| In recent years, 4D printing technology has been the subject of much research. Just this week, researchers at Dartmouth College developed a 3D-printable smart ink that can change shape and color, and they use 4D printing technology. The other teams doing novelty are different. Suong Van Hoa, a professor of mechanical and industrial and aerospace engineering at Concordia University, is using 4D printing technology to make composites that can be bent on their own without the use of molds. '4D printing allows us to make curved composite structures without the need to make curved molds,' Hoa said. 'My main discovery is that people can make curved composites - long continuous fibers with high mechanical properties that can achieve even more Faster, more economical. 'Usually, several steps are required in the manufacture of components like composite leaf springs, which are lightweight shock absorbers in vehicles. In order to make S-shaped parts, S-shaped moulds need to be made of solid materials such as metals. After that, the reinforcing fabric impregnated with the resin system was placed on the mold to form a composite part. However, Hoa said that using 4D printing technology can eliminate the initial step of building a complex mold.  'The 4D printing of composites takes advantage of the shrinkage of the matrix resin, as well as the difference in the thermal shrinkage coefficient of the layers of different fiber orientations, thereby activating the change in shape during curing and cooling,' he said. 'This behavior can be used to make Parts with curved geometries do not require complex molds. Therefore, the manufacturing of curved shapes can be quick and economical. However, the degree of shape change depends on the material properties, fiber orientation, stacking sequence and manufacturing process. Some of Hoa's studies involve rethinking the anisotropic properties of the composite layer. Anisotropy is the way in which a material behaves when it is subjected to loads along different axes. The anisotropic property of a material measures how it changes in relation to other factors. A measure. For example, shrinkage of the resin can cause deformation of the material, or temperature changes can cause the fiber to expand or contract. According to Hoa, understanding and controlling these changes is the key to making curved laminates for curved molds. He said: 'Anisotropy has been regarded as a burden in the past. Now I think of them as an asset.' Hoa believes that the technology can be applied to aerospace and other fields. 'Another application is like satellites. Spatial structure, these structures are affected by extreme temperature fluctuations,' he said. 'The daytime structure can be opened (when the temperature is high) to collect solar energy and close at night to protect its interior.' Source: 3D Tiger |
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