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Listen to our podcast Cogitons Sciences: Guide to choosing the right materials [Matériaux, histoire d’une vie #2]

Welcome to the fourteenth episode of Cogitons Sciences, the podcast that deciphers the challenges of science! In this second episode of our mini-series on materials, we wonder with our guest Bruno Chenal about the choice of material, for a given use and in a given context. The current president of the SF2M, the French Society of Metallurgy and Materials, brings us his insights and his experiences in this area.

How to make a relevant choice of material and according to what criteria? For which application? What selection method can be used? These questions were put to Bruno Chenal, president of SF2M, the French Society of Metallurgy and Materials.

Listen to the episode!

The material identity card [6:00 – 16:07]

The number of materials increases and their choice is more and more complex. “New materials allow a new use and improve the performance of a product. Aluminum and its alloys, linked to the history of aeronautics, have enabled faster, larger capacity, lighter aircraft. The choice of a material for a given application is based on its properties, its development and manufacturing process, and its design. ” This is what the specifications define. » Bruno Chenal distinguishes “the intrinsic properties, which define the identity card of the material”, from one side and the other, “its extrinsic properties which come into play during its final selection: its price, its environmental impact, its availability, the health and safety aspect. »

Evolutions of the bicycle frame [16:20 – 20:26]

This cycling enthusiast illustrates his point with a bicycle frame. ” The expected properties are rigidity, elasticity, dynamism, weight, durability, but also the price and the fact of being able to manufacture it in series. “. Bicycle frames have long been made of steel. They have been lightened, thanks to steel alloys, and thinned tubes. Aluminum is three times lighter than steel, more expensive and less resistant. The diameter of the tubes has been increased to strengthen them. Carbon fiber composites offer lighter frames. More expensive, titanium combines low density with the high characteristics of steel. Finally, composites allow the shapes of airplane wings, for improved aerodynamics. Different trade-offs lead to different choices.

Select… [20:35 – 24:07]

Bruno Chenal proposes to rely on ” a rational method of choice which makes it possible to make the optimal choice of a material », Developed by Professor Michael Ashby. In Ashby diagrams, a given property is represented and the materials are positioned, each in domains. It makes it possible to restrict the choice of materials, to arrive at a single solution.

…And manufacture! [24:16 – 30:38]

There remains the question of the manufacture of the material and the product. ” Additive manufacturing gives access to geometries impossible to produce by machining. Being able to produce these parts all at once with a single material opens up new perspectives. New, better adapted materials can be developed. “. Bruno Chenal recommends the most open approach possible. A choice is a compromise.

Listen to the episode here.

Cited references:

Bell Labs Laboratories

Professors Michael Ashby, from the University of Cambridge, and Yves Bréchet, from the University of Grenoble

Ashby diagrams

Ansys Granta Design Software

“An industry addicted to conflict minerals”, second episode of this mini-series from the Cogitons Sciences podcast

Resources to go further:

– Michael Ashby books:
Choice of materials in mechanical design », Dunot, 2012
Materials and environment: eco-responsible choice in design », Dunot, 2011
– Books co-authored Michael Ashby and Yves Bréchet:
Selection of materials and implementation processes », Eyrolles, 2001.
– Choice and use of materials, article of documentary resources of Techniques of the Engineer co-authored by Yves Bréchet, Michael Ashby, Michel Dupeux and François Loucher.

Let’s think about Sciences is a podcast produced by Engineering Techniques. This episode was directed by Marie-Caroline Loriquet, in collaboration with Intissar El Hajj Mohamed. The credits were directed by Pierre Ginon and the visual of the podcast was created by Camille Van Belle.

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