Optimisation of composite structures – Enforcing the feasibility of lamination parameter constraints with computationally-efficient maps

Abstract

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Optimisation of Composite Structures -Enforcing the Feasibility of Lamination Parameter constraints with Computationally-efficient Maps AbstractComposite materials are increasingly used in high performance structural applications because of their high strength and stiffness to weight ratios together with their significant tailoring capabilities. The stiffness of a monolithic laminate can be expressed as a linear combination of material invariants, one thickness variable, and twelve lamination parameters, which is an efficient alternative to using fibre angles as design variables. However, feasibility constraints originating from the interdependency between lamination parameters must be satisfied to obtain laminates with realistic stiffness properties. Currently, enforcing these feasibility constraints is a computationally intensive task. In this paper we propose to use normalised design variables that inherently map (i.e. correspond) to feasible lamination parameters, effectively removing the need to evaluate feasibility constraints altogether. To this end, linear and B-spline maps of the feasible lamination parameter subspace are proposed and evaluated. Results of 2D and 4D benchmark analyses and optimisation studies suggest that the proposed methodology does successfully provide an efficient means of achieving feasible results at lower computational costs.

Bend-free design of ellipsoids of revolution using variable stiffness composites

“…which limit the feasible region for V A 1 and V A 2 [22,23]. This feasible region for V A 1 and V A 2 that makes the structure moment-less and curvature-less, is also shown in Fig.…”

A novel design method for the fast and cost-effective manufacture of composite parts employing the Quilted Stratum Process

“…They are, however, not independent since they are computed from a given stacking sequence. Deriving compact sets of feasibility constraints for the lamination parameters space has attracted the attention of many researchers since the first studies using lamination parameters as design variables for laminate optimization and different sets of equations are available depending on the number of non-zero parameters [21,22,25,[36][37][38].…”

Generic stacks and application of composite rules for the detailed sizing of laminated structures

“…Usually, lamination parameters [15] are employed to model the stiffness properties of the laminate. Many researchers [16,17,18] have used a gradient-based optimisation exploiting lamination parameters and a lot of work has been conducted to determine their feasible design space [19], enforce composite design guidelines [20,21] and strength requirements [22,23]. The reason for their wide acceptance is that they provide a compact formulation for the properties of a structural zone with a maximum of 12 design variables, in the most general case, plus an additional design variable for the thickness of the zone.…”