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 The plastic zone of crack tip of wedge opening loading specimens were studied by positron annihilation technique. The lineshape parameters of Doppler broadening of annihilating radiation were measured. The value of S parameters was calibrated by specimens with known amount of strain. Then the distribution of the plastic strain in the plastic zone as a measure of the density of defects was determined. Experimental results indicate:1. The dimension of plastic zone is exactly the same as that determined by fracture... The plastic zone of crack tip of wedge opening loading specimens were studied by positron annihilation technique. The lineshape parameters of Doppler broadening of annihilating radiation were measured. The value of S parameters was calibrated by specimens with known amount of strain. Then the distribution of the plastic strain in the plastic zone as a measure of the density of defects was determined. Experimental results indicate:1. The dimension of plastic zone is exactly the same as that determined by fracture mechanics.2. The distribution of strain in the plastic zone is not homogeneous.3. There is a high strain area at the very tip of the crack.4. The strain in the plastic zone is increased after electrochemical hydrogenation. Isostrain curves are expanded preferentially in the direction of greatest shear stress. It is concluded that hydrogen facilitates the propagation of dislocations or the sliding of movable dislocations and vacancies can generate at the same time.  用楔形加载试样测定了裂纹顶端区正电子湮没多普勒加宽谱的S参数,并确定了试样充氢以后S参数的变化。经过标定,定出塑性区内的等应变曲线。充氢以后,使塑性内的等应变曲线向外扩展,在最大切应力方向发展最快。作者认为氢使塑性区内的位错增殖或可动位错滑移,同时产生空位。  In the present paper the stress intensity factors K_1 of rectangular plates with pointloaded edge cracks, for various combinations of lengthwidth ratios, crack lengths and locations of loading, are calculated and analyzed. Based on the superposition principle, the problem of a plate with loaded edge crack, corresponding to stress intensity factor designated K_1,is changed into that of a plate subject to known stress distribution on the boundary but free from loading on the crack, corresponding to stress intensity... In the present paper the stress intensity factors K_1 of rectangular plates with pointloaded edge cracks, for various combinations of lengthwidth ratios, crack lengths and locations of loading, are calculated and analyzed. Based on the superposition principle, the problem of a plate with loaded edge crack, corresponding to stress intensity factor designated K_1,is changed into that of a plate subject to known stress distribution on the boundary but free from loading on the crack, corresponding to stress intensity factor desig nated K_1~Ⅲ. For the convenience of analysis the stresses on various sides of the rec tangular boundary are represented by a single function f(s), where s represents a point on the boundary. The boundary condition is given by Westergaard stress function, which is in turn approximated by a Williams stress function Wm(s) in the calculations. The approximation employed is one in the least square sense, i. e.,average approximation. The stress intensity factors are then calculated by a boundary collocation procedure. The validity of the solution thus obtained depends on the accuracy of approximation. This can be evaluated by a "criterion of validity" based on the idea of uniform approximation. The usefulness of the criterion is tested in calculations of six specimens with Iinearwedge loading as well as of three compact specimens: the results calculated agree well with known results and thus the criterion stands up in these cases. The effect of various parameters on the results of approximation and calculation is studied, such as lengthwidth ratio (L/W), relative crack length, location of loading on the crack, number of nodes and number of terms of the truneated series. It is found in the calculations that the stress intensity factor K_1~Ⅲ changes with these parameters in a regular fashion and the physical meaning of these changes appears to be acceptable. Calculations become difficult for narrow plates of large L/W (e.g, L/W> 1.5). However, from the results obtained it is seen that K_1~Ⅲ is nearly constant in the range of L/W between 1.5 and 2.5. It is therefore suggested that the K_1~Ⅲ for L/W=1.5 be taken as an approximation of K_1~Ⅲ for 1.5  本文对各种长宽比、裂纹长度及载荷作用点在裂纹面上变化的,有限宽板边裂纹问题的应力强度因子K_1,用平均逼近(最小二乘)的边界配置法进行了分析计算,得出了数值结果。分析研究了各种参数对函数逼近及计算精度的影响。计算结果的有效性根据函数一致逼近的观点建立的有效性标准判断,并在特定状态与线楔形加载试样及紧凑拉伸试样的数据进行对比,吻合得都很好,从而也验证了有效性标准的实用价值。  A wedged load test method was used to evaluate the adhesion strength of hard coatings. In this test, a wedge indenter was put in a wedge shaped groove on the sample surface and the midline of the indenter superposed with the interface of the substrate/coating exactly. Then static load was exerted until the coating cracked along the interface. Based on the critical forced condition, an equation for the adhesion strength of the coating and substrate was presented. The adhesion strength of samples with three kinds... A wedged load test method was used to evaluate the adhesion strength of hard coatings. In this test, a wedge indenter was put in a wedge shaped groove on the sample surface and the midline of the indenter superposed with the interface of the substrate/coating exactly. Then static load was exerted until the coating cracked along the interface. Based on the critical forced condition, an equation for the adhesion strength of the coating and substrate was presented. The adhesion strength of samples with three kinds of different hard coatings were determined. The results show that the wedged load test method can be used to evaluate the adhesion strength of hard coating and substrate. The disparity of experimental data consist with the ASTMC 66379 Standard. The results were not influenced by non stochastic factors.  提出用楔形加载法评价高强度涂层材料与基体的结合强度。该方法利用楔形压头置于有楔形槽的试样中 ,使楔形压头中心线与涂层基体界面重合 ,施加静态载荷至试样沿涂层界面开裂 ,根据试样受力边界条件 ,给出涂层与基体结合强度的公式。对三种不同涂层的基体材料进行了结合强度试验。结果表明 ,用楔形加载法可对高强涂层与基体的结合强度进行测试 ,所得数据分散度与 ASTMC633 79标准相同 ,试验数据不受非随机因素的影响。  
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