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Nurettin Arslan - One of the best experts on this subject based on the ideXlab platform.
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expansion of plastic zone and residual stresses in the Thermoplastic Matrix laminated plates 0 θ 2 with a rectangular hole subjected to transverse uniformly distributed load expansion
Computational Materials Science, 2009Co-Authors: Tamer Ozben, Nurettin ArslanAbstract:Abstract The present paper focused on the understanding of elastic stress, residual stress and plastic zone growth in layers of stainless steel woven fiber-reinforced Thermoplastic Matrix composite laminated plates with rectangular hole by using the finite element method (FEM) and first-order shear deformation theory for small deformations. Moreover, the computer program was developed for small elasto-plastic stress analysis of laminated plates. The laminated plate with rectangular hole consists of four reinforced layers bonded symmetrically and antisymmetrically in [0°/θ°]2 configuration. Various applied distributed loads with different layer orientation angles and rectangular hole dimensions were used for obtaining corresponding variation of residual stresses and the expansions of the plastic regions. It was observed that the intensity of the stress components and plastic zones were the maximum near corners of the rectangular hole.
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prediction of the elastic plastic behavior of Thermoplastic composite laminated plates 0 θ 2 with square hole
Composite Structures, 2002Co-Authors: Nurettin Arslan, Mehmet Celik, Nuray ArslanAbstract:Abstract An elastic–plastic stress analysis in symmetric and antisymmetric woven-reinforced polyethylene Thermoplastic Matrix composite is studied by using finite element method (FEM) and first-order shear deformation theory for small deformations. The Thermoplastic Matrix composite layer reinforced by long stainless steel fiber is manufactured by using molds under the action of 15 MPa pressure and heating up to 160°C. The laminated plate ([0°/θ°]2) with square hole consists of four composite layers and bonded symmetrically and antisymmetrically. Each layer with constant thickness is meshed into 64 elements and 288 nodes with simply supported and in-plane loading conditions. The loading and reinforcement angle are gradually increased from the yield point of the plate. The load steps increased as 0.01 MPa at each iteration are selected as 100, 200, 300 and 400. The expansions of plastic zones and residual stresses are obtained according to load steps and orientation angles. The intensity of the residual stress components is maximum near the square hole.
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Elasto-Plastic Behavior of Thermoplastic Matrix Plates with Rectangular Hole
Journal of Reinforced Plastics and Composites, 2000Co-Authors: Nurettin ArslanAbstract:The elasto-plastic stress analysis of the Thermoplastic Matrix plates with rectangular hole is carried out by using finite elements. A two-dimensional finite element computer program is developed for elasto-plastic stress analysis. Isoparametric quadratic element with nine nodes is used with Lagrange polynomial as an interpolation function. The spreads of the plastic zones and variations of the residual stresses are obtained in different orientation angles and loads. It is shown that the path around the hole location can be designed to decrease the stress concentrations. The results are presented in diagrams and compared with some of the relevant studies in the literature.
Alfonso Maffezzoli - One of the best experts on this subject based on the ideXlab platform.
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lay up and consolidation of a composite pipe by in situ ultrasonic welding of a Thermoplastic Matrix composite tape
Materials, 2018Co-Authors: Riccardo Dellanna, Francesca Lionetto, Francesco Montagna, Alfonso MaffezzoliAbstract:In this work, the potential of preformed Thermoplastic Matrix composite tapes for the manufacturing of composite pipes by filament winding assisted by in situ ultrasonic welding was evaluated. Unidirectional tapes of E-glass-reinforcedamorphous poly (ethylene terephthalate) were laid up and consolidated in a filament winding machine that was modified with a set-up enabling ultrasonic welding. The obtained composite specimens were characterized by means of morphological and dynamic mechanical analysis as well as void content evaluation, in order to correlate welding parameters to composite properties.
