The development of residual strains and stresses is critical to manufacture composite structures with the required dimensional stability and mechanical performance. This work uses Fiber Bragg Grating (FBG) sensors to monitor strain build-up in carbon fiber composites with a polyurethane (PU) matrix designed for high production volume applications. The PU matrix presents an initially low viscosity combined with a fast cure reaction, which makes it adequate to very short processing cycles. FBG sensors were incorporated into PU-matrix composites manufactured by vacuum assisted resin transfer molding (VARTM). The measured strains were compared with those obtained with different benchmark epoxy-matrix composites and with those obtained through micromechanical finite element simulations. Results showed that most of the residual strains were built-up during cool-down from the post-curing temperature and that stresses in the PU-matrix composites were comparable to those obtained for epoxies with similar T-g. (C) 2015 Elsevier Ltd. All rights reserved.
#1Marc Waris(Ecole nationale supérieure des mines de Saint-Étienne)H-Index: 1
#2Pierre-Jacques Liotier(Ecole nationale supérieure des mines de Saint-Étienne)H-Index: 13
Last. Sylvain Drapier(Ecole nationale supérieure des mines de Saint-Étienne)H-Index: 20
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Fiber Bragg gratings provide accurate and non-intrusive strain sensors. They can be embedded into fibrous preforms to deliver real-time information on ongoing processes. The possibility of using the strain-induced birefringence of the fiber Bragg gratings to extract information on the effective strain state of the composite at the end of the process has already been demonstrated. This effect can be used to estimate the residual strain field in composites manufactured by resin transfer molding. T...
Composites based on thermosetting resin and reinforcement fibers present generally unwanted residual internal stresses inherent to their elaboration process. In this article, different curing experiments of thermosets (isothermal and anisothermal) were monitored using optical fiber Bragg grating (FBG) sensors and thermocouples, to assess the cure-induced strains. A thermokinetic model evaluates the degree of conversion of the resin. At the onset of stress transfer to the optical fiber, the degre...
Current applications of carbon fibre reinforced plastics (CFRP) can be found mostly in sectors where their use is not principally cost-driven and which have limited production volumes, such as aerospace and sports cars. In order to achieve a step-change in the application of high-performance composites in larger-volume applications, new materials systems are needed that combine very short production cycle times with performance that meets automotive requirements. The EU-FP 7-project HIVOCOMP is ...
#1M. Lai(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 5
#2John Botsis(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 37
Last. Joël Cugnoni(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 26
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Abstract The hydrothermal ageing of glass/epoxy interface is investigated using an experimental–numerical approach on cylindrical epoxy specimens with centrally located optical fibers. A 24 mm long Bragg grating sensor is inscribed on the optical fiber and used to monitor strains along the fiber, due to processing and subsequent ageing in water at 50 °C. The distributed strains are used to: (a) evaluate the residual strain field developed during processing, employing a parametric finite element ...
Last. Luigi Torre(University of Perugia)H-Index: 42
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Abstract The cure kinetics and chemorheology of a highly reactive poly(urethane-isocyanurate) was characterized by DSC and parallel plate rheometry. The cure kinetics were modeled with a modified autocatalytic approach. The relationship between the transition temperature ( T g ) of the urethane and isocyanurate networks as a function of conversion was obtained with DSC analysis. Even at low curing temperatures ( T T > 90 °C), the parallel plate configuration was not suitable to resolve how the v...
#1Luis P. Canal(UPM: Technical University of Madrid)H-Index: 11
#2Carlos González(UPM: Technical University of Madrid)H-Index: 42
Last. Javier LLorca(UPM: Technical University of Madrid)H-Index: 73
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Abstract The fracture behavior parallel to the fibers of an E-glass/epoxy unidirectional laminate was studied by means of three-point tests on notched beams. Selected tests were carried out within a scanning electron microscope to ascertain the damage and fracture micromechanisms upon loading. The mechanical behavior of the notched beam was simulated within the framework of the embedded cell model, in which the actual composite microstructure was resolved in front of the notch tip. In addition, ...
#1Javier LLorca(UPM: Technical University of Madrid)H-Index: 73
#2Carlos González(UPM: Technical University of Madrid)H-Index: 42
Last. Luis P. Canal(UPM: Technical University of Madrid)H-Index: 11
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A bottom-up, multiscale modeling approach is presented to carry out high-fidelity virtual mechanical tests of composite materials and structures. The strategy begins with the in situ measurement of the matrix and interface mechanical properties at the nanometer-micrometer range to build up a ladder of the numerical simulations, which take into account the relevant deformation and failure mechanisms at different length scales relevant to individual plies, laminates and components. The main featur...
