Optimising the ply dropping order in variabel stiffness, variable thickness laminates using stacking sequence tables

Modern composite structures o<br/>er two avenues of optimising performance. One, optimising a single stacking sequence over the structure leading to constant sti<br/>ness designs. Two, varying the sti<br/>ness over the structure. This may be achieved by dropping plies, changing the thickness, or by steering the fibres, changing the fibre angles....

Stacking sequence constraints in non-conventional composite laminate optimisation

Efficient sizing of structures under stress constraints

Optimisation algorithms used to automatically size structural members commonly involve stress constraints to avoid material failure. Therefore the cost of optimisation grows rapidly as the number of structural members is increased due to the corresponding increase in the number of constraints. In this work, an efficient method for large scale...

Effect of Steering Limit Constraints on the Performance of Variable Stiffness Laminates

A method to optimise the fibre angle distribution of variable stiffness laminates is proposed. The proposed method integrates a fibre angle retrieval step with a fibre angle optimisation procedure. A multi-level approximation approach is used in combination with the method of successive approximations. First, fibre angle retrieval is done by...

Buckling and first-ply failure optimization of stiffened variable angle tow panels

A computationally efficient two-level design methodology is developed for the optimization of stiffened compression loaded panels having variable stiffness panels as their skin. In the first step extensive bay panel optimization is performed using a Rayleigh-Ritz energy method coupled with a specialized Genetic Algorithm. Results in agreement...

Buckling optimization of steering stiffeners for grid-stiffened composite structures

Grid-stiffened composite structures, where the skin is stiffened by a lattice of stiffeners, not only allow for significant reduction in structural weight but are also competitive in terms of structural stability and damage tolerance compared with sandwich composite structures. As the development of Automated Fiber Placement (AFP) technology...

Damage resistance of dispersed-ply laminates

This paper presents the design procedure of a quasi-isotropic (QI) laminate employing dispersion of ply orientations. The goal is to improve damage resistance of a laminate under low velocity impact (LVI). The LVI is treated as a quasi-static loading and instead of a plate a laminated beam is considered. Therefore, this situation simplifies the...

Continuous-time state-space unsteady aerodynamic modelling for efficient aeroelastic load analysis

Over the years, wings have become lighter and more flexible, making them more prone to aeroelastic effects. Thus, aeroelasticity in design becomes more important. In order to determine the response of an aircraft to, for example, a gust, an unsteady aerodynamic model is required to determine the dynamic loads. The three most-commonly used...

Structural Modeling of Thin Membranes for Wind Energy Systems

Buckling Analysis of Grid-Stiffened Composite Shells

There is a renewed interest in grid-stiffened composite structures; they are not only competitive with conventional stiffened constructions and sandwich shells in terms of weight but also enjoy superior damage tolerance properties. In this paper, both global and local structural instabilities are investigated for grid-stiffened composite panels...

Design of anisotropic composite shells using an isogeometric approach

Thin-walled composite structures, typically modeled as Cosserat continua during the design phase, are of particular importance in aerospace and automotive applications. At the dawn of industrial scale adoption of advanced fibre placement technology, it became viable to better exploit the directional properties of composite materials. In the...

Maximum Buckling Load Design of General Cross-section Cylinders Using Lamination Parameters

For a non-circular cylinder the radius of curvature changes around the circumference. Therefore for constant stiffness non-circular cylinders, some specific locations in the circumference are more prone to buckle. The same problem exists for circular cylinders with non-uniform loading in the cross-section like a cylinder under bending. This...

Energy-based aeroelastic analysis of a morphing wing

Aircraft are often confronted with distinct circumstances during different parts of their mission. Ideally the aircraft should fly optimally in terms of aerodynamic performance and other criteria in each one of these mission requirements. This requires in principle as many different aircraft configurations as there are flight conditions, so...

Active aeroelastic control aspects of an aircraft wing by using synthetic jet actuators: Modeling, simulations, experiments

This paper discusses modeling, simulations and experimental aspects of active aeroelastic control on aircraft wings by using Synthetic Jet Actuators (SJAs). SJAs, a particular class of zero-net mass-flux actuators, have shown very promising results in numerous aeronautical applications, such as boundary layer control and delay of flow separation...