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finite element modeling of continuous induction welding of Thermoplastic Matrix composites
Materials & Design, 2017Co-Authors: Francesca Lionetto, Silvio Pappada, Giuseppe Buccoliero, Alfonso MaffezzoliAbstract:Abstract Continuous induction welding for Thermoplastic Matrix composites requires an accurate modeling of the temperature distribution in the laminates, depending on the electromagnetic field. In this work, a transient three-dimensional finite element (FE) model was developed in order to study the heat transfer phenomena, and melting and crystallization in the welding area during the continuous induction welding of carbon fiber reinforced Poly(ether ether ketone) (CF/PEEK) laminates. The multiphysics problem was solved by coupling electromagnetic and heat transfer equations considering Matrix melting and crystallization behavior. The model was able to simulate the continuous process along a linear path at a constant speed. The computed temperatures were in good agreement with experimental measurements. Several numerical simulation were used for selecting a processing window as a function of coil speed and current, for the welding of CF/PEEK joints. The results of welding experiments were evaluated by single lap shear tests and morphology characterization of the welded interfaces and fracture surfaces.
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fabrication of a Thermoplastic Matrix composite stiffened panel by induction welding
Aerospace Science and Technology, 2015Co-Authors: Silvio Pappada, Andrea Salomi, Jeanette Montanaro, Alessandra Passaro, Antonio Caruso, Alfonso MaffezzoliAbstract:Abstract In this work, the experimental and numerical study of induction welding devoted to the fabrication of a composite stiffened panel, representative of a typical aeronautic sub-component, is presented. A Thermoplastic Matrix composite, polyphenylene sulfide (PPS) reinforced with carbon fibers, is used. The influence of the fundamental process parameters, such as generator power, distance between induction coil and laminate, coil geometry and laminate lay-up on the heating rate and the heat distribution was analyzed applying finite element simulations. The model was validated through the comparison of experimental and model results obtained in static experiments. Optimized parameters for composites welding were found out, and the mechanical properties of the welded joints were evaluated by single lap shear and pull-off experiments. Finally, a prototype panel made of a flat laminate stiffened with four “L” shaped stringers is fabricated by continuous induction welding, exploiting modeling and experimental results. A C-scan of the panel was also performed.
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selective reinforcement of lldpe components produced by rotational molding with Thermoplastic Matrix pultruded profiles
Composites Part B-engineering, 2014Co-Authors: Antonio Greco, G Romano, Alfonso MaffezzoliAbstract:Abstract This work is aimed to study the use of pultruded profiles for the selective reinforcement of linear low density polyethylene (LLDPE) parts produced by rotational molding. A preliminary screening on different types of pultruded profiles was performed, highlighting the relevance of adhesion to LLDPE in order to prevent debonding of the reinforcing pultruded profiles. As expected, high density polyethylene (HDPE) Matrix pultruded tapes are characterized by a very high adhesion to rotomolded LLDPE. Therefore, HDPE Matrix pultruded tapes, fastened on the inner surface of the mold, are incorporated into LLDPE during rotomolding. Plate bending tests performed on reinforced rotomolded plates and pressurization tests performed on the box shaped prototypes showed a significant increase of the stiffness with a negligible amount of reinforcement and increase of the weight of the component.
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spring in angle as molding distortion for Thermoplastic Matrix composite
Composites Science and Technology, 2008Co-Authors: Andrea Salomi, T Garstka, Kevin Potter, Antonio Greco, Alfonso MaffezzoliAbstract:Abstract In this work, the spring-in angle behavior of a U-channel shaped Thermoplastic Matrix laminate is studied. The consolidation of the U-channel shaped profile having two different corner radii took place in an autoclave. Spring-in angle was measured at room temperature, after cooling in the autoclave, and during subsequent heating at different temperatures and after final cooling to room temperature. Different thermally induced spring-in angle behaviors were observed for the two inner radii of U-specimen. Thermal expansion coefficients in the through the thickness and in-plane directions were measured. Experimental spring-in angle data were then compared with a differential model derived from the Radford model. Some differences between the model results and experimental spring-in data were observed. The differences observed between the two radii and between experimental and model results were attributed to the existence of fibers distortion at the corner, leading to significant fibers misalignment and wrinkling. Consequently, the Radford model was modified to account for the increase of thermal expansion coefficient in the through the thickness direction. Results showed a better agreement with experimental data. Finally, the difference observed in the spring-in angle before and after heating of the composite indicates the relevance of non-thermoelastic effects in Thermoplastic Matrix composites.
Nuray Arslan - One of the best experts on this subject based on the ideXlab platform.
