3D-Light-Trans Project Material Definition and Characterization

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:

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

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

Example material chart (2) 5

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

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

Simulation Case - Calculation 8

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

Simulation Results- Thinning Ply1 Ply2 Ply1 Ply3 Ply2 Ply4 10

Simulation Results- Fiber Orientation Shear Angle Fiber Orientation 11

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

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

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

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

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