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A probabilistic stress analysis tool predicting reliability of composite wind turbine rotor blades was developed and validated by comparing with results from a three‐dimensional shell finite element model of a blade. Stress analysis was based on thin wall multicellular Euler–Bernoulli beam theory using as input section stress resultants directly from aeroelastic simulations; a finite strip method was implemented for elastic stability calculations. Reliability analysis was performed at the ply level of the multidirectional laminates implementing various methods such as the response surface method, β‐index and crude Monte Carlo simulation. Physical and statistical uncertainties of the basic variables was taken into account while several model uncertainties related to the material properties were further introduced and quantified in the light of appropriate test results. To prove the efficiency of the code as a design tool, the effect of various probabilistic assumptions concerning the material properties was directly investigated on the estimated reliability β‐index values for two rotor blade design cases typical of stall‐regulated and pitch‐regulated wind turbines. Copyright © 2014 John Wiley & Sons, Ltd.

The present study introduces a trade-off framework to evaluate assembly concepts to make informed decisions for aircraft wing structures. This includes (1) the design of the assembly concepts and the estimation of the probability of achieving specific Assembly Key Characteristics, (2) the estimation of the associated costs for each assembly concept using technical cost modelling in combination with Monte Carlo simulation techniques to deal with the uncertainty of the input cost and process parameters and (3) the formulation of the decision matrix to assess the alternative concepts. The suggested trade-off concept can easily be expanded to include weight and performance criteria. Results for a 4m generic composite wing indicated that both conventional and determinate assembly can be successfully implemented with high value probabilities to achieve the predetermined assembly key characteristics.

The Rapid And Cost Effective Rotorcraft (RACER) is being developed by Airbus Helicopters (AH) to demonstrate a new Vertical Take-Off and Landing configuration to fill the mobility gap between conventional helicopters and aeroplanes. RACER is a compound rotorcraft featuring wings and multiple rotors. The wing arrangement suggested by AH is defined as a staggered bi-plane joined configuration with an upper and a lower straight wing, either side of the fuselage, connected at their outboard extent to form a triangular structure. The ASTRAL consortium, consisting of the University of Nottingham and GE Aviation Systems, are responsible for the design, manufacture, assembly and testing of the wings. Producing an optimised strategy to assemble a joined-wing configuration for a passenger carrying rotorcraft is challenging and novel. The objective of this work concerns all aspects of assembling the joined-wing structure.The joined-wing and fuselage structures will be produced independently and mated together during the final RACER assembly. A multi-stage process will deliver the joined-wing assembly and ensure it will fit to the fuselage. Producing the individual wing structures requires a novel build philosophy driven by the innovative, one-piece composite moulding that forms the leading edge (LE) and upper aerodynamic surface of each wing. Using the Flap subassembly as the tool to set interfacing wing-box items provides a cost effective solution to assembly jig design. The independent wing structures must be joined at the outboard hinge line, whilst meeting the fuselage interchangeability definition. Matched tooling, replicating the fuselage interface, will be employed to overcome this hurdle. Successfully joining the wing structures also requires the innovative application of 3D tolerance analysis methods to size bush diameters within the interface.The overall build philosophy is summarised in this work, including assembly sequencing; definition of datum frames; assembly tooling; design tolerances and the analysis required to deliver assembly key characteristics.

One of the major elements when performing a design for manufacturing and assembly methodology is the cost modelling method. A probabilistic cost approach is introduced herein for the series production of a composite wing structure. The proposed methodology should be able to capture changes in the design, the materials and the fabrication processes. Critically, the assembly strategy of the product should also be included to enable realistic multi-disciplinary tradeoff studies among several potential build philosophies of the wing structure at the early phase of the design. Furthermore, uncertainty related to the various input parameters, i.e. production, process and cost parameters due to incomplete knowledge, can be considered. Thus, the main effort of the present work is to set up the framework of this methodology, to develop the appropriate cost approach in order to capture manufacturing and assembly costs and further to establish a sensitivity analysis module in order to clarify the dominant cost-drivers of the product. To deal with the uncertainty, Monte Carlo simulation is implemented while Spearman's correlation coefficients are evaluated and used to perform the sensitivity study. The efficacy of the suggested methodology is demonstrated by comparing a traditional wing design against new more integrated manufacturing techniques, e.g. the co-curing process, for a simplified wing configuration.