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prediction of the elastic plastic behavior of Thermoplastic composite laminated plates 0 θ 2 with square hole
Composite Structures, 2002Co-Authors: Nurettin Arslan, Mehmet Celik, Nuray ArslanAbstract:Abstract An elastic–plastic stress analysis in symmetric and antisymmetric woven-reinforced polyethylene Thermoplastic Matrix composite is studied by using finite element method (FEM) and first-order shear deformation theory for small deformations. The Thermoplastic Matrix composite layer reinforced by long stainless steel fiber is manufactured by using molds under the action of 15 MPa pressure and heating up to 160°C. The laminated plate ([0°/θ°]2) with square hole consists of four composite layers and bonded symmetrically and antisymmetrically. Each layer with constant thickness is meshed into 64 elements and 288 nodes with simply supported and in-plane loading conditions. The loading and reinforcement angle are gradually increased from the yield point of the plate. The load steps increased as 0.01 MPa at each iteration are selected as 100, 200, 300 and 400. The expansions of plastic zones and residual stresses are obtained according to load steps and orientation angles. The intensity of the residual stress components is maximum near the square hole.
Zoltan Major - One of the best experts on this subject based on the ideXlab platform.
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thermomechanical viscoelastic analysis of woven reinforced Thermoplastic Matrix composites
Composite Structures, 2016Co-Authors: Martin Machado, Umut D Cakmak, Imre Kallai, Zoltan MajorAbstract:Abstract The behaviour of four different woven-reinforced Thermoplastic-Matrix laminates was analysed using dynamic mechanical thermal analysis. The investigation was focussed on a temperature range relevant for applications in the automotive industry, namely between −30 °C and 80 °C. Storage modulus master curves were built for each material in three different orientations. Dependence of the tensile and shear moduli on frequency was described using Prony series. This description was then introduced in a phenomenological transversely isotropic viscoelastic material model. Shift factors determined in the frequency domain were converted to time domain and used in the proposed constitutive model. The model was implemented in Abaqus/Standard using a user material subroutine (UMAT) and validated by comparing relaxation and creep predictions with experimental data.
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analysis of the thermomechanical shear behaviour of woven reinforced Thermoplastic Matrix composites during forming
Composites Part A-applied Science and Manufacturing, 2016Co-Authors: Martin Machado, Michael Fischlschweiger, Luca Murenu, Zoltan MajorAbstract:Abstract Shear behaviour of a glass fibre/polypropylene composite is characterized over a wide range of strain rates and forming temperatures using the bias extension test. A temperature- and rate-dependent material model is here introduced to describe the observed behaviour. The model is based on a continuous approach and formulated considering a stress objective derivative based on the warp and weft yarns rotation. The effects of temperature and strain rate on the shear behaviour are analysed via bias extension test simulations. Temperature change in the sheet during forming was measured. This data is used to model cooling during forming. Isothermal and transient forming simulations were performed in order to show the effects of temperature and forming speed on the obtained shear angle distribution. It was found that at low forming speeds the assumption of isothermal forming is not valid anymore since the cooling of the sheet affects the shear behaviour.
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a rate dependent non orthogonal constitutive model for describing shear behaviour of woven reinforced Thermoplastic composites
Composites Part A-applied Science and Manufacturing, 2016Co-Authors: Martin Machado, Michael Fischlschweiger, Zoltan MajorAbstract:Abstract A rate dependent constitutive model for woven reinforced Thermoplastic Matrix composites at forming temperatures is proposed in this work. The model is formulated using a stress objective derivative based on the fibre rotation. Nonlinear shear behaviour is modelled as a polynomial function and the rate dependence is described using a Cowper–Symonds overstress law formulated in terms of shear angle rate. The model parameters are determined by means of bias extension tests. The applicability of the material model is validated through a forming experiment.
R Ozcan - One of the best experts on this subject based on the ideXlab platform.
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elastic plastic stress analysis in Thermoplastic composite laminated plates under in plane loading
Composite Structures, 2000Co-Authors: R OzcanAbstract:Abstract In this paper, an elastic–plastic stress analysis is carried out in a Thermoplastic composite laminated plate for in-plane loading. Thermoplastic Matrix (LDFE, F.2.12 ) and steel fibers are used to produce the composite plates by using moulds. Mathematical formulation is given for the elastic–plastic stress analysis of a laminated plate for small deformations. Yield points and stresses are obtained for symmetric and antisymmetric laminated plates with or without a hole. Residual stresses in plates are given in tables. The expansion of plastic zones is illustrated for 100, 150 and 200 loading steps. Yield points and the expansion of plastic zones are compared for different plates.
