| 1. |
- Al-Maqdasi, Zainab, 1986-, et al.
(författare)
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Wood fiber composites with added multifunctionality
- 2018
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Ingår i: ECCM 2018 - 18th European Conference on Composite Materials. - : Applied Mechanics Laboratory. - 9781510896932
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Konferensbidrag (refereegranskat)abstract
- Graphene nanoplatelets (GNPs) are used to enhance the mechanical properties and functionality of wood plastic composite (WPC) targeting applications such as de-icing or anti-icing and fast thermal diffusivity. The GNPs are integrated into neat polymer using a masterbatch containing functionalized graphene by melt compounding through a twin-screw extruder without the use of any coupling agent or compatibilizer. The same manufacturing process (melt compounding) but with the use of compatibilizer is employed to produce WPC with nano-doped matrix. The effect of different GNP loadings (up to 15 wt.%) on morphology, crystallinity, mechanical and thermal conductivity of the nanocomposites and the WPCs was investigated. It was found that both strength and modulus of nanocomposites, in tension and bending, were increased with the addition of GNPs. With the aid of MAPE compatibilizer WPCs show higher flexural strength and modulus than neat polymer. GNP has marginal effect on the flexural stress but further increases flexural modulus of WPC. The preliminary results related to the thermal conductivity of studied materials indicate that the incorporation of GNP may be beneficial for faster and more uniform heat distribution in WPC.
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| 2. |
- Al-Ramahi, Nawres, 1980-, et al.
(författare)
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FEM analysis of stresses in adhesive single-lap joints with non-linear materials under thermo-mechanical loading
- 2018
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Ingår i: ECCM 2018 - 18th European Conference on Composite Materials. - : Applied Mechanics Laboratory. - 9781510896932
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Konferensbidrag (refereegranskat)abstract
- This study presents comprehensive numerical stress analysis in the adhesive layer of a single-lap joint subjected to various loading scenarios (mechanical and thermal loading). For this purpose numerical model (finite element method) with novel displacement coupling conditions able to correctly represent monoclinic materials (off-axis layers of composite laminates) has been developed. This model includes nonlinear material model and geometrical nonlinearity is also accounted for. The effect of thermal residual stresses (in adhesive) is analysed for various methods of manufacturing of single lap joint. The sequences of application of thermal and mechanical loads for the analysis of the thermal residual stresses in joints are proposed. It is shown that the most common approach used in many studies of linear superposition of thermal and mechanical stresses works well only for linear materials and produces wrong results if material is non-linear. The present study demonstrates suitable method to apply combined thermal and mechanical loads to get accurate stress distributions. Based on the analysis of these stress distributions the conclusions concerning the effect of the thermal residual stresses on peel and shear stress concentrations are made. The comparison between effect of thermal stresses in case of the one-step and two-step joint manufacturing techniques is made
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| 3. |
- Cameron, Christopher J., et al.
(författare)
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A rapid method for residual cure stress analysis for optimization of cure induced distortion effects
- 2018
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Ingår i: ECCM 2018 - 18th European Conference on Composite Materials. - : Applied Mechanics Laboratory. - 9781510896932
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Konferensbidrag (refereegranskat)abstract
- Within this paper, the authors present a rapid method for residual cure stress analysis. The method uses a high-fidelity path-dependent cure kinetics analysis subroutine implemented in Abaqus to calibrate values for a linear elastic analysis. The path dependent model accounts for the tool-part interaction, forming pressure, and the changing composite modulus during the rubbery region of matrix curing during an arbitrary cure cycle. Results are used to calculate equivalent lamina-wise coefficients of thermal expansion (CTE) in 3 directions for a linear temperature analysis. The goal is to accurately predict distortions for large complex geometries with a single linear temperature load as rapidly and accurately as possible for use in an optimization framework. A carbon-epoxy system is studied. Simple parts are manufactured using unbalanced layups and out-of-autoclave methods. The resulting distortions are scanned with a 3D scanner and compared with simulation results for the same geometries. Further, a more complicated part is studied to compare the two methods using complex geometry. Results are presented and the accuracy and limitations of the rapid simulation method are discussed with particular focus on implementation in a numerical optimization framework.
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| 4. |
- Costa, Sergio, 1987, et al.
