Cable Formulation Research Articles

A quasistatic ALE cable formulation for multibody systems applications

A quasistatic ALE cable formulation for multibody systems applications

Optimization of poly(vinyl chloride)-based cable formulation with higher K value for tensile properties

Optimization of poly(vinyl chloride)-based cable formulation with higher K value for tensile properties

A nodal position finite element model for fluid-structure interaction analysis of floating bodies with mooring

A numerical model based on the Nodal Position Finite Element Method (NPFEM) is proposed in this work for fluid-structure interaction (FSI) analysis of moored bodies subject to multiphase free surface flows. The semi-implicit CBS (Characteristic-Based Split) method is utilized here for discretization of the flow fundamental equations in the context of the Finite Element Method, where linear tetrahedral elements are adopted. Turbulence is analyzed using Large Eddy Simulation (LES) with the dynamic sub-grid scale model and the Level Set method is utilized for simulation of multiphase free surface flows. The structural system is modeled using a three-dimensional rigid body approach for the floating object, while the mooring is discretized using a geometrically nonlinear cable formulation based on the NPFEM. A partitioned coupling scheme is adopted for fluid-structure interaction analysis taking into account the fluid-structure and cable-structure couplings, where the flow equations are kinematically described employing an Arbitrary Lagrangean-Eulerian (ALE) formulation with a numerical scheme for mesh motion. The algorithms constituting the numerical model are verified first considering classical applications on fluid dynamics and FSI, in addition to applications involving the dynamic analysis of cables. Finally, problems involving floating bodies with and without mooring are simulated to demonstrate the applicability and accuracy of the proposed numerical model.

Study of an unknown PVC cable formulation by mechanical properties

PVC is a type of thermoplastic material which affected by heat due to the presence of chlorine and which is not used alone but with addition of additives such as stabilizers, plasticizers, fillers and others according to the required properties of the desired product based in suitable formulations. In this work many experiments were carried out to evaluate the additives and the type of PVC used on the formulation in cables application. The first experiments were to vary the amount of filler (calcium carbonate) and that ingredients such as PVC K67 resin, lubricant (stearic acid), stabilizer (tri-base lead sulfate), and plasticizer (Dioctyl phthalate) were constant in the formulation and then samples were tested for density, hardness, tensile strength, and sample burn test to determine the content of fillers or plasticizers. The results of the density test showed that it was 23.91wt% of the filler and in the hardness test, the plasticizers used were estimated at 52.61wt%. The tensile test results were 10.6 wt% of filler when the plasticizer value was 60wt% or 20wt% of filler with 65wt% of plasticizer weight. And it turned out that the unknown sample used PVC and high molecular weight such as pvck70-72 and not Pvck67 which we used in all experiments and the result of burning the sample gave 21.9% of the ash which is a filler. In the second experiments, the stabilizer was changed and the rest of the components were considered fixed, and the result was that the weight of the stabilizer was less than the lowest value used in the experiments 6wt% and finally. The study concluded that the sample used high molecular weight PVC, the filler percentage was 20wt%-23.9wt%, and the plasticizer was 52.61wt%-65.7wt%. This study shows that the proportions of the components of the PVC formulation can be estimated by studying the effect of fillers and heat stabilizers by using mechanical tests.

Study of an unknown PVC cable formulation by mechanical properties

Study of an unknown PVC cable formulation by mechanical properties

A varying-radius cable equation for the modelling of impulse propagation in excitable fibres.

In this study, we present a varying-radius cable equation for nerve fibres taking into account the varying diameter along the neuronal segments. Finite element neuronal models utilising the classical (fixed-radius) and varying-radius cable formulations were compared using simple and realistic morphologies under intra- and extracellular electrical stimulation protocols. We found that the use of the classical cable equation to model intracellular neural electrical stimulation exhibited an error of 17% in a passive resistive cable model with abrupt change in radius from 1 to 2 μm, when compared to the known analytical solution and varying-radius cable formulation. This error was observed to increase substantially using more realistic neuron morphologies and branching structures. In the case of extracellular stimulation however, the difference between the classical and varying-radius formulations was less pronounced, but we expect this difference will increase under more complex stimulation paradigms such as high-frequency stimulation. We conclude that for computational neuroscience applications, it is essential to use the varying-radius cable equation for accurate prediction of neuronal responses under electrical stimulation.

