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van Kuijk, J.J.A. (author), Alderliesten, R.C. (author), Benedictus, R. (author)This paper discusses the appropriateness of crack length as a reference dimension for fatigue damage. Current discussion on short crack versus long crack data is still divided between various approaches to model small crack growth. A proper physical explanation of the probable cause of the apparent differences between short crack and long...journal article 2018
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Quan, H. (author), Alderliesten, R.C. (author), Benedictus, R. (author)Plastic energy dissipation is inevitable during fatigue crack growth. There have been previous attempts reported in literature to correlate the plastic dissipated energy (dW/dN) to fatigue crack growth rate (da/dN). However, at a given dW/dN, the da/dN changes with the ratio of minimum and maximum loads, known as the stress ratio. This paper...journal article 2018
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Tapeinos, I. (author), Rajabzadeh, Aydin (author), Zarouchas, D. (author), Groves, R.M. (author), Koussios, S. (author), Benedictus, R. (author)In the field of cryogenic storage, the medium inside the pressure vessel is in a liquid state and thus is incompressible. Therefore the storage tank should be designed in a way, that makes the best possible use of the available space within an aircraft. A composite-overwrapped pressure vessel (COPV) based on intersecting spheres (multi-sphere)...conference paper 2018
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Zhao, T. (author), Broek, C.A. (author), Palardy, G. (author), Villegas, I.F. (author), Benedictus, R. (author)The research in this paper is an essential part of a bigger effort on developing robust sequential ultrasonic welding of multi-spot welded joints in thermoplastic composites. It mainly focused on assessing the impact of the changes in boundary conditions on the welding process and whether it could be circumvented by using an appropriate...journal article 2018
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Wang, W. (author), Rans, C.D. (author), Benedictus, R. (author)Mechanically fastened joints are susceptible to the presence of multiple-site damage (MSD) cracks in the critical fastener row. Different from the MSD growth in joints consisting of metallic substrates, the two coupled metal crack growth and interfacial delamination propagation failure mechanisms in Fibre Metal Laminates (FMLs) make the...journal article 2018
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Köhler, F. (author), Jongbloed, B.C.P. (author), Morgado Martins Filipe, T.M. (author), Herrmann, Axel (author), Villegas, I.F. (author), Benedictus, R. (author)The increasing use of fibre-reinforced plastics in the aerospace industry leads to challenges in joining these materials. The traditionally used mechanical fasteners introduce damage when used in composites by disrupting the fibres. However, thermoplastic composites allow for fusion bonding processes to join parts. Ultrasonic welding has shown...conference paper 2018
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Eleftheroglou, N. (author), Zarouchas, D. (author), Loutas, Theodoros (author), Alderliesten, R.C. (author), Benedictus, R. (author)A novel framework to fuse structural health monitoring (SHM) data from different in-situ monitoring techniques is proposed aiming to develop a hyper-feature towards more effective prognostics. A state-of-the-art Non-Homogenous Hidden Semi Markov Model (NHHSMM) is utilized to model the damage accumulation of composite structures, subjected to...journal article 2018
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Zhao, Y. (author), Alderliesten, R.C. (author), Zhou, Zhengong (author), Fang, Guodong (author), Zhang, Jiazhen (author), Benedictus, R. (author)In general, a finite width correction to stress intensity factor (SIF) is required in the fatigue crack growth. The finite width correction factor can be explained physically from the energy point of view. It is assumed that the finite width correction factor primarily constitutes an energy correction factor, i.e. it corrects the applied load...journal article 2018
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Eleftheroglou, N. (author), Zarouchas, D. (author), Loutas, Theodoros (author), Mansouri, Sina Sharif (author), Georgoulas, George (author), Karvelis, Petros (author), Nikolakopoulos, George (author), Benedictus, R. (author)This paper examines diagnostics and prognostics of Lithium-Polymer (Li-Po) batteries for unmanned aerial vehicles (UAVs). Several discharge voltage histories obtained during actual indoor flights constitute the training data for a data-driven approach, utilizing the Non-Homogenous Hidden Semi Markov model (NHHSMM). NHHSMM is a suitable candidate...conference paper 2019
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Eleftheroglou, N. (author), Zarouchas, D. (author), Benedictus, R. (author)The procedure of fatigue damage accumulation in composite structures is still unknown and depends on several parameters such as type and frequency of loading, stacking sequence and material properties. Additionally, the nonhomogeneous and anisotropic nature of composites result to a stochastic activation of the different failure mechanisms and...conference paper 2019
