RT - Journal Article T1 - Fracture assessment of specimens weakened by U-notch made of functionally graded materials under mode I loading JF - mdrsjrns YR - 2017 JO - mdrsjrns VO - 17 IS - 2 UR - http://mme.modares.ac.ir/article-15-774-en.html SP - 1 EP - 9 K1 - Critical load K1 - Functionally graded material K1 - Integral J K1 - Electro slag remelting K1 - U-notch AB - In this paper, fracture behavior of functionally graded material weakened by U-notches under mode I loading has been investigated. Electro slag remelting process has been used to produce functionally graded specimens in a notch arrester configuration. Hardness test has been utilized to define the position of each layer. Mechanical properties, including elastic modulus and poisson's ratio, vary along the width of U-notched specimens. The critical fracture load (Fcr) was achieved by performing three point bending examination and using force-displacement curve. Then, the process simulation was done by finite element software. Firstly, Jcr of each specimen was calculated by using critical value of strain energy averaged over a well-defined control volume. Then the critical fracture load was evaluated by means of the J Integral criterion. In this research, the effect of the notch root radius, for a fixed notch depth, on the Jcr value as well as the critical fracture load has been studied. To compare fracture behavior of the FG specimens with the corresponding homogeneous ones, have the same properties with the notch root layer in FG specimen, Fcr and Jcr value of each have been investigated. The average difference between the predicted Fcr by J integral criteria and experimental results is 17.84%. Finally, the effect of number of graded area layers on Jcr and Fcr has been investigated. The results shows, the value of Jcr and Fcr do not be affected while the number the number of layers more than 20. LA eng UL http://mme.modares.ac.ir/article-15-774-en.html M3 ER -