1. 3D-Light-Trans Project
Material Definition and Characterization

2. Simulation software and material model
Software  PamFORM (ESI Group) can simulate pressure forming, vacuum forming, and mechanical thermoforming with tools
Numerical method  Finite Elements with explicit time integrations
Composite material  each ply is represented by thin shell elements (combination of elastic fibres with a thermo-visco-elastic matrix); 1 up to 100 plies can be simulated
Calibration of material, in order to find the optimal parameters for simulation
Material model:

3. Material simulation parameters
Density [kg/m3]: single ply.
Thickness [m]: single ply.
Young’s modulus E1 and E2 [MPa]: constant or a function of strain, via Tensile test (ASTM D412) and Compression test (ASTM D575).
Intra-ply shear modulus G and G lock [MPa]: specified either as a constant value or function of shear strain, or two values to represent the modulus before and after tow contact, it is determined via Bias-extension or Picture frame test.
Locking angle a lock [°]: fiber angle at which the out-of-plane buckling initiates, it is measured by identifying the first out-of-plane displacement during Bias-extension test.
Matrix model viscosity - either constant or a function of rate, shear strain and temperature (e.g. power law, Cross equation).
Ply/tool and ply/ply friction - constant or function of rate, temperature and applied pressure.
Ply bending stiffness [MPa]: measured according to ASTM 1388.
Bending factor Fb: the software assumes uniform distribution of fibres through the thickness of a ply. This will over-estimate the out-of-plane bending stiffness of a fabric and Fb can compensate for this.
Ply/tool and ply/ply heat transfer coefficients (Thermal conductivity [W/m.K]): constant or function of temperature if non-isothermal simulation is required. 3

4. Example material chart (1)
In verde alcune cosa aggiunte da me, sulla base di info da altro materiale.
Ho aggiunto G lock (shear modulus after locking): non è da misurare anche questo per la completa determinazione dello shear behaviour? 4

5. Example material chart (2)5

6. Simulation Case - Setup
Process Parameter
Thermoforming type: vacuum, pressure or mechanical
Temperature history: pre-heat temperature, punch temperature
Pressure or vacuum value
Punch displacement, forming velocity
Blank holder design and pressure …
Fibres orientation in a ply
Material Parameters
Boundary conditions
Contacts
General Parameters (mass scaling, control, …) 6

7. Simulation Case - Model
punch
Thermoforming Simulation
die
composite (4 plies) 7

8. Simulation Case - Calculation8

9. Example – Material definition
Ply1 Fiber Direction & Thickness
Ply1 Material
Ply1 properties
Objects 9

10. Simulation Results- Thinning
Ply1
Ply2
Ply1
Ply3
Ply2
Ply4 10

11. Simulation Results- Fiber Orientation
Shear Angle
Fiber Orientation 11

12. Simulation Results- Major Stress and Ocntact Pressure
Major Stress (Upper fiber)
Normal Contact Pressure 12

13. Material simulation parameters
Density [kg/m3]: single ply.
Thickness [m]: single ply.
Young’s modulus E1 and E2 [MPa]: constant or a function of strain, via Tensile test (ASTM D412) and Compression test (ASTM D575).
Intra-ply shear modulus G and G lock [MPa]: specified either as a constant value or function of shear strain, or two values to represent the modulus before and after tow contact, it is determined via Bias-extension or Picture frame test.
Locking angle a lock [°]: fiber angle at which the out-of-plane buckling initiates, it is measured by identifying the first out-of-plane displacement during Bias-extension test.
Matrix model viscosity - either constant or a function of rate, shear strain and temperature (e.g. power law, Cross equation).
Ply/tool and ply/ply friction - constant or function of rate, temperature and applied pressure.
Ply bending stiffness [MPa]: measured according to ASTM 1388.
Bending factor Fb: the software assumes uniform distribution of fibres through the thickness of a ply. This will over-estimate the out-of-plane bending stiffness of a fabric and Fb can compensate for this.
Ply/tool and ply/ply heat transfer coefficients (Thermal conductivity [W/m.K]): constant or function of temperature if non-isothermal simulation is required. 13

14. Experimental tests – In-Plane (intra-ply) Shear
Bias extension (aspect ratio = length/width ≥ 2):
very good to determine a lock
2) Picture-frame shear test: Load vs. Dispacement  Shear Force vs. Shear Angle 
 G, a lock, G lock
Le immagini le ho prese dla documento che comincia con “PAM-FORM simulates the entire forming process, making possible…”: ho solo il cartaceo, non è che, per caso, Marco, hai il .doc o .pdf? La qualità delle figure aumenterebbe notevolmente… Grazie 
Thermoset prepregs testes at room T
Thermoplastics tested at elevated T (environmental chamber), at different T and strain rates 14

15. Experimental tests – Ply/Tool Friciton
Friction for composites  Dependencies on Rate, Temperature, Pressure
IDEM come la precedente 15

16. Experimental tests - Summary
Notes
Evaluation
Ply Density measure
Leitat can perform the test OK
Ply Thickness measure
Tensile test (ASTM D412)  fibre moduli
This test is equated to ISO 37 which is for vulcanized rubber and elastomeric thermoplastic. We propose to continue with our proposed normative ISO 527
Compression test (ASTM D575)  fibre moduli
This test is designed for rubber
Picture frame or Biaxial tensile tests at 190, 205, 220 °C and 50, 300, 1000 mm/min  intra ply viscosity, in-plane shear modulus, a lock
Leitat can carry them out under ISO 527 at 50 and 100 mm/min. Temperatures we can work at temperatures up to 100ºC.
To be conducted at process T
Self-weight bend test (ASTM 1388)  bending stiffness
Leitat can equate this to ISO 178 which is the one we proposed
Pull-out Test at 180, 200, 220 °C and 0.5, 0.8, 1.2 mm/s (normal pressure between 80 kPa and 2.5 MPa)  ply/tool friction
Leitat cannot carry out this test
Data from ESI
Viscosity test (power law or cross equation)
Leitat can measure viscosity by Ubbeholde viscosimeter, and ashes measurement
Test Method for Thermal Conductivity  ply/tool heat transfer coefficients
Leitat can carry out this test, although it requires more time to do so.
Nel documento che comincia con “PAM-FORM simulates the entire forming process, making possible…”, c’è un riferimento alla ASTM 5035 per i tensile tests on dry fabrics to derive the stiffness characteristics in the warp and weft directions (immagino per ricavare E1 e E2 della slide 5) 16