解析事例-8

部分閉口が発生する曲げ荷重状態でのき裂形状進展

Brazilian National Council for Scientific and Technological Development (CNPq)の協力のもと行われた、面外曲げ荷重による初期貫通き裂を持つ平板のき裂形状進展の実験、計算研究の事例。 き裂は、き裂面一部の閉口接触を考慮したき裂前縁の進展形状を再現するような、ステップバイステップの3次元要素技術により数値解析された。

資料より抜粋:
Finally, two different FCG rate expressions fitted by the Elber modified model were used to evaluate the influence of the growth rate in the incremental simulation of the successive crack fronts process. Crack front geometries from the incremental process are in good agreement with the experimental beach marks using both growth rates.



Fig1. Statement of the problem: (a) out-of-plane pure bending loads and (b) pre-crack under fatigue tension loads.



Fig2. Images of: (a) four-point bending test; (b) top and (c) bottom surface.



Fig3. Comparison of the observed and idealized crack fronts using non-concentric quarter-elliptical curves in: (a) SP01, (b) SP02 and (c) SP03 (dimensions in millimeter).


Fig4. Typical 3D FE model: (a) FE mesh with loading and support conditions; (b) Element arrangements at crack faces; (c) top surface mesh near the notch and, (d) schematic representation of core region around crack front.


Fig5. Finite element arrangements at crack faces: (a) schematic representation of crack growth; (b) top surface mesh near the notch; (c) Step 0 (Pre-crack); (d) Step 25; (e) Step 50; (f) Step 75 and, (g) Step 96.

参照:Corbani, S., Castro J.T.P., Miranda, A.C.O., Martha, L.F., Carter, B., Ingraffea, A. (2019) Crack shape evolution under bending-induced partial closure. Engineering Fracture Mechanics, 188, 1, 493-508,
http://www.sciencedirect.com/science/article/pii/S0013794416303927