PSI - Issue 40

S.A. Bochkareva et al. / Procedia Structural Integrity 40 (2022) 61–69 Bochkareva S. A., Panin S. V. / Structural Integrity Procedia 00 (2019) 000 – 000

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the maximum value of which was equal to the PEEK yield point. If delamination had occurred in any nodes then they were no longer connected between CF and the binder. The fracture limit of the welded joint as a whole was determined based on the fulfillment of one of two conditions. The first one was that the area of fractured elements reached 10% of the corresponding material area. The second condition was fulfilled when the number of ‘delaminated’ nodes of a layer r eached 10% of the total number of initial contact ones. The following calculation models were considered, reflecting experimental schemes for the formation of the laminated composites (Figure 2): ‘PEEK - PEEK’, ‘PEEK -PEEK prepreg/USW- PEEK’, ‘PEEK -PEEK film- PEEK’, and ‘PEEK -PEEK film-PEEK prepreg /USW-PEEK film- PEEK’.

Fig. 2 – A schematic representation of the laying process: ‘PEEK - PEEK’ (a); ‘PEEK -PEEK prepreg/USW- PEEK’ (b); ‘PEEK -PEEK film PEEK’ (c); ‘PEEK -PEEK film-PEEK prepreg/USW-PEEK film- PEEK’ (d) 3. Results of computer simulation of the welded joints under tension Figure 3 shows the computational domain with the finite element mesh for the welded lap joint of the PEEK plates under tension when the fracture criteria were met. In this case, the sample as a whole experienced macro bending because the plates were not located in the same plane.

Fig. 3 – T he computational domain with the finite element mesh for the ‘ PEEK-prepreg- PEEK’ welded lap joint under tension

Therefore, a torque and a complex stress-strain state were observed, since the sample was exposed to tension, compression and shear in different places at the same time. Figure 4 presents the intensity distribution surfaces for strains (a) and stresses (b) in the ‘PEEK - PEEK’ welded lap joint without an intermediate layer

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Fig. 4 – The intensity distribution surfaces for strains (a) and stresses (b) in the ‘PEEK - PEEK’ US -welded lap joint after tension and the corresponding half-tone relief images