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Prof. Bodo Fiedler
Hamburg University of Technology

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0 Carbon Fiber
0 Nanotechnology
0 NDT
0 sensor
0 degradation mechanisms

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nanotube
impact damage
Carbon Fiber
sensor
Composite materials
glass fiber
degradation mechanisms

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Conference
Belfast, UK
Date: 1-6 August 2021
Has been a speaker at the conference:
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Bodo Fiedler
Conference
Hamburg, Germany
Date: 1-4 September 2020
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Bodo Fiedler
Journal article
Published: 08 June 2021 in Composite Structures
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Adhesive bonding is a well-established technique for composite materials. Despite advanced surface treatments and preparations, surface contamination and application errors still occur, resulting in localised areas with a reduced adhesion. The dramatic reduction of the bond strength limits the applicability of adhesive bonds and hampers further industrial adaptation. This study aims to detect weak-bonds due to manufacturing errors or contamination by analysing and interpreting the vibroacoustic modulation signals with the aid of machine learning. An ultrasonic signal is introduced into the specimen by a piezoceramic actuator and modulated through a low frequency vibration excited by a servo-hydraulic testing system. Tested samples are single-lap shear specimens, according to ASTM D5868-01, with artificial circular debonding areas introduced as PTFE-films or a release agent contamination. It is shown that an artificial neural network can identify various defects in the bonded joint robustly and is able to predict residual strengths and hence demonstrates great potential for non-destructive testing of adhesive joints.

ACS Style

Benjamin Boll; Erik Willmann; Bodo Fiedler; Robert Horst Meißner. Weak adhesion detection – Enhancing the analysis of vibroacoustic modulation by machine learning. Composite Structures 2021, 273, 114233 .

AMA Style

Benjamin Boll, Erik Willmann, Bodo Fiedler, Robert Horst Meißner. Weak adhesion detection – Enhancing the analysis of vibroacoustic modulation by machine learning. Composite Structures. 2021; 273 ():114233.

Chicago/Turabian Style

Benjamin Boll; Erik Willmann; Bodo Fiedler; Robert Horst Meißner. 2021. "Weak adhesion detection – Enhancing the analysis of vibroacoustic modulation by machine learning." Composite Structures 273, no. : 114233.

Journal article
Published: 08 June 2021
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ACS Style

Benjamin Boll; Erik Willmann; Bodo Fiedler; Robert Meißner. Weak adhesion detection – enhancing the analysis of vibroacoustic modulation by machine learning. 2021, 1 .

AMA Style

Benjamin Boll, Erik Willmann, Bodo Fiedler, Robert Meißner. Weak adhesion detection – enhancing the analysis of vibroacoustic modulation by machine learning. . 2021; ():1.

Chicago/Turabian Style

Benjamin Boll; Erik Willmann; Bodo Fiedler; Robert Meißner. 2021. "Weak adhesion detection – enhancing the analysis of vibroacoustic modulation by machine learning." , no. : 1.

Journal article
Published: 25 April 2021 in Composites Part A: Applied Science and Manufacturing
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In this study, temperature-dependent material properties are implemented into a continuum-damage-based (CDM) model to describe the progressive failure of CFRP under temperature influence. Low-velocity impact (LVI) simulations showed that the material model could accurately represent the damage resulting from LVI at different temperatures and impact energies. The simulations show that an increase of the interlaminar ERR does not cause the reduction in delamination size, but the change in intralaminar damage and overall structural response. Compression after impact (CAI) simulations are in good agreement with experimental data. The results emphasise that an increased temperature during compression has a more decisive influence on residual strength than the impact of energy. The proposed approach and CDM model can predict the material behaviour of CFRP under temperature influence and complex load cases.

ACS Style

Johann Körbelin; Nilas Junge; Bodo Fiedler. Modelling of low-velocity impact and compression after impact of CFRP at elevated temperatures. Composites Part A: Applied Science and Manufacturing 2021, 147, 106418 .

