Simplified adhesive modeling of joint lightweight structures by use of meta models. Prof. Dr.-Ing. Sandro Wartzack

Transcription

1 Simplified adhesive modeling of joint lightweight structures by use of meta models

2 Outline Introduction: Problem statement and goals Experimental characterisation Detailed simulation and setup of meta models Validation: Lateral crash 2

3 Adhesively joint hybrid structures Lightweight vehicle door Setting: Lightweight vehicle door Aluminium outer skin Inner CFRP door module Adhesively bonded by polyurethane adhesive CFRP Door Module Detailed simulation of adhesive joint is complex and expensive Adhesive Goal: Creating a simulation workflow that allows high-quality results in an efficient and easy method Source: Brose Aluminium Skin 3

4 Research Project REAL4HYBRID Overview Setup of a parametric simulation model Creation of DOE and experimental setup Partners: Virtual Characterisation Experimental Characterisation Calibration of simulation model Calculation of meta model Simplified Simulation Method 4

5 Chair of Engineering Design Research Group Lightweight Design Lightweight Design Simulation Driven Design Material Characterisation Structural Optimization Design of fibre reinforced plastics at the early embodiment design stage Determination of material parameters relevant for design Integration of structural optimization methods in the design process 5

6 Lightweight Design Material Characterisation High speed testing machine Zwick HTM5020 Temperature chamber Temperatures between -60 and 150 C Source: Zwick GOM Aramis optical measurement High speed tensile and impact tests (0,001 up to 20 m/s) Source: GOM Filming of tests with up to fps and optical strain measurement 6

7 Name C. Witzgall Chair of Engineering Design Optical Strain Measurement High-Speed Cameras Recording up to fps Stereoscopic Alignment 0,01% - 100% strain resolution Digital Image Correlation Strain calculation by relative movement of specle area Identification of necking and thickness reduction Example Tensile test of fibre reinforced plastic, 5 m/s; 15 fibre orientation fps recording, strain-overlay LEHRSTUHL FÜR KONSTRUKTIONSTECHNIK 7

8 Experimental characterisation of adhesive joints F Adapter Testing conditions: Temperatures from -30 to +80 C Variable testing velocities Variable stress states of normal and shear stress within the joint Different CFRP stackups F T F N Specimen Carrier Specimen Aims: Investigation of different failure modes Investigation of failure strength 8

9 Test results Failure modes adhesive failure on aluminium surface cohesive failure delamination of CFRP mixed modes cohesive failure delamination 9

10 In-Detail Simulation of Testing Virtual Characterisation: Detailed Modelling of the testing conditions: Parametric simulation model Solid mesh of the adhesive Cohesive Zone Method Solid, Layer-wise mesh of the CFRP stackup Calibration of the detailed simulation model on the experimental results Sampling of simulation results to serve as a data basis for meta models Further use of meta models: Instead of detailed modelling the adhesive, contact elements access the database of the meta models Contact state and stiffness are calculated within the meta model 10

11 Dynardos MOP/CoP Workflow 11

12 Use of the meta model Meta modelling: Mathematical representation of the detailed simulation model s results: Maximum displacement Maximum force Identification of dominant parameters: Velocity Load angle Temperature Coefficient of Prognosis of 99%(force) bzw. 90% (displacement) suitable to substitute the detailed simulation model Response Surface of maximum displacement over loading speed and angle dots: simulation results 12

13 Validation Lateral crash test of a vehicle door Lateral impact on lightweight vehicle door Component test rig, representing compliance of the vehicle body Test setup according to EuroNCAP Impact velocity 30 km/h Comparison of simulation and experiment: Failure of adhesive joint Intrusion of pole: 265 mm (experiment) vs. 262,8 mm (simulation) Source: Brose Experiment Simulation Source: Brose 13

14 Summary Experimental characterisation Testing of adhesive joints at different testing velocites, temperatures and different stress states within the joint Discovering several different failure modes Detailed simulation Parametric simulation of the characterisation experiments calibrated on the test results Repeated sampling to build meta models F T F F N Adapter Specimen Carrier Specimen Validation Lateral crash test of vehicle door Good correlation of experiment and simulation Future work Expanding the simulation method towards other joints, e.g. rivets or flowdrill screws. 14