Nomenclature API = American Petroleum Institute ASME = American Society of Mechanical Engineers ASTM = American Society for Testing and Materials a = crack length C(T) = compact tension da/dV = fatigue crack growth rate
[DELTA]K = stress intensity factor range FCGR = fatigue crack growth rate
HAZ = heat-affected zone HA-FCG = hydrogen-assisted fatigue crack growth GH = girth heat-affected zone GW = girth weld N = number of cycles SH = seam heat-affected zone SW = seam weld w = width of the specimen Keywords: fatigue crack growth rate
; high-pressure hydrogen; hydrogen embrittlement; pipe steels; residual stress.
Caption: Figure 6: Crack growth rate
versus number of fatigue loading cycles (mode I).
 regard parameters C and m of Paris formula as random variables and then obtain the relation of those two variables through curve fitting; thus the crack growth rate
can be calculated by a single variable.
It was indeed surprising to find that the unaged fatigue crack growth rate
for the NAS system is superior to that of the conventional sulfur system in the model compounds (figure 5).
Among the topics are enhancing simulation in complex systems, a numerical investigation of deployable drag surfaces used for recovery systems, liquid crystal thermography for determining the heat transfer coefficient in rectangular ducts, evaluating crack growth rate
and the growth model of ultrafine-grained copper, the compression property of a waste polyurethane rubber/unsaturated polyester composite cube, a non-contact breath sensor based on a Doppler detector, new solid-state organic membrane based lead-selective micro-electrode, simulating intergranular crack nucleation and evolution in polycrystal metals on mesoscale, a coupled numerical-experimental study of armor perforation by armor piercing projectiles, and lessons from airlines for railway disruption recovery.
Thermographic assessment of fracture enabled determination of the crack growth rate
. An infrared camera was placed at a distance from the specimen.
The variation of fatigue crack growth rate
with cyclic stresses which produce a range of [DELTA]K and the associated fracture mechanisms is shown in Figure 1(5).
Where [Delta][K.sub.0], represents the amplitude value of the stress intensity factor for which the crack growth rate
is equal to [10.sup.-4] mm/cycle.
The morphology of fatigue fracture surface (caused by constant cycle loading) is strictly related to crack growth rate
. This relation may be expressed, among other methods, by means of fractal analysis.
Initial measurements indicate a crack growth rate
at the early stages of impact-fatigue in excess of 2.4 x [10.sup.-3] mm/cycle.
The dependences of crack growth rate
versus the stress intensity factor range were determined (Fig 8) by testing requirements and the specified calculation technique (according to ASTM E 647-00).