JEC COMPOSITES MAGAZINE - Issue #57 - May 2010 - 54

KNOW-HOW
Thermoplastics
Dual expertise
The ability to accurately describe the behaviour of short-fibre composites is the result of a long-term undertaking that started in 2007 with the support of Eureka. The project became a reality when the DIGIMAT® software application developed by e-Xstream Engineering was combined with the complex matrix behaviour models developed by Rhodia Polyamide. DIGIMAT® is a multi-scale modelling software platform that analyzes the behaviour of reinforced engineering plastics at any point of a part by integrating matrix and fibre properties and orientation under static or impact conditions. Rhodia’s Simulation and R&D teams in Saint-Fons co-operated with various external experts, such as the CEMEF research centre at the Ecole des Mines de Paris engineering school. This collaboration helped establish the behaviour laws of several materials using experimental databases and identification procedures based on genetic algorithms, among others. g…/… Modeling tool to predict the behaviour of filled polymers

Fig. 2: Effects of tensile speed on tensile behaviour (a) Microstructure of glass fibre reinforced polyamide (b)

Working together to boost competitiveness
Rhodia developed the MMI Confident Design™ technology to give its customers a stronger competitive advantage. Through partnerships with its customers, Rhodia actively contributes to creating value at every stage of the design process – from the initial concept through to the production of the finished part. “If our customer does not have the DIGIMAT® application, we handle the entire application development process. If the customer has the software, we provide access to the behaviour laws of the materials concerned throughout the project,” stresses Rhodia Simulation and Validation Manager, Didier Chomier.

monitored in real time during various mechanical tests to gain a better understanding of the damage and fracture behaviour of filled materials. The body of results obtained constitutes an extremely rich database, which was used to identify the behaviour laws of the matrix in a wide range of temperature, humidity and stress conditions. Among others, the database contains the mechanical characteristics of polyamide 66 filled with 15 to 50% glass fibre (Fig. 2).

First functions and applications
To date, four features – elasticity, elasto-plasticity, elastoviscoplasticity and viscoelasticity-viscoplasticity – can be used jointly with glass fibre orientation to provide information on the matrix behaviour under load. Other

An array of sophisticated techniques
To model the behaviour of materials, Rhodia went far beyond gross test results. Advanced resources and the best available techniques were used to make sure the entire chain of physical and mechanical characterization helps improve the reliability of the behaviour laws identified. To maximize Digimat’s potential, the microstructure of glass-fibre filled materials was analyzed using the European Synchrotron in Grenoble, where microtomography experiments were performed. This technique is comparable to medical scanning techniques, but with a much higher resolution. To precisely measure and understand the mechanical behaviour of glass-fibre filled materials, advanced mechanical characterizations were carried out, including impact tensile tests performed on a high-performance machine. Several 0.3 ms tensile tests were conducted with an unparalleled degree of accuracy and reproducibility. All the measurements performed in the lab at slower speeds were controlled by videometric deformation measurements. The volume of test specimens was

Fig. 3: Rhodia and Trelleborg Automotive Carbody used MMI for the Technyl® pedal and pedal module of the new Citroën C5 (Photo: Rhodia)

jec composites magazine / No57 May 2010

JEC COMPOSITES MAGAZINE - Issue #57 - May 2010

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #57 - May 2010