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Uday K Vaidya - One of the best experts on this subject based on the ideXlab platform.
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Colored inorganic-pigmented Long-Fiber thermoplastics:
Journal of Thermoplastic Composite Materials, 2013Co-Authors: Uday K Vaidya, K. Balaji Thattaiparthasarthy, Selvum Pillay, Shalmalee Vaidya, Haibin Ning, Dhruv BansalAbstract:Long-Fiber thermoplastic (LFT) composite materials are rapidly expanding in automotive, transportation, and recreational industry. Most of these materials are natural or black in color with a need for secondary painting of the manufactured products. Standard organic pigments and dyes are not stable above 250°C and degrade during processing. Alternatively, inorganic pigments are thermally stable to at least 800°C. High-performance inorganic pigments offer resistance to outdoor weathering, chemicals, and acids. However, in Fiber-reinforced composites, the pigment causes Fiber attrition and thereby shows reduction in strength. This work explores colored inorganic-pigmented LFT composites. The ability to integrate the color in the manufacturing steps eliminates the need for secondary painting. Pigment variables such as particle size, distribution, chemistry, and coatings have been investigated. The article presents the processing and performance envelopes of colored inorganic-pigmented LFTs in comparison with...
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characterization of fatigue behavior of Long Fiber reinforced thermoplastic lft composites
Materials Characterization, 2009Co-Authors: A Goel, Uday K Vaidya, K K Chawla, Nikhilesh Chawla, M KoopmanAbstract:Abstract Fatigue behavior of Long Fiber reinforced thermoplastic composites (polypropylene/20 vol.% E-glass Fiber) is presented in terms of stress – number of cycles to failure curves. Samples tested aLong Longitudinal direction showed a higher fatigue life than the transverse samples which can be explained by the preferential orientation of the Fibers aLong the Longitudinal direction developed during the processing. Fatigue life decreased with increase in frequency. Hysteretic loss and temperature rise were measured; they depended on the stress amplitude as well as the cyclic frequency. Long Fiber reinforced thermoplastic composite showed a lower temperature rise compared to unreinforced PP because Long Fiber reinforced thermoplastic has higher thermal conductivity than unreinforced PP and thus faster heat dissipation to the surroundings occur. The hysteretic heating also led to decrease in the modulus of Long Fiber reinforced thermoplastic as a function of number of cycles due to the softening of the matrix during fatigue cycling and depended on stress amplitude and frequency of the test.
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Characterization of fatigue behavior of Long Fiber reinforced thermoplastic (LFT) composites
Materials Characterization, 2009Co-Authors: A Goel, Uday K Vaidya, K K Chawla, Nikhilesh Chawla, M KoopmanAbstract:Abstract Fatigue behavior of Long Fiber reinforced thermoplastic composites (polypropylene/20 vol.% E-glass Fiber) is presented in terms of stress – number of cycles to failure curves. Samples tested aLong Longitudinal direction showed a higher fatigue life than the transverse samples which can be explained by the preferential orientation of the Fibers aLong the Longitudinal direction developed during the processing. Fatigue life decreased with increase in frequency. Hysteretic loss and temperature rise were measured; they depended on the stress amplitude as well as the cyclic frequency. Long Fiber reinforced thermoplastic composite showed a lower temperature rise compared to unreinforced PP because Long Fiber reinforced thermoplastic has higher thermal conductivity than unreinforced PP and thus faster heat dissipation to the surroundings occur. The hysteretic heating also led to decrease in the modulus of Long Fiber reinforced thermoplastic as a function of number of cycles due to the softening of the matrix during fatigue cycling and depended on stress amplitude and frequency of the test.
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Characterization of Long Fiber thermoplastic/metal laminates
Journal of Materials Science, 2008Co-Authors: R. R. Kulkarni, M. C. Koopman, Krishan Kumar Chawla, Uday K Vaidya, A. W. EberhardtAbstract:Long Fiber thermoplastic (LFT) composite/metal laminate (LML) is a hybrid composite consisting of alternate layers of metals such as aluminum and an LFT composite, which combines advantages from both the constituents. The LFT/Al laminates (LMLs) were processed by compression molding and were characterized for their Young’s modulus, mechanical strength, and low-velocity impact (LVI) properties. The average values of specific elastic modulus and specific tensile strength were approximately 20 GPa/(gcm−3) and 108.5 MPa/(gcm−3), respectively. Failure mechanisms included delamination between LFT composite and Al, Fiber fracture and pullout in LFT composite, and shear fracture of aluminum and LFT composite layers. Rule-of-mixtures (ROM) predictions of laminate properties in tension compared well with the experimental values. Specific perforation energy of the laminates determined by LVI tests was 7.58 J/(kgm−2), which is significantly greater than that of the LFT composite alone, 1.72 J/(kgm−2). Overall, the LML showed significant improvement in the properties as compared to the LFT composite.
