ASTM D5656 | Adhesives | Shear Testing
ASTM D5656 is a testing specification that determines the stress-strain behavior of adhesives in shear. A tensile load is applied to thick-adherend lap-shear samples and the adhesive is placed in shear. Shear stress-strain properties of the adhesive are obtained. This test method is intended to characterize the adhesive properties and is useful for the design and analysis of adhesively bonded joints.
A universal testing machine capable of maintaining a load rate of 2455 N/min (550 lbf/min) is needed to perform this test. The breaking load of the specimens should fall between 15 and 85 % of the full-scale capacity of the machine. The grips used should be self-aligning and the two specifically-designed extensometers should be capable of measuring displacements in the adhesive bond overlap area. Before conducting ASTM D5656, it is important to read the entire specification in the relevant ASTM publication.
ASTM D5656 | Adhesives | Shear Testing
- Prepare a minimum of three replicate samples as described in the standard. Apply the adhesive in a uniform layer to one face of one of the adherend plates. Place the other adherend plate on top of the adhesive-coated plate. Cure the adhesive before starting the test. After the cure, saw-cut the specimen to the desired dimensions as specified in the standard.
- Measure the load and displacement values of the adherend metal, first. Use a solid bar made out of the adherend material machined to the same overall dimensions and geometry as the test sample.
- Attach one end of the extensometers to the each edge of the bar. Mount the bar in the testing machine.
- Apply the load to 417 N (900 lbf) at a constant rate of 2455 N/min (550 lbf/min). Repeat the loading six times and record load versus displacement for each loading.
- Calculate the displacement value at 4464 N (1000 lbf) by extrapolating the load-displacement curve of the six loadings. Average the results to obtain metal load-displacement values.
- Measure the load and displacement values of the adhesively bonded test sample, second.
- Mount the extensometer on each edge of the sample so that the adhesive bondline is centered between contact points of each extensometer. Make sure both extensometers are centered between the notches in the test specimen. Mount the sample in the testing machine.
- Apply the load to 417 N (900 lbf) at a constant rate of 2455 N/min (550 lbf/min). Test a minimum of three samples. Record load versus displacement.
- Shear Stress at Linear Limit
- Knee and Fracture
- Shear Strain at Linear Limit
- Shear Modulus
ASTM D5656 | Adhesives | Shear Testing
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