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Abouhamzeh, M. (author), Sinke, J. (author), Benedictus, R. (author)Distortions and residual stresses are predicted in Fibre Metal Laminates (FMLs) under large deformations. A new modelling procedure is presented for small and large deformation analysis of thermo-viscoelastic problems of orthotropic materials. The material model is implemented in a finite element package which can be used for cure and/or...journal article 2019
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Abouhamzeh, M. (author), Sinke, J. (author), Benedictus, R. (author)This paper reviews predictive models developed for the development of residual stresses and shape distortions during the manufacturing of thermoset polymeric/composite materials. Different sources that produce residual stresses and shape changes in the laminated panels are described and reviewed. An overview is presented on the...review 2019
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Jongbloed, B.C.P. (author), Teuwen, Julie J.E. (author), Villegas, I.F. (author), Benedictus, R. (author)Continuous ultrasonic welding is a new promising high-speed joining technique for thermoplastic composites. At the moment no straightforward method exists to find an optimum welding speed to easily obtain high strength joints. However, for static ultrasonic welding a systematic approach is available. Therefore, the aim of this study is to...conference paper 2019
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Tapeinos, I. (author), Rajabzadeh, Aydin (author), Zarouchas, D. (author), Stief, Malte (author), Groves, R.M. (author), Koussios, S. (author), Benedictus, R. (author)This study focuses on the understanding of the thermal and structural behavior of an innovative Type IV multi-spherical composite-overwrapped pressure vessel through an experimental assessment that consists of hydrostatic testing at ambient conditions and pressure cycling with a cryogenic medium (LN<sub>2</sub>). During hydro-burst testing at...journal article 2019
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Kupski, J.A. (author), Teixeira De Freitas, S. (author), Zarouchas, D. (author), Benedictus, R. (author)The goal of this study is to investigate new designs of composite bonded joints in order to improve their strength under tensile loading. Multiple stacked overlaps are compared with single overlap designs. The concept of multiple stacking is well known as ply-interleaving technique for co-curing dissimilar materials. For a secondary bonding...conference paper 2019
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Kupski, J.A. (author), Teixeira De Freitas, S. (author), Zarouchas, D. (author), Camanho, P. P. (author), Benedictus, R. (author)Single lap bonded joints with four different composite adherend stacking sequences were tested and numerically simulated. The aim was to evaluate the effect of the layups on the quasi-static tensile failure of the bonded joints. The study shows that increasing the adherends bending stiffness postpones the damage initiation in the joint....journal article 2019
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Ochôa, Pedro (author), Groves, R.M. (author), Benedictus, R. (author)The successful utilization of guided wave-based structural health monitoring (SHM) for detailed quantitative diagnostic of damage in composite aircraft primary structures depends on the excitation frequency, geometry, and positioning of the piezoelectric transducers. This study proposes a novel methodology to consistently define those parameters...journal article 2019
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Zhao, Yuan (author), Alderliesten, R.C. (author), Wu, Zengwen (author), Zhou, Zhengong (author), Fang, Guodong (author), Zhang, Jiazhen (author), Benedictus, R. (author)Finite-width-correction factors (FWCF) are required for GLARE to accurately predict fatigue crack growth using linear elastic fracture mechanics. As demonstrated in earlier work, these factors effectively correct for the change in specimen compliance, which in GLARE relates to intact fibre layers and the formation of delaminations between...journal article 2019
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Ochôa, Pedro (author), Villegas, I.F. (author), Groves, R.M. (author), Benedictus, R. (author)This article presents research about the propagation of ultrasonic guided waves in ultrasonically welded thermoplastic composite joints. The goal of the study was to understand the effect of weld manufacturing defects on guided wave transmission across the joint. Triangular energy-directors integrated into the lower composite adherends...journal article 2019
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Ewald, Vincentius (author), Groves, R.M. (author), Benedictus, R. (author)In our previous work, we demonstrated how to use inductive bias to infuse a convolutional neural network (CNN) with domain knowledge from fatigue analysis for aircraft visual NDE. We extend this concept to SHM and therefore in this paper, we present a novel framework called DeepSHM which involves data augmentation of captured sensor signals...conference paper 2019