David Chapelle

Development of a Reliability-Mechanical: Numerical Model of Mechanical Behavior of a Multilayer Composite Plate

Due to the design of uncertainty caused by manufacturing processes and measures, that may affect composite structures, mechanical reliability analysis of a multilayer composite plate, using the finite element method, been the subject of this paper. To that end, we propose a reliability-mechanical numerical model, conditioned by Tsai-Wu failure criterion. This model was developed in two steps, first, the development of a deterministic model, afterwards, a probabilistic computation. To get to our lens, a probabilistic study was carried out to highlight the influence of design parameters on random damage to composite structures, using the Monte Carlo simulation method, which made it possible to estimate the failure P f probability of the studied structure. The results obtained show that the uncertainties loading and winding angle are the first two responsible for the composite structure failure.

Prediction of reliability analysis of composite tubular structure under hygro-thermo-mechanical loading

ABSTRACT The present paper focuses on reliability prediction of composite structure under hygro-thermo-mechanical loading, conditioned by Tsai-Wu failure criterion, where the Monte–Carlo method is used to estimate the failure probability(Pf). This model was developed in two steps: first, the development of a deterministic model, based on an analytical and numerical approach, and then, a probabilistic computation. Using the hoop stress for each ply, a sensitivity analysis was performed for random design variables, such as materials properties, geometry, manufacturing, and loading, on composite cylindrical structure reliability. The probabilistic results show the very high increase of failure probability when all parameters are considered.

Towards the Development of Filament Wound Composite Structures Submitted to Very High Internal Pressure, Based on Complex Geometry Shapes

Industrial applications, especially composite structures bearing high internal pressure, and fabricated using the filament winding process face certain difficulties like the reinforcement of complex shapes, as well as the correct placement of fibers over the surface of a mandrel. In some cases the definition of the manufacturing parameters respond more to cost or time criteria rather than engineering standards, reducing largely the advantages of the said manufacturing process. In order to overcome these obstacles, this research aims to propose a solution that permits to fabricate complex shapes with the desired winding angles at a certain region of complex-shaped mandrels. A numerical tool that simulates the placement of fiber tows over the surface of complex geometries is developed and validated by means of the fabrication of convex and concave composite structures using detachable mandrels. Previous results show that it is feasible to wind complex geometries with good accuracy.Copyright

Assessment of the Gas Permeation through Thin Coated Polymeric Membranes; Improvement of the Gas Barrier Ability for Hydrogen Storage

We investigate and simulate the permeation behavior of PET membranes on which thin coatings are deposited. Depending on the parameters of deposition and on the thin coating thickness, we assume this alteration could make it possible to decrease by one order of magnitude the permeation coefficient. Some specific developments have been necessary, all the more not only a decrease of permeation is expected but also the mechanical strength of the thin coating during severe mechanical loadings. We consequently design devices dedicated to the permeation test but also to the bulge and blister tests which permit to check the mechanical properties of the film and its adhesion on the PET surface. This paper focuses on the permeation test.