Resistance welding methods and apparatus

An electrical connection apparatus for use in resistance welding to form a closed-geometry composite structure defining a high-aspect ratio substantially enclosed volume, the electrical connection apparatus comprising:

• a probe arrangement comprising:
• a foot portion having an engagement surface for engaging a surface of the substantially enclosed volume and comprising an electrical contact element;
• a shoulder portion having an engaging surface for engaging an opposite surface of the substantially enclosed volume;
• a reconfigurable body portion operatively coupled between the foot portion and the shoulder portion, wherein the reconfigurable body portion is remotely configurable between a contracted configuration and an expanded configuration;
• wherein in the contracted position the engagement surfaces are spaced apart by less than a distance between opposed surfaces of a substantially enclosed volume defined between composite articles, and in the expanded configuration the engagement surfaces are further spaced apart sufficient to engage opposed surfaces of the substantially enclosed volume and to urge the electrical contact element into electrical contact with an inner electrode within the substantially enclosed volume.

A composite structure comprising:

• a first composite article;
• a second composite article;
• a join having an area defined by respective faying surfaces of the first and second composite articles, wherein the join comprises a meltable or softenable material by which the composite articles are held together, wherein the join has a length and a width;
• and
• a conductive element in the join between the faying surfaces or embedded within one of the said faying surfaces along the join, the conductive element having a mesh or lattice configuration with pores or apertures through which the meltable or softenable material extends through, the conductive element comprising:
• a longitudinal portion having a length extending at least a portion of the length of the join, and
• a plurality of lower resistivity electrode portions spaced apart along the length of the longitudinal portion, each of the plurality of lower resistivity electrode portions extending at least partially across a respective width of the conductive element and comprising an electrode at ends thereof, wherein the electrodes extend beyond the respective widths of the join.