(författare)
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Validation and improvements of a mesoscale finite element constitutive model for fibre kinking growth
- 2019
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Ingår i: ECCM 2018 - 18th European Conference on Composite Materials. - : European Society for Composite Materials. - 9781510896932
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Konferensbidrag (refereegranskat)abstract
- The present work is focused on the computational challenges and further verification and validation of an advanced fibre kinking model. This model was previously developed by the authors and implemented in a Finite Element (FE) code with a mesh objective formulation. The previous validation in terms of comparison with an analytical and a micromechanical model is herein extended to also encompass FE simulations of longitudinal compression in multiaxial stress states. In addition, numerical improvements have been added to the model targeting its computational efficiency and stability in order to handle multiaxial stress states and large structures.
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| 5. |
- Grammatikos, Sotirios, 1985, et al.
(författare)
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Recycling and re-purposing decommisioned construction polymer composites for construction applications
- 2018
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Ingår i: ECCM 2018 - 18th European Conference on Composite Materials. - : Applied Mechanics Laboratory. - 9781510896932
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Konferensbidrag (refereegranskat)abstract
- Fibre reinforced polymer composites (FRPs) are being increasingly used in aerospace and automotive applications due to their high specific mechanical properties. The construction industry has also started taking advantage of the potential of FRPs for both structural and non-structural purposes. The result of this remarkable absorption of FRPs within the worldwide production market, has led to an immense increase of decommissioned thermoset-matrix components. Nowadays, the majority of the decommissioned FRP components are recovered energy-wise through incineration or simply discarded in landfills around the globe. Within the framework of this paper, we present a solution for the extension of the service life of decommissioned FRP components. Decommissioned electrical insulation FRP pipes were granulated and incorporated as fillers within both cementitious and polymer matrix composites. The effect of FRP granulates on the mechanical performance of cementitious and polymer matrix composites is examined to determine the maximum granulate-filler fraction that can be recycled without compromising the mechanical performance and manufacturing process.
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| 6. |
- Olsson, Robin
(författare)
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Fibre lock-up and other mechanisms at large fibre rotations, and their effect on axial compression of composites.
- 2018
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Ingår i: Proc. 18th European Conf. on Composite Materials.. - : European Society for Composite Materials. - 9781510896932
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Konferensbidrag (refereegranskat)abstract
- This paper studies the sequence of fibre kinking, the fibre lock-up and the subsequent constitutive behaviour. The conditions governing these phenomena are discussed with focus on the conditions for fibre lock-up. Lower bounds for the fibre lock-up angle a and the kink band angle b are derived purely from geometrical conditions for 3D arrays of fibres, with the aim to define the termination of fibre kinking in homogenized material models for FE analysis. It is concluded that the limit of the lock-up angle is 90° for low fibre volume fractions, decreases to about 50° for fibre volume fractions common in high performance composites, and reaches zero for fully packed fibres.
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| 7. |
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| 8. |
- Zhang, Emma, 1985, et al.
(författare)
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Electrical monitoring of concrete using a novel structural sensor based on conductive cementitious mortar
- 2020
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Ingår i: ECCM 2018 - 18th European Conference on Composite Materials. - 9781510896932
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Konferensbidrag (refereegranskat)abstract
- This paper presents the development of a durable structural sensor based on cement-mortar modified with graphene and other carbon-based fillers. The purpose of the structural sensor is to indirectly monitor curing and service performance of concrete via electrical resistivity measurements. Electrical resistivity is an efficient parameter which can non-destructively capture intrinsic structural features of cementitious materials. The developed structural sensor is used to record electrical resistivity as a durability indicator during the whole service life of the concrete structure. To date, performance monitoring systems usually fail in the long-run before the failure of the actual monitored structure. The proposed sensor is embeddable in the interrogated structure and ensures sustainable consolidation with appropriate physico-chemical adherence and mechanical interlocking. This allows the monitoring system to surpass the expected service life of the parent concrete. Within this on-going work, the effects of different concentrations of carbon fillers on the electrical properties of cementitious mortars are reported. After an initial investigation to select the appropriate synthesis, the ability of the sensor to monitor the development of resistivity during setting and hardening was tested and the results are presented herein. Finally, the durability of the sensor was tested via electrical stability measurements under freeze-thaw cycles.
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