AMA Style

Johann Körbelin, Nilas Junge, Bodo Fiedler. Modelling of low-velocity impact and compression after impact of CFRP at elevated temperatures. Composites Part A: Applied Science and Manufacturing. 2021; 147 ():106418.

Chicago/Turabian Style

Johann Körbelin; Nilas Junge; Bodo Fiedler. 2021. "Modelling of low-velocity impact and compression after impact of CFRP at elevated temperatures." Composites Part A: Applied Science and Manufacturing 147, no. : 106418.

Journal article
Published: 24 April 2021 in Composites Part C: Open Access
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Different bio-inspired Bouligand thin-ply Carbon-Fibre-Reinforced Plastic (CFRP) laminates with a pitch angle as low as 2.07∘ are realised, which is the smallest pitch angle realised in literature. The angle is therefore close angles found in biological microstructures. Low-Velocity Impact (LVI) and residual compressive strength tests determined the damage tolerance of the structures. Investigated were two different interlaminar fracture toughnesses and two different metal-Bouligand-CFRP-layups. The low pitch angle results in significantly higher residual strengths than 45∘ quasi-isotropic (QI) layups, despite the significantly lower proportion of 0∘ fibres. Higher fracture toughness and hybridisation with steel layers lead to reduced matrix damage without increasing residual compressive strength. In-plane plane tension properties are determined with a pitch angle of 2.59∘. The results reveal, that the unnotched tensile strength is significantly lower. However, only helicoidal, sub-critical matrix cracking and no delaminations occur before final failure. The sub-critical matrix cracking leads to almost no notch sensitivity and a similar open-hole-tensile strength to 45∘-QI layups despite the low number of 0∘-fibres.

ACS Style

Johann Körbelin; Philip Goralski; Benedikt Kötter; Florian Bittner; Hans-Josef Endres; Bodo Fiedler. Damage tolerance and notch sensitivity of bio-inspired thin-ply Bouligand structures. Composites Part C: Open Access 2021, 5, 100146 .

AMA Style

Johann Körbelin, Philip Goralski, Benedikt Kötter, Florian Bittner, Hans-Josef Endres, Bodo Fiedler. Damage tolerance and notch sensitivity of bio-inspired thin-ply Bouligand structures. Composites Part C: Open Access. 2021; 5 ():100146.

Chicago/Turabian Style

Johann Körbelin; Philip Goralski; Benedikt Kötter; Florian Bittner; Hans-Josef Endres; Bodo Fiedler. 2021. "Damage tolerance and notch sensitivity of bio-inspired thin-ply Bouligand structures." Composites Part C: Open Access 5, no. : 100146.

Journal article
Published: 31 March 2021 in Composites Science and Technology
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Low impact resistance and high notch sensitivity are significant drawbacks of carbon-fibre-reinforced plastics (CFRP). The addition of carbon nanoparticles (CNP), a third phase, reduces this deficit through additional energy-consuming mechanisms. The influence of CNP modification on strength and damage behaviour cannot be separated from the effect of layer thickness because it controls the stress state in the entire laminate. This study investigates the influence of few-layer graphene (FLG) modification on CFRP with layer thicknesses varying from ultra-thin-ply (28μm, 30g/m2) to thick-ply (220μm, 240g/m2). The mode I and mode II inter-laminar energy release rates increased significantly with the FLG modification. It also increased the damage initiation stress for notched laminates of all layer thicknesses, thereby increasing the useable design space. The FLG modification also increased the ultimate notched strength for the ultra-thin ply laminates, thereby reducing the high notch sensitivity which is the limiting factor for their application. In the case of low-velocity impact damage, the modification of thick-layer laminates improves the residual compressive strength. FLG modification leads to a considerable improvement in the compressive strength. The selection of CNP was based on a comprehensive investigation of the fracture toughness of the prepreg resin/CNP nanocomposites. The particle loading and type was selected for FLG with a 25μm sheet size and 0.05 wt %.

