PSI - Issue 13

Tsanka Dikova / Procedia Structural Integrity 13 (2018) 461–468 Tsanka Dikova / Structural Integrity Procedia 00 (2018) 000–000

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loaded section, the places for crack initiation are closer each other (Pegues et al. (2018). Thus, more rapid coalescence of the many generated cracks in larger and correspondingly destruction of the specimen occur.

Fig. 4 Loadings of cracking and destroying of dental bridges during bending test. (Technology 1 – conventional casting with wax patterns, technology 2 – casting with 3D printed patterns and technology 3 – SLM).

Co-Cr dental bridges, produced using additive technologies, are cracked at average load of 10.171 kN in casting with 3D printed patterns or destroyed at 9.255 kN in SLM. These loadings exceed many times the total chewing load on the four teeth of the studied bridge construction - 0.962 kN (Filtchev and Kalachev (2008). Optimization of the technological regimes of the SLM process - laser power and scanning speed will result in a dense microstructure, hence a higher flexural strength.

Fig. 5 Fractured surface of Co-Cr dental bridge, cast with 3D printed pattern.

3.2. Fracture of cast Co-Cr dental bridges In the picture of the fracture surface of the sample, cast from Biosil-F alloy with 3D printed pattern, it is clearly seen the place of the crack originating and its development (Fig. 5). During bending process the crack generation