System tool for weight optimization of thin wall structures

Abstract

A thin wall profile member (TPM) with a cross-sectional shape and dimensions constant along its length is pre-constructed for use as a load carrying, weight optimized structural element. The TPM has at least one main strip having longitudinal reinforcing ribs and at least one additional strip having longitudinal reinforcing ribs. The at least one additional strip has a width that does not exceed a width of the at least one main strip and has a thickness that equals or exceeds a thickness of the at least one main strip. A ratio of the width of the at least one additional strip to the width of the at least one main strip is in the range of 0.05 to 1.0. A ratio of the thickness of the at least one additional strip to the thickness of the at least one main strip is in the range of 1.0 to 5.0.

I claim: 
     
         1 . A thin wall profile member (TPM) with a cross-sectional shape and dimensions constant along its length, the TPM being pre-constructed for use as a load carrying, weight optimized structural element under compressive load, the TPM comprising:
 at least one main strip having longitudinal reinforcing ribs at end portions thereof; and   at least one additional strip having longitudinal reinforcing ribs at end portions thereof, the at least one additional strip having a width that does not exceed a width of the at least one main strip and having a thickness that equals or exceeds a thickness of the at least one main strip;   wherein a ratio of the width of the at least one additional strip to the width of the at least one main strip is in the range of 0.05 to 1.0;   wherein a ratio of the thickness of the at least one additional strip to the thickness of the at least one main strip is in the range of 1.0 to 5.0; and   wherein for each value in the width ratio range from 0.05 to 1.0, there is a corresponding maximum value in the thickness ratio range from 1.0 to 5.0 corresponding to a maximum shape efficiency factor value.   
     
     
         2 . A TPM according to  claim 1 , wherein the longitudinal reinforcing ribs of the at least one additional strip comprise two common reinforcing ribs; and wherein
   δ a   /a≥δ   b   /b , where:
   b is the width of the at least one main strip,   a is the width of the at least one additional strip having the two common reinforcing ribs,   δ b  is the thickness of the at least one main strip, and   δ a  is the thickness of the at least one additional strip having the two common reinforcing ribs.   
     
     
         3 . A TPM according to  claim 1 , wherein the at least one additional strip has a common reinforcing rib and a free reinforcing rib; and wherein δ c /c≤δ b /b, where:
 b is the width of the at least one main strip, 
 c is the width of the at least one additional strip having the common reinforcing rib and the free reinforcing rib, 
 δ b  is the thickness of the at least one main strip, and 
 δ c  is the thickness of the at least one additional strip having the common reinforcing rib and the free reinforcing rib. 
 
     
     
         4 . A TPM according to  claim 1 , wherein:
 the at least one additional strip comprises at least one additional strip having two common reinforcing ribs as the longitudinal reinforcing ribs, and at least one additional strip having a common reinforcing rib and a free reinforcing rib as the longitudinal reinforcing ribs;   and wherein the width of the at least one additional strip having the two common reinforcing ribs equals or exceeds the width of that at least one additional strip having the common reinforcing rib and the free reinforcing rib, and the thickness of the at least one additional strip having the two common reinforcing ribs does not exceed the thickness of the at least one additional strip having the common reinforcing rib and the free reinforcing rib; wherein
   δ b   /b≤δ   a   /a≤δ   c   /c , where:
 
   a is the width of the at least one additional strip having the two common reinforcing ribs,   b is the width of the at least one main strip,   c is the width of the at least one additional strip having the common reinforcing rib and the free reinforcing rib,   δ a  is the thickness of the at least one additional strip having the two common reinforcing ribs,   δ b  is the thickness of the at least one main strip, and   δ c  is the thickness of the at least one additional strip having the common reinforcing rib and the free reinforcing rib.   
     
     
         5 . The TPM according to  claim 3 , wherein the TPM has a Z-shaped cross-section. 
     
     
         6 . The TPM according to  claim 3 , wherein the TPM has a L-shaped cross-section. 
     
     
         7 . The TPM according to  claim 3 , wherein the TPM has an I-shaped cross-section. 
     
     
         8 . The TPM according to  claim 7 , wherein the TPM is made of steel. 
     
     
         9 . The TPM according to  claim 4 , wherein the TPM has a U-shaped cross-section. 
     