ACS Style

Johann Körbelin; Benedikt Kötter; Hauke Voormann; Lukas Brandenburg; Stefan Selz; Bodo Fiedler. Damage tolerance of few-layer graphene modified CFRP: From thin-to thick-ply laminates. Composites Science and Technology 2021, 209, 108765 .

AMA Style

Johann Körbelin, Benedikt Kötter, Hauke Voormann, Lukas Brandenburg, Stefan Selz, Bodo Fiedler. Damage tolerance of few-layer graphene modified CFRP: From thin-to thick-ply laminates. Composites Science and Technology. 2021; 209 ():108765.

Chicago/Turabian Style

Johann Körbelin; Benedikt Kötter; Hauke Voormann; Lukas Brandenburg; Stefan Selz; Bodo Fiedler. 2021. "Damage tolerance of few-layer graphene modified CFRP: From thin-to thick-ply laminates." Composites Science and Technology 209, no. : 108765.

Journal article
Published: 26 March 2021 in Composites Part C: Open Access
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This study investigates the influence of load ratio and impact damage on the fatigue behaviour of high-performance carbon fibre reinforced polymers (CFRP) with areal fibre weights between 30 gsm and 360 gsm. For undamaged samples, the ultimate tensile and compressive strength, as well as the fatigue properties, are evaluated with regard to their layer thicknesses. The fatigue tests were performed under tension-tension (R=0.1), tension-compression (R=-0.5) and compression-compression (R=10) regime. The results are illustrated as a constant-life diagram, and a piecewise linear interpolation examines a first prediction. The results show that static and fatigue performance improves with decreasing layer thickness. Particularly under tension-compression loading, significant improvements are observed, due to the suppression of matrix cracks and delaminations with thinner layers. In addition, the effect of low-energy impact on the fatigue behaviour of Thin- and Thick-Ply laminates is investigated. The tests demonstrate that although the delamination area is larger, Thin-Ply laminates can sustain higher stresses and still reach the same number of load cycles in contrast to Thick-Ply laminates. Computed tomography measurements visualize 3-dimensional the damage progression after various cycles and prove that the Thin-Ply composites show no increase in the damaged area during fatigue. The interlaminar stress at the delamination is not sufficient for expansion. In contrast, in the case of thicker layers, the damage growths progressively throughout the whole sample with increasing number of cycles.

ACS Style

Benedikt Kötter; Janina Endres; Johann Körbelin; Florian Bittner; Hans-Josef Endres; Bodo Fiedler. Fatigue and fatigue after impact behaviour of Thin- and Thick-Ply composites observed by computed tomography. Composites Part C: Open Access 2021, 5, 100139 .

AMA Style

Benedikt Kötter, Janina Endres, Johann Körbelin, Florian Bittner, Hans-Josef Endres, Bodo Fiedler. Fatigue and fatigue after impact behaviour of Thin- and Thick-Ply composites observed by computed tomography. Composites Part C: Open Access. 2021; 5 ():100139.

Chicago/Turabian Style

Benedikt Kötter; Janina Endres; Johann Körbelin; Florian Bittner; Hans-Josef Endres; Bodo Fiedler. 2021. "Fatigue and fatigue after impact behaviour of Thin- and Thick-Ply composites observed by computed tomography." Composites Part C: Open Access 5, no. : 100139.

Journal article
Published: 05 March 2021 in Polymer
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Until now, detecting weak spots in composite structures remains a key challenge in the aviation industry. The correct assessment of the load-bearing capability after structural overloading or the occurrence of barely-visible damages is particularly important to maintain structural integrity. Nonetheless, a reliable and overarching non-destructive inspection method to estimate the residual mechanical properties while covering all major damage scenarios has not been found yet. Several non-destructive techniques have been proposed to approach these challenges and are already in place for specific damage cases. However, each technique has its sources of information and therefore, limitations in practice due to a lack of generalisation. In this work, we present a concept and approach to gain access to the residual mechanical properties of a thermosetting polymer solely based on its inherent material state independent from its life-cycle history. Therefore, the material state is obtained by combining Fourier-transformed infrared spectroscopy with feature extraction algorithms based on Gaussian peak fitting. As proof of concept, tensile, creep, and cyclic tests are conducted to demonstrate this approach's advantage. A complementary theoretical investigation using quantum chemical calculations is employed to support the experimental work by identifying the investigated polymer's characteristic vibrational modes and predicting their evolution during the experiments. The results show that the quantification of molecular changes can estimate the material state and that the method is suitable to improve the understanding of the degradation processes and severity. This publication shall particularly serve as the basis for further research to study the interaction between molecular forces and material properties.

