PSI - Issue 47

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Rachid Bensaada et al. / Procedia Structural Integrity 47 (2023) 503–512 R. Bensaada et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 2. a) Arcan device with angle orientation and b) specimen coordinate system, c) beaks within the substrates (Alfonso, Badulescu, and Carrere 2018)

The other particularity of the modified Arcan testing is the introduction of beaks within the substrates (Fig. 2c) in order to reduce edge effects (Cognard 2008). This modification makes it possible to obtain a homogeneous stress

distribution and avoiding stress singularities. 2.3.2 Adhesive selection and surface treatments

The bonding of Tensylon® presents some obstacles that turn out to be challenging. The poor thermal properties of Tensylon® requires an adhesive with low curing temperature and able to bond its low energy surface. Permabond® TA4610 was a reliable candidate to bond Tensylon® given its curing temperature (23°C in 24-36h). Surface treatments are also performed on both substrates and Tensylon® surfaces. These steps are of paramount importance to increase the Tensylon® surface energy. The surfaces are firstly sandpapered with 200µm sandpaper granulation. A corona treatment is subsequently performed to charge positively the surfaces. This treatment was proven to increase efficiently the surface energy, notably between UHMWPE and PMMA (Oosterom et al. 2006). 2.3.3 Substrate selection using pull-off testing Concerning the substrate selection, three materials were pre-selected, steel, aluminum, and ABS. The idea is to achieve fracture within the Tensylon® thickness i.e., cohesive fracture. To do so, the adhesive strength should be higher than the composite interlaminar strength. The three combinations were tested through the pull-off test in accordance to the ASTM C633 standard (ASTM C633 2013). The results obtained (Fig. 3) show that only ABS give cohesive fracture in all the cases while steel fail systematically to give the expected result and fracture using aluminum substrates is mostly adhesive.

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