is 0.3429 m and its depth is 0.05715 m.
(da) is the crack length
increase (a) as a function of cycle number (dN).
We have used spherical coordinates for the mesoscopic variables crack length
l [member of] [0, [infinity]] and crack orientation n [member of] [S.sup.2], and we represent the divergence with respect to the mesoscopic variables in spherical coordinates.
Measurements of crack length
from both specimen's edges during the loading history (Fig.
The method is based on determination of a crack length
, occurring in the material around an imprint in indentation of the diamond pyramid according to Vickers method at a low load.
The supposition is that residual strength is correlated with the damage, or crack length
. The measurements were performed at room temperature on 20 uniform chip resistor solder joints of 1206 and 0603 sizes.
Taking one micrometer as the final crack length
in the flexure, this one micrometer, over a 10 year period, translates to an average crack growth rate of one atomic distance per day.
[K.sub.IC] is evaluated from the fracture's torque and the final crack length
with an aid of a 3-D finite-element computer code.
where c is the crack length
, n is the cycles, and G is the tear energy.
where C = [delta]/P is the specimen compliance and a is the corresponding crack length
for a given displacement of [delta].
Descriptions Values Diameter D (mm) 75 Thickness B (mm) 30 Initial chevron notched 9.89 crack length
[a.sub.0] (mm) Final chevron notched 24.37 crack length
[a.sub.1] (mm) Saw radius [R.sub.s] (mm) 26 Dimensionless stress 0.84 intensity factor Descriptions Dimensionless expression Diameter D (mm) -- Thickness B (mm) [[alpha].sub.B] = B/R = 0.8 Initial chevron notched [[alpha].sub.0] = [a.sub.0]/R = 0.2637 crack length
[a.sub.0] (mm) Final chevron notched [[alpha].sub.i] = [a.sub.i]R = 0.65 crack length
[a.sub.1] (mm) Saw radius [R.sub.s] (mm) [[alpha].sub.s] = [R.sub.s]/R = 0.6933 Dimensionless stress -- intensity factor Table 4: Dynamic fracture toughness and dynamic tensile strength of 410 m.
where a is the crack length
, is based on the cyclic stress intensity factor [DELTA]K, the cyclic J-integral and the C*-integral and, thus, accounts for contributions from elastic, plastic and time-dependent deformations to crack growth .