Nonlinear Acoustic Shear Wave Detection of Zero Gap Kissing Bonds in Encapsulated Packs
Nonlinear acoustic shear wave harmonic detection resolves zero gap kissing bonds in encapsulated battery packs by measuring contact acoustic nonlinearity.
Adhesive Bond Integrity
Meaning
Physical state where the contact surfaces between a battery cell and its cooling plate maintain mechanical and thermal connection under load. Adhesive bond integrity defines the limit where a joint fails to transfer stress or heat across the boundary. Quantitative assessment of this property measures the resistance to delamination and cohesive failure within the adhesive layer.
Failure Mode
Mechanical stresses often arise from thermal expansion or vibration during vehicle operation. When adhesive bond integrity drops, the resulting air gaps create thermal bottlenecks that cause local overheating. Separation usually starts at the edges where peel forces are highest.
Testing Method
Lap shear tests and pull-off assessments provide empirical values for the joint strength. Standard ASTM D1002 specifies the geometry for measuring adhesive bond integrity in single-lap-joint metal specimens. These tests verify if the production process achieved the required cross-linking density.
Beyond simple strength, the test also evaluates the failure type, distinguishing between cohesive failure within the adhesive and adhesive failure at the substrate interface. Consistency in surface preparation remains the most influential factor in achieving reproducible results across different production batches.
Assembly Benefit
Procurement specifications for cell-to-pack assemblies require proof of long-term durability. High adhesive bond integrity ensures the battery pack remains a rigid structural unit throughout its service life. This reduces the need for heavy mechanical fasteners.