ACS Style

Audrius Doblies; Christian Feiler; Tim Würger; Eduard Schill; Robert H. Meißner; Bodo Fiedler. Mechanical degradation estimation of thermosets by peak shift assessment: General approach using infrared spectroscopy. Polymer 2021, 221, 123585 .

AMA Style

Audrius Doblies, Christian Feiler, Tim Würger, Eduard Schill, Robert H. Meißner, Bodo Fiedler. Mechanical degradation estimation of thermosets by peak shift assessment: General approach using infrared spectroscopy. Polymer. 2021; 221 ():123585.

Chicago/Turabian Style

Audrius Doblies; Christian Feiler; Tim Würger; Eduard Schill; Robert H. Meißner; Bodo Fiedler. 2021. "Mechanical degradation estimation of thermosets by peak shift assessment: General approach using infrared spectroscopy." Polymer 221, no. : 123585.

Journal article
Published: 07 February 2021 in Composites Part A: Applied Science and Manufacturing
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In this study, fiber metal laminates (FMLs), which consisted of thin-ply prepreg and stainless steel layers with a ply thickness of 0.04 mm, were fabricated with the aim of suppressing the fiber breakage that decreases the compression-after-impact (CAI) strength. Then, static flexural tests of FMLs were conducted to investigate the effects of the number of metal layers on the failure mode and mechanical properties during static out-of-plane loading, and the results were compared with those of our previous impact and CAI tests. The results confirmed that the plastic deformation of metal layers improved the energy dissipation and thus failure occurred in a limited range of locations. Furthermore, the investigation of the in situ stress during flexural tests by finite element method (FEM) analysis revealed that a hybrid material that both suppresses ply failure and has a high modulus of the metal can be realized owing to the constraining effect of thin-ply laminates.

ACS Style

Kohei Yamada; Benedikt Kötter; Masaaki Nishikawa; Shuto Fukudome; Naoki Matsuda; Kazumasa Kawabe; Bodo Fiedler; Masaki Hojo. Mechanical properties and failure mode of thin-ply fiber metal laminates under out-of-plane loading. Composites Part A: Applied Science and Manufacturing 2021, 143, 106267 .

AMA Style

Kohei Yamada, Benedikt Kötter, Masaaki Nishikawa, Shuto Fukudome, Naoki Matsuda, Kazumasa Kawabe, Bodo Fiedler, Masaki Hojo. Mechanical properties and failure mode of thin-ply fiber metal laminates under out-of-plane loading. Composites Part A: Applied Science and Manufacturing. 2021; 143 ():106267.

Chicago/Turabian Style

Kohei Yamada; Benedikt Kötter; Masaaki Nishikawa; Shuto Fukudome; Naoki Matsuda; Kazumasa Kawabe; Bodo Fiedler; Masaki Hojo. 2021. "Mechanical properties and failure mode of thin-ply fiber metal laminates under out-of-plane loading." Composites Part A: Applied Science and Manufacturing 143, no. : 106267.

