Based on the assumption, [P.sub.yv] and [P.sub.mv] may be believed to be equal; that is, the void volume fraction of the tows equals the void volume fraction of the resin pocket
matrix as a whole.
Figure 8(b) shows the resin matrix failure in resin pocket after the global average strain [[epsilon].sub.zz] exceeds 6000 [mu][epsilon].
When the global average strain [[epsilon].sub.zz] reached 6200 [mu][epsilon], the resin pocket damage began to initiate at the stress concentrations.
Further loading results in the formation of crack branches in adjacent tows, with the number of crack branches increasing while the composite is elastically loaded from 3 to 5, while the resin pockets
between tows remain undamaged.
However, the main drawback associated with the stitching process is the heterogeneity at the scale of the tows, which is attributed to fibers breakage caused by the introduction of needles into the tows used for the penetration of the stitching within the plies, as well as to imperfections between tows, such as resin poor areas known as "resin pockets
The visual grading technique for wood quality assessment is based on measurement of the singularities and characteristics present in timber pieces, such as: knot size, slope of grain, presence of pith, splits and checks size, bark and resin pockets length, etc.
The main reasons for the rejection of pieces center on bark pocket length, knot size, and resin pockets length, at 20.8 percent, 17.7 percent, and 10.9 percent, respectively.
The SLS-2000 includes new composite resin pockets
, linked into their own drive chain and requiring no lubrication.
Generally, all defects except resin pockets were less frequent in boards from pruned logs.
Intergrown knots, partially intergrown knots, loose knots/holes, spike knots, pith, bark pockets/blemishes, resin pockets, needle flecks, and wane were identified as separate defect categories.
Intergrown knots, partially intergrown knots, loose knots/holes, spike knots, bark pockets/blemishes, resin pockets, needle flecks, and wane were classified as separate defect categories.
Finally, analyses were carried out in which all knot types were grouped in one single category and resin pockets, bark pockets and blemishes were grouped into another.