     
         10 . The TPM according to  claim 3 , wherein the TPM has one of a Z-shaped, L-shaped or I-shaped cross-section and is made of an aluminum alloy. 
     
     
         11 . The TPM according to  claim 9 , wherein the TPM has a U-shaped cross-section and is made of an aluminum alloy. 
     
     
         12 . A thin wall profile member (TPM) and panel sheet combination comprising:
 a panel sheet, and   a plurality of TPMs installed longitudinally across the width of the panel sheet with even pitch, each of the plurality of TPMs having a cross-sectional shape and dimensions constant along its length and being pre-constructed for use as a load carrying, weight optimized structural element under compressive load;   wherein each of the TPMs comprises at least one main strip, and at least one additional strip having a width that does not exceed the width of the at least one main strip and having a thickness that equals or exceeds the thickness of the at least one main strip;   wherein the ratio of the width of the at least one additional strip to the width of the at least one main strip is in the range of 0.05 to 1.0;   wherein the ratio of the thickness of the at least one additional strip to the thickness of the at least one main strip is in the range of 1.0 to 5.0; and   wherein for each value in the width ratio range from 0.05 to 1.0, there is a corresponding maximum value in the thickness ratio range from 1.0 to 5.0 corresponding to a maximum shape efficiency factor value.   
     
     
         13 . A combination according to  claim 12 , wherein for each of the plurality of longitudinally installed TPMs, the corresponding at least one main strip and at least one additional strip form, with the panel sheet, an open cross-section configuration; and wherein the thickness of the panel sheet satisfies the expression δ=(0.0006 to 0.0035) l s , the pitch of the longitudinally installed TPMs satisfies the expression b s =(20 to 65) δ, and the width B of the TPM and panel sheet combination is determined from the expression B=n s ·b s , where:
 δ is the thickness of the panel sheet, 
 l s  is the length of each of the longitudinally installed TPMs, 
 b s  is the pitch of the longitudinally installed TPMs forming with the panel sheet the open cross-section configuration; and 
 n s  is the number of longitudinally installed TPMs forming with the panel sheet the open cross-section configuration. 
 
     
     
         14 . The TPM and panel sheet combination according to  claim 13 , further comprising a plurality of TPMs installed transversally to the longitudinally installed TPMs. 
     
     
         15 . The TPM and panel sheet combination according to  claim 14 , wherein the pitch l r  of the transversally installed TPMs satisfies the expression l r =(10 to 60) b s ; and wherein the length L of the TPM and panel sheet combination is determined from the expression L=n r ·l r , where n r  is the number of transversally installed TPMs corresponding to the longitudinally installed TPMs forming with the panel sheet the open cross-section configurations. 
     
     
         16 . A combination according to  claim 12 , wherein the TPMs are installed longitudinally across the width of the panel sheet with even pitch such that for each of the plurality of longitudinally installed TPMs, the corresponding at least one main strip and at least one additional strip form, with the panel sheet, a closed cross-section configuration; and wherein the thickness of the panel sheet satisfies the expression δ=(0.0006 to 0.0035) l 1   s , the pitch of the longitudinally installed TPMs satisfies the expression b 1   s =(40 to 130) δ, and the width B of the TPM and panel sheet combination is determined from the expression B=n 1   s ·b 1   s , where:
 δ is the thickness of the panel sheet, 
 l 1   s  is the length of the longitudinally arranged TPMs, 
 b 1   s  is the pitch of the longitudinally installed TPMs forming with the panel sheet the closed cross-section configuration, and 
 n 1   s  is the number of longitudinally installed TPMs forming with the panel sheet the closed cross-section configuration. 
 
     
     
         17 . The TPM and panel sheet combination according to  claim 16 , further comprising a plurality of TPMs installed transversally to the longitudinally installed TPMs. 
     
     
         18 . The TPM and panel sheet combination according to  claim 17 , wherein the pitch l 1   r  of the transversally installed TPMs satisfies the expression l 1   r =(1.5 to 10) b 1   s ; and wherein the length L of the TPM and panel sheet combination is determined from the expression L=n 1   r ·l 1   r , where n 1   r  is the number of transversally installed TPMs corresponding to the longitudinally installed TPMs forming with the panel sheet the closed cross-section configuration.