Issue 50

M.R.M. Aliha et alii, Frattura ed Integrità Strutturale, 50 (2019) 602-612; DOI: 10.3221/IGF-ESIS.50.51 604 were stored inside a freezer at -8 o C for 24 h. The specimens were then loaded by a three-point bend fixture with bottom loading span of 40 mm. Thus the loading span ratio was equal to S/L =0.8. The cross head speed of loading was fixed at rate of 1 mm/min for all test samples. Figs. 2 and 3 show the schematic of test specimen and test setup used for fracture toughness testing of the bovine bone. Each specimen was loaded monotonically until the failure of specimen. The critical peak load F cr which was measured by the load cell of testing machine was used to calculate the mode I fracture toughness value, using the following equation: cr Ic 6F a a K  f  Bw w        (1) where the geometry factor f ( a/W ) is function of crack length ratio ( a/W ) and is written as: f ( 2 3/2 a a 3.93a a 1.99 1 2.15 2.7 w w w w a )  w 2a a 1 1 w w                                     (2) The fracture energy G f which is the representative of energy required for breaking the test specimen was also calculated from the area under the load-displacement curve of each test. In the next section, the experimental results of mode I fracture toughness ( K Ic ) and mode I fracture energy ( G f ) are presented. Figure 1 : Test specimen preparation from the bovine femur in the shape of rectangular beam samples.