected to axial load. The performed parametric analysis shows how varying of the interphase mechanical properties (Young ’s modulus and Poisson ’s ratio) and their geometric properties (thickness and length) influence the value of the model ISS and IPS. The obtained results could be useful for the proper design and safety application of similar nanoclay/polymer composites in industry. 2. Problem statement and obtained analytical solutions Fig. 1 shows a representative volume element (RVE) of a three-layerd nanoclay-interlayer(interphase)-polymer nanocomposite structure. The axial tensile force P (N.m) is applied to the polymer layer. The coordinate system Oxy is placed at the left end of the structure with a length l , the y-coordinates for the layers are: 2 2 2 1 , , a t a b h c h h y h h h = = + = + + For the nanocomposite structure shown in Fig 1 the two - dimensional stress function method provided by Petrova et al (2022) has been applied and as a result, analytical solutions for the ISS and IPS in the middle layer (interphase) of the structure could be obtained The details for the solution development are given in Petrova et al (2022) Here, for brevity, only the most basic equations have been used

y

Nanoclay platelet, h 1 Interphase layer, h a

b = h 2

Polymer matrix, h 2

P

P

x

Fig. 1. RVE of three-layer nanoclay-interlayer(interphase)-polymer nanocomposite structure.