Fraunhofer Institute for Microstructure of Materials and Systems IMWS
Fraunhofer Institute for Microstructure of Materials and Systems IMWS

Holistic assessment of UD-Tapes and Laminates for lightweight applications

Mechanical testing of polymer-based fiber composites

In the group "Assessment and Design of Composite Structures", the focus is on evaluating the use of polymer-based fiber composites in highly stressed lightweight structures and components. Thermoplastic unidirectional reinforced tapes -UD-Tapes- play a decisive role here and can be produced and tested in various polymer and fiber combinations.

Several Matrix and Fiber combinations Glass-, Carbon- and Natural-Fiber UD-Tapes

NFK UD-Tape
© Fraunhofer IMWS/Sven Döring
UD tapes made from glass, carbon and natural fiber-reinforced plastics.

Several matrix and fiber combinations can examine. One focus of the work is the material-mechanical characterization of composite materials by means of destructive testing and the evaluation of manufacturing defects by inline inspection methods (thermography, etc.).

Methods for assessment of UD-Tapes and made there of Laminates

  • Physical properties (thickness, density, fibre content, void content)
  • Mechanical properties (tension, fibre-matrix bonding, compression, bending, impact, …)
  • Morphological properties (fibre weaviness, line outs, spreading, etc.) with light microscopy and scanning electron microscopy
  • Integrated inline inspection methods (thickness, quality, defect detection) with thermography, line laser, ISRA inspection system
© Fraunhofer IMWS
Scanning electron micrograph of a carbon fiber tape after cryogenic fracture.

Specific methods

  • Inline Thickness measurement by two line laser sensors at UD500
  • Fiber volume content determination by:
    • Ashing according to Standard DIN EN ISO 1172
    • Wet chemically according DIN EN 2564
    • Thermogravimetric analysis
    • Computer tomography (CT)
    • Chemical extraction (Soxleth)
  • Density according to DIN EN ISO 1183-1
  • Tensile Test for UD-Tape and Laminate according to DIN EN ISO 527 -5 with macro extensometer, strain gauge, laser or optical strain measurement
  • Interlaminar shear strength (ILSS) Short Beam Bending Test according to ASTM D2344
  • Rail Shear Test according to ASTM D7078 for UD-Tape and Laminate
  • Bending test according to ISO 178 for Laminate
  • Compression in Wyoming Fixture according to ASTM 6641 for Laminate
© Fraunhofer IMWS
Zugversuch an einem Laminatband.
Short bar bending test

Tensile test on UD laminate

Non-Destructive Method

  • Inline Thermography UD-Tape inspection
    • Uncooled bolometer camera INFRATEC VarioCAMR(R) head 820 S/15mm
    • Line infrared source OPTRON IRD S750SM + control unit
  • Non-destructive testing of TPC structural components X-ray CT on coupon laminate samples
© Fraunhofer IMWS
X-ray computed tomography image of coupon laminate samples.
  • Non-destructive testing of Thermoplastic Composites (TPC) structural components Quantitative CT image analysis (fiber orientations)
    • Fiber orientation analysis on 3D image data in VG-Studio®
    • Segmenting the fiber bundles
    • Orientation analysis
    • Histogram of fiber orientations in the laminate plane
© Fraunhofer IMWS
Fiber orientation analysis of a laminate cross-section.
  • Non-destructive testing of TPC structural components
  • Continuous laminate testing with pulse phase thermography
© Fraunhofer IMWS