System tool for weight optimization of thin wall structures

A TPM pre-constructed for use in assembling a weight optimized wing box, the TPM having a main strip and an additional strip with common reinforcing ribs and characterized in that the ratio of the width of the additional strip with common reinforcing ribs to the width of the main strip satisfies the range:

• a/b=0.3 to 0.7,
• and the ratio of the thickness of the additional strip with common reinforcing ribs to the thickness of the main strip satisfies the range:
• δa/δb=1.0 to 3.0,
• where:
• a is the width of the additional strip with common reinforcing ribs,
• b is the width of the main strip,
• δa is the thickness of the additional strip with common reinforcing ribs, and
• δb is the thickness of the main strip;
• and
• wherein δa/a≧δb/b.

A TPM pre-constructed for use in assembling a weight optimized wing box, the TPM having a main strip and an additional strip defined by a free reinforcing rib and a common reinforcing rib and characterized in that the ratio of the width of the additional strip with the free reinforcing rib and the common reinforcing rib to the width of the main strip satisfies the range:

• c/b=0.05 to 0.3,
• and the ratio of the thickness of the additional strip with the free reinforcing rib and the common reinforcing rib to the thickness of the main strip satisfies the range:
• δc/δb=1.0 to 3.0,
• where:
• b is the width of the main strip,
• c is the width of the additional strip with the free reinforcing rib and the common reinforcing rib,
• δb is the thickness of the main strip, and
• δc is the thickness of the additional strip with the free reinforcing rib and the common reinforcing rib;
• and
• wherein δc/c≧δb/b.

A TPM pre-constructed for use in assembling a weight optimized wing box, the TPM having a main strip, a free reinforcing rib, and a common reinforcing rib and characterized in that the ratio of the width of the one common reinforcing rib to the width of the main strip satisfies the range:

• a/b=0.3 to 0.7,
• the ratio of the thickness of the one common reinforcing rib to the thickness of the main strip satisfies the range:
• δa/δb=1.0 to 3.0,
• the ratio of width of the free reinforcing rib and the common reinforcing rib to the width of the main strip satisfies the range:
• c/b=0.05 to 0.3,
• and the ratio of the thickness of the free reinforcing rib and the common reinforcing rib to the thickness of the main strip satisfies the range:
• δc/δb=1.0 to 3.0,
• where:
• a is the width of the common reinforcing rib,
• b is the width of the main strip,
• c is the width of the free reinforcing rib and the common reinforcing rib,
• δa is the thickness of the common reinforcing rib,
• δb is the thickness of the main strip, and
• δc is the thickness of the free reinforcing rib and the common reinforcing rib;
• and
• wherein δa/a≧δb/b and δc/c≧δb/b.

A TPM and panel combination pre-constructed for use in assembling a weight optimized wing box, the TPM and panel combination comprising a panel defined by a sheet and a number of TPMs, and further defined in that each TPM includes the TPM having a main strip and an additional strip defined by a free reinforcing rib and a common reinforcing rib and characterized in that the ratio of the width of the additional strip with the free reinforcing rib and the common reinforcing rib to the width of the main strip satisfies the range:

• c/b=0.05 to 0.3,
• and the ratio of the thickness of the additional strip with the free reinforcing rib and the common reinforcing rib to the thickness of the main strip satisfies the range:
• δc/δb=1.0 to 3.0,
• where:
• b is the width of the main strip,
• c is the width of the additional strip with the free reinforcing rib and the common reinforcing rib,
• δb is the thickness of the main strip, and
• δc is the thickness of the additional strip with the free reinforcing rib and the common reinforcing rib;
• wherein δc/c≧δb/b);
• wherein the TPMs are laid out longitudinally across the width of the sheet and with even pitch such that for each TPM the corresponding at least one main strip, free reinforcing rib and common ribs form, with the sheet, an open cross-section configuration;
• and
• wherein the thickness of the sheet satisfies the expression:
• δ=(0.0006 to 0.0035)l,
• and the pitch of the longitudinal installation satisfies the expression:
• bc=(20 to 65)δ,
• where:
• δ is the thickness of the sheet of the panel;
• l is the length of each TPM forming with the sheet the open cross-section configuration;
• and
• bc is the pitch of the longitudinal installation of the TPMs that form with the sheet the open cross-section configuration.

A wing box comprising a weight optimum configuration comprised of at least one of TPMs and TPM and panel combinations reinforced with (1) vertical walls manufactured out of sheets reinforced with pillars and (2) at least one of stringers or stringers and ribs, the wing box being designed using a modeling tool that includes a process that divisions wing design into the following structural members:

• stringer, stringer panel, rib-reinforced stringer panel, and pillar-reinforced wall panel, the process involving:
• in a first stage, defining six variable cross section dimensions of a stringer profile as a function of a compressing force associated with the stringer, which force does not appear as a variable;
• in a second stage, mapping eight variable parameters, taking into account the results of the first stage, to two variable parameters, these two variable parameters being normal stress and sheet thickness;
• in a third stage, mapping an additional thirteen variable parameters, using the two variable parameters;
• and
• in a fourth stage, mapping a further seven new variable parameters through two further new variable parameters, these two further new variable parameters being the maximum thickness of the wing profile and the wall thickness, thereby arriving at a total of four variable parameters used to model the wing box design prior to its construction.