Experimental study of the cyclic visco-elasto-plastic behaviour of a polyamide fibre strap

WOSInternational audienceExperimental tensile tests were performed on polyamide-based (PA66) woven strap samples. A strain measuring device was used to measure the strain in the middle and effective part of the woven tensile sample. The tests were performed, on the one hand under monotonous tension at different strain rates and on the other hand under sophisticated cyclic loading histories, including relaxation and creep sequences. The analysis of experimental results was made through a visco-elasto-hysteresis model, based on the superimposition of three stress components. The proposed method allows for characterizing the steady state viscous stress as a function of strain and strain rate, the time-independent irreversible behaviour and the instantaneous modulus increasing with the strain. Based on the visco-elasto-hysteresis model, an analysis enabled us to understand and predict the change in relaxation and creep orientations during complex loading histories

Viscoelastoplastic cyclic behaviour of sail materials

International audienceA tensorial visco-elasto-hysteresis model has been used previously in order to describe the thermomechanical behaviour of woven fabrics. Thus, it takes into account the essential features of behaviour, such as the steady state viscous stress as a function of strain and strain rate, the time-independent irreversible behaviour and the instantaneous modulus increasing with the strain. The aim of the study is to suggest the interest of the theory in the field of sail fabrics concerning characterization, testing and design. Moreover, we focus attention on two questions which are of fundamental interest, both at the level of principles and in the field of technological research, namely the viscous behaviour of sail fabrics and his nonlinear character

Developments in finite element simulations of continuous casting

peer reviewedTwo complementary approaches of steel continuous casting modelling using the finite element code LAGAMINE have been developed in the M&S Department. We propose here a description of the context in which the study started, then a description of both macroscopic and mesoscopic approaches. The first one describes the whole continuous casting process, from the free surface in the mould and through the entire machine, including thermal and mechanical behaviour of the steel. The second approach focuses on the prediction of cracks and is developed at the grain scale. Some results are also presented for both models

Vertically integrated modules for low power embedded sensor systems

A typical embedded sensor system consists of an environmental sensor, data storage, and a control circuit (such as a microcontroller). Two main traits desired of these embedded sensor systems are small form factor and low power consumption. However, due to the diverse nature of the design and applications, monolithic solutions incorporating the three main components are often not available on a large cost effective scale. This work describes a method of integrating heterogeneous circuit components into a single module. When combined with efficient operating algorithms the system size is reduced and lifetime is extended. Production or custom designed component chips are thinned and stacked vertically while interconnects are fabricated within the module providing a 3-D integration (3DI) of the system. A Global Positioning System (GPS) location recording sensor system is designed with the intention of applying the 3DI process to reduce its size and power consumption