Shape optimization of interior cutouts in composite panels

Abstract

This paper presents validated results of the optimization of cutouts in laminated carbon-fibre composite panels by adapting a recently developed optimization procedure known as Evolutionary Structural Optimization (ESO). An initial small cutout was introduced into each finite element model and elements were removed from around this cutout based on a predefined rejection criterion. In the examples presented, the limiting ply within each plate element around the cutout was determined based on the Tsai-Hill failure index. Plates with values below the product of the average Tsai-Hill number and a rejection ratio (RR) were subsequently removed. This process was iterated until a steady state was reached and the RR was then incremented by an evolutionary rate (ER). The above steps were repeated until a cutout of a desired area was achieved. = stress in fibre direction = stress in transverse direction = shear stress = tensile/compressivestrength infibre direction = tensile/compressive strength in transverse direction = shear strength = plate element number lying on edge of cutout = plate element number = total number of plates = Tsai-Hill number = limiting Tsai-Hill number of plate e = limiting Tsai-Hill number of plate p = rejection ratio = global stiffness matrix = displacement vector = force vector = stress vector --ply number = number ofpliesper plate = failure index = specified condition on which to terminate evolution(e.g, areaof cutout) = stress at major vertexof ellipse = stress at minor vertex of ellipse = ellipse major axis = ellipse minor axis = increment number = evolutionary rate

Buckling and post-buckling of a composite C-section with cutout and flange reinforcement

“…Studies were also performed in finding optimised cutout shape, e.g. Falzon et al [5] showed that for a quasi-isotropic panel under in-plane shear load the optimum cutout shape was a diamond rather than the conventional circular. From the results of Kumar and Singh [6], quasi-isotropic laminate under combined in-plane loads with elliptical vertical cutout has the maximum buckling load and post-buckling strengths, whereas the laminate with elliptical-horizontal cutout has the minimum strengths.…”

Optimum Design of Composite Structures: A Literature Survey (1969–2009)

“…116 In composite optimization studies, usually the material system or dimensions (size) were optimized. In some studies, shape 55,72,183,190,200,241,242,289,313,354,383,547 774,776,806,826,828,846,860,882,886,888,894,925,939,966,968,976,982 of the structure was optimized. In a few studies, concurrent optimization was performed, in which the design of the part as well as its manufacturing process were optimized.…”

“…In composite optimization studies, usually the material system or dimensions (size) were optimized. In some studies, shape 55,72,183,190,200,241,242,289,313,354,383,547,588,619,668–670,675,683,707,733,742,779,800,810,829,855,875,916,1000,1003 or topology 149,219,243,247,291,325,348,358,378,427,446,447,463,466,472,490,503,514,528,547,582,596,607,651,688,730,732,744,774,776,806,826,828…”

“…A downhill proceeding algorithm monotonically decreasing the value of an objective function may get stuck into a locally optimal design other than the globally optimal one. For this reason, some researchers preferred global search algorithms like genetic algorithms, 184,226,248,249,254,255,260,286,288,291,296,313,315,321,324,328,329,339,362,373,379,395,398,402,404,405,415,421,424,428,430,443,445,448,457,458,465,467,468,473,477,494,495,497,499–501,504,505,508,511,518,520,526,537,547– 549,552,555,558,563,…”

Cutout shape and reinforcement design for composite C-section beams under shear load

“…One way of reducing stress concentration without adding structural weight is to find the optimum cutout shape. Falzon et al [7] used the Evolutionary Structural Optimisation (ESO) method to optimise cutout shapes in a square composite panel under different types of loading. They found that under shear load, the optimum cutout shape for a quasi-isotropic laminate was a rectangle of aspect ratio 1.86 and orientated 45° to the horizontal axis.…”