Precise defect detection with sensor data fusion

Transcription

1 Precise defect detection with sensor data fusion Composite Europe 2016 Dipl.-Ing. Philipp Nienheysen Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University, Germany Chair of Metrology and Quality Management Prof. Dr.-Ing. Robert Schmitt November 30 th 2016, Düsseldorf, Germany

2 Production Engineering at RWTH Aachen University Machine Tools Laboratory (WZL) Institute of the RWTH Aachen established in 1906 about 840 employees (about 250 research assistants) m² office and laboratory area Fraunhofer Institute of Production- Technology (IPT) Institute of the Fraunhofer-Corporation established in 1980 about 450 employees (about 124 research assistants) m² office and laboratory area Associate-Institute in Boston/USA: CMI Fraunhofer Center for Manufacturing Innovation WZL Forum Offers further educational measures and workshops (e.g. Executive MBA) Seite 2

3 Uncertainty/m m Simulation der Sichtverbindung Simulation der Messunsicherheit Chair of Metrology Signalstabilität and Quality Management Signalqualität Department for Model-Based Systems Virtual world Real world x y z Metrology assisted assembly Modell der Sichtlinien Fixtureless assembly, assembly in motion, robotics, positioning systems, process and capability analysis, industrial statistics Laser-based metrology in large volumes, computer vision, thermography, computer tomography, ultrasonic testing, quality assurance along the FRP process chain Analyse der Sichtbarkeit Mobile Coordinate and Machine Vision Systems Optimierungsstrategien Target index Unsicherheit des verwendeten Messsystems Seite 3

4 Chair of Metrology and Quality Management Quality assurance along the FRP process chain and product life cycle Optical sensor systems X-ray sensor Sensor-assisted handling Ultrasonic system Thermography system Semi-finished production process Preforming Finishing processes Trimming, joining Repair Quality assurance Defect detection Area density Testing of adhesive joints Impact damage detection and evaluation Fiber orientation Digitization Delamination and inner folds Seite 4

5 NDT technologies 3D digitization Laser Cylindrical lens CCD matrix Optics Laser beam is expanded to a line with the help of a cylindrical lens The diffuse light reflected by the work piece is projected on a CCD matrix The projected image on the CCD changes according to the distance between the workpiece and the lens Laser light section principle Workpiece From multiple CCD images a 3D height profile of the workpiece can be calculated Steinbichler T-scan TS digitizing device Consists of a hand-held laser light section scanner and a tracking unit Resolution: 0,1 mm Steinbichler T-scan TS Source: optotechnik.zeiss.com Seite 5

6 NDT technologies Applications for 3D digitization CFRP body of the BMW i3 3D model created with Steinbichler T-scan TS Seite 6

7 NDT technologies Ultrasonic testing Transmitter/Receiver Gel coat Defect Pulse-echo testing Surface echo Defect echo A-scan High-frequency sound waves (20 KHz 2 GHz) generated by a piezoelectric element or a laser Reflection and transmission of sound at any material interface (CFRP steel air) Pulse-echo: Measuring of the reflected sound Runtime based depth (d) determination of defects d = cm t 2 cm: Average sound velocity of the material t: Sound propagation time A-scan: Sound intensity plotted against time B-scan: Vertical cut through the workpiece C-scan: Horizontal cut through the workpiece D-scan: TOF of the first back wall echo B-scan vs. C-scan Seite 7

8 NDT technologies Applications for ultrasonic testing Photo US C-scan Testing of adhesive hybrid joints (such as CFRP & steel) Adhesive size and spread is not predictable How big is the area of the adhesion? Detection of voids and inner cavities in FRP parts 43 mm 42,83 mm Measurement of adhesive hybrid joints Detection and classification of delamination caused by impact defects How big is the defective area? Which layers are affected? (depth of the defect) Wall-thickness measurement with one-sided accessibility Detection of impact defects Seite 8

9 NDT technologies Lockin-thermography All materials with T > 0K emit thermal radiation Stefan-Boltzmann law (radiated power from a black body) P = σ A T 4 σ: Stefan-Boltzmann constant A: surface area Sinusoidal thermal excitation Stefan-Boltzmann law Pixel-wise Fourier transform of image sequences In the resulting phase images, all effects due to illumination inhomogeneity and infrared surface emission are canceled out Visualization of thermal wave propagation by the phase images Lockin-thermography Seite 9

10 Ultrasonic testing and Lockin-thermography Comparison Ultrasonic testing Lockin-thermography testing Axial resolution Lateral resolution Testing range Testing speed Penetration depth Thermography suited for a fast, extensive near surface defect detection Ultrasonics most suitable for a high-resolution defect classification even in deeper layers Conclusion: 1.) Fast large area thermography scan for ROI determination 2.) Ultrasonic scan of the ROI for defect detection and classification 3.) Fusion of NDT data sets Seite 10

11 NDT data fusion General approach Generation of multiple NDT data sets 3D damage detection and visualization Registration of damage data in the same coordinate system Fusion of damage data and classification Damage information: - size, shape - position, orientation Source: olympus-ims.com, flir.de Seite 11

12 NDT data fusion I 3D digitization of the external geometry Cameras Laser light section scanner IR-LEDs Using of a tracked laser light section scanner Detection and localization of external defects Generation of a reference model for locating the ultrasound data Seite 12

13 NDT data fusion I Ultrasound testing for internal defects Camera IR-LEDs Ultrasound probe Ultrasound system Using of a tracked ultrasound probe Detection and localization of internal defects Generation of ultrasound D-scan data Seite 13

14 NDT data fusion I Automated damage detection and 3D visualization Automated detection of the damage out of the conventional ultrasound D-scan data Generation of a 3D model of the damaged volume Seite 14

15 NDT data fusion I Fusion of the damage data with the geometric model Localization of the damaged volume inside the geometric volume Fusion of the external and the internal geometric data Seite 15

16 NDT data fusion I Analyzing the affects of the damage on the structure FEM simulation for analyzing the affects of the damage on the structure Building use cases for quick damage evaluations in the future Seite 16

17 NDT data fusion II Machine Vision for CFRP textiles and preforms Surface Geometry Robotically guided 3D-fiber orientation Source: Mersmann, C.: Industrialisierende Machine-Vision-Integration im Faserverbundleichtbau. Aachen: Apprimus-Verlag, 2012 Seite 17

18 NDT data fusion II 3D preform digitization with the WZL Fiber Measurement System 1 Raw scanning data 3D-mesh interpolation 2 3 Model based analysis Surface mapping Geometry profile Local regression Seite 18

19 Thank you for your attention. Seite 19 Dipl.-Ing. Philipp Nienheysen /