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Design and Development of a Long Fiber Thermoplastic Bus Seat
Journal of Thermoplastic Composite Materials, 2006Co-Authors: Shane Bartus, Uday K Vaidya, Chad A. UlvenAbstract:Long Fiber thermoplastics (LFTs) are increasingly being used in automotive applications for front-ends, bumper beams, dashboards, and under body shields. They have a significant potential for mass-transit applications in buses, trucks, and railroad vehicles. The LFTs are processed with a thermoplastic matrix such as polypropylene (PP) or polyamide (PAI) reinforced with Long glass (or carbon, aramid, etc.) Fibers, with starting Fiber lengths >12 mm, through a pultrusion processing method. The LFT components are typically produced using extrusion-compression molding. In the present work, a bus seat was chosen as a candidate component to assess the viability of LFT technology to reduce weight and cost, without compromising performance over presently used designs. A conservative estimate of 43% weight reduction and 18% cost reduction per seat was predicted over presently implemented seat designs that contain a circumferential steel frame. Cadpress-Thermoplastic (EXPRESS) compression molding software for LFTs ...
Mark J Van Raaij - One of the best experts on this subject based on the ideXlab platform.
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Structure of the C-terminal head domain of the fowl adenovirus type 1 Long Fiber
Journal of General Virology, 2007Co-Authors: Pablo Guardado-calvo, Antonio L Llamas-saiz, Gavin C Fox, Patrick Langlois, Mark J Van RaaijAbstract:Avian adenovirus CELO (chicken embryo lethal orphan virus, fowl adenovirus type 1) incorporates two different homotrimeric Fiber proteins extending from the same penton base: a Long Fiber (designated Fiber 1) and a short Fiber (designated Fiber 2). The short Fibers extend straight outwards from the viral vertices, whilst the Long Fibers emerge at an angle. In contrast to the short Fiber, which binds an unknown avian receptor and has been shown to be essential to the invasiveness of this virus, the Long Fiber appears to be unnecessary for infection in birds. Both Fibers contain a short N-terminal virus-binding peptide, a slender shaft domain and a globular C-terminal head domain; the head domain, by analogy with human adenoviruses, is likely to be involved mainly in receptor binding. This study reports the high-resolution crystal structure of the head domain of the Long Fiber, solved using single isomorphous replacement (using anomalous signal) and refined against data at 1.6 A (0.16 nm) resolution. The C-terminal globular head domain had an anti-parallel β-sandwich fold formed by two four-stranded β-sheets with the same overall topology as human adenovirus Fiber heads. The presence in the sequence of characteristic repeats N-terminal to the head domain suggests that the shaft domain contains a triple β-spiral structure. Implications of the structure for the function and stability of the avian adenovirus Long Fiber protein are discussed; notably, the structure suggests a different mode of binding to the coxsackievirus and adenovirus receptor from that proposed for the human adenovirus Fiber heads.
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Structure of the C-terminal head domain of the fowl adenovirus type 1 Long Fiber.
The Journal of general virology, 2007Co-Authors: Pablo Guardado-calvo, Antonio L Llamas-saiz, Gavin C Fox, Patrick Langlois, Mark J Van RaaijAbstract:Avian adenovirus CELO (chicken embryo lethal orphan virus, fowl adenovirus type 1) incorporates two different homotrimeric Fiber proteins extending from the same penton base: a Long Fiber (designated Fiber 1) and a short Fiber (designated Fiber 2). The short Fibers extend straight outwards from the viral vertices, whilst the Long Fibers emerge at an angle. In contrast to the short Fiber, which binds an unknown avian receptor and has been shown to be essential to the invasiveness of this virus, the Long Fiber appears to be unnecessary for infection in birds. Both Fibers contain a short N-terminal virus-binding peptide, a slender shaft domain and a globular C-terminal head domain; the head domain, by analogy with human adenoviruses, is likely to be involved mainly in receptor binding. This study reports the high-resolution crystal structure of the head domain of the Long Fiber, solved using single isomorphous replacement (using anomalous signal) and refined against data at 1.6 A (0.16 nm) resolution. The C-terminal globular head domain had an anti-parallel beta-sandwich fold formed by two four-stranded beta-sheets with the same overall topology as human adenovirus Fiber heads. The presence in the sequence of characteristic repeats N-terminal to the head domain suggests that the shaft domain contains a triple beta-spiral structure. Implications of the structure for the function and stability of the avian adenovirus Long Fiber protein are discussed; notably, the structure suggests a different mode of binding to the coxsackievirus and adenovirus receptor from that proposed for the human adenovirus Fiber heads.
