Hydraulics aid load bearing capacity of ultra lightweight structures
23 April 2012
Researchers from the University of Stuttgart, along with hydraulics experts from Bosch Rexroth, have come much closer to the goal of achieving maximum load carrying capacity in structures with minimal use of materials. They have constructed a wooden shell - just 40mm thick - spanning a surface of over 100 square metres, which is able to withstand adverse loads, thanks to active manipulation of the structure using hydraulic rams.
The shell structure at the University of Stuttgart campus
Structures are normally designed with a high load margin, but these loads generally only occur very rarely and then only for a short period. The ultra lightweight structure developed at the University of Stuttgart is able to achieve significant savings in the quantity and weight of building materials without compromising its tolerance of momentary high dynamic loads through active manipulation of the structure.
In the case of the Stuttgart wooden shell this manipulation is achieved by hydraulic rams connected to three of the four shell support points. These generate specific movements that compensate for deformations and material stresses caused by wind, snow and other loads.
This is the first time that an adaptive structure has been achieved on this scale, say the researchers. While the shell is supported at four points, three of these points can be moved independently and freely positioned in space, with sensors recording the loads at numerous points over the structure.
The load balancing is achieved by a Rexroth control system, specially developed for the project, which is able to react to changes in the structural loading within milliseconds.
The researchers developed simulation models to predict the behaviour of the structure, and the stresses within it, under different types of load, both static and dynamic. These simulation models will serve as a basis for the development of control algorithms for the compensating hydraulic actuation.
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