摘要
本文通过在焦散线上取点,用具有选代过程的最小二乘法得到了光学各向同性材料试件应力强度因子K_Ⅰ、K_Ⅱ的求法,确定了含裂纹的有机玻璃试件的K_Ⅰ、K_Ⅱ,并将所得结果及直接用焦散线法所得结果与相应的理论计算值进行了比较,精度有所提高。
In 1964, Manogg proposed the method of caustic. Since then Theocaris Proposed the
reflected method of caustic[1]; Dang, the mirror transplanted method of caustic[1]; Xue, the
slice sticked method of caustic[3], etc. Up to now, in measuring Stress Intensity
Factors(SIF) with caustic, errors occur. These errors are caused by: (1) insufficient meas-
ured data, (2) influence of artificial crack.
This paper modifies Manogg's method to overcome the above-mentioned shortcom-
ings. An arbitrary straight line that is parallel to the crack is taken as the x-axis. The
coordinates of the position of crack tip are X_0 and Y_0. X_0, Y_0, r_0(the radius of the initial
curve of the caustic), μ(numerical factor) are taken as unknown parameters. Then
least-squares method with the nonlinear iterate [4] is used to determine SIF.
The two contributions of this paper are first stated and then concisely explained in the
next two paragraphs.
The accuracy in determining SIF for mode I crack is improved. Coordinates of rela-
tively large number of points along caustic are measured. In contrast, the traditional way
measures only the maximum diameter of the caustic along the direction perpendicular to
crack. Thus errors due to insufficient measured data are much reduced by the authors im-
provement.
The accuracy in determining SIF for I-II mixed mode crack is improved. This im-
provement is made possible by eliminating the deficiencies of past methods. These deficien-
cies are three in number. The first deficiency is due to that the accurate measurement of the
width of the artificial crack is very difficult. The second deficiency is due to the relatively
large distortion of the shape of caustic caused by plastic deformation at the edge of crack
produced by processing. The third deficiency is the graphical inaccuracy of determination
of numerical factor μ with double-diagram.
Some experiments are done. SIFs determined by this paper's method are somewhat
closer to theoretical values than those determined by traditional caustic method.
出处
《西北工业大学学报》
EI
CAS
CSCD
北大核心
1992年第2期259-266,共8页
Journal of Northwestern Polytechnical University
关键词
最小二乘法
焦散线法
应力强度因子
least-squares method
caustic method
isotropical material
stress intensity factor
