Propagation values

The propagator P(z z, A) is a function of the co-ordinates z and z, the z-dependence in Eq. (15) must be hidden in the coefficients c, and c j. From the fact that the propagator value does not change when we interchange the co-ordinates z and z (time reversibility), we find immediately ... 

Propagation values of the fracture toughness under mode n loading were insensitive to test environment for both CF/epoxy and ALF/epoxy laminates. Only initial values increased by changing the environment from RT-air to 77K-LN. This amount of increase was similar to that under mode I loading. Deformation and fracture of hackles are responsible for this insensitivity. 

Corrected Beam Theory (CBT) values of initiation from the Mode-1 pre-crack according to [1] are summarised in Tables 2-4 for the two laboratories. The values in Table 2 can be compared with the average values for the unidirectional lay-up reported by a third participating laboratory in [4] for initiation from the insert 273 J/m (standard deviation 2.1%), initiation from the Mode-I pre-crack 304 J/m (2.8%), and maximum propagation values of 369 JW (1.9%). The sign convention for the A-value is explained in the notes to the tables. 

The values in Table 4 can be compared with values reported in [4], their average values for the non-symmetric lay-up for initiation from the insert were 317 J/m (5.7%), initiation values from the Mode-I pre-crack were 518 jW (4.1%), and the maximum propagation values were 1 295 J/m (14.5%). 

Tables 2-4 show that, for the unidirectional lay-up, averages of initiation and maximum propagation values do agree with each other and with the data presented in [4]. The R-curves are rather flat, with an increase between about 30 and 60 J/m (10-20%) over the total delamination length (Fig. 5). For the cross-ply laminates, however, this is not the case. The average initiation values for the symmetric lay-up differ by more than one standard deviation (values from [4] are not available) while for the non-symmetric lay-up, laboratory 1 and [4] agree within 15%, while laboratory 2 obtains larger average values. The averages of the maximum propagation do agree within one standard deviation and within about 20% are the same for both types of cross-ply laminates. These differences will be fiirther explored in the discussion.

Propagate values of variables from the abstract to the more detailed context (or, vice versa), using the compatibility links established above. 

Barium No propagation No propagation value but not stable Little or none... 

A comparison between unidirectionally reinforced and plain-weave CFRP epoxy laminates (IM7/8552) for quasi-static mode I, mode II and mixed mode I/H [83] found similar initiation values, but for the woven CFRPs significantly higher propagation values of delamination resistance were observed. 

Tj N mm crack propagation value from R-curve of elastomers... 

Initiation Value Ji [N mm ] Propagation Value Tj [N mm ] Specimen Thickness [mm] Test Speed [mm min ] ... 

Table 5.21 Crack initiation and crack propagation values of elastomers determined by using the MSM.

Fig. 5.7 Crack propagation values 7/ of S-SBR vulcanizates with different contents of silica, determined at different sizes of crack opening /r.

In order to obtain a nondimensionalized expression, characteristic laminar flame propagation values of velocity (laminar burning velocity S ) and length scale (laminar flame thickness are introduced. Now Eq. (4) writes... 

FIGURE 13.12 The relation between experimental and calculated according to the Eq. (13.17) critical stress intensity factor (stability to crack propagation) values for PASF film samples [1]. 

Upon unloading the joint, the force-displacement trace not returning to the origin may indicate that plastic deformation of the substrates has occurred see ISO (2009) for full procedures. Such an occurrence would invalidate the values of Qc determined. The presence of stick-slip crack propagation in the continuously loaded BS or ISO methods requires some special considerations to be taken into account. Again, fiill details are provided in ISO (2009). Under these conditions, steady-state propagation values of Qc are not determined, instead values at crack initiation and crack arrest are obtained. 

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