Numerical Modeling Of Thermo-mechanical Stress Field Associated With Mode-i And Mixed-mode Fracture In Homogenous Isotropic Materials

Engineering components exposed to different loading include mechanical, thermal or combinedrnthermo-mechanical loading. Some of the components subjected to thermomechanical loading arerngas turbines, engines, reactor components, fuel chambers, and so forth. Defects and flaws arernprimal causes for materials failure and exist in almost all materials. In this work, the effect ofrnthermomechanical loading on the stress fields was investigated under pure Mode-I and MixedrnMode fracture by assuming a two-dimensional model under plane strain condition. To study therncombined effect of thermo-mechanical loading on the stress field around the crack tip, sequentiallyrncoupled thermal-stress analysis employed by ABAQUS software was used under differentrnconditions. The parameters used in this work i.e., material dimension selected based on BSrnstandard, the applied remote stress also calculated analytically using limit load formula asrn20MPa, 50MPa and 100MPa. The temperature gradient employed at the surface of the model isrntaken from literature ranges from��20℃ to 89℃. The crack was considered as thermally insulatedrnmeans adiabatic crack and the temperature field used as an input for the thermomechanical stress.rnThis temperature field was solved by the assumption of steady-state heat transfer and the heatrntransfer procedure is utilized to solve it. The temperature field is incorporated as an input for thernstress analysis as a predefined field in the static general procedure for developing arnthermomechanical stress field. The extended finite element method (XFEM) was employed tornmodel the crack for reducing the time of meshing and processing and to define the temperaturernand displacement discontinuity along the crack. The thermomechanical stress field was solved byrnapplying different parameters i.e., remote stress, crack angle, crack length and temperaturerngradient. The mechanical and thermo-mechanical stress fields were evaluated and extracted fromrnthe crack tip for the radian value of �� �� 0.002�� and angular position value between ��180° ≤rn�� ≤ 180° for both Mode–I and Mixed Mode fracture cases.rnBased on the result, the stress fields i.e.,��������, ������ and ������ around the crack tip were affectedrnby the temperature gradients. The extreme thermo-mechanical stress field values ������ and ������ werernrise by 13.4 to 36.39% and 4 to 17.6% respectively while the in-plane stress ������ drop by 8 torn43.49% relative to extreme mechanical stress value for temperature change Δ���� to Δ���� in case ofrnconsidering the maximum value in pure mode-I loading case. Even though, the phenomenon of thernextreme values for the case of mixed and pure mode-I loading cases are differ, the mixed modernthermo-mechanical stress field values ������ and ������ are drop by 6.78 to 25.64% and 12.85 to 30.3%rnrespectively while the in-plane stress ������ rise by 4.75 to 25.09% in rising of temperature changernΔ���� to Δ���� in case of considering the maximum value. This extreme values variation was becausernof the temperature gradient from the boundary of the plate as compared to mechanical stress field.rnBesides the angular position of the extreme stress field values shifted for a certain angle asrncompared to the isothermal stress field. The contour of these stress fields around the crack tiprndeveloped numerically has a good agreement with the analytical developed results.

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