The crack tip constraint effect should be considered in the fracture assessment of structures with cracks, and the in-plane constraint and out-of-plane constraint should be illustrated simultaneously for the three-dimensional cracks in practical engineering structures. The constraint effect of central cracked plate (CCP) specimens with I-II mixed mode crack under uniaxial compression has been investigated quantitatively in present work. The relationship between T-stress components (T_x, T_y, T_xy) and in-plane constraint parameter T₁₁ has been established. The effects of a wide range of in-plane and out-of-plane geometrical configurations (including relative crack length a/W and thickness to width ratio t/W), material parameters (including elastic modulus E and Poisson's ratio ν), crack inclination angle β and friction coefficient μ corresponding to stress intensity factors (K), in-plane constraint parameter T₁₁ and out-of-plane constraint parameters T₃₃ and T_z at the crack tip have been calculated and discussed theoretically and numerically. It demonstrates that the constraint parameters can effectively express the stress-strain field at the crack tip. The relative crack length a/W has an influence on the in-plane and out-of-plane constraint parameters, and the thickness to width ratio t/W mainly affects the out-of-plane constraint parameters T₃₃ and T_z. The out-of-plane constraint parameters should be considered for long cracks. There is a loss of out-of-plane constraint under compression when t/W less than or equal to 0.9, which can be much more directly and evidently investigated through the analysis of T_z than T₃₃. The empirical equations for K_II, T₁₁ and T_z have been obtained according to theoretical analysis and simulation results, which are convenient and effective for application.

有裂纹结构的断裂评价应考虑裂纹尖端约束效应，对实际工程结构中的三维裂纹应同时说明面内约束和面外约束。目前的工作已经定量研究了单轴压缩下具有 I-II 混合模式裂纹的中央裂纹板 (CCP) 试样的约束效果。之间的关系Ť -stress组分（Ť _X，Ť _ÿ，Ť _XY）和面内约束参数Ť ₁₁已经建立。各种平面内和平面外几何配置（包括相对裂纹长度a / W和厚宽比t / W）、材料参数（包括弹性模量E和泊松比ν）、裂纹的影响倾角β和摩擦系数μ对应于应力强度因子（K），面内约束参数T ₁₁和面外约束参数T ₃₃和T _z在裂纹尖端处进行了理论和数值计算和讨论。表明约束参数可以有效地表达裂纹尖端的应力应变场。相对裂纹长度a / W 对面内和面外约束参数有影响，厚宽比t / W主要影响面外约束参数T ₃₃和T _z。对于长裂纹，应考虑面外约束参数。当t / W时，压缩下的面外约束丢失小于或等于0.9，这可以通过T _z的分析比T ₃₃更直接和明显地研究。根据理论分析和仿真结果得到了K _II、T ₁₁和T _z的经验方程，便于应用。