Which design principles unify the diversity of life on earth? To understand how biological designs emerged by natural selection, biomechanics studies organisms by applying engineering science and mechanics. Biomechanics studies life from molecules to ecosystems. Questions range ‘how do cells form tissue’, over ‘what shapes a muscle’ to ‘how do animals fly’ and ‘which mechanical constraints govern body shape and -dynamics when animals increase in size’. Biomechanics is applied not only to extant but also fossil organisms to reconstruct the way of life of extinct plants and animals.
Most biomechanists aim to unravel the building principles of nature by reverse engineering. But they also work in the opposite direction from biomechanical solutions to engineering designs. This field is known as biomimetics, and several examples are discussed in this issue. One famous example is George de Mestral’s invention of Velcro that was inspired by the cockleburs ingenious attachment mechanism. We are only beginning to exploit the rich source of stunning designs found in nature.
How to perform measurements in a hovering animal’s wake: Physical modelling of the vortex wake of the hawkmoth, Manduca sexta” (Tytell, E.D., and Ellington, C.P.)
How difficult is it to estimate forces on the wings of a flying insect or bird by measuring the airflow in its wake? Difficult, but not impossible, according to our study modelling the wake of a flying hawkmoth, and maybe easier on smaller animals. One of the major difficulties in studying animal flight has been that the wings often move too fast to make any useful measurements of the air flow around them. This is a sizeable problem, because insects and some small birds take advantage of a wide array of ‘high lift’ mechanisms that may be useful for future generations of flying machines. Rather than trying to make the difficult measurements around actual moving wings, most researchers have tried to deduce the forces on the wings from the airflow in the wake. While theoretically possible, this type of measurement had a setback in the ‘80s, when two studies on birds measured too little force to keep the animals aloft. Our study examines the feasibility of these measurements by studying the flow behind a highly simplified physical model of a hawkmoth. The trouble, it turns out, is turbulence. Large animals, including all but the smallest birds, produce wakes with substantial turbulence that causes the wake to loose strength rapidly, making it very difficult to back-calculate the forces around the wings. This back-calculation is not impossible, just difficult; but it is probably not feasible in a real experimental setup. Most insects, though, are small enough that their wakes are laminar, with smooth and even flow, which makes the wake strength stay constant for a long time. Our study shows that it is feasible to examine insects’ high lift mechanisms by observing the airflow in the wake behind them because of their laminar wakes.
Cyberkelp: An integrative approach to the modeling of flexible organisms (M. Denny and B. Hale)
Biomechanical models come in a variety of forms: conceptual models, physical models, and mathematical models (both of the sort written down on paper and the sort carried out on computers). There are model structures (such as the muscles that power insect flight muscle the tendons of rats’ tails), model organisms (such as the moth, Manduca sexta), even model systems of organisms (such as the communities that live on wave-swept rocky shores). These different types of models are typically employed separately, but their value often can be enhanced if their insights are combined. In this brief report we explore a particular example of such integration among models, as applied to a flexible marine alga, the giant bull kelp Nereocystis leutkeana. Because of these seaweeds’ large size and wave-swept habitat, it is difficult to make measurements on them directly. But because of their economic and ecological importance, it would be advantageous to understand how they work. A conceptual model (a submerged buoyant ball tethered to the seafloor by a rubbery string) serves as a template for the construction of a mathematical model of this model species of kelp. The validity of this numerical model is then tested in the laboratory using small physical models. The validated mathematical model is then used in conjunction with a computer-controlled testing apparatus to simulate the forces that would be placed on a real, full-size kelp in the ocean. This combination of models (what we call “cyberkelp”) allows us to experiment with a species that would otherwise be beyond our abilities.
Tim Watson | alfa
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More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
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The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
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