Vlastimil Kunc - One of the best experts on this subject based on the ideXlab platform.
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a model for Fiber length attrition in injection molded Long Fiber composites
Composites Part A-applied Science and Manufacturing, 2013Co-Authors: Jay H Phelps, Vlastimil Kunc, Ahmed Abd I Elrahman, Charles L. TuckerAbstract:Abstract Long-Fiber thermoplastic (LFT) composites consist of an engineering thermoplastic matrix with glass or carbon reinforcing Fibers that are initially 10–13 mm Long. When an LFT is injection molded, flow during mold filling degrades the Fiber length. Here we present a detailed quantitative model for Fiber length attrition in a flowing Fiber suspension. The model tracks a discrete Fiber length distribution at each spatial node. A conservation equation for total Fiber length is combined with a breakage rate that is based on buckling of Fibers due to hydrodynamic forces. The model is combined with a mold filling simulation to predict spatial and temporal variations in Fiber length distribution in a mold cavity during filling. The predictions compare well to experiments on a glass–Fiber/PP LFT molding. Fiber length distributions predicted by the model are easily incorporated into micromechanics models to predict the stress–strain behavior of molded LFT materials.
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Modeling Fatigue Damage in Long-Fiber Thermoplastics
2009Co-Authors: Ba Nghiep Nguyen, Vlastimil Kunc, Satish K BapanapalliAbstract:This paper applies a fatigue damage model recently developed for injection-molded Long-Fiber thermoplastics (LFTs) to predict the modulus reduction and fatigue lifetime of glass/polyamide 6,6 (PA6,6) specimens. The fatigue model uses a multiscale mechanistic approach to describe fatigue damage accumulation in these materials subjected to cyclic loading. Micromechanical modeling using a modified Eshelby-Mori-Tanaka approach combined with averaging techniques for Fiber length and orientation distributions is performed to establish the stiffness reduction relation for the composite as a function of the microcrack volume fraction. Next, continuum damage mechanics and a thermodynamic formulation are used to derive the constitutive relations and the damage evolution law. The fatigue damage model has been implemented in the ABAQUS finite element code and has been applied to analyze fatigue of the studied glass/PA6,6 specimens. The predictions agree well with the experimental results.
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Modeling of Low Velocity Impact Damage in Injection-Molded Long Fiber Composites
2009Co-Authors: Satish K Bapanapalli, Ba Nghiep Nguyen, Vlastimil KuncAbstract:Apart from increase in failure strength, increase in the impact resistance is one of the major reasons for the interest in Long-Fiber polymer composites for automotive structural applications. The in-house code EMTA has been adapted to accommodate dynamic problems. It combines with ABAQUS Explicit solver to model impact behavior of Long-Fiber thermoplastics. At the present stage, the model captures the elastic behavior of LFTs in a dynamic formulation that incorporates the Eshelby equivalent inclusion method, the Mori-Tanaka assumption and the Fiber orientation averaging technique. The effect of average Fiber length on the impact behavior of discontinuous Fiber composites has been studied with the aid of the preliminary model. Fiber lengths from short Fiber range to Long Fiber range were explored with Fiber orientation distributions from obtained from previous studies. The numerical examples indicate a slight improvement in the energy absorption capabilities of Long Fiber thermoplastics over short Fiber thermoplastics. Advanced impact models need to be incorporated into the current code to model impact behavior with greater accuracy.
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An Elastic-plastic Damage Model for Long-Fiber Thermoplastics
International Journal of Damage Mechanics, 2009Co-Authors: Ba Nghiep Nguyen, Vlastimil KuncAbstract:This article proposes an elastic-plastic damage model that combines micromechanical modeling with continuum damage mechanics to predict the stress— strain response of injection-molded Long-Fiber thermoplastics. The model accounts for distributions of orientation and length of elastic Fibers embedded in a thermoplastic matrix whose behavior is elastic-plastic and damageable. The elastic-plastic damage behavior of the matrix is described by the modified Ramberg—Osgood relation and the 3D damage model in deformation assuming isotropic hardening. Fiber/matrix debonding is accounted for using a parameter that governs the Fiber/matrix interface compliance. A linear relationship between this parameter and the matrix damage variable is assumed. First, the elastic-plastic damage behavior of the reference aligned Fiber composite containing the same Fiber volume fraction and length distribution as the actual composite is computed using an incremental Eshelby—Mori—Tanaka mean field approach. The incremental response ...
