1.1.13.2 Function
One source suggests dividing adhesives into structural and non-structural classes, depending specifically on their ability to produce shear strength above 6.9 N/mm2 (1,000 psi).1 While the figure is somewhat arbitrary, the concept is sound: a structural joint (or bond) is expected to be load-bearing, strong, rigid, durable and able to last for the life of the assembly. Examples of non-structural applications include the attachment of lightweight, non-load-bearing components, coating, potting and gasketing.
While adhesive types like epoxies and acrylics are generally considered structural bonders, the conditions of the application – substrate, environment, geometry, etc. – will strongly influence the strength and durability of the joint. Likewise, in the right conditions, adhesives not normally considered ‘structural’ (silicones, threadlockers and even pressure-sensitive tape) may create a structural bond. The context and conditions of the application are key considerations.
1) Petrie, Digital Engineering Library; digitalengineeringlibrary.com, 280-281, McGraw-Hill, 2000.