Numerical simulation of EN 50399 standard test – Calibration and validation of a numerical virtual test

Wires and cables have recently been included in the EN 13501-6 classification standard within the Construction Products Regulation (CPR). Thus they need to be tested according to the EN 50399 standard. It consists in a large scale test for classification of vertically mounted cables. This test represents a limit to the development of new flame retarded cable formulations because of time and material consuming. Moreover, all the developed formulations cannot be tested. A solution for the development and orientation tests phase could be to predict the fire behavior of cables inside the EN 50399 apparatus, thanks to CFD simulations carried out with the computational fluid dynamics code Fire Dynamics Simulator (FDS). Nevertheless, due to their particular geometries and the complex phenomenon cables undergo, it is difficult to simulate and predict how they perform in such large scale test.So a first step is to evaluate the ability of FDS to reproduce quantitative results in terms of gas temperatures, velocity and heat fluxes distribution inside the test apparatus and in the cables environment for further evaluation of their fire performances. A numerical model of the test facility without burning cables is developed and assessed.When experimental results are compared with numerical calculations, good agreement is found for gas temperature and heat flux. Temperatures with order of magnitude up to 1000 °C in front of the burner and up to 200°C are observed between 400 and 500 mm above the burner. For the thermocouples located 1.3 m and 2.6 m above the burner, the maximum gas temperature achieved are close to 100 °C. The proposed numerical model gives correct thermal loads in the vicinity of the ladder and the cables during calibration tests and can be used for further evaluation of combustible material on cables.

Isogeometric rotation-free bending-stabilized cables: Statics, dynamics, bending strips and coupling with shells

An isogeometric cable formulation is derived from a 3D continuum, where large-deformation kinematics and the St. Venant–Kirchhoff constitutive law are assumed. It is also assumed that the cable cross-sections remain circular, planar, and orthogonal to the cable middle curve during the deformation. The cable geometry representation reduces to a curve in 3D space, and, because only displacement degrees of freedom are employed, only membrane and bending effects are accounted for in the modeling. Torsion is neglected and bending is confined to an osculating plane of the curve. In the case structural loading and response are confined to a plane, the formulation is reduced to a 2D Euler–Bernoulli beam of finite thickness. Bending terms also stabilize the cable formulation in the presence of compressive forces. The resulting cable formulation is validated in the regime of linear and nonlinear statics, and nonlinear dynamics. The concept of bending strips is extended to the case of multiple cables, and cable-shell coupling is also investigated. The formulation is presented in sufficient mathematical detail for straightforward computer implementation.

Numerical simulation of dynamic characteristics of a cable-stayed aqueduct bridge

In this paper, a full-scale 3-D finite element model of the Jundushan cable-stayed aqueduct bridge is established with ANSYS Code. The shell, fluid, tension-only spar and beam elements are used for modeling the aqueduct deck, filled water, cables and support towers, respectively. A multi-element cable formulation is introduced to simulate the cable vibration. The dry (without water) and wet (with water) modes of the aqueduct bridge are both extracted and investigated in detail. The dry modes of the aqueduct bridge are basically similar to those of highway cable-stayed bridges. A dry mode may correspond to two types of wet modes, which are called the in-phase (with lower frequency) and out-of-phase (with higher frequency) modes. When the water-structure system vibrates in the in-phase/out-of-phase modes, the aqueduct deck moves and water sloshes in the same/opposite phase-angle, and the sloshing water may take different surface-wave modes. The wet modes of the system reflect the properties of interaction among the deck, towers, cables and water. The in-phase wet frequency generally decreases as the water depth increases, and the out-of-phase wet frequency may increase or decrease as the water depth increases.

Tin‐containing layered double hydroxides: Synthesis and application in poly(vinyl chloride) cable formulations

