TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF NAVARRA

1
Surface Fitting Approach For Tensile Membranes
Design
Javier Sánchez Miguel A. Serna Paz
Morer
IASS 2004. Montpellier, 20-24 September
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
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University of Navarra
Main Campus Pamplona (Navarra)
San Sebastián. TECNUN
Barcelona. IESE. MBA
Madrid. IESE. MBA
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
2/19
3

• overview
• applied research project at mechanical civil
  engineering department
• a new approach to tensile membrane design is
  given
• to generate and modify shapes in real time
• end users designers, covering the first stages
  of design process
• hybrid method combines structural (formfinding)
  geometry (surface fitting)

• contents
• Design process
• Existing Software tools
• Proposed method
• (formfinding-surface fitting)
• Examples, results
• Conclusion

Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
3/19
4
Tensile membrane design process

Architects, designers
Construction, elevation
Membrane cutting manufacturing
Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
Detailing
Engineers (Computer based tools)
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
4/19
5

• Cad attributes
• Parametric
• Featured based
• Flexible
• Easy to modify
• Customer-supplier
• Formats

Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
5/19
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Membrane Design tools specifications,
requirements

• ask the end user (designer) for the tool
  (requirements)
• easy to use
• easy to generate and modify
• shapes
• real time shapes regeneranation
• not many tech parameters
• model tree (objet based)
• Combine objets (buildings,
• membranes)
• integrated tool (exp-import)
• acad,3DStudio,Rhino
• formfinding
• flexible

Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
6/19
7
Proposed approach combines structural(formfinding)
geometry (surface fitting)
Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
7/19
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analysis tools accurate models
required Specialised users, structural knowledge
required Example 172 nodes, 314 elements
Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
design tools not so accurate models
required Easy and fast way to generate shapes, no
experts required example38 nodes, 62 elements,
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
8/19
9
Form Finding theory traditional methods
Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
9/19
10
Form Finding-computer time
Computational time has decreased, a few years ago
it was not possible to think in real time tools
Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
Computational times for different grid sizes and
formfinding methods
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
10/19
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Geometry. Nurbs Curve and Surface fitting
NonUniform Rational B-Splines, NURBS  Advanced
Surface Representation and Construction Nurbs
Curve and Surface Fitting Interpolation,
approximation theory
Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
Curve and surface construction parameters and
terms Control nets, basis functions, control
polygon, knot vectors, range, open, periodic,
uniform, parameterization, degree, knot insertion
removal, order, tangent twist vectors,
continuity, weight factors
Application for testing algorithms
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
11/19
12
Rectangular nets

• N. of sides
• Grid size x-y
• Warp-Weft angles
• Mesh points
• Internal pressure
• Edges forces
• External nodal force
• External dist. Force
• Formfinding method
• Mouse control
• (rotate,translate,scale)
• Real time regeneration
• Surface parameters

Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
Application for testing algorithms
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
12/19
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Radial nets

• N. of sides
• Grid size radial-merid
• Diameter
• Mesh points
• Internal pressure
• Edges forces
• External nodal force
• External dist. Force
• Formfinding method
• Mouse control
• (rotate,translate,scale)
• Real time regeneration
• Surface parameters

Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
13/19
14
some examples
load Sequence, using the same boundary conditions
Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
modifying position of a vertex
distributed force applied - value changed
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
14/19
15
Example 3 edges membrane. 33 nodes. (2111)
Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
15/19
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Example 7 edges membrane. 39 nodes (1821)
Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
16/19
17
Example 12 edges membrane.75 nodes (3243)
Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
17/19
18
conclusions

• New design approach for tensile membrane design
• Fast method. Real-time interaction user-shape
• The user can fell the shape
• More applications. Freeform modelling
• Material behauviour modelling
• Integrate the method in commercial tools as
  plug-ins (Autocad, Rhino)
• More Designers will try to generate these shapes
  as it becomes easier

Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
18/19
19
Surface Fitting Approach For Tensile Membranes
Design. Javier Sánchez. Montpellier. IASS 2004
TECNOLOGICAL CAMPUS OF THE UNIVERSITY OF
NAVARRA School of Engineering. San Sebastián.
Spain www.tecnun.es/labcad/membranes
19/19