Steel Sheets

Bone inspired steel made, as described in Science (AAAS) News and New Scientist 9 March 2017 and Science doi: 10.1126/science.aal2766, 10 March 2017.

Metal fatigue is the weakening of a metal structure when it is repeatedly subjected to forces (“load cycling”), leading to the formation of microscopic cracks, as happens where aeroplane wings move up and down in flight. If these cracks are allowed to propagate they can lead to the structure breaking, which can have catastrophic results, e.g. in aircraft, motor vehicles, bridges, etc.

A group of metallurgists and engineers from Germany, Japan and USA have taken “inspiration from bone to develop a steel with a laminated substructure that arrests cracks”. Bone is able to resist fracturing from normal body movement partly because of its multi-layered structure. At the microscopic level, bone is made of layers of collagen fibres and calcium crystals. In each layer the fibres are laid down in the opposite direction to the adjacent layers.

The research team developed a metal made of two different types of steel with a microscopic layered structure that works the same bone. The different alloy components also have different degrees of hardness, and some areas within the steel are more flexible than others. This combination of properties means that if a microscopic crack forms it is much less likely to be propagated through the structure and lead to a fracture.

Admir Masic who researches the structural and mechanical properties of biological materials at the Massachusetts Institute of Technology commented: “The insights into biological strategies to build crack-resistant materials … is an outstanding source of inspiration for the design of advanced materials, including steels”

New Scientist, Science

Editorial Comment: The new metal alloy mix is an interesting copy of natural bone which is a mix of a strong material with different properties. Collagen fibres are flexible and have high tensile strength, whilst the hard calcium crystals resist bending and distorting. As well as microscopic organisation of the collagen fibre layers, a bone is also organised into dense compact bone surrounding a latticework interior. The long limb bones, which have to bear our weight and act as levers during walking and manipulating objects, are built like tubular steel with strong cylindrical walls and hollow interiors, making a light but strong structure. Altogether, this combination of the right substances and the right organisation fulfils the need for both rigid support and endurance under load cycling.

As Admir Masic commented, building crack resistant materials is helped by looking at “biological strategies.” But the weakness in all this is the trend to deliberately forget that strategy is a property of a mind, and the kind of plan and purpose that selects the right materials and organises them into a functional substance that can only come from a creative designer and engineer who is outside the structure. Therefore, it is right to give credit to the engineers and metallurgists who made the new steel, but it is even more important to give praise and honour to the Creator God who designed and made bones, which also have properties that go beyond what any metal alloy can do.

Evidence News vol. 17, No. 3
15 March 2017
Creation Research Australia

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