13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- Plastic factor of front face compact tension specimens KAIKAI SHI1,*, LIXUN CAI1, CHEN BAO1 1 School of Mechanics and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China * Corresponding author: lix_cai@263.net Abstract To estimate fracture toughness of irradiated material in nuclear engineering, the testing specimens with half thickness of a standard compact tension specimen are used to get the J resistance curve of materials according to Standard Test Method for Measured of Fracture Toughness (ASTM E1820). The normalization method recommended by ASTM E1820 is not directly applied in obtaining the fracture toughness of metallic materials because it does not provide the plastic factor of Front Face Compact Tension specimen with 12.5mm thickness and 25mm width (1/2 FFCT specimen). Based on the energy of J integral and the detailed finite element analysis, the plastic factor of a 1/2 FFCT specimen is presented. With the plastic factor of 1/2 FFCT, the J resistance curve of a 1/2 FFCT specimen and its fracture toughness can be obtained by Using the normalization method. Keywords Front face compact tension, Load line compact tension, Plastic factor, Finite element, normalization method 1. Introduction Structural materials, A508-Ⅲ steel which long-term service in the radiation environment , must have material damage and material aging in nuclear engineering. Long-term, department of design and operations has focused on the nuclear reactor material damage by surveillance and prevention. The problem that measuring the fracture behavior of irradiated material A508-Ⅲ steel is need to be solved as quickly as possible. The fracture behaviors of material include the fracture toughness and crack growth rate of material and so on. Based on single specimen method, the 1/2FFCT specimen is selected to estimate the fracture toughness. Because the test material is irradiated, all operations are completed by the mechanical arm. The unload compliance method require the high of neutral and test accuracy, so applying of unload compliance is restricted in fracture mechanics automatic test technology. The unload compliance method does not good coordinate with the mechanics arm. It is recommended that the normalization data reduction technology be used to in ASTM E1820-11 to determine J resistance curve and reduced test costs as well. The normalization data reduction technology involves the plastic factor of test bending specimen, so the plastic factor of 1/2FFCT specimen is quickly studied. There are two ways to obtain the plastic factor which are SLF (Slip Line Field) theory [1-4] and FEA (Finite Element Analysis) [5-10]. The SLF theory assume that material behavior is perfectly elastic-plastic. It establishes the contact the plastic factor with the limit load. The FEA studies the plastic factor which considering the different stain hardening, so the FEA can more accurate analysis the plastic factor. Based on the J integral energy theory [11] and the detailed finite element, the plastic factor of compact tension specimen is researched. 2. Plastic Factor 2.1. Plastic Factor of Load Line Compact Tension Specimen Rice [11] proposed the parameter J-integral for nonlinear elastic material as a measure of crack-tip
RkJQdWJsaXNoZXIy MjM0NDE=