Abstract: A metal sheet (1) having a first upstanding hook formation (3) along one edge (2) and a second, upstanding hook receiving formation (6) and a valley (7) along an opposite edge (5) the arrangement being such that the sheet can be fastened directly to a support without the interposition of separate clips and so that the first formation of one sheet can hook over the second formation of an adjoining sheet and cover its valley characterized by latching means (11, 12, 13, 14, 15 and 16b, 17, 19, 21) acting between the formations so that after interlocking the sheets said one sheet can be rotated about the hook receiving formation of the other sheet through at least 25.degree. before the formations can be disengaged.

Abstract: A frame structure of aluminum alloy having a pair of spaced apart side rails (1) and a plurality of spaced apart cross-members (2) each comprising a central tubular formation and extending between the side rails, characterized in that at least over a major part of its length each side rail (1) comprises at least three hollow extrusions (4-6) welded together at positions of low stress and has more than two longitudinally extending re-entrant formations opening inwardly thereof at selected low stress locations thereon to receive the heads of bolts and in that an end plate formation (3) is welded to each end of the tubular formations, the bolts engaging through apertures in the associated end plates (3) to removably secure together the side rails (1) and the cross-members (2) only by the bolts at any desired location along the major part of the length of each side rail (1).

Abstract: A continuous process for making a core for a composite panel comprising cutting spaced apart tongues in columns from a metallic sheet, the tongues being foldable about base lines in the columns each base line being separated from the next tongue in the column by a web; folding the sheet to form a castellated structure having continuous side walls constituted by the spaces between adjacent columns of tongues with the webs of adjoining rows respectively lying in spaced apart parallel planes and oppositely folding the tongues of adjoining columns to lie alongside adjacent side walls with their extremities remote from their base lines extending in an appropriate one of the planes. The invention also includes a composite panel comprising the core covered on each side with sheet material as well as a process for making such a panel.

Abstract: A load-bearing structural member (5, 6) comprising a least two hollow extrusions (12, 13) of light metal alloy each formed with two surfaces mated together with a layer of adhesive therebetween by relative linear movement of the extrusions in a single direction, the surfaces on one of the extrusions being formed on limbs (29) projecting therefrom and the angle between the mating surfaces and said direction being within the range 5.degree. to 15.degree., the surfaces on the other extrusion terminating in shoulders (21) to be approached by the tips of the limbs (29) and a gap (75) to ensure that the layer of adhesive always extends between the shoulders (21) and the tips (74).