12 A. B. Irez et al. Fig. 2.1 Microstructure of the composites developed for the wings spars for this research (a) CJ I (b) CJ II (c) CJ III 2.2.3 Wear Resistance (Scratch Test) and Damage Analysis Via 3D Optical Roughness Meter In the current research basic idea on the tribological behaviour of the epoxy and recycled elastomer based composites was evaluated performing scratch tests. A 3D optical surface scanner was utilized to assess damage zone after the scratch test in terms of scratch depth and average scratch roughness. Scratch were created over the polished specimens in two different loading conditions (10–15 N) for ten cycles on the same amplitude by using Anton Paar™ MST3 micro scratch tester. 2.3 Results and Discussions 2.3.1 Microstructural Evaluation of the Composites After hot compaction, sectioning was made then mounted specimens were polished. Then, general microstructures of the each composites were observed and they were shown in Fig. 2.1. Then, mapping analyses was carried out for each composition were presented in Fig. 2.2 with together the general microstructures of the each composition. This type of analyze allows us to observe the distribution of the reinforcements in the matrix. It seems that a homogenous distribution of the reinforcements in the structure for each composition. 2.3.2 Three Point Bending Tests and Fracture Surface Observation Three-Point Bending (3 PB) tests have been carried out for each different type of compositions with at least three specimens. Flexural stress is calculated during three-point bending test according to the Eq. 2.1: σ = 3Pl 2bh2 (2.1) In this formula, l is the span length, Pis the maximal bending load, bandhare the sample thickness and depth, respectively. Flexural strain, εf, was determined according to the Eq. 2.2: εf = 6Dh l2 (2.2) D is the maximum deflection at the center of the specimen.EB is the modulus of elasticity in bending and it is expressed with the Eq. 2.3 as follows: EB = l 3 m 4bh3 (2.3) m is the tangent of the initial straight portion of the force-displacement curve.
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