SUMMARYLayered double hydroxides (LDHs) and Sn‐containing LDHs have been synthesized using a co‐precipitation method, and the resulting products have been characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), Fourier‐transform infrared spectroscopy (FTIR) and Brunauer‐Emmett‐Teller(BET) surface area measurement, clearly showing that Sn‐containing LDH hybrids have been successfully prepared. TEM shows the ‘house‐of‐cards’ structure of the Sn‐LDHs produced, resulting from the edge‐to‐face interaction of the LDH layers. Higher tin levels lead to an additional magnesium hydroxystannate, MgSn(OH)6, (‘MHS’) phase that is present in the form of approximately 40‐nm cubic particles in an LDH/MHS hybrid structure. FTIR and XRD suggest that, at low levels of Sn, the Sn4+ may exist in the form of amorphous hydrated tin(IV) oxide rather than being incorporated into the LDH lattice. These powders have been compounded into poly(vinyl chloride) (PVC), and their fire performance has been evaluated using limited oxygen index and cone calorimeter techniques. Peak rate of heat release and smoke parameter can be reduced by 64% and 81%, respectively, when replacing 10 wt% of the primary ATH fire‐retardant filler by the synthesized Sn‐LDHs, while keeping the total fire‐retardant loading at 100 phr. Thermogravimetric analysis indicates that Sn‐LDH is an effective char promoter for PVC. Copyright © 2011 John Wiley & Sons, Ltd.

A novel method to prepare zinc hydroxystannate‐coated inorganic fillers and its effect on the fire properties of PVC cable materials

AbstractFire‐retardant (FR) properties, including limiting oxygen index, peak rate of heat release, and smoke parameter have been measured and compared for unfilled and filled polyvinyl‐chloride (PVC)‐based cable formulations, containing 15 wt% amounts of uncoated and zinc‐hydroxystannate (ZHS)‐coated magnesium hydroxide (MH) and calcium carbonate (CaCO3) fillers at the same addition level. Of the uncoated fillers, MH was more effective at lowering flammability than CaCO3. When the ZHS coating was applied to MH and CaCO3, CaCO3 became the most effective additive at lowering PVC flammability and smoke output. POLYM. ENG. SCI., 47:1163–1169, 2007. © 2007 Society of Plastics Engineers

Crosslinking of PVC formulations treated with UV light

AbstractTypical wire and cable formulations of plasticized Poly(vinyl chloride) were prepared with three different stabilizer systems: Ca/Zn (2:1 or 1:1) and dibasic lead phthalate. The mixtures contained trimethylolpropane trimethacrylate (TMPTMA) as crosslinking agent and a UV photoinitiator (Irgacure 819). Mixtures were dry‐blended, then roll‐milled and to finally hot‐pressed at 180°C to obtain sheets of 1 and 1.5 mm thickness. Small specimens (3 × 3 cm) were irradiated with UV light for up to 10 days while monitoring changes at different time intervals. The presence of TMPTMA in the samples, as expected, influenced the storage modulus (E′) and gel content percentage, specifically for the thinner samples. These results indicated that UV irradiation produced surface crosslinking. The samples with crosslinking agent also reached higher carbonyl index values. The Ca/Zn formulations showed higher mechanical properties with respect to the Pb ones, thus suggesting that during the stabilization period of the Ca/Zn mixtures, an effective crosslinking was promoted. Irregular behavior was observed during the last days of treatment for both types of formulations, thereby suggesting an optimum irradiation time for this procedure. J. VINYL. ADDIT. TECHNOL. 12:49–54, 2006. © 2006 Society of Plastics Engineers.

Radiation-induced modifications of PVC compounds stabilized with non-lead systems

The radiation crosslinking of polyvinyl chloride (PVC) formulated with two different stabilizer systems (Ca/Zn and dibasic lead phthalate) and trimethylolpropane trimethacrylate, a polyfunctional monomer, has been studied with the purpose of observing their behaviour and with the idea of replacing the lead stabilizer used in the typical wire and cable formulation for Ca/Zn systems. The compounds of PVC were irradiated by 60Co γ radiation at doses of 50, 75 and 100 kGy and two different atmospheres (argon and air). The dosimetry used to establish the irradiation times was carried out by both theoretical and experimental methods. The tensile test and gel measurements showed the highest values at 100 kGy although Young's Modulus showed that 75 kGy and argon atmosphere are optimum conditions for wire and cable formulations. The formulation with Ca/Zn stabiliser showed a very similar behaviour to the one made of lead, which, incidentally, produces high concentration of polyenes, in contrast to the Ca/Zn system.

