CARRYING PIPE-SHELL OF COMPOSITE MATERIALS, METHOD AND MANDREL FOR ITS MANUFACTURE Russian patent published in 1997 - IPC

FIELD: manufacture of shell structures of body members used in aviation material and operating in heavy-load conditions. SUBSTANCE: the carrying pipe-shell of composite materials has a cellular structure load-bearing framework formed of systems of crossing helical, longitudinal and circular bands repeating on thickness of the pipe-shell and made of unidirectional threads forming stiffening ribs between the cross assemblies. The assemblies of crossings of longitudinal and circular bands with each helical band are made in the form of closed load-bearing triangles with a common vertex of corners of crossing platforms of longitudinal bands with circular bands and longitudinal and circular bands with helical ones. The volume relation of helical, longitudinal and circular bands makes up 1:0.3:0.3 to 1:3:3. The mandrel is coated with rubber-like material with mutually crossing slots. Crossing helical, longitudinal and circular bands of unidirectional threads preliminarily impregnated with binder to make up stiffening ribs between the crossing assemblies are laid in slots; moulding members are applied onto the bands and subjected to heat treatment with subsequent extraction of the core and rubber-like material. To form the stiffening ribs, an allowance of rubber-like material is provided at laying of the bands in slots, the allowance is within 0.02 to 0.3 of their height. At application of the shaping members the allowances of rubber- like material are subjected to elastic deformation in radial direction with formation of an external protective coating fastened to the stiffening ribs and crossing assemblies. Circular bands of the external layer are used as moulding members, and the crossings of longitudinal and circular bands are formed with contiguity to helical bands. The realize the method, use is made of a mandrel. The rubber-like material in it is made of flexible plates with straight-line mutually crossing slots on their external surface with formation of blunted lugs and three-surfaces seats in the points of crossings, bent on the radius of curvature of the core surface and slots joined in directions. The planes of the side surfaces of the blunted lugs intersect inside the three-surfaced seats on the common line of crossing. EFFECT: enhanced reliability. 3 cl, 9 dwg , 1 tbl