TPMS 3d Printed Tokens Compression Tests Discussion

For this first part of the research 3D printed Samples of TPMS Geometries designed, produced are tested.

The Triply Periodic Minimal Surfaces (TPMS) are modeled by meshing an interpolation of points distributed according to the equation aproximation of Gyroid and P-Schwartz surfaces within a specified domain of 0 to x Pi, for which Sawapan´s Millipede Component in Grasshopper is used.

DENSITY COMPARISON GRAPH

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Experimentation consists of:

  1. Compression tests and print tests to set base parameters: Volume, Scale of reliable and consistent prints.
  2. Compression tests to review differences of performance between Materials and to assess differences between simulation performance and phyiscal performance.
  3. Compression tests to assess differences between base tokens and algorithmically optimized tokens.
  4. Compression tests of bespoke matrices based on TPMS for optimal deformation and compression performance.

GYROID BASED TOKEN PERFORMANCE GRAPHS

Gyroid Based Token      >>     Algorithmically Optimized      >>     With Free Domain

GYROID BASED GRAPHS

Future work:

In order to advance the viability of 3d printing in architecture further research will compare printability and performance of large scale robotically augmented 3d printed fibrous structures.


Initial Tests: Scale and thickness print quality reliability: choosing the appropiate material, geometry, period and print thickness. 
  • C1: PLA 0.6 mm for a continuos well fused print. Deformation by collapse show clear “camel back” behaviour, corresponding with each of the layers, although a good tension distribution is initially achieved, these collapse deformations are to be held into account for a correct application to large scale architectural components.
    • Best Performance before first layer collapse: 3960 N
    • Deformation at N: 2.99 mm
    • Best Performance before collapse: 4233 N
  • C1_Gráfico.xls - 0001729.jpg
    C1 PLA Token Test: Compression – Displacement
  • T1- T5:  TENAX 1.0mm wall thickness tokens show the most succesful compression results.
    T1-T5_Foto_Recepción
    initial samples – gyroid 3d print – 6pi – 6cm2 with variable hieght

    t1-t5 graph
    T1 – T6 TENAX Token Test: Compression – Deformation
  • T6- T7:  TENAX 0.4 mm wall thickness tokens show the minimum wall thickness for a succesful layer by layer print with a 0.4 mm diamater nozzle at 60 mm/s print speed.
    • Best Performance before first layer collapse: 3960 N,
    • Deformation at N: 2.99 mm
    • Best Performance before collapse: 4233 N

The definition of a standard case of 6cm3 size and 3pi period is chosen for next tests


1st Set of Tests: Plastic Comparison on BASE Period GEOMETRIES 

Tokens with the same volume and density (as per virtual model) are modeled. The model is then deformated through a process of iteration deformation simulation for optimization.

Volume and Domain of 3pi are fixed constraints and no Deformations are produced.

Contours Standard Gyroid Token along Z axis
P1080159.jpg
Gyroid and P-Schwartz PLA Token Production in WASP 3d Printer
  • Test 1: 1G1-1G2: TENAX P-Schwartz Base Piece
    • Best Performance before first layer collapse: 2150 N,
    • Deformation at N: 3.69 mm
    • Best Performance before collapse: 1G1:2153 N, 1G2: 4739 N
G1-G2 graph.jpg
TENAX P-Schwartz Base Token Test: Compression – Deformation
  • Test 2: 2P1-2P2:  TENAX Gyroid Base Piece
    • Best Performance before first layer collapse: 4750 N
    • Deformation at N: 4.54 mm
    • Best Performance before collapse: 4750 N
2P1-P2 graph.jpg
TENAX Gyroid Base Token Test: Compression – Displacement
  • Test 3: 3B1-3B3: PLA Gyroid Base Piece
    • Best Performance before first layer collapse: 2550 N
    • Deformation at N: 4.05 mm
    • Best Performance before collapse: 3034 N
B1- B3 graph.jpg
PLA Gyroid Base Token Test: Compression – Deformation
  • Test 4: 4P1-4P3: PLA P-Schwartz Base Piece
    • Best Performance before first layer collapse: 1220 N
    • Deformation at N: 2.68 mm
    • Best Performance before collapse: 1380 N
4P1-P3 graph.jpg
PLA P-Schwartz Base Token Test: Compression – Deformation

The presence of “camel back” humps in the graphics indicate the collapse of a level corresponding to  a period. This is particularly clear among the 3Pi pieces which present three clear humps.

After the collapse of the three levels in these base cases, the piece is compacted and starts to behave more like a solid.


2nd Set of Tests: PLA Optimized Tokens with Fixed Domain.

Gyroids, as per better performance for equal material distribution compared to P- Schwartz tokens are chosen for optimization studies.

