Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing

A systematic way to vary the power-law scaling relations between loading parameters and volume of material aids the hierarchical design process.

Mechanics Research Communications 46, 41 (2012)

D. Rayneau-Kirkhope, Y. Mao, R. Farr, J. Segal

Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing
Hierarchical space frames for high mechanical efficiency: Fabrication and mechanical testing

It has been demonstrated theoretically that under certain loading conditions hierarchical structures hold a distinct advantage in efficiency over more conventional designs. Here a particular hierarchical design is studied, and we show that the power-law scaling relations between loading parameters and volume of material required to make a stable structure can be varied systematically. Through computer simulation, we construct mechanism diagrams depicting likely failure modes for a given geometry, which give insight into the optimisation. Using rapid prototyping technologies, the same structure is fabricated and mechanical testing undertaken; the results are compared to theoretical and finite element models.

More in Fractal structures

  • Physics World

    Towers of strength

    The Eiffel tower is now a longstanding example of hierarchical design due to its non-trivial internal structure spanning many length scales.

  • Physical Review E

    Structural imperfections

    Fractal structures need very little mass to support a load; but for current designs, this makes them vulnerable to manufacturing errors.

  • Physical Review E

    Hierarchical structures

    The most efficient load-bearing fractals are designed as big structures under gentle loads ... a situation common in aerospace applications.

  • Physical Review Letters

    Ultralight fractal structures

    The transition from solid to hollow beams changes the scaling of stability versus loading analogously to increasing the hierarchical order by one.