Adhesive Interface
Interface region where an adhesive or resin connects a pultruded composite profile to another structural element. The pultrusion bondline is critical for the load transfer between continuous fiber members and their steel or composite connectors. Achieving a durable connection requires surface preparation to remove the release agents used during the original manufacturing process.
Surface Preparation
Mechanical abrasion or plasma treatment increases the surface energy of the thermoset material. Without this step, the pultrusion bondline may suffer from premature delamination because the smooth outer layer of the profile offers poor mechanical interlocking. The use of peel plies during the initial pultrusion run creates a fresh, uncontaminated surface for later bonding.
Mechanical Loading
Shear and peel stresses concentrate at the edges of the joined area. A thick pultrusion bondline can help distribute these forces more evenly, but excessive thickness might introduce voids that weaken the overall assembly. Engineers calculate the required overlap length based on the known shear strength of the adhesive and the modulus of the composite members.
Failure Mode
Cohesive failure within the adhesive indicates a well prepared joint. If the pultrusion bondline separates at the interface, the failure suggests contamination or improper curing of the bonding agent.
