The effect of stress concentrations on the fracture strength of polymethylmethacrylate

Analysis of notch effect in the apparent fracture toughness and the fracture micromechanisms of ferritic–pearlitic steels operating within their lower shelf

“…The critical radius has been reported in other research on the notch effect in different types of materials [1][2][3][4][5][6]11,12]. In others words, the smallest finite notch radius introduced in the material (0.15 mm) generates a noticeable notch effect, with a higher apparent fracture toughness than that obtained in cracked conditions.…”

“…The Theory of Critical Distances (TCD) is actually a group of methodologies, all of which use a characteristic material length parameter (the critical distance, L) when performing fracture and fatigue assessments [11,12]. The origins of the TCD date back to the middle of the twentieth century, with the works of Neuber [13] and Peterson [14], but it has been in the last few years, driven by the proliferation of finite elements stress analysis, that this theory has been systematically analysed and applied to different types of materials (metals, ceramics, polymers and composites), failure or damage processes (basically fracture and fatigue) and conditions (e.g., linear-elastic vs. elastoplastic) [15][16][17][18][19][20][21][22].…”

“…Following the literature (e.g., [10,12]), the simulation was conducted in purely linear-elastic conditions, despite the non-linear (plastic) phenomena occurring on the defect tip in some of the specimens. Finally, the mesh was performed using SOLID186 elements (3D, 20-node solid elements with quadratic displacement behaviour), the mesh being much more refined at the defect tip, because of the higher gradients appearing in this zone, with element sizes of the same order as the finally obtained critical distances.…”

On the Line Method apparent fracture toughness evaluations: Experimental overview, validation and some consequences on fracture assessments

“…The Theory of the Critical Distances (TCD) comprises a group of methodologies with a common aspect: they all use a characteristic material length parameter (the critical distance) when performing fracture assessments [9,10]. The origins of the TCD are located in the middle of the twentieth century [11,12], but in the last two decades this theory has had a wider development, providing answers to different scientific and engineering problems (e.g., [3,6,[13][14][15][16][17][18][19][20]).…”

Estimation of Fracture Toughness by Testing Notched Fracture Specimens and Applying the Theory of Critical Distances

“…The Theory of Critical Distances (TCD) [5,13] is actually a group of methodologies, all of them using a characteristic material length parameter (the critical distance) when performing fracture (and fatigue) assessments of components containing any kind of stress risers (i.e., cracks, U-shaped notches, V-shaped notches, pores, etc.). Although it was first presented in the 1950 s [14,15], it has been in the last decade, driven by the use of finite elements modelling, that this theory has been systematically analysed, establishing its applicability to different types of materials (e.g., metals, ceramics, polymers, and composites), failure processes (mainly fracture and fatigue), and conditions (e.g., linear-elastic versus elastoplastic) (e.g., [6,7,[16][17][18][19][20][21]).…”