Journal article
Published: 12 January 2021 in Functional Composite Materials
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For the reliable and cost-efficient application of glass fibre polymer composites in structural applications, knowledge of the damage state of the material during operation is necessary. Within this work, a structural health monitoring method based on in-situ electrical capacitance measurements is presented, which enables damage monitoring in glass fibre reinforced polymers. For this purpose, individual glass fibre rovings in a non-crimp fabric were replaced by carbon fibre rovings at regular intervals. Additionally, specimens with solid or stranded copper conductors were manufactured to gain insights into the influences of conductor material and composition. The modified fabrics were implemented as 90 ∘ layers of [0/904] s glass fibre polymer cross-ply laminates. To monitor the progressive damage, conductive rovings were contacted, forming the capacitor walls of interleaved capacitors. Carbon fibre conductors show higher sensitivity of the capacitance to crack formation than solid or stranded copper conductors. Capacitance decrease measured in-situ during tensile tests on specimens with carbon fibre conductors shows a high correlation with crack initiation, further crack formation and speed of crack evolution. An analytical model can describe the correlation based on the assumptions of an ideal plate capacitor. Thus, the structural health monitoring method developed in this work can reveal in-situ knowledge of the material damage state.

ACS Style

Christina Buggisch; Abedin Gagani; Bodo Fiedler. Capacitance measurements on integrated conductors for detection of matrix cracks in GFRP. Functional Composite Materials 2021, 2, 1 -13.

AMA Style

Christina Buggisch, Abedin Gagani, Bodo Fiedler. Capacitance measurements on integrated conductors for detection of matrix cracks in GFRP. Functional Composite Materials. 2021; 2 (1):1-13.

Chicago/Turabian Style

Christina Buggisch; Abedin Gagani; Bodo Fiedler. 2021. "Capacitance measurements on integrated conductors for detection of matrix cracks in GFRP." Functional Composite Materials 2, no. 1: 1-13.

Journal article
Published: 13 December 2020 in Composites Part C: Open Access
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This study investigates the influence of local hybridization of Thin and Thick-Ply CFRP laminates on the open-hole and bearing properties. The area weight of the CFRP unidirectional prepregs used is 40 gsm in the case of Thin-Ply layers and 160 gsm in the case of Thick-Ply layers. The steel used is a 1.4310 stainless-steel foil with the same layer thickness as the prepregs. In the hybrid area, 90∘ layers were locally replaced by stainless steel patches. The local metal foil content varies from 6.25%, 12.5% to 25.0%. For notched laminates, the open hole tensile strength is significantly decreased with thinner layer thicknesses. The failure behavior changes from complex delamination dominated failure to brittle failure. By using stainless steel foils in the regions of stress concentrations, energy can be dissipated by plastic deformation of the steel foil and stresses can be deflected to neighbouring areas. For Thin-Ply samples with a local steel content of 25% the open hole tensile strength increases by 64% in comparison to the reference Thin-Ply specimens and the sensitivity towards stress concentrations decreases. The bearing strength of the hybrid CFRP laminates is increased by up to 54.6% in comparison to the reference material, due to the confinement of the steel foil and the resulting higher compressive strength and the plastic deformation at high stresses. The stress–strain diagrams and micrographs of the fibre metal samples reveal that damage is initiated before the maximum bearing strength. However, the damage offset bearing strength increase concerning the specific density of the material significantly.

ACS Style

Benedikt Kötter; Kohei Yamada; Johann Körbelin; Kazumasa Kawabe; Masaaki Nishikawa; Masaki Hojo; Bodo Fiedler. Steel foil reinforcement for high performance bearing strength in Thin‐Ply composites. Composites Part C: Open Access 2020, 4, 100085 .

AMA Style

Benedikt Kötter, Kohei Yamada, Johann Körbelin, Kazumasa Kawabe, Masaaki Nishikawa, Masaki Hojo, Bodo Fiedler. Steel foil reinforcement for high performance bearing strength in Thin‐Ply composites. Composites Part C: Open Access. 2020; 4 ():100085.

Chicago/Turabian Style

Benedikt Kötter; Kohei Yamada; Johann Körbelin; Kazumasa Kawabe; Masaaki Nishikawa; Masaki Hojo; Bodo Fiedler. 2020. "Steel foil reinforcement for high performance bearing strength in Thin‐Ply composites." Composites Part C: Open Access 4, no. : 100085.

