Jérôme Pailhes

Modelling of the stress/strain behaviour of a carbon/carbon composite with a 2.5 dimensional fibre architecture under tensile and shear loads at room temperature

The paper presents a macroscopic model of the non-linear stress/strain behaviour and the ultimate failure of a needled, woven carbon/carbon (C/C) composite, under tensile and shear loads parallel to the plies. The model is based upon continuum damage mechanics concepts for the description of damage evolution, and the approach to plasticity for the description of inelastic strains induced by matrix damage, according to the general approach developed by Ladeveze for composites. Modelling was guided by the experimental data on the matrix damage modes obtained from extensive microscopy examination of the test specimens under load. The model involves three scalar damage parameters including two tensile parameters, and one shear parameter resulting from a combination of the tensile ones. Identification of the damage parameters requires one off-axis (at 45° in the plane of the plies), and two on-axis (parallel to tow directions) uniaxial tensile tests. The model was validated with tensile stress/strain curves measured from various off-axis tests. The ultimate failure was predicted by the use of damage accumulation criteria.

Energy Based Functional Decomposition in Preliminary Design

The authors wish to thank Dr. Jonathan Maier, Dr. Gregory Mocko and Mr. Benjamin Caldwell for their valuable comments on the draft of the paper.

Aided Decision-Making for an Embodiment Design Problem

In the early phases of a traditional design process, many decisions are made by designers. For that purpose, they take advantage of their experience and company knowledge. These decisions are necessary in a sequential design process but may hide many embodiment solutions. Moreover, designers often use a trial-and-error mode to find a working combination of standard elements. To overcome these difficulties, a decision support system based on constraint programming is proposed. The object of the design process set out in this paper is to facilitate the embodiment design phase by avoiding a-priori decision making and searching for feasible architectures in which all the points of view of the various participants in the project are taken into account. A preliminary search of structuring characteristics of the design problem is necessary and is detailed here. This methodology is applied to embodiment design of the automatic weight-winding system of a monumental clock. To determine the most interesting solutions , objectives and performance indicators are entered. Finally, the benefits of our approach are discussed.

Exploring design spaces in the search for embodiment design solutions and decision support

The design of an air-conditioning system for a commercial aircraft, which functions in various life cycle stages, proves difficult because atmospheric conditions differ greatly according to the flight phase. This paper proposes the use of constraint programming in the exploration of design spaces and the search for feasible embodiments. This approach produces the best design compromises between various design objectives, whatever the life cycle stage. The entire design space is explored for potential solutions and their performance assessed, thus allowing for decision support at the end of the embodiment design phase