For almost 10 years, the topic of the so-called 4D printing. This concept was first presented in 2013 by Skylar Tibbits – a young architect, artist and scientist who at the TED conference presented an extraordinary vision of creating objects that spontaneously changed, transforming from the initial state to the final state under the influence of a specific physical influence. Now, researchers at the Hebrew University of Jerusalem are returning to this idea, having developed a novel wood-based 3D printing material that can transform into pre-designed shapes.
What is 4D printing? Theoretically, the explanation is quite simple – it’s 3D printing, to which we add another, fourth dimension. 3D is a shape defined by three XYZ coordinates – in the case of 4D, we add a fourth factor to the length, height and depth – e.g. time, humidity or temperature. The essence of 4D printing is the so-called auto-assembly, which consists in the fact that an object with certain properties or structure changes its shape under the influence of external factors. The printed item, after performing an action, folds or unfolds, creating something completely new.
Israeli scientists have created an ecological raw material based on a mixture of wood flour and plant extracts, which is able to change shape due to the orientation of the fibers in the wood content, which causes its deformation during drying. The material was invented a few years ago, but only recently did scientists discover that by controlling the way it is laid, they can determine the evaporation time of moisture in a way that allows complex objects to be created.
So far, scientists have printed 3D models in the shape of a saddle, dome, and helix, but with further development, they say it can be used to create more complex self-organizing items such as home furniture. In an attempt to use the natural ability of wood to change shape, scientists integrated it with a material consisting of water and cellulose and xyloglucan nanocrystals – natural binders extracted from plants. The team found that the behavior of this raw material can be precisely controlled by adjusting the speed and 3D printing path of the printhead used to apply it.
It was also found that each shrinkage was perpendicular to the wood fibers contained in the material, and adjusting the rate of deposition can change the way they are arranged. As a result, accelerating 3D printing allows the material to warp in a predictable manner, while applying it slowly causes the wood content to become randomly oriented and shrink in all directions.
It has already been proven during tests that it is possible to arrange two rectangular layers of material into a spiral of different orientations, while adjusting its warpage in order to control the direction in which the spiral moves. The team assumes that one day their material can be used to 3D print furniture pieces, insert them into flat packages, which then turn into products ordered by customers when opened.
Source: www.3dprintingindustry.com
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