Plastic Shell Research Articles

Kinetic studies on the pyrolysis of plastic waste using a combination of model-fitting and model-free methods.

In this work, the pyrolysis behavior of plastic waste-TV plastic shell-was investigated, based on thermogravimetric analysis and using a combination of model-fitting and model-free methods. The possible reaction mechanism and kinetic compensation effects were also examined. Thermogravimetric analysis indicated that the decomposition of plastic waste in a helium atmosphere can be divided into three stages: the minor loss stage (20-300°C), the major loss stage (300-500°C) and the stable loss stage (500-1000°C). The corresponding weight loss at three different heating rates of 15, 25 and 35 K/min were determined to be 2.80-3.02%, 94.45-95.11% and 0.04-0.16%, respectively. The activation energy (Ea) and correlation coefficient (R2) profiles revealed that the kinetic parameters calculated using the Friedman and Kissinger-Akahira-Sunose method displayed a similar trend. The values from the Flynn-Wall-Ozawa and Starink methods were comparable, although the former gave higher R2 values. The Eα values gradually decreased from 269.75 kJ/mol to 184.18 kJ/mol as the degree of conversion (α) increased from 0.1 to 0.8. Beyond this range, the Eα slightly increased to 211.31 kJ/mol. The model-fitting method of Coats-Redfern was used to predict the possible reaction mechanism, for which the first-order model resulted in higher R2 values than and comparable Eα values to those obtained from the Flynn-Wall-Ozawa method. The pre-exponential factors (lnA) were calculated based on the F1 reaction model and the Flynn-Wall-Ozawa method, and fell in the range 59.34-48.05. The study of the kinetic compensation effect confirmed that a compensation effect existed between Ea and lnA during the plastic waste pyrolysis.

Fabrication of hoop-wound glass fiber reinforced plastic cylindrical shells using filament winding machine

Glass Fiber Reinforced Plastic (GFRP) composites are playing an important role in the commercial industries like aerospace, marine and automotive, due to its notable material properties over metals. Development of these GFRPs for complex structures is really a challenging task owing to its heterogeneous and anisotropic nature. The present work is an attempt to develop an experimental setup to produce Hoop wound GFRP cylindrical shells using filament winding process. A constant mandrel speed of 45 revolutions per minute and glass fiber tension of 20 N is maintained during hoop winding process. The achieved samples had geometry of 140 mm length, 102 mm internal diameter and 2 mm thickness, which can fulfils the ASTM standards of transverse tensile and compressive tests.

Investigation of hardness characteristics of waste plastics and egg shell powder reinforced polymer composite by stirring route

This research work was done to find out the feasibility of reinforcement of the waste products into polymer matrix to enhance mechanical properties. In this work, the waste plastics and the wasted egg shells are made into particulates and powders respectively and mixed to the epoxy polymer resin and made into a hybrid composite. In this work, rather than using the traditional layup methods like hand layup or spray layup, the stirring method is followed. As the reinforcements are in particulates and powder form, the stirring process is followed to obtain uniform mixing and dispersion throughout the composite. The reinforcements are added in fixed proportions proposed by Taguchi’s design through MINITAB software. After manufacturing the composites as per the proposed design, the specimens from each combination are tested for its hardness as per the standards. Then the results are optimized to find out the best combination with high hardness values. The composite with 30 wt% inclusions of waste plastics and 15 wt% inclusions of egg shells generate maximum hardness.

Experimental Studies of the Parameters of the Contact Problem in the Design of Plastic Tube Concrete Structures

The article presents numerical studies of the stress-strain state of the centrally compressed short plastic-concrete-tubal vertical constructions (PCT). The authors experimentally obtained and analyzed the effect of friction on the boundary between the layers of the concrete core and the plastic tube on the stress-strain state of the PCT vertical constructions. The need to carry out these studies is associated with a deficiency of theoretical and numerical studies of this phenomenon, including for the traditional pipe concrete in a steel tube. In this regard, mathematical modeling and the creation of engineering methods for calculating the PCT based on the study of the factual joint operation of the concrete core and the cylindrical plastic shell has significant scientific potential. The calculations and experimental analysis demonstrated the validity with engineering accuracy of using the mathematical model of a short PCT column for engineering calculations and structural analysis. It has been established that the use of an analytical model makes it possible to investigate the influence of the variation of the physical and mechanical characteristics properties of the materials of the core and tube of the PCT on the parameters of the stress-strain state design and to carry out a rational design of the PCT elements in the structures of civil and industrial buildings with reference to the materials actually used widely represented in the market.

On the response of Foam filled hat-stiffened CFRP shells under axial compression: experiments and FE modelling

A generic quasi-static experimental and finite element procedures have been presented in this paper aimed at improving the energy absorption capabilities of Carbon Fiber reinforced Plastics (CFRP) shell structures bonded with foam-filled hat-stiffeners. Typical monocoque aircraft structures fabricated from cylindrical fuselage with longitudinal stringers offers significant increase in load resistance under compression loading environments. Foam is a structural material which provides extra skin assistance with high bending stiffness and resistance towards buckling under compression and shear loading. The response of CFRP shell structures viz. Unstiffened and Polyurethane (PU) foam filled hat-stiffened under quasi-static axial compression were experimentally investigated in this paper. The experimental results for the CFRP shell structures were compared with the Finite Element Analysis (FEA) counterparts. Based upon the experimental and FEA investigations, it has been asserted that foam filled hat-stiffened CFRP shell structures are better than the unstiffened counterparts in terms of energy absorption and collapse load.

ИССЛЕДОВАНИЕ ПРОЧНОСТИ КОНТАКТА ПЛАСТИКОВОЙ ТРУБЫ И БЕТОНА ПРИ РАСЧЕТЕ ПЛАСТИКОТРУБОБЕТОННЫХ КОНСТРУКЦИЙ

This article presents numerical studies of the stress-strain state of centrally compressed short plastic-tube-concrete (PTC) cylindrical cores, having experimentally obtained and analyzed the influence of the tangential friction forces at the boundary of the concrete core and plastic shell layers on the stress-strain state of the PTC core under the assumption of elastic work of the core materials and shell. The need for these studies is associated with a lack of theoretical and numerical studies of the influence of tangential friction forces on the stress-strain state of this type of structural elements, including the classical solution with a steel shell. In this regard, mathematical modeling and the creation of engineering methods for calculating the PTC based on the study of the actual joint work of the concrete core and the cylindrical plastic shell has significant scientific potential. The performed calculations demonstrated the relevance with engineering accuracy of using the mathematical model of a short PTC rack for engineering calculations and structural analysis of the structure. It has been established that the use of an analytical model allows us to study the effect of variations in the physical and mechanical characteristics of the materials of the core and shell of the PTC on the parameters of the stress-strain state of the structure and to rationally design the PTC elements in the construction of civil and industrial buildings with reference to the widely used materials market.

Volume-aware design of composite molds

We propose a novel technique for the automatic design of molds to cast highly complex shapes. The technique generates composite, two-piece molds. Each mold piece is made up of a hard plastic shell and a flexible silicone part. Thanks to the thin, soft, and smartly shaped silicone part, which is kept in place by a hