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Item type:Publication, Access status: without files , Maximizing bearing fatigue lifetime and CAI capability of fibre metal laminates by nanoscale sculptured Al pliesThis paper presents an experimental investigation of multifunctional fibre metal laminates (FMLs). Metal sheets are embedded into the hybrid composites by means of glass fibre reinforced polymer (GFRP) ply substitution, avoiding any laminate thickening and providing high bearing and compression after impact (CAI) capabilities. The Al sheets (AA6082) are nanoscale sculptured to prevent premature delamination between the metal and the matrix, which commonly occurs in conventional FMLs. The laminates are manufactured by resin transfer moulding. As a result the FMLs show drastically increased mechanical properties compared to conventional GFRP laminates for structural applications, achieving values for static pin-bearing (up to 21%), static bolt-bearing (up to 2%), resistance under fatigue pin-bearing (up to 100 times), resistance under fatigue bolt-bearing (up to 28 times) and CAI (up to 9%). The pre-treatment leads to a three-dimensional mechanical interlocking surface structure with highly improved inter-ply bonding between metal surface and resin. The fracture surface demonstrates that the adhesive bond between the nanoscale sculptured surface structure of the Al and matrix remains intact.Publicationtype: Journal Article224 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Multifunctional fibre metal laminates with improved load bearing capability(2018-12); The subject of this work is the investigation of multifunctional fibre metal laminates (FML) with permeable and surface treated metal plies to improve the mechanical performance and bolted joint fatigue lifetime compared to conventional glass fibre reinforced polymers (GFRP). In addition, a new approach for health monitoring to detect damages in FML is being developed. The laminates are manufactured by resin transfer moulding.Publicationtype: Doctoral Thesis370 570 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Reaching maximum inter-laminar properties in GFRP/nanoscale sculptured aluminium ply laminatesThe aim of the present work is to reach maximum inter-laminar properties in fibre metal laminates (FML) consisting of glass fibre reinforced polymer (GFRP) and aluminium (Al) plies. The Al plies are AA5019 and AA5754 alloys and pre-treated by nanoscale sculpturing before the FMLs are manufactured by resin transfer moulding. The nanoscale sculpturing of the Al plies leads to the formation of cubical hook-like structures on the surface giving rise to a three-dimensional mechanically interlocking surface. The inter-laminar properties of the FML are investigated by double-notch shear as well as double cantilever beam (Mode I) and end notched flexure (Mode II) testing methods and compared to untreated Al plies and conventional GRFP laminates as reference. As result the nanoscale sculptured Al plies show drastically increased inter-laminar mechanical properties due to highly improved inter-ply bonding between metal surface and resin. For all FMLs with nanoscale sculptured Al plies the delamination appears in the transition zone between glass fibres and matrix due to the lower adhesion of the glass fibre/matrix interface compared to the nanoscale sculptured Al ply/matrix interface. This proves that the maximum necessary inter-laminar properties are achieved.Publicationtype: Journal Article185 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Structural health monitoring of fibre metal laminates under mode I and II loading(2018-04); ; Delamination is one of the most common defects in FRP and occurs due to low interlaminar strength. Such defects are difficult to detect and lead often to catastrophic failure of the composite. In this work a new approach of a multi-functional FML for structural applications is investigated. The interlaminar fracture toughness is determined and the capacitance change between the metal plies during crack propagation is measured in-situ. The metal sheet component undergoes a chemical pre-treatment by nanoscale sculpturing before manufacturing by resin transfer moulding, to prevent adhesive failure of the interfacial metal/matrix bond. The experimental test results show high potential for detecting defects in FMLs. Delamination, which occurs between the glass fibre/matrix interface, can be electrically detected using the capacitance measurement. The fracture surface of the pre-treated metal sheet demonstrates that the adhesive bond between the cubical hook-like surface structure of the aluminium and the matrix remains intact.Publicationtype: Journal Article129 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Structural health monitoring of multifunctional fibre metal laminates under mode i loadingDelamination is one of the most common degradation mechanisms in fibre reinforced polymer (FRP) composites and occurs due to low interlaminar strength. Such defects are difficult to detect and yield often to catastrophic failure of the composite. In this work a new approach for structural health monitoring (SHM) of fibre metal laminates (FML) for structural applications is investigated, which does not require additional sensors. Therefore, FMLs consisting of glass fibre reinforced polymer (GFRP) with different metal plies are manufactured by the resin transfer moulding process. The interlaminar fracture toughness GIc(Mode I) is determined and the capacitance change between the metal plies during crack propagation is measured insitu. Within one FML configuration, a metal sheet is applied additionally, which undergo a pre-treatment before application, to improve the mechanical adhesion of the metal/matrix interface bond. Metal sheets are conventionally used in FMLs to improve the mechanical performance such as the bearing behaviour. The experimental test results show a high potential detecting defects in FMLs. Delamination, which occurs between the fibre/matrix interface, can be electrically detected using the capacitance measurement. The FML with the surface structured metal sheet demonstrates promising results for designing tough composites for structural applications. The fractography demonstrates a higher interfacial bonding between the metal sheet and matrix compared to the glass fibre/matrix interface. Consequently, the pre-treated metal leads to higher resistance against delamination in comparison with the GFRP layers.Publicationtype: Conference Paper188 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Charactersiation of fibre-metal-laminates under bearing loadingIn this work fibre metal laminates (FML) consisting of glass fibre reinforced polymers (GFRP) with solid and permeable metal sheets are manufactured by vacuum assisted resin transfer moulding (VARTM). The results are composites of high quality without void imperfection. In the next step, the composites are investigated by quasi-static pin-loaded bearing tests. The bearing strain is measured by Digital Image Correlation (DIC). The experimental bearing responses are compared whereas hybrids demonstrate a more ductile fracture behaviour and higher bearing strength in contrast to the conventional GFRP. The perforated metal sheet demonstrates a higher resistance against delamination compared to the solid metal sheet, which leads to a higher residual strength of this hybrid composite. Furthermore, it yields to a weight reduction compared to the solid metal sheet.Publicationtype: Conference Paper47 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Bearing response of fibre metal laminates consitsting of gfrp and woven metallic fabrics(International Committee on Composite Materials, 2015-07); ; The subject of this work is the bearing response of fibre metal laminates (FML) consisting of glass fibre reinforced polymers (GFRP) and permeable woven metallic fabrics (WMF) using experimental methods. The hybrid composites are manufactured by using a single step vacuum assisted resin transfer moulding process (VARTM). Resulting in high quality composites for load introducing areas. The results are compared with quasi-isotropic GFRP composites. The hybrid composites show a more ductile fracture behaviour in comparison to the quasi-isotropic GFRP laminate. With a metal volume fraction Vf < 20 vol.% a higher bearing strength is possible compared to GFRP. The permeable WMF increases the matrix flow through all layers in thickness direction while injection with the RTM-process. Furthermore, it yield to a weight reduction compared to solid metal plies.Publicationtype: Conference Paper34