Tokens with the same volume and density (as per virtual model) are modeled. The model is then deformated through a process of iteration deformation simulation for optimization.

Volume and 3 Pi Period Domain are fixed constraints.

Contours Optimized (Fixed Period) Gyroid Tokens along Z axis
(FIX DOMAIN 3 Pi TRANFORMATIONS ON BASE GEOMETRY BASED ON COMPRESSION SIMULATION)
P1080285.jpg
Optimized Gyroid PLA Token Production in WASP 3d Printer

This first optimization process only varies the distribution of material within the 3Pi constrain.

  • Test 5: 501-506:
    • Best Performance before first layer collapse: 4294 N
    • Deformation at N: 3.16 mm
    • Best Performance before collapse: 4294 N
501-506 graph.jpg
501- 506 Gyroid Optimized Token Test: Compression – Deformation

3nd Set of Tests: Optimized Tokens with Non-Fixed Domain.

Tokens with the same volume and density (as per virtual model) are modeled. The model is then deformated through a process of iteration deformation simulation for optimization.

Total wall volume is fixed and Period of set variable. Immedeatly the algorithm searches for a more complex material distribution that reduces the span of cells by reducing wall thickness to 0.4 mm and producing a noticeable differentiation between core and perimeter.

ContoursOptimized Gyroid Tokens along Z axis
(VARIABLE PERIOD TRANFORMATIONS ON BASE GEOMETRY BASED ON COMPRESSION SIMULATION)
P1080839.jpg
Gryoid_opt_0-5PI_6cm3_highres_0.4mm
:: IMAGEN DE PROCESO DE OPTIMIZACION ::
  • Test 6: A1-A2:
    • Best Performance: 10071 N
    • Deformation at N: 29.01 mm
6a1 - 6a2 graph.jpg
A1-A2 Gyroid Optimized Token Test: Compression – Deformation
  • Test 7: B1-B2:
    • Best Performance: 5941 N,
    • Deformation at N: 36.80 mm
7B1 - 7B2 graph.jpg
B1-B2 Gyroid Optimized Token Test: Compression – Deformation

Tokens present an Energy Absortion similar to that of Foams and commencte to behaves solids as it is continuosly compacted by deformation. Here a link to MIT open course by Prof. Lorna Gibson: Energy Absorption Notes on Celular Solids Structure Properties and Applications.

Screenshot 2018-04-19 23.22.33
Gibson, L. J., and M. F. Ashby. Cellular Solids: Structure and Properties
  • Foams — roughly isotropic — can absorb energy from any direction – light and cheap
  • Capacity to undergo large deformation at constant σ
  • Absorb large energies with little increase in peak stress


While the number of tests conducted is not enough to be statistically conclusive, the preliminary results suggest nevertheless that optimization of specimens through the proposed workflow can lead to improved structural behaviour compared to the initial non-optimized specimens.

Both experimental and simulation results demonstrate the benefit of material redistribution by optimization as seen in the improved peformance of 501-506, A1, A2 and B1, B2.

Similarly the combined benefits of domain optimization in A1, A1 and B1,B2 eliminte the problem of hump like deformation behaviour and shows potential in the design of Additevely Manufactured spongy lattices which their solid like behaviour is triggered as deformed. A designed anisotropy shows great potential in the performance improvement of fibrous components by introducing controlled complex deformation behaviours.


  • Tests have been produced in the Universal Test Machine INSTRON Type, which possess a highly sensitive system for measuering load, with a load cell whose calibration and force measurement tolerance is less than 1% and whose full scale is 100 kN (10T).
  • Tokens printed with WASP 20-40 Turbo 3d Printer
  • With 1.75 black TreeD PLA filament
  • Slic3r software with settings at 190 ºC and max print speed of 100 mm/s
  • Surface Modeled in Rhino, through Millipede Component, calculated with Karamba shell FEM analysis and iterated for optimization with Galapagos, full workflow file available for download.
  • More information for TPMS surface modeling approximation method here. Another interesting and very useful approach using Kangaroo here.
3D Print GIF-source
Tokens 3d Printed with Wasp 20-60 Turbo
TPMS layer optimized.gif
Slic3r Ouptu for 3D Printer – Token A1 Optimized Material Distribution

Download Full Set of Compression Tests Data . Click on Test Headers for additional information

Special thanks to:

Rafael Claramunt, Asocciate Professor in Mechanical Engineering Department at the Univesidad Politecnica de Madrid.

Marta Muñoz Sánchez, Laboratory Technician at the Material Resistance Laboratory at the Univesidad Politecnica de Madrid.

http://rm.mecaest.etsii.upm.es/

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