Journal article
Published: 17 November 2020 in Journal of Applied Physics
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ACS Style

Hao Zhang; Joseph Horvat; R. A. Lewis; Rainer Adelung; Bodo Fiedler; Yogendra K. Mishra. Aerographite phonon density of states affects double resonant Raman scattering. Journal of Applied Physics 2020, 128, 195101 .

AMA Style

Hao Zhang, Joseph Horvat, R. A. Lewis, Rainer Adelung, Bodo Fiedler, Yogendra K. Mishra. Aerographite phonon density of states affects double resonant Raman scattering. Journal of Applied Physics. 2020; 128 (19):195101.

Chicago/Turabian Style

Hao Zhang; Joseph Horvat; R. A. Lewis; Rainer Adelung; Bodo Fiedler; Yogendra K. Mishra. 2020. "Aerographite phonon density of states affects double resonant Raman scattering." Journal of Applied Physics 128, no. 19: 195101.

Journal article
Published: 12 November 2020 in Composites Part C: Open Access
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This study investigates the influence of temperature and impact-energy on low-velocity impact damage in CFRP and the resulting residual tensile and compressive strength. Impacts were introduced at −20∘C, 20∘C and 80∘C, which are moderate temperature compared to the glass transition temperature of 203∘C of the used CFRP. A change in temperature leads to a substantial change in damage behaviour. With increasing temperature, the delamination area is reduced, and at 80∘C fibre-failure occurs on the impacted side. The residual tensile strength was tested at 20∘C utilising a new jig, which counteracts the stresses resulting from free-edge effects and thus prevents that edge delaminations are overshadowing the effect of the impact damage due to the specimen size. The fibre failure reduces the residual tensile strength significantly compared to the damage resulting from impaction at 20∘C. The compressive residual strength was determined at 20∘C and 80∘C. The results point out that the temperature mainly determines the residual compressive strength. Consequently, it is essential to identify the material’s behaviour in the range of the in-service temperatures, even if they are far away from the glass transition temperature, to evaluate the damage tolerance and performance.

ACS Style

Johann Körbelin; Chiara Dreiner; Bodo Fiedler. Impact of temperature on LVI-damage and tensile and compressive residual strength of CFRP. Composites Part C: Open Access 2020, 3, 100074 .

AMA Style

Johann Körbelin, Chiara Dreiner, Bodo Fiedler. Impact of temperature on LVI-damage and tensile and compressive residual strength of CFRP. Composites Part C: Open Access. 2020; 3 ():100074.

Chicago/Turabian Style

Johann Körbelin; Chiara Dreiner; Bodo Fiedler. 2020. "Impact of temperature on LVI-damage and tensile and compressive residual strength of CFRP." Composites Part C: Open Access 3, no. : 100074.

Journal article
Published: 06 November 2020 in Macromolecules
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ACS Style

Robert H. Meißner; Julian Konrad; Benjamin Boll; Bodo Fiedler; Dirk Zahn. Molecular Simulation of Thermosetting Polymer Hardening: Reactive Events Enabled by Controlled Topology Transfer. Macromolecules 2020, 53, 9698 -9705.

AMA Style

Robert H. Meißner, Julian Konrad, Benjamin Boll, Bodo Fiedler, Dirk Zahn. Molecular Simulation of Thermosetting Polymer Hardening: Reactive Events Enabled by Controlled Topology Transfer. Macromolecules. 2020; 53 (22):9698-9705.

Chicago/Turabian Style

Robert H. Meißner; Julian Konrad; Benjamin Boll; Bodo Fiedler; Dirk Zahn. 2020. "Molecular Simulation of Thermosetting Polymer Hardening: Reactive Events Enabled by Controlled Topology Transfer." Macromolecules 53, no. 22: 9698-9705.

