PSI - Issue 66

Ram Lal Riyar et al. / Procedia Structural Integrity 66 (2024) 181–194 Ram Lal Riyar et. al./ Structural Integrity Procedia 00 (2025) 000–000

187

7

large beams compared to small and medium beams. Additionally, a large reinforcement bar has more stiffness, thus requiring more load for crack propagation.

(a) (c) Fig. 5. Load versus crack length graphical representation for (a) Small, (b) Medium, and (c) Large beams with varying percentages of reinforcement. 3.2. Fracture toughness and fracture energy In comparison to larger beams, smaller beams often have greater fracture energies and shorter crack lengths. This is because small beams often have fewer flaws and a more uniform microstructure, which might increase their resistance to fracture. Furthermore, since the beam is narrower, there is less material accessible for the fracture to travel through, which might shorten the crack's length. However, when compared to smaller beams, larger beams often have lower fracture energy and longer crack lengths. This is because larger beams often contain more flaws, such as voids or inclusions, which may serve as stress concentrators and encourage fracture development. Additionally, a longer fracture length may arise from the larger beam size, providing more material for the crack to propagate through. It can be seen from Figure 6, that the beams follow the same pattern for both fracture energy and fracture toughness. It grows until the maximum load is reached, then declines with increasing crack length. This point is called the critical point, and the behaviour of beams at this point is explained below. In the case of a small beam, the fracture toughness and energy increase slowly, and after the critical point, they decrease slowly. But in the case of large beams, these are increasing rapidly and decreasing rapidly. For beams with high reinforcement bars, fracture energy and fracture toughness are higher because the reinforcement resists crack propagation, requiring more energy for the crack to propagate. (b)

(a) (c) Fig. 6. Fracture toughness (K IC ) vs crack length for (a) Small, (b) Medium, and (c) Large beams with varying percentages of reinforcement. (b)