PSI - Issue 51

M. Vaško et al. / Procedia Structural Integrity 51 (2023) 173–178

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M. Vaško et al. / Structural Integrity Procedia 00 (2022) 000–000

1. Introduction 3D printing is a relatively new and modern production technology based on the creating objects by layering materials. The development of additive manufacturing has led to the improvement and providing many benefits and it offers application in various industries (Barbero (2017), Chua et al. (2010), Jones (1999), Melenka (2016)). There are also many different variations of additive manufacturing, each with its own unique working process. Fused filament fabrication (also known as FFF) is the most widely used 3D printing method. It involves depositing layers of thermoplastic material in specific locations on a printing bed, through the use of a moving printer head and a nozzle that extrudes molten material (Krawiec et al. (2021), Rojek et al. (2020)). The working principle predetermines this method primarily for printing thermoplastics. Composites are materials composed of two or more components. One component, referred to as the matrix, holds the object shape, transfers loads to the reinforcement and protects the reinforcement. The second component is the reinforcement. It has a strengthening function in composite. The composite strengthening provides fibres, flakes or whiskers (Goh et al. (2019), Khalid et al. (2021)). Advancement in the Fused Filament Fabrication (FFF) method, which involves the use of an additional nozzle, has made it possible to print composites made of continuous fibre-reinforced thermoplastics. In comparison to conventional production methods the user can adjusts the location of the fibre in the composite structure and adapts it mechanical properties (Kastratović et al. (2021), Marsalek et al. (2021)). Most research on the topic of additive manufacturing has focused on tensile or bending tests (Šofer et al. (2021)). A previous scientific article by the authors examined the Charpy impact test and comparison of selected printing parameters (infill orientation, fibre type, fibre volume fraction) influence on impact toughness (Vaško et al. (2020)). The study showed that all of these parameters have an influence on impact toughness. Specimens reinforced with HSHT glass fibre and arranged in concentric rings achieved the highest values. The study used specimens without notches as allows the relevant standard. However, in similar studies (Caminero et al. (2018), Scrocco et al. (2018)) the other authors selected notched specimens. In the review process, the question arose as to how the presence of a notch will affect the results. Therefore the authors aimed to perform the initial assessment of the notch application possibility and identification of notch effect on the impact toughness. 2. Specimen preparation and experimental procedure The Charpy impact test was performed on a set of specimens with the shape and dimensions defined in Fig. 1. Each of series comprised five specimens.

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Fig. 1. Shape and dimensions of specimens: (a) without notch; (b) V-notched.