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A multiscale strategy for the simulation of braided composites with ENVYO

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Abstract

Manufacturing processes and parameters have played a crucial role in the design and analysis of composite structures. To exploit potential advantages of composite materials, it is necessary to predict and optimize the manufacturing steps in respect to the optimization of the structure itself. During the past years, the project DigitPro (Digital Prototype) has been developed within the research campus ARENA2036. A multiscale simulation strategy is investigated to cover a full product generation cycle of textile composite components from structure pre-design up to part manufacturing. Start parameters are firstly identified for each step of the cycle. Subsequently, appropriate materials, geometries and manufacturing parameters are found during optimization loops. Finally, the result is sent into real manufacturing process. The mapping tool ENVYO stands as a connector between the various simulations and simulation softwares. Hence, ENVYO allows the transmission of information from one simulation to another. The presentation will focus on two key aspects of the simulation of textile composites. On the mesoscopic scale, detailed finite-element models of the textile laminate are generated, representing closely the complex yarn architecture. The mechanical properties of the laminate are numerically identified by simulating the models under tension, compression and shear loading. The transition to the structure simulation on macroscopic scale is performed via the tool ENVYO following two approaches. The first approach directly uses the material properties generated on the mesoscale for the structure simulation. In the second approach, information from the process simulation is mapped on the structure mesh to take into account the influence of local yarn architecture on the structural behaviour. Both methods will be compared to standard structure simulation and to experimental results. The developed methodology will be illustrated with the example of braided composites and the potential of the process chain will be discussed.
ARENA2036 DigitPro: Digital Prototype
A Multiscale Strategy for the Simulation of Braided Composites with ENVYO
17. Oktober 2018
LS-DYNA Forum 2018, Bamberg
Mathieu Vinot, Martin Holzapfel, Christian Liebold
DigitPro Digital Prototype
braided structures
Open-Reed-Weaving parts
-50% development time
min. -10% weight
closed, numerical process chain
from the presizing to the final product
simulation on the meso and macroscale
various simulation tools
HDF5 format
Draping simulation
DIGITALER
PROTOTYP
Structure analysis
Structure optimisation
Braiding robot
Braiding simulation
Virtual braid
mapping tool
ENVYO
Experimental investigation
stepwise failure
different yarn
strengths (material
variability)
linear behavior
tension and
compression loading
of axial yarns
structural integrity
loading of
braiding yarns
high reproduceability of braiding process
transfer of test condition in the simulation (impactor and support displacement, testing speed etc.)
Investigation of a braided reinforcement structure under quasistatic 3-point bending
complex structure geometry potential deffects due to manufacturing conditions
use as reference for the investigation of different modelling approaches
Displacement
Force
4
1 Standard approach
3. Structure simulation without tuning
Overprediction of structural strength
4. Changes of material parameters try-and-error
no predictive simulation, only a post-test simulation
5
Reference approach
1. Modelling with UD-plies
2. Calculation of yarns stiffness and strength
Use of material properties from datasheets
30°
-30°
-30°
30°
Principle of the approach
Analytical calculation according to Chamis „Mechanics of composite
materials: past, present, and future, NASA TM-100793, 1984”
Matrix
Fibre
FVC
Yarn
3. Structure simulation
6
Reference approach
1. Modelling with UD-plies
2. Calculation of yarns stiffness and strength
Use of material properties from datasheets
Principle of the approach
Advantages
universal“ approach (weave / UD...)
fast model generation
low computing time
Drawbacks
local effects are not considerated
fibre architecture is not reproduced
adjustment cycles necessary
overpredictive if not tuned
Analytical calculation according to Chamis „Mechanics of composite
materials: past, present, and future, NASA TM-100793, 1984”
30°
-30°
-30°
30°
7
2 Multiscale approach
8
Example of a 30°-triaxially braided laminate compaction simulation
Simulation on the mesoscale
Breite = 𝑓
1𝜃, 𝑑, 𝑘, η
Länge = 𝑓
2𝜃, 𝑑, 𝑘, η
Lücke = 𝑓
3𝜃, 𝑑, 𝑘, η
Braiding angle
Braiding core diameter
Size of yarn
FVC
CT-Scan
Parametric model of the dry textile
9
Simulation on the mesoscale
Example of a 30°-triaxially braided laminate tension simulation
Data for generation of a material card (E11, E22, S11, S22...)
