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双悬臂梁(DCB)试样在材料的损伤容限性能评价,特别是应力腐蚀开裂门槛值(KISCC)测定中有重要应用。由于该试样几何的特殊性,一般采用与试样端部(裂纹嘴)有一定距离的特定位置裂纹面位移加载方式,然而该加载点的位移测量不但费时而且精度低,位移测量最方便和准确的位置是在DCB试样的裂纹嘴。通过对一种参考载荷条件的有限元计算,应用边缘裂纹的经典权函数解法,推导出DCB试样的权函数解析解,并与复变函数泰勒级数展开的权函数解法作了比较验证。在此基础上根据特定加载点的位移反算出相应位置均布应力加载下的应力强度因子,进而建立DCB试样在特定位置的裂纹面位移加载条件下的应力强度因子与裂纹嘴位移之间的关系式,为采用这种试样的材料损伤容限性能评价,特别是KISCC的高精度自动化测定奠定了基础。
Double cantilever beams (DCB) specimens have important applications in the evaluation of material’s damage tolerance, especially the stress corrosion cracking threshold (KISCC). Due to the particularity of the sample geometry, the displacement of the crack surface at a specific location with a certain distance from the end of the sample (crack tip) is generally used. However, the displacement measurement of the loading point is not only time-consuming but also low in precision, and the displacement measurement is most convenient The exact location is the crack tip on the DCB specimen. Through a finite element calculation of a reference load condition, the classical weight function method of edge crack is used to derive the analytic solution of weight function of DCB sample, which is compared with the weight function method of Taylor series expansion of complex functions. On the basis of this, the stress intensity factor under the uniform stress loading is calculated according to the displacement of the specific loading point, and then the stress intensity factor and the displacement of the crack tip of the DCB specimen at the specific location with the crack surface displacement are established The relationship between the samples for the use of this material damage tolerance performance evaluation, especially KISCC high-precision automated determination laid the foundation.