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Item type:Publication, Access status: without files , Damage mechanisms of tailored few-layer graphene modified CFRP cross-ply laminatesA tailored nanoparticle modification approach for fibre reinforced polymers (FRP) is presented that allows exact analysis of the impact of a nanoparticle matrix modification in either 0°- or 90°-layers of cross-ply laminates on the mechanical properties and damage mechanisms. A modification of the 0°-layers unexpectedly increases the quasi-static tensile strength, although dominated by fibre properties. Positive crack stopping effects as well as negative effects, such as accelerated delamination growth, are discussed. The applicability of nanoparticle modified resin systems to improve the performance of FRP-laminates is sensitive to the loading case. For laminates only loaded in tension a modification appears to be advantageous, whereas in case of bending or compression loads the effect of nanoparticles is ambiguous and should be applied carefully.Publicationtype: Journal Article180 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Impact of carbon nanoparticles on fatigue properties and damage mechanisms of carbon fibre-reinforced epoxyPublicationtype: Doctoral Thesis66 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Ply-tailored nanoparticle matrix modification in cross-ply CFRP laminatesThe influence of a matrix modification with few-layer graphene (FLG) nanoparticles in different layers of carbon fibre reinforced plastic cross-ply laminates is investigated. Either the 90°-layers or the 0°-layers are modified with FLG nanoparticles. Quasi-static-tension tests with combined acoustic emission analysis are executed to determine the influence of the nanoparticle modification on tensile strength and stiffness, as well as the stress at inter fibre failure (IFF) initiation. FLG modification of the 0°-layers increases the tensile strength, whereas a modification of the 90°-layers increases the stress at IFF initiation. Fractography analysis of the fracture surfaces using scanning electron microscopy reveals microdamage at the nanoparticles that dissipates energy and is an explanation for the observed delay of transverse cracking in the 90°-layers when modified with FLG nanoparticles.Publicationtype: Conference Paper59 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , The effect of carbon nanoparticles on the fatigue performance of carbon fibre reinforced epoxy(Elsevier, 2014-09-01); ; ; ; The aim of this study is to investigate the influence of different types of carbon nanoparticles like multi-wall carbon nanotubes (MWCNT) and few layered graphene (FLG) on the damage mechanisms of carbon fibre reinforced epoxy (CFRP) under fatigue loading up to the high cycle regime. Specimens were manufactured from in-house made prepregs to ensure good and reproducible nanoparticle distribution within the CFRP and penetration of the fibre rovings. The quasi-static mechanical properties of the crossply laminates were not affected by the nanoparticle modification. The fatigue life, however, increased significantly for both types of carbon nanoparticles, being most pronounced for FLG at high fatigue loads. Scanning electron microscopy-analysis revealed enormous plastic deformation of the matrix due to the nanoparticles. The fatigue life increasing effect was discussed by means of energy absorption. Nanoparticle-based damage mechanisms in CFRP were displayed and differences due to the varying nanoparticle structures identified.Publicationtype: Journal Article16 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Evaluation of a critical impact energy in GFRP under fatigue loading(Elsevier, 2014-07-18); ; ; ; Defects in fibre reinforced polymer structures, such as impact damages, have a major influence on the fatigue behaviour. Impacts may occur during the lifetime of composite structures and lead to delaminations between adjacent layers with different fibre orientations and to matrix cracks within the layers. Specimens made of a glass fibre non crimp fabric were produced by vacuum assisted resin transfer moulding. Low velocity impact damage was introduced by use of a drop weight with a hemispherical head. The specimens were tested under fatigue loading with a stress ratio of R= -1 (tension-compression). The aim was to characterise damage development in fatigue testing of fibre reinforced polymers as a function of impact energy, lifetime and stress level. Therefore, the stiffness degradation during fatigue testing due to matrix cracks, delaminations, fibre failure and temperature development of the specimens was plotted vs. the number of load cycles. In interrupted fatigue tests with defined numbers of load cycles the influence of impact damages on matrix crack development was determined and correlated with stiffness degradation. Furthermore, thermoelastic stress analysis was performed during the interrupted tests in order to determine stress concentrations in the area of impact damage.Publicationtype: Journal Article29 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Damage mechanisms of nanoparticle-modified CFRP under very high cycle fatigue-loading(2014-06); ; ; ; In this work the influence of different types of carbon nanoparticles like multi-walled carbon nanotubes and few layered graphene on the damage mechanisms of CFRP under HCF and VHCF-fatigue loading are investigated. An improvement of fatigue life and change in dominating damage mechanism due to the nanoparticle modification were revealed.Publicationtype: Conference Paper14