Transverse failure [-] Unit cell number 2
10
Structure simulation of the reinforcement structure
automatic postprocessing of unit cell results with ENVYO
generation of material cards for the different textile types
Simulation on the mesoscale
Virtual material data
MAT_262_LAMINATED_FRACTURE_DAIMLER_CAMANHO
CONTACT_SURFACE_TO_SURFACE_TIEBREAK
MAT_187_SAMP-1
11
Predictive structure simulation of the reinforcement structure
Simulation on the mesoscale
Stiffness prediction
Strength prediction
Prediction of residual strength
delayed failure of axial yarns
Force
Displacement
Multiscale approach
12
Structure simulation of the reinforcement structure
Simulation on the mesoscale
Multiscale approach
Force
Displacement
Advantages
consideration of textile architecture
realistic textile behaviour in simulation
automatisation possible
predictive simulation, no tuning
Drawbacks
increased computing times
more complex model generation
13
3 Process chain approach
14
Braiding simulation
Process chain approach
Machine parameters
Number of bobbins
Fibre typ
Yarn pretension
Braiding Speed
Robot path
Simulation model
Manufacturing effects
Orientation
Ondulation
Dry spots
Gaps to core
Opt. machine parameters
Gaps in the braided textilte
Gap between yarn and
braiding core matrix-
rich zones
Digital Twin
Original textile architecture after braiding simulation
15
Braiding simulation
Process chain approach
Machine parameters
Number of bobbins
Fibre typ
Yarn pretension
Braiding Speed
Robot path
Simulation model
Manufacturing effects
Orientation
Ondulation
Dry spots
Gaps to core
Opt. machine parameters
Digital Twin
Upper movable mould
Lower fixed mould Braided textile with closed gaps
Closing of the gaps
Simulation
16
Information mapping to structure mesh
Process chain approach
Model from the braiding simulation
Mapping of:
Yarn orientations
Ondulation
Dry spots
Yarn geometry (width/thickness)
Resin
PID 1001
PID 1002
PID 1002
MID 1002
MID 1001
MID 24
MID 1002
MID 1001
MID 1002
MID 1002
neighbour element
t1
t1 < t2
17
Process chain approach
Structure simulation with mapped information
Stiffness prediction
Strength prediction
Prediction of residual strength
Prediction of yarn influence on local strain field
Tension-loaded axial yarns
(compression-loaded on the lower side)
Shear-loaded braiding yarns
Plastic deformation of the structural foam
Force
Displacement
18
Process chain approach
Structure simulation with mapped information
Stiffness prediction
Strength prediction
Prediction of residual strength
Prediction of yarn influence on local strain field
Force
Displacement
Advantages
consideration of textile architecture
realistic textile behaviour in simulation
automatisation possible
local strain field can be predicted
Drawbacks
increased computing times
more complex model generation
investigation of information mapping
with ENVYO is necessary
19
Conclusion
mapping tool as link between process simulations and structure simulations
transfer and simplification of information from the mesoscale to the macroscale
a sensitivity analysis have to be performed before starting the structure simulation
increase of prediction capabilities of structure simulation
Mesoscale
process simulation
reduction of experimental effort
increased structure quality
through optimisation loops
Macroscale
structure simulation
consideration of manufacturing
effects
relative low CPU time
Envyo
HDF5 format Displacement
Force
Mapping
Unit cell
Reference
20
Mathieu Vinot
mathieu.vinot@dlr.de
Questions & Discussion
Thank you very much for your attention
... In the recent past, a lot of effort has been made towards the closing of the simulation process chain for all different kinds of materials. Besides the regular transfer of resulting stress, strain, and history data, main focus from a material's perspective has been on the transfer of fiber orientations from process simulations for continuous fiber reinforced composites [1] together with various homogenization approaches for short fiber reinforced plastic materials [2]. ...
Conference Paper
Full-text available
In the recent past, a lot of effort has been made towards the closing of the simulation process chain for all different kinds of materials. Besides the regular transfer of resulting stress, strain, and history data, main focus from a material’s perspective has been on the transfer of fiber orientations from process simulations for continuous fiber reinforced composites [1] together with various homogenization approaches for short fiber reinforced plastic materials [2]. In the following, three new features of the mapping software envyo® [3] will be presented. The first one allows for the mapping of resulting temperature-time curves from a preliminary simulation using the software tool THESEUS-FE OVEN, which is used to simulate paint-drying processes. This process also effects the degree of hardening, e.g. of aluminum structures and therefore leads to locally varying material properties such as the yield stress, strengths etc. It will be explained how these parameter variations can now be considered with the proper mapping and homogenization approach. The second new feature allows for the identification of different parts and therefore material properties based on a portable graymap (*.pgm) format. Therefore, any arbitrary colored image can be translated into a grayscale representation given in the ascii based *.pgm format, using a third-party software such as GIMP. In the mapping input command file, the user can then define ranges between 0 and 255 which will be assigned to the various parts and therefore material properties. The applicability of the method will be investigated on a wood-forming use case [4]. Another new feature is the consideration of simulation results gained with the Finite Pointset Method (FPM) [5]. Based on a resulting HDF5® data container which stores the coordinates of the particles and their pressure results at specific simulation stages, load curves can be generated which will be used to calculate the component’s deformation with LS-DYNA®, making use of the *LOAD_SEGMENT keyword.
... The logical successor to DigitPro is the new Digitaler Fingerabdruck (DFA) research project in which the intelligent data collection, processing and transfer across the entire value creation chain -from the idea, through design, production and in-service to end-of-life -for the intelligent component and the versatile, autonomous factory of tomorrow [2] is to be realized. Whereas in DigitPro the focus was on closing the simulation process chain [3] for various fiber-based manufacturing processes such as braiding [4,5,6], infiltration [7], draping and Open Reed Weaving (ORW) [8] via various scales from the micro to the meso to the macroscopic scale, the focus of the research project DFA is now to collect data from production as well as sensor data from the life cycle of a component. These data can then be fed back into the simulation and thus enable conclusions to be drawn about an in-situ life cycle assessment, adaptation of the production environment and improvement of future components with similar requirements. ...
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