Zinc hydroxystannate-coated metal hydroxide fire retardants: Fire performance and substrate-coating interactions

Fire retardant (FR) properties, including limiting oxygen index, peak rate of heat release and smoke parameter have been measured and compared for unfilled and filled polyvinyl-chloride (PVC) based cable formulations, containing various amounts of uncoated and zinc-hydroxystannate (ZHS)-coated alumina trihydrate (ATH) and magnesium hydroxide (MH) fillers. Uncoated ATH or MH proved to be efficient FR additives, but when coated with ZHS, further improvements were observed. ATH was more effective than MH in both uncoated and ZHS-coated forms. For a halogen-free ethylene-vinyl acetate (EVA) cable formulation, the content of vinyl acetate and loading of ZHS-coated ATH required to yield optimum FR properties was determined. The interaction between ATH substrate and ZHS coating was also studied by X-ray photoelectron spectroscopy and diffuse reflectance infrared Fourier-transform spectroscopy, using samples with ZHS-contents ranging from 1 to 15 wt%. An increase in the binding energies of the Zn 2p3/2 and Sn 3d5/2 peaks was found, together with alterations in the positions of the (Sn)O—H stretching bands. There was no evidence for condensation and the formation of Al—O—Sn bonds.

Study of the natural ageing of PVC insulation for electrical cables

The characterisation of high voltage cable insulation waste is addressed in an effort to determine their further utilisation either as feed in reprocessing or for the recovery of the energy and material content by pyrolysis. Electrically aged (18 years outdoors at 6–10 kV) polyvinyl chloride (PVC) cables were ground by mechanical or cryogenic procedures. The waste was studied in comparison with a PVC virgin resin and a PVC virgin formulation similar to that of the cables both in quantities of additives and structure of polymer. After successive extractions in acetone and benzene the base polymer and extracts were analysed by elemental analysis, GPC, viscometry, IR and 1H-NMR spectroscopy, TG, DSC, and several standard methods of plastic analysis (plasticizer absorption, static thermal stability, etc.). From the acetone extracted quantities and the plasticizer absorption measurements it appears that only 1–2% di-2-ethylhexylphthalate (DOP) was lost during the service-life of cables and most of the initial quantity remained in the cable composition so only a small addition is necessary for the reprocessing. The IR spectra of polymer extracted from electrical cable waste exhibit important changes concerning double bonds and carbonyl groups. The T g value is higher for the waste material indicating that it was rigidized due to the polyene fragments arising from partial dehydrochlorination. This is also supported by the viscometric and GPC measurements, the PVC from waste having a higher molecular weight than virgin PVC. Based on T g curves and static thermal stability the following order of thermal stability has been established: PVC waste jacket<PVC electrical cable waste<virgin PVC<PVC virgin cable formulation. One can conclude that PVC cable wastes have retained most of the characteristics required for reprocessing, but a higher level of stabilisers must be used to ensure the stabilisation of the deteriorated structure and compensate partial deactivation of the initial stabiliser system.

Application of one‐dimensional mechanical formulations to model the sagging behavior of a polymer sheet

AbstractThe deformation of a heated plastic sheet clamped on two opposite sides subject to sagging under its own weight was examined experimentally and then modeled using two separate one‐dimensional approaches based upon cable (membrane) and beam formulations. The cable formulation neglects both bending and shear deformation, but includes a generalized Maxwell viscoelastic constitutive model to capture the time‐dependent nature of sheet sag. The resulting equations are integrated using a Runge‐Kutta technique and solved via a shooting method. The beam formulation is based upon the Timoshenko theory and thus includes shear deformation along with the flexural contributions. A finite element method is developed from application of the principle of virtual work for the beam written in curvilinear coordinates in order to include the effects of finite deformation. A generalized Maxwell model is again employed to account for the time‐dependent material response. In both formulations, the method of reduced variables is used to describe the variation of material response with temperature. The effect of temperature and thermal relaxation is included. The particular case of a styrenic material is discussed in detail.

Non‐lead stabilizer systems for PVC wire and cable extrusion (an update)

AbstractRecent introduction of non‐lead stabilizer systems to the wire and cable industry have shown a rising interest in these new products. Based on new regulations on the usage of lead stabilizers and the difficulties of disposing of vinyl containing lead in regular landfills, the interest to replace these products is in fact very high. The objective of this paper is to show what non‐lead systems are currently available and where their strengths and weaknesses are. Test results of laboratory studies are presented comparing environmentally and physiologically acceptable Ca/Zn, Mg/Zn, and Ca/Al/Zn stabilizer systems to conventional lead compounds in typical wire and cable formulations. In addition, data are presented on products that are already in use commercially.