Block shear

Fig. 11. Effect of polyolefin primers on bond strength of ethyl cyanoacrylate to plastics. All assemblies tested in accordance with ASTM D 4501 (block shear method). ETFE = ethylene tetrafluoroethylene copolymer LDPE = low-density polyethylene PFA = polyper-fluoroalkoxycthylene PBT = polybutylene terephthalate, PMP = polymethylpentene PPS = polyphenylene sulfide PP = polypropylene PS = polystyrene PTFE = polytetrafluoroethylene PU = polyurethane. From ref. [73].

ISO 11003-1 2001 Adhesives - Determination of shear behaviour of structural adhesives -Part 1 Torsion test method using butt-bonded hollow cylinders ISO 11003-2 2001 Adhesives - Determination of shear behaviour of structural adhesives -Part 2 Tensile test method using thick adherents ISO 13445 2003 Adhesives - Determination of shear strength of adhesive bonds between rigid substrates by the block-shear method... 

Fig. 2.19 Example of a process for deriving a block structure by a successive shear operation on ReOj-type structure (100)5[i0i] -> (010)5[0ii]. (a) Shear plane of (100) of ReOj-type. The mark O denotes the oxygens to be removed, (b) Derivation of a one-dimensional block (shear) structure by the shear operation (100)j[101]. (c) Block structure [3 x 4) obtained by a successive shear operation of (010)1(011] on structure (b). This type of block structure is characterized by edge-sharing of all octahedra at the corners of the blocks with four adjacent blocks.

VANE CUP REDUCTION GEARS SAFETY BLOCKS-SHEAR Pin... 

TABLE 9.12 Effect of Fillers on Block Shear Strength, psi, of Adhesive Formulation30... 

Marcinko, J. J., Parker, A. A., and DiPietrantonio, B., Block Shear Analysis, Viscoelastic Behavior, and Structural Adhesive Development, Biographies and Abstracts of the Forest Products Society 57" Annual Meeting, Forest Products Society, Madison, WI, 2003, p.21, http i/Zw vw. forestprod. org/confpast.html. 

KEYWORDS laser, profilometer, adhesion, block-shear, wood failure Introduction... 

After calibration, a block-shear specimen was positioned in the profilometer. Two stepper motors, controlled by timed relays, were used to maneuver the specimen under the laser. Specimen position was measured by two linear variable differential transformers (LVDTs), one placed on each axis. A data acquisition system was configured to capture sensor outputs at the rate of 30 Hz. Initially the specimen was scanned across the non-bonded portion of the adherend (Fig. 5). About 1000 sensor readings were acquired for each profile (or about one reading per 25 pm). The specimen was then advanced 1 mm lengthwise and ain scanned across its width. This process was repeated up to 25 times to define a precise beam grid (Fig. 5) for scanning all specimens. 

At this point in the analysis, it was possible to define a tolerance for bondline thickness, whereby all points within a prescribed tolerance would be considered adhesive failure, and all points outside this tolerance would be considered wood failure. Furthemtore, a second tolerance could be specified to distinguish shallow" wood failure fi-om deep" wood failure (Fig. 10). For the specimens evaluated in this study, two tolerances ( 40 pm and 60 pm) were selected for both the bondline thickness and the depth of shallow wood failure. A typical bondline thickness for block-shear specimens is about 80 pm, and the thickness of a small fiber bundle is 40-60 pm (or 2-5 fiber diameters). Table 1 summarizes the results from this analysis as well as the visual grading values obtained from the trained observers. 

The laser-scanning device described above appeared to accurately measure the surface failure topography of a variety of failed block-shear specimens. The laser selected was sensitive to veiy small displacements and appeared to adequately resolve a variety of surface irregularities. Also, the incremental scan pattern or beam grid used to map the failure surface was sufficient to reconstruct a digital contour of that surface. 

Figure 5 Modified ASTM D905 specimens for block-shear test, (a) Phenolic FRP-wood specimen (b) epoxy FRP-wood specimen.

Fig. 11. Block shear strength of ECA on polypropylene blocks with different amines as primers.

Plastics-to-plastics joints Block shear specimen... 

Fig. 24. Schematic representation of the possible deformation processes of a stack of crystal lamellae (a) the initial state, (b) interlamellar shear, (c) interlamellar separation, (d) intralamellar block shear, (e) intralamellar fine shear (not shown bending and rotation of lamellae), and (f) cavitation within the amorphous regions.

Block shear strength 3637 psi, 57% wood failure Glue line pH 2.9-3.2... 

ASTM D 4501-85 Test Method for Shear Strength of Adhesive Bonds Between Rigid Substrates by the Block-Shear Method. 

ISO 13445 1995 Ed.1 Adhesives - Determination of shear strength of adhesive bonds between rigid substrates by the block shear method. 

D-3024. Specification for Protein-Base Adhesives for Structural Laminated Wood Products for Use Under Interior (Diy Use) Exposure Conditions. Employs the D-0>905 block shear, D-0906 plywood shear, and D-4300 mold resistance tests to evaluate mostly casein-base adhesives for use in interior grade laminated beams. 

D-3110. Specification for Adhesives Used in Nonstructural Glued Lumber Products. Employs the D-0905 block shear test and a finger joint test, along with several exposures, to evaluate interior and semi-exterior adhesives, in end, edge and face bonded joints, especially for the molding and millwork field. Most of the applicable adhesives are based on polyvinyl acetate. 

D-4317. Specification for Polyvinyl Acetate-Based Emulsion Adhesives. Somewhat similar in scope to D-3110, this standard employs the D-0905 block shear and D-0906 plywood shear tests in evaluating polyvinyl acetate based adhesives for common wood gluing applications. 

D-4501. Test Method for Shear Strength of Adhesive Bonds Between Rigid Substrates by the Block-Shear Method. Fig. 9 shows the two specimen configurations and the test head for this new, general-purpose, compression shear test which should be suitable for testing adhesives for plastics, metals, glass, wood, and other substrates. 

Fig. 8. Wood block shear test head and specimen (D-0905).

Fig. 9. New block shear specimens (top) and test head (bottom) (D-4501).

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