Method of fabricating a stringer-stiffened shell structure using fiber reinforced composites

A method of fabricating a stringer-stiffened shell structure including a fiber reinforced composite material, said method comprising the following steps:

• a) providing a skin member comprising a first fiber reinforced composite material having opposite first and second skin surfaces;
• b) laying said skin member onto a mold surface of a shell mold so that said first skin surface lies conformingly on said mold surface and said skin member has a skin contour configuration matching a mold surface contour of said mold surface;
• c) providing a strip-shaped stringer core blank comprising a second fiber reinforced composite material and having a narrow edge and two opposite broad side faces extending along a strip length;
• d) arranging said stringer core blank on said skin member which is lying on said mold surface, such that said narrow edge of said stringer core blank lies conformingly in contact on said second skin surface of said skin member and said broad side faces of said stringer core blank extend away from said skin member, and wherein said narrow edge of said stringer core blank has an edge contour configuration matching said skin contour configuration where said narrow edge is in contact with said second skin surface;
• e) providing an auxiliary jig frame including a frame wall defining a perimeter of said frame and having slits in said frame wall facing each other pairwise inwardly across an area bounded within said perimeter, and arranging said auxiliary jig frame on said shell mold with respective ends of said stringer core blank received and supported in said slits, wherein said auxiliary jig frame holds said stringer core blank in a position protruding substantially perpendicularly from said second skin surface;
• f) providing a flexibly deformable elongate stiffening profile member which is more flexible than said stringer core blank and which comprises a flexible third fiber reinforced composite material and includes a lengthwise extending base web and a lengthwise extending protruding web that runs along and protrudes from said base web;
• g) laying said stiffening profile member with said protruding web lying conformingly in contact along one of said broad side faces of said stringer core blank and with said base web lying conformingly in contact along said second skin surface adjacent to said stringer core blank;
• and
• h) carrying out a hardening process wherein said stiffening profile member hardens and becomes rigidly and intimately bonded with said stringer core blank and with said skin member.

A method of fabricating a stringer-stiffened shell structure including a fiber reinforced composite material, said method comprising the following steps:

• a) providing a skin member comprising a first fiber reinforced composite material having opposite first and second skin surfaces;
• b) laying said skin member onto a mold surface of a shell mold so that said first skin surface lies conformingly on said mold surface and said skin member has a skin contour configuration matching a mold surface contour of said mold surface;
• c) providing a strip-shaped stringer core blank comprising a second fiber reinforced composite material and having a narrow edge and two opposite broad side faces extending along a strip length;
• d) arranging said stringer core blank on said skin member which is lying on said mold surface, such that said narrow edge of said stringer core blank lies conformingly in contact on said second skin surface of said skin member and said broad side faces of said stringer core blank extend away from said skin member, and wherein said narrow edge of said stringer core blank has an edge contour configuration matching said skin contour configuration where said narrow edge is in contact with said second skin surface;
• e) providing two flexibly deformable elongate stiffening profile members which are more flexible than said stringer core blank and which comprise a flexible third fiber reinforced composite material and which each respectively include a lengthwise extending base web and a lengthwise extending protruding web that runs along and protrudes from said base web;
• f) laying said two stiffening profile members with said protruding webs thereof respectively lying conformingly in contact along said two opposite broad side faces of said stringer core blank and with said base webs thereof respectively lying conformingly in contact along said second skin surface adjacent to said stringer core blank;
• g) arranging at least one additional strengthening member to be in contact with said protruding web and said base web of at least one of said two profile stiffening members, wherein said strengthening member consists essentially of a previously cured and hardened fiber reinforced material and has a length extending along said at least one of said stiffening profile members less than said strip length;
• and
• h) carrying out a hardening process wherein said stiffening profile members harden and become rigidly and intimately bonded with said stringer core blank and with said skin member, and wherein at least said stringer core blank and said two protruding webs of said two stiffening profile members together form a stiffening and strengthening stringer on said skin member upon completion of said step h).