Case Study

Composite Landing Gear Struts

The massive Airbus A340 landing gear, designed and manufactured by Messier-Dowty at Gloucester with the aid of LUSAS software symbolizes state-of-the-art engineering design. As part of continually advancing its designs, the company is using LUSAS Composite to investigate the design of composite landing gear components with the aim of reducing the cost and weight of future landing gear assemblies.

Messier-Dowty is a 50:50 joint venture bringing together the landing gear businesses of TI Group of UK and SNECMA of France. It is the world leader in aircraft landing gear systems, with sales of £250 million, employing 2500 people worldwide. It has five manufacturing operations in France, Canada and the UK team of 750 people based in Gloucester.

Under a government funded LINK Composite Structures Scheme a composite landing gear strut was designed and tested. Using LUSAS, a linear static analysis of three composite strut configurations was undertaken to determine the optimum layup arrangement under compressive and tensile loads. Because of symmetry, only one eighth of the strut needed to be modelled. Advanced 16 noded solid composite elements were used to model each section of the model and the LUSAS tied-slideline facility was used to effectively 'glue' dissmilar meshes between sections together. Representative pin loads were applied to the lug with boundary conditions being used for the free edges. Six analyses in total (3 tension and 3 compression) were carried out. Peak shear stresses for compression and tension analyses were obtained and an optimum layup arrangement of the composite strut was determined by examining the shear stress distribution between the different composite sections.

With help from LUSAS the LINK scheme achieved its objective of advancing composite design technology on a broad front covering analysis methods, failure modelling, the evaluation of new resin transfer moulding systems and fabrication of engineering components. As an extension to this work another composite project known as CDAM (Composite Design Analysis Methods) is currently in progress. Funded by CARAD (Civil Aerospace Research and Development), Messier-Dowty is making use of LUSAS to, amongst other things, study the propagation of damage under static, fatigue and impact loading. The project has already extended the LUSAS interface element to model interlaminar failure; extended the 3D solid composite element to model large deformations and increased the capability of both these elements to model implicit impact problems. Work is now in hand to extend the existing superelement facility to cater for nonlinear and dynamic analyses.