Book chapter
Published: 26 August 2020 in Synthesis and Applications of Nanocarbons
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With the first development of carbon aerogels at the end of the 1980s and the beginning of the 1990s based on pyrolysis of resorcinol‐formaldehyde organic aerogels, this material class grew with high interest in research. In 2012, Mecklenburg et al. introduced a novel three‐dimensional interconnected carbon morphology based on tetrapods, named Aerographite. This chapter discusses the most important and most common fabrication processes for carbon aerogels and some specific three‐dimensionally interconnected networks. Important to note is that the variety of morphologies is hardly limited and mostly depends on the manufacturing process. The chapter also discusses the properties of aerogels which are often related to their density or their porosity. For improving the material properties, various modifications can be realized with different methods.

ACS Style

Hubert Beisch; Bodo Fiedler. Nanocarbon Aerogels and Aerographite. Synthesis and Applications of Nanocarbons 2020, 247 -274.

AMA Style

Hubert Beisch, Bodo Fiedler. Nanocarbon Aerogels and Aerographite. Synthesis and Applications of Nanocarbons. 2020; ():247-274.

Chicago/Turabian Style

Hubert Beisch; Bodo Fiedler. 2020. "Nanocarbon Aerogels and Aerographite." Synthesis and Applications of Nanocarbons , no. : 247-274.

Journal article
Published: 03 August 2020 in International Journal of Mechanical Sciences
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The rapid progress in additive manufacturing enables the generation of complex structures that can be customized according to the application. For instance, lattice structures show potential in medical and lightweight applications as their mechanical properties can be scaled by the volume fraction of the cells according to the local requirements given by the load paths. In order to use lattice structures in design of structural parts, the mechanical properties need to be characterized. Due to the complex nature of the selective laser melting process, manufacturing imperfections as well as the microstructure play an important role and their effects can differ depending on volume fraction, building direction and especially load case (tension and compression). The aim of this study is to analyze these effects. In addition, a deeper understanding of the failure process is necessary which is gained by 3D digital image correlation and finite element simulations incorporating progressive damage. We found that surface defects are larger for horizontal struts printed directly on the powder bed and thus show a higher influence for specimens where building and loading direction are not aligned. Moreover, porosity leads to significantly different mechanical properties contingent on the load case. Depending on the volume fraction, different failure modes are observed which are captured and explained by finite element simulations allowing to avoid stress concentrations or undesired buckling in future designs. Finally, simulations of lattice structures are compared to computationally inexpensive simulations of unit cells with periodic boundary conditions. Good agreement is found and further insights into the influence of the load introduction are gained.

ACS Style

Sven Drücker; Martina Schulze; Hendrik Ipsen; Laura Bandegani; Helge Hoch; Maximilian Kluge; Bodo Fiedler. Experimental and numerical mechanical characterization of additively manufactured Ti6Al4V lattice structures considering progressive damage. International Journal of Mechanical Sciences 2020, 189, 105986 .

AMA Style

Sven Drücker, Martina Schulze, Hendrik Ipsen, Laura Bandegani, Helge Hoch, Maximilian Kluge, Bodo Fiedler. Experimental and numerical mechanical characterization of additively manufactured Ti6Al4V lattice structures considering progressive damage. International Journal of Mechanical Sciences. 2020; 189 ():105986.

Chicago/Turabian Style

Sven Drücker; Martina Schulze; Hendrik Ipsen; Laura Bandegani; Helge Hoch; Maximilian Kluge; Bodo Fiedler. 2020. "Experimental and numerical mechanical characterization of additively manufactured Ti6Al4V lattice structures considering progressive damage." International Journal of Mechanical Sciences 189, no. : 105986.

Journal article
Published: 10 June 2020 in Nanomaterials
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In this work, composites based on epoxy resin and various carbon nanotubes (CNTs) were studied regarding their thermoelectric properties. The epoxy composites were prepared by infiltration of preformed CNT buckypapers. The influence of different types of CNTs on the Seebeck coefficient was investigated, namely lab-made and commercially available multi walled carbon nanotubes (MWCNTs), lab-made nitrogen doped MWCNTs (N-MWCNT) and commercially available single walled carbon nanotubes (SWCNTs). It was found that only by varying the lab-made MWCNT content could both n- and p-type composites be produced with Seebeck coefficients between −9.5 and 3.1 µV/K. The incorporation of N-MWCNTs resulted in negative Seebeck coefficients of −11.4 to −17.4 µV/K. Thus, the Seebeck coefficient of pure SWCNT changed from 37.4 to −25.5 µV/K in the epoxy/1 wt. % SWCNT composite. A possible explanation for the shift in the Seebeck coefficient is the change of the CNTs Fermi level depending on the number of epoxy molecules on the CNT surface.