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prediction of the elastic plastic stress strain response for injection molded Long Fiber thermoplastics
Journal of Composite Materials, 2009Co-Authors: Ba Nghiep Nguyen, Satish K Bapanapalli, Vlastimil Kunc, Jay H Phelps, Charles L. TuckerAbstract:This article proposes a model to predict the elastic-plastic response of injection-molded Long-Fiber thermoplastics (LFTs). The model accounts for elastic Fibers embedded in a thermoplastic resin that exhibits the elastic-plastic behavior obeying the Ramberg-Osgood relation and J-2 deformation theory of plasticity. It also accounts for Fiber length and orientation distributions in the composite formed by the injection-molding process. Fiber orientation was predicted using an anisotropic rotary diffusion model recently developed for LFTs. An incremental procedure using Eshelby's equivalent inclusion method and the Mori-Tanaka assumption is applied to compute the overall stress increment resulting from an overall strain increment for an aligned-Fiber composite that contains the same Fiber volume fraction and length distribution as the actual composite. The incremental response of the latter is then obtained from the solution for the aligned-Fiber composite by averaging over all Fiber orientations. Failure during incremental loading is predicted using the Van Hattum-Bernado model that is adapted to the composite elastic-plastic behavior. The model is validated against the experimental stress-strain results obtained for Long-glass-Fiber/polypropylene specimens.
Amelia Lavinia Ricchiuti - One of the best experts on this subject based on the ideXlab platform.
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Temperature Gradient Sensor Based on a Long Fiber Bragg Grating and Time Waveform Analysis
Sensors, 2014Co-Authors: Amelia Lavinia Ricchiuti, David Barrera, Koji Nonaka, Salvador SalesAbstract:A novel sensor based on a 10 cm-Long Fiber Bragg grating and a simple scheme is proposed, dedicated to detect the position and distribution of a temperature gradient with a 1 mm spatial resolution.
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Long Fiber bragg grating sensor interrogation using discrete time microwave photonic filtering techniques
Optics Express, 2013Co-Authors: Amelia Lavinia Ricchiuti, David Barrera, Salvador Sales, Luc Thevenaz, J CapmanyAbstract:A novel technique for interrogating photonic sensors based on Long Fiber Bragg gratings (FBGs) is presented and experimentally demonstrated, dedicated to detect the presence and the precise location of several spot events. The principle of operation is based on a technique used to analyze microwave photonics (MWP) filters. The Long FBGs are used as quasi-distributed sensors. Several hot-spots can be detected aLong the FBG with a spatial accuracy under 0.5 mm using a modulator and a photo-detector (PD) with a modest bandwidth of less than 1 GHz. The proposed interrogation system is intrinsically robust against environmental changes.
Salvador Sales - One of the best experts on this subject based on the ideXlab platform.
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Temperature Gradient Sensor Based on a Long Fiber Bragg Grating and Time Waveform Analysis
Sensors, 2014Co-Authors: Amelia Lavinia Ricchiuti, David Barrera, Koji Nonaka, Salvador SalesAbstract:A novel sensor based on a 10 cm-Long Fiber Bragg grating and a simple scheme is proposed, dedicated to detect the position and distribution of a temperature gradient with a 1 mm spatial resolution.
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Long Fiber bragg grating sensor interrogation using discrete time microwave photonic filtering techniques
Optics Express, 2013Co-Authors: Amelia Lavinia Ricchiuti, David Barrera, Salvador Sales, Luc Thevenaz, J CapmanyAbstract:A novel technique for interrogating photonic sensors based on Long Fiber Bragg gratings (FBGs) is presented and experimentally demonstrated, dedicated to detect the presence and the precise location of several spot events. The principle of operation is based on a technique used to analyze microwave photonics (MWP) filters. The Long FBGs are used as quasi-distributed sensors. Several hot-spots can be detected aLong the FBG with a spatial accuracy under 0.5 mm using a modulator and a photo-detector (PD) with a modest bandwidth of less than 1 GHz. The proposed interrogation system is intrinsically robust against environmental changes.
