Conductive bonded/bolted joint seals for composite aircraft

In an aircraft, composite plates formed of reinforced epoxy resin, said plates forming wall structures having bonded sealed joints, comprising:

• adhesive bonding means forming a bonding seal between surfaces of overlapping wall structures to form a joint;
• the adhesive bonding means having a thickness of about 0.013";
• each wall structure plate being formed having layers of reinforcing graphite fibers impregnated with epoxy resin to form multiple generally parallel laminations in the plates on the layers of fibers;
• the adhesive bonding means including generally hollow carbon microspheres having diameters in the range of 5 to 150 microns and a resin mixed with thin fibers, the resin in the mixture being cured between the overlapping surfaces;
• said microspheres forming a continuous conductive contact path within the bonding means and being substantially in the form of a thin discontinuous, approximate layer;
• the microspheres being irregularly spaced by resin adjacent the continuous conductive contact path;
• the approximate layer of microspheres forms part of a bondline in the joint, the microspheres being present in an amount sufficient to weaken the bonding means to permit the laminated plastic plates to be wedged apart at the bondline, whereby damage from the wedging is limited to the bondline within the bonding means and there is no structural change to the laminations of the plates;
• fasteners extending through the plates and the overlapping surfaces to further secure the plates together at the joint;
• and
• means associated with the fasteners to render them dielectric;
• the weight percent of the microspheres with respect to the resin in the bonding means is in the range of between 20 to 35, and the density of the carbon microspheres is substantially less than that of the resin in the bonding means.

In an aircraft, composite plates formed of reinforced epoxy resin, said plates forming wall structures having bonded sealed joints, comprising:

• adhesive bonding means forming a bonding seal between surfaces of overlapping wall structures to form a joint;
• each wall structure plate being formed having layers of reinforcing graphite fibers impregnated with epoxy resin to form multiple generally parallel laminations in the plates on the layers of fibers;
• the laminations having thicknesses in the range of between 0.005" and 0.015";
• the adhesive bonding means including generally hollow carbon microspheres having diameters in the range of 5 to 150 microns and an epoxy resin mixed with thin structural fibers, the resin in the mixture being cured between the overlapping surfaces;
• said microspheres forming a continuous electrically conductive contact path within the bonding means and being substantially in the form of a thin discontinuous, approximate layer;
• the microspheres being irregularly spaced by resin adjacent the continuous conductive contact path;
• the approximate layer of microspheres forms part of a bondline in the joint, the microspheres being present in an amount sufficient to weaken the bonding means to permit the laminated plastic plates to be wedged apart at the bondline, whereby damage from the wedging is limited to the bondline within the bonding means and there is no structural change to the laminations of the plates;
• fasteners extending through the plates and the overlapping surfaces to further secure the plates together at the joint;
• and
• means associated with the fasteners to render them dielectric;
• the weight percent of the microspheres with respect to the resin in the bonding means is in the range of between 20 to 35, and the density of the carbon microspheres is substantially less than that of the resin in the bonding means.