The wood failure
and dimensional stability of RR, RT, and TT glue-line samples subjected to three wet--freeze--ovendry cycles were also evaluated.
Each 5-mm thick panel was tested for its shear strength, cohesive wood failure
, and formaldehyde emission.
This is because the tendency of wood failure
near the bolts of the two-bolt connections is higher than that of single-bolt connections.
A weak joint, exhibiting little or no wood failure
, might result from poor machining or under-cured or frosted joints, whereas too abrasive a grit or dull saw blades are typical culprits behind weak joints that fail along the glue lines.
While shear tests showed good bond performance when tested in dry condition, moisture treatment revealed differences between surfaces, in particular with regard to wood failure
and maximum load were recorded for each test.
The failure types included: glue failure (failure of the epoxide at the pin/paint interphase), cohesive coating failure, cohesive wood failure
, failure between the coating layers, and failure of the wood-coating interphase (Figure 1).
He notices that there is very little wood failure
, but that there is a crystal-like appearance to the glue that is present on the edges of the glued pieces.
Deterioration of the wood structure can be easily observed from failed wood members (see Claims, March 1991, "Wood Failure
Figures 4a and 4b show the percent wood failure
test results after the plywood specimens were treated with water either under the vacuum--pressure (VP) condition or under the boil-dry-boil (BDB) condition.
The shear strength is calculated with relation 1 and the cohesive wood failure
of shear area is determined.
Moreover, the percent area of wood failure
percentage, WFP) on the bonding surface was determined optically.