ACS Style

Katharina Kröning; Beate Krause; Petra Pötschke; Bodo Fiedler. Nanocomposites with p- and n-Type Conductivity Controlled by Type and Content of Nanotubes in Thermosets for Thermoelectric Applications. Nanomaterials 2020, 10, 1 .

AMA Style

Katharina Kröning, Beate Krause, Petra Pötschke, Bodo Fiedler. Nanocomposites with p- and n-Type Conductivity Controlled by Type and Content of Nanotubes in Thermosets for Thermoelectric Applications. Nanomaterials. 2020; 10 (6):1.

Chicago/Turabian Style

Katharina Kröning; Beate Krause; Petra Pötschke; Bodo Fiedler. 2020. "Nanocomposites with p- and n-Type Conductivity Controlled by Type and Content of Nanotubes in Thermosets for Thermoelectric Applications." Nanomaterials 10, no. 6: 1.

Journal article
Published: 07 May 2020 in International Journal of Adhesion and Adhesives
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A commonly used design for the repair of carbon fibre reinforced polymers (CFRP) is the bonded scarf joint. As contaminations on the adherend surface or bondline flaws can reduce the bonding strength drastically, the effect of such strength reducing phenomena has to be known. This is also the case for bonded joints that had to sustain hot-wet conditions. Therefore, the aim of this study was to investigate the influence of weak bonds and hot-wet conditioning on the mechanical properties of scarf bonded CFRP joints. Circular zones of weak bonding have been artificially produced by application of release agent on the adherend surface. Different sizes and locations were studied. Additionally, two scarf ratios and two lay-ups have been investigated, to account for different stress states in the bondline. The investigation showed that the effect of a weak bond on bond strength is strongly dependent on the location, size and lay-up of the adherend, while hot-wet conditioning reduces the bond strength in all cases.

ACS Style

Sergej Harder; Florian Röper; Dennis Gibhardt; Benedikt Koert; Bodo Fiedler. Strength of scarf-bonded CFRP repairs containing disc-shaped zones of weak bonding considering hot-wet conditioning. International Journal of Adhesion and Adhesives 2020, 102, 102643 .

AMA Style

Sergej Harder, Florian Röper, Dennis Gibhardt, Benedikt Koert, Bodo Fiedler. Strength of scarf-bonded CFRP repairs containing disc-shaped zones of weak bonding considering hot-wet conditioning. International Journal of Adhesion and Adhesives. 2020; 102 ():102643.

Chicago/Turabian Style

Sergej Harder; Florian Röper; Dennis Gibhardt; Benedikt Koert; Bodo Fiedler. 2020. "Strength of scarf-bonded CFRP repairs containing disc-shaped zones of weak bonding considering hot-wet conditioning." International Journal of Adhesion and Adhesives 102, no. : 102643.

Short communication
Published: 01 April 2020 in Composites Communications
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ACS Style

Yunlong Jia; Bodo Fiedler. Tensile creep behaviour of unidirectional flax fibre reinforced bio-based epoxy composites. Composites Communications 2020, 18, 5 -12.

AMA Style

Yunlong Jia, Bodo Fiedler. Tensile creep behaviour of unidirectional flax fibre reinforced bio-based epoxy composites. Composites Communications. 2020; 18 ():5-12.

Chicago/Turabian Style

Yunlong Jia; Bodo Fiedler. 2020. "Tensile creep behaviour of unidirectional flax fibre reinforced bio-based epoxy composites." Composites Communications 18, no. : 5-12.