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Engineering & Simulation

Recent project: Composite delamination prediction for a front bumper beam
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  • Mitsui Chemicals and ARRK as part of the Mitsui Chemicals Group work together on the development, manufacture and elaboration of applications of these materials for the automotive industry.
  • With extensive knowledge on the starting materials and long experience in the product development process, the two companies pool their expertise for the optimum use of fibre-reinforced thermoplastics in vehicles and other parts. 


New modelling approach by ARRK Engineering for composite development

Accurate prediction of delamination in composite materials is a challenge and often limits the application of lightweight materials in safety relevant components, as it may reduce the available strength significantly. In order to correctly evaluate delamination of composites while retaining a good runtime performance, a new modeling approach in LS-DYNA® was studied by ARRK Engineering using a full thermoplastic front bumper beam as demonstrator to perform a virtual vehicle evaluation.
Using a new modeling approach from ARRK Engineering, a full-vehicle simulation with TAFNEX™ CF-PP UD from Mitsui Chemicals has shown robust delamination prediction capability while still retaining high run time performance. Thus, the approach can be adopted in full-vehicle crash in order to evaluate composite delamination.
Modeling approach from ARRK Engineering:
Model Approach3

Engineering & Simulation - Element Level

Material Calibration of TAFNEX™ CF-PP UD

Engineering & Simulation - Element Level

ARRK Engineering: Material calibration

  • Series of tests with 11 different load applications to characterized TAFNEX™ CF-PP UD
  • Two digital material cards were created (for in-plane and out-of-plane properties)
  • Material card can be used to predict damage, failure and delamination in static and dynamic simulations.
 
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Engineering & Simulation - Component Level

Front Bumper Beam Production

Part Production Value Chain:
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Engineering & Simulation - Component Level

1. Production of UD tape sheets based on multi-axial patches

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Engineering & Simulation - Component Level

2. Thermoforming and overmolding of UD tape sheet

The FiberForm process developed by KraussMaffei combines the thermoforming of organo sheets and injection molding into one process.
Component and System Evaluation
Engineering & Simulation - Component Level

ARRK Engineering: Validation of material model 

  • Testing of component and virtual evaluation
  • The bumper beam was used for component validation
  • Dynamic and quasi-static 3-point bending was investigated
  • Results from simulation and test correlate well, showing a high prognostic property of the material car
  • Good correlation of load levels and failure mechanism
Physical failure mechanism:
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Simulated failure mechanism:
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Comparision of physical and virtual displacement results:
Delamination
Engineering & Simulation - System Level

ARRK Engineering: Full vehicle evaluation

The bumper beam was evaluated virtually in a full vehicle setup according to FMVSS-US Part 581 regulation, showing insufficient energy absorption, resulting in significant damage of the cooler.
A reduced spring model was created in order to evaluate the energy absorption target derived from full vehicle simulation in a simplified and fast to run simulation model.
Full vehicle model:
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Strain Simulation result:
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Full Vehicle Simulation:
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Engineering & Simulation - Component Level
ARRK Engineering: Component optimization
Based on the energy target from full vehicle simulation a parametric study was performed in order to clarify the correlation between stiffness and absorbed energy. The results of this study are used to define a stiffness target and a lay-up to achieve this.
Parametic study to define stiffness target for required energy absorption
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Lay-up change to achieve stiffness target:
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Based on these results a new bumper prototype with optimized lay-up was manufactured
Physical Testing
Engineering & Simulation - Component Level
ARRK Engineering: Component reevaluation for improved Lay-up
  • A new batch of bumper beams with improved lay-up was produced and tested.
  • Load level and stiffness were improved according to prediction.
Deflection of the bumper beam after lay-up change:
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Force/Deflection curve of physical results and simulation results:
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Reevaluation on Virtual Vehicle and Final Results

Engineering & Simulation - System Level

ARRK Engineering: Reevaluation on virtual vehicle and final result 

The optimised lay-up was re-evaluated in full vehicle model. Contact force and absorbed energy were doubled with less failure occuring and a major decrease in intrusion. Further improvements can easily be achieved by adjusting the design. By using CAE to evaluate material performance early in the development, unnecessary but costly tooling, prototyping and testing can be reduced.
Virtual vehicle results after lay-up change:
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Displacement before and after lay-up change:
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Final result: Comparison of original lay-up and newlay-up:
Finalresult-Comparision-Layup
The new stacked shell modeling approach from ARRK Engineering has shown promising results at coupon and component level. At the full-vehicle simulation scale, the new modeling approach has presented robust delamination prediction capability while still retaining high run time performance. Thus, the approach can be adopted in full-vehicle crash in order to evaluate composite delamination.
Mitsui Chemicals and ARRK Engineering are looking forward to new opportunities and component evaluation using TAFNEX™ CF-PP UD.

Other webspecial sites:

New Material Studies
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Newest investigation of material properties

From Tape to Sheet

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Tape based sheet opportunities

Local Tape Placement

Bumper
Use cases of using TAFNEX™ as local reinforcement

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