Substrate or wood failure
was recognized when the failure happened at the wood substrate side.
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.
The shear strength is calculated with relation 1 and the cohesive wood failure
of shear area is determined.
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.
6 Tear strength, pli 336 500 210 Brittle Table 7 -- Adhesion of Aliphatic Polyurea to Various Substrates Adhesion, Substrate Psi at Failure Method of Failure Concrete with aged epoxy sealer 876 Adhesive, intercoat Bare concrete, 25[degrees]C 876 Concrete failure Bare concrete, applied and cured at 0[degrees]C 836 Concrete failure 2 X 4 wood with latex sealer 815 Wood failure
2 X 4 wood with latex sealer (wet on wet) 958 Wood failure
Steel with zinc rich epoxy/urethane topcoat 1447 Adhesive, intercoat Steel with flexible epoxy primer 937 Adhesive, intercoat Steel with epoxy amine protective coating >1835 No failure Aluminum, smooth, untreated 692 Adhesive, from substrate Blasted steel, 1.
Furthermore, the amount of wood failure
increased for the PRF-bonded samples and decreased for the PU-bonded samples after accelerated aging tests.
Values of shear stress (a, c, e) and wood failure
(b, d, f) determined for three species glued as part of an inside-out (moving the pith out) test.
Most adhesives were found to bond wood well enough to give wood failure
under dry conditions.
2] with wood failure
of 50 percent for the wet test and 6.
Additional PRF tests were stopped after the initial series of glue-line tests showed unacceptable bonding results with respect to very shallow wood failure
modes critical not only for maximum shear load capacity but for durable structural performance over time.