The aim of the work to be presented is to develop a specimen and a stable test procedure to establish the mode II traction-displacement law of composite interfaces. Modellers and designers use accurately measurable values of fracture toughness and interfacial shear strength in their analysis but only assume the usually bilinear shape of the traction-separation law. This is because it is extremely hard to work out the actual displacements and shear stresses in situ during a complicated, usually unstable mode II fracture test. The authors will present their attempt to overcome these experimental difficulties. The novel approach to be presented is based on the idea of capturing the full displacement field on the edge of a laminate with a cut central layer. This information can then be used to work out the interface properties. The displacement fields can be captured at subsequent load steps by taking micrographs in-situ in a scanning electron microscope (SEM) during a tensile test and post-process them with digital image correlation (DIC). The sample design and fabrication including surface preparation and application of a particle coating as a speckle pattern for DIC will be discussed in detail. The data post processing steps of stitching the SEM images and finally the application of image correlation will be shown as well. Some of the most interesting results of the study are the damage process zones of sheared composite layer interfaces which were successfully captured on a 4 µm grid with better than 100 nm resolution.
|Publication status||Published - 14 Sep 2014|
|Event||ESIS TC4 conference - Les Diablerets, Switzerland|
Duration: 14 Sep 2014 → 18 Sep 2014
|Conference||ESIS TC4 conference|
|Period||14/09/14 → 18/09/14|