Performance verification testing of DIN 6701 bonded joints

When applying adhesives, bonding strength is a parameter that must be considered. Bonding strength refers to the stress required to cause damage to the interface between the adhesive in the adhesive part and the adherend or its vicinity under the action of external forces. Bonding Strength is also called bonding strength.

If the bonding strength is insufficient, the adhered material may fall off during use, which is a serious failure event. In the design and verification of DIN6701-3 bonded joints, we often use some test methods to characterize the performance of adhesives, including the following three:

(1) Shear strength Shear strength refers to the shear force that the unit bonding surface can withstand after the adhesive forms a joint. The unit is MPa and can be subdivided into tensile shear, compression shear, torsional shear, etc. In most cases, as shown in Figure 1 below, we use the "lap test" to test the shear force of the adhesive, and the corresponding standard is EN 1465 or GB/T 7124.

Figure 1 Schematic diagram of tensile shear test specimen

(2) Tensile strength Tensile strength refers to the tensile force per unit area on the cross section when the narrow part is damaged by force after the adhesive body is cured. The unit is expressed in MPa. It examines the tensile properties of the adhesive body. As shown in Figure 2 below, the corresponding standard is ISO 37 or GB/T 528.

Figure 2 Schematic diagram of tensile shear test specimen

(3) Peel strength Peel strength is the maximum load that the unit width can bear when the bonded parts are separated under the specified peeling conditions, and its unit is expressed in kN/m. In actual tests, dancer roller peeling is more commonly used. The sample form is shown in 3. It is suitable for evaluating the bonding performance of flexible to rigid materials. The corresponding standards are EN 1464 or GB/T 7122.

Figure 3 Schematic diagram of the dancer roller peeling test sample

The above tests can all be carried out by a universal testing machine. The difference lies in the different test fixtures, which can be used as a reference when selecting adhesives or verifying the performance of bonded joints.