Monday 15 February 2016

A load of old balls

Looking at the development of double curve geometries in building materials I was drawn to the design of sports balls and in particular footballs to see where developments in this area can inform building structures and architecture, as a source of inspiration and reference.  Materials, geometries and fabrication processes have developed to enable the products to be accurately made and perform under specific structural loads and performance criteria.

Relating to the Building Industry
From a building point of view, the sheets of material which make up the ball's outer skin might equate to prefabricated building panels and some key difficulties remain in creating double curved panels which are:
  • Achieving the optimal size of the panels or components within the restrictions of manufacturing, logistical and site handling constraints,
  • Details of the junctions between panels including accuracy of fit and position, especially where multiple panels meet at corners, or where junctions are required to meet accurately along complexed curved edges,
  • Sheets can often curve in one direction but curves in two directions without the special preparation or a mould is often difficult, 
  • Being able to achieve the desired design with a controlled set of geometries.  Creating multiple double curve moulds adds significant cost to a project.
Curved building materials and issues of logistics,
accuracy of fit, weather tightness and prefabrication

Football Ball Design
The evolution of the design of the football has addressed some of these issues and offers parallels.  Looking at how the product has been optimised over time suggests a few tricks which might work for the structural envelopes of buildings.  For example:

c.1937 Football design 
Traditional football consists of:
  • 18 panels,
  • 32 three-panel junctions,
  • 48 linear seams
Use of linear strips of materials to make larger double curved panels.  Strips bend in one direction, with the seamed panels creating the curve in the second direction.  Six of the larger panel arrangements work like a rounded cube - set around an x, y, z, (three) axis arrangement.

1963 Adidas Santiago World Cup Ball

1963 Santiago Ball consists of:
  • 18 panels, of which 6 are octagons and 12 are symmetrical polygons,
  • 40 three-panel junctions,
  • 58 linear seams
Arranged with a greater understanding of spherical geometries but still based around an x, y, z (three) axis arrangement.

1970 Adidas Telstar World Cup Ball

1970 Adidas Telstar Ball consists of:
  • 32 panels, 20 of which are hexagons and 12 are pentagons, 
  • 58 three-panel junctions
  • 90 equal linear straight seams
Based on the truncated icosahedron, one of the Archimedean polyhedra, also known as the Bucky ball or carbon 60 atom.  Probably the first ball design which adopts more complex three dimensional geometric design.  The pentagons align with six axis rather than three as used before.  The quantities of panels, seams and junctions make it relatively more complicated than the others.

2006 Adidas Teamgeist World Cup ball

2006 Adidas Teamgeist World Cup ball consists of:
  • 18 panels of two types (6 of one and 8 of the second),
  • 20 three-panel junctions,
  • 36 seams, of which 24 are curved and 12 are straight.
The Telstar design has probably become the most common football ball design and has experienced a long design life, but more contemporary designs have investigated how the ball and its performance can be optimised with fewer components and junctions.  The Teamgeist  ball demonstrates this.  It also returns to a three-axis geometrical arrangement.

2010 Adidas Jabulani World Cup Ball

2010 Adidas Jabulani World Cup ball consists of:
  • 8 panels of two types (4 of each type).  
  • 12 three-panel junctions,
  • 18 linear seams of which 12 are long and curved, 6 are short and straight. 
These panels are pre-moulded in to a double curved shape to assist precision of build and performance.  The ball's performance is assisted with an additional intermediate lining between the outer skin and the bladder.  There are less panels and junctions than the Telstar ball, and it is based around a four-axis geometry.

2013 Nike Ordem Premiership Ball
2013 Nike Ordem is based on a dodecahedron and consists of:
  • 12 equal panels, each fabricated in to six sections which adapt to take on a double curved shape,
  • 20 three-panel junctions,
  • 30 straight linear seams.
A relatively simple design based on the dodecahedron.  The pentangle panels are articulated to create an effective double curve.  It might be seen as a simplified and optimised take on the Telstar ball design.  As with the Telstar ball the pentagons align a six-axis geometric arrangement.

2014 Adidas Brazuca World Cup Ball
2014 Adidas Brazuca World Cup ball design consists of:
  • 6 equal cruciform panels,
  • 8 three-panel junctions
  • 12 curved linear seams
The cruciform panels are effective for curving down the long arms with the pressure of the bladder creating the second curve across their width.  The curved pattern of the seams meeting around a spherical geometry presents an assembly tolerance / accuracy of fit issue which looks dynamic but might prove difficult to achieve with building materials.  This ball returns to a three-axis geometric arrangement.

It doesn't always look the same when it comes through the post.
Junction alignment of panels around a double curve geometry.

A Load of Old Balls

A Load of Old Balls Simon Inglis

Simon Inglis's book A Load of Old Balls (2005) examines the development of the ball in British sports up to the twenty-first century and reveals much relevant information in relation to the development of materials, manufacturing processes, geometrical development and performance reliability.

On materials, it charts the greatest advances with the development of synthetic and composite materials to replace natural materials and animal parts.  It describes how material technologies from different industrial sectors were investigated to meet the requirements of the developing sports industries.  Mass production and standardisation allowed developments in ball design to progress with greater accuracy of manufacture and performance precision.  Even the 'crack' of the golf ball when hit by the driver is explained as a carefully engineered acoustic property.

Other Designs and Experiments
Haresh Lalvani's soccer ball

More recently Haresh Lalvani, Professor of Architecture at the Pratt Institute, has been experimenting with tessellating polygons which combine to create three dimensional spheres or ellipsoids.  His work is available to see at the Patents site.

Using intersecting cylinders set out around the axis of different platonic solids (cube 3-cylinders, tetrahedron 4-cylinders and dodecahedron 6-cylinders) allows surfaces to come close to double curve geometries, using single curve planes.

The cockpit roof lights for the Central Module at Halley VI
designed with the idea of intersecting cylinders
as an economy over double-curved glass

Examples in Buildings

Examples of double curved geometries in building materials are mostly seen with timber, concrete, glass, perspex, metal and FRP:

Achieving double curved geometries with building materials

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