#1Robert A. Witik(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 4
#2Jérôme Payet(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 12
Last. Jan-Anders E. Månson(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 68
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Life cycle assessment (LCA) and manufacturing focused life cycle costing are used to evaluate the potential advantages of composites in automotive applications. The life cycle costs and environmental performance of several suitable lightweight polymer composites are quantified and compared against magnesium and steel for a representative component. The results indicate that weight reduction will not always lead to improved environmental performance. Materials offering high weight savings such as...
A comprehensive understanding of the development of residual strains in composite processing is essential to manufacture high quality composite parts. In this paper, the use of fibre Bragg grating (FBG) optical sensors was investigated to measure in situ the build-up of the process-induced strains in composite panels manufactured by resin transfer moulding. The FBG sensors, embedded in the composite laminate, successfully measured the evolution of the composite in-plane strains due to the temper...
The effect of fiber, matrix and interface properties on the in-plane shear response of carbon-fiber reinforced epoxy laminates was studied by means of a combination of experiments and numerical simulations. Two cross-ply laminates with the same epoxy matrix and different carbon fibers (high-strength and high-modulus) were tested in shear until failure according to ASTM standard D7078, and the progressive development of damage was assessed by optical microscopy in samples tested up to different s...
Abstract null null The numerical modelling and simulation of empirical cure rate models presented for the non-isothermal resin transfer moulding curing process cycle. The nth order model, Kamal and Sourour’s (K & S) model and their modified forms used to study the efficacy of Comsol multi-physics simulator without adding any user defined program. The appropriate value of mould temperature selected from the isothermal curing simulation of nth order model. The transient variation of degree of cure...
Abstract This study presents an incremental variational formulation (IVF) for the thermo-mechanical problem of resin products subjected to curing, for which a dual dissipation potential (DDP) for the cure state is originally derived in conjunction with that for viscoelasticity. Following the thermodynamically consistent formulation for the time evolution equation of the degree of cure (DOC) of a thermosetting resin and the linear viscoelastic law, we derive these DDPs by way of Legendre-Fenchel ...
#2Michael Sandberg(DTU: Technical University of Denmark)H-Index: 5
Last. Remko Akkerman(UT: University of Twente)H-Index: 28
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Abstract This study presents a detailed material characterization study of a pultrusion specific polyurethane resin system. Firstly, the chemical behaviour was characterized by utilizing differential scanning calorimetry. The cure kinetics was fitted well to an autocatalytic cure kinetics model with Arrhenius temperature dependency. The resin system did not show any inhibition time. Then, the viscosity evolution was observed using a rheometer. From these measurements, the gelation point was esti...
#2Hangil You(SNU: Seoul National University)H-Index: 3
Last. Gun Jin Yun(SNU: Seoul National University)H-Index: 21
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This paper proposes a stochastically coupled thermo-chemical and viscoelastic model and provides new insights from comparisons of the cure-induced residual stresses and distortions between various ...
Last. Carlos González(UPM: Technical University of Madrid)H-Index: 42
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Abstract In this paper, novel resin frontal flow monitoring electrically resistive sensors made of reinforced continuous carbon fibers and manufactured by composite additive manufacturing (AM) are examined. For such manufacture, two adjacent and parallel fiber yarns made with carbon-fiber embedded in the polymer matrix were deposited by using a 3D printer system. These flexible flow sensors were made of two nylon wall layers, had a fixed separating distance between conductive carbon filament and...
#1Anxin Ding(TUM: Technische Universität München)H-Index: 9
#2Jihui Wang(WUT: Wuhan University of Technology)H-Index: 15
Last. Shuxin Li(UoB: University of Bristol)H-Index: 13
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Abstract This paper aims to understand formation mechanism of the process-induced distortions in the L-shaped composite parts by analytical solutions. To this end, an analytical solution for the total spring-in of L-shaped composite parts is derived by defining the total spring-in as the integrated process-induced distortions in the flange and corner components in combination with shear-lag theory. The new solution, together with previously proposed analytical solution for the corner spring-in o...
Last. Yishou Wang(Ha Tai: Xiamen University)H-Index: 14
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The excellent properties of advanced composite materials provide great opportunities for making industrial structures large-scale and intelligent. Liquid composite molding process is suitable for m...
#2Gergely Hegedus(BME: Budapest University of Technology and Economics)H-Index: 2
Last. Tibor Czigány(BME: Budapest University of Technology and Economics)H-Index: 33
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This article examines the use of fiber Bragg grating sensors for cure monitoring purposes in resin transfer molding processes. Within a resin transfer molding test series a thermoset epoxy-amine re...
Abstract This article investigates the interest of a novel promising approach, dealing with the use of an in-situ piezoelectric (PZT) disk to monitor the whole manufacturing process of a glass fiber/polyester Polymer-Matrix Composite (PMC) plate using the Liquid Resin Infusion (LRI) technique. The real-time in-situ Process Monitoring (PM) is conducted using the electrical signature (capacitance) variation of the embedded PZT transducer, which has never been done so far in the literature for such...
