Wood foam with metal muscle

researchers at the FIWR have been developing wood foams made entirely of wood.

The natural adhesive properties of wood make synthetic adhesives superfluous. From an ecological standpoint, this makes wood foams ideal for a whole range of applications, such as usage as core material in lightweight construction and sandwich panels, as packaging material and in thermal insulation and soundproofing.

In order to extend the application range of wood foam, a group led by Frauke Bunzel from Fraunhofer WKI developed a wood-metal foam hybrid that unites the properties of both wood foam and metal sponge.

In the course of the project, they elaborated on the principles for manufacturing the composite and determined its initial key properties.

“Strengthening the wood foam with a metal skeleton, for example, can substantially enhance its characteristically low bending strength,” Bunzel said. In the case of Home foam, the bending strength of the hybrid is greater than that of its two components.

Another advantage is that unlike wood foam, metal sponge can conduct electricity. The outstanding properties of wood foam are its high levels of sound absorption and low thermal conductivity.

peratures from 1901 to 2012 from the Goddard Institute for Space Studies, and that derived from isotope measurements of ice cores and cave formations for the preindustrial temperature record dating back more than 100,000 years.

Using a method from statistical physics known as multifractal analysis, the team found that the temperature data contained pink noise-like fluctuations. Because pink-noise features were observed in both the pre- and post-industrial datasets, the authors have concluded that such noise must be caused by natural processes.

ANNULAR

SYSTEMS that harvest energy from ocean waves can be important renewable energy sources, especially if methods for energy extraction can be improved. Some existing ocean energy systems work by concentrating the waves into a smaller area, making energy harvesting easier. But the extraction efficiency gets limited when too much wave energy gets reflected.

Chinese researchers from Xiamen University and Zhejiang University have now developed a new structure that concentrates water waves without reflecting them back from the shore.

They have exploited ideas from modern optical engineering and have devised a ringshaped structure that achieves wave concentration without reflection. They have also tested the device performance using 3D-printed and smallscale prototypes and numerical simulation. With further development, the technique may find practical deployment in offshore wave energy projects. Another aspect of this development is the possibility of using this device to lessen the impact of tsunami waves, the researchers said.