Microwave NDT System for Industrial Composite Applications

Transcription

1 NDT Online Workshop 2011 Microwave NDT System for Industrial Composite Applications , Dr.-Ing. Gerald Busse

2 Visual Inspection(I) Light Source Object Eye Scattering Transparency Reflection Absorption Transparency is essential to inspect the inside of an object! 2

3 Visual Inspection(II) Gas Fluid Different indices of refraction! 3

4 No Vista! Wood Metal Many plastic materials and foams Glass Fiber-Reinforced Plastics (GFRP) Natural Fiber-Reinforced Plastics (NFRP) Carbon Fiber-Reinforced Plastics (CFRP) Wood-Plastic-Composites (WPC) Fiber-Reinforced ceramics Internal structure defines mechanical characteristics! Visual inspection of many modern materials impossible! Non-destructive testing is required or desired! 4

5 Conceptual Formulation Suitable NDT system with the following properties is wanted: Contactless testing Single side access to the device-under-test (DUT) No couplant No additional safety measures Thick materials testable Soft materials testable Reasonable resolution Robust against harsh environmental conditions Compatible to conventional automatization Inexpensive technology Use microwaves! 5

6 Fundamentals: Detection Principle Microwave reflection at the discontinuity of two materials: Refraction Index! n = ε r r Non-conducting materials (no CFRP) Discontinuity in permittivity Defect size in the order of wavelength x 6

7 Fundamentals Antenna Arrangement Reflection monostatic (preferred) Reflection bistatic Transmission 7

8 Fundamentals Test System Microwave Circuitry Control Probe Positioning System 8

9 Probe Type Rectangular Waveguide E-Field (real part) WR42 waveguide (10.67 mm x 4.31 mm) 0,25 0,2 Re(r) 0,15 0,1 z = 15 mm 0, , x 50-0,1 z = 1 mm -0,15-0,2-0,25 9

10 Probe Type Coaxial Probe Coaxial Probe KS1 (Innerconductor 1 mm, outer 2mm) 0,95 0,9 0,85 0,8 0,75 0,7 0,65 0,6 0,55 Re(r) z = 1 mm z = 0,05 mm x Geometry forces concentration of E-Field Coaxial probe radiates almost no energy 10

11 Probe Type -Lens Lens WR42 waveguide r 0,018 0,016 0,014 0,012 0,01 0,008 0,006 0,004 0, Object distance Objekttiefe: from lens: 0mm 2mm 5mm 10mm 15mm 25mm 40mm x/mm Fokus 11

12 Probe Applicablility 160 Coaxial probe Defectsize in mm WR42 waveguide Big defect, medium depth Lens Small defect, small depth Defectdepth in mm Small defect, big depth 12

13 NDT-System Scanning a DUT Lens Z-Axis X-Axis GripforDUT Microwave Circuitry Y-Axis Axis-Control 13

14 Results- Delamination Top view photo of GFRP sample Top view microwave image(coaxial probe) Delaminations about150 µm about200 µm Micrograph Micrograph 14

15 Results- Homogeneity Top view photo of an unknown, obviously homogeneous fiber reinforced material Top view microwave image(coaxial probe) 15

16 Results Defective Bonding/ Ondulation Sandwich Structure Top view photo Top view microwave image (waveguide) Resin GFRP (0.5 mm) PVC (3 mm) Resin GFRP (0.5 mm) about 0.3 mm Defective Bonding Area Sectional view of NFRP sample (jute) with ondulation Top view microwave image (waveguide) 16

17 Results- Cracks Sectionalviewofa WPC hollow chamber profile 72 mm Top view microwave image (waveguide) Cracks 17 mm Cracks Cracks Sectional view of a WPC solid profile Top view microwave image (waveguide) 145 mm 21 mm Crack zone 17

18 Results- Defects Aluminium foil under PC stack Top view microwave image(lens) Defect depth: 3 mm Defect depth: 40 mm Flake board with air gaps Top view microwave image(lens) 2 mm 24 mm 10 mm 18

19 Thank You For Your Attention!

20 NDT Online Workshop 2011 Microwave NDT System for Industrial Composite Applications Contact: Hochschule Magdeburg-Stendal MINTECO Breitscheidstraße2 D Magdeburg Holger Meier Fon: / Fax: / Mail: holger.meier@hs-magdeburg.de Web: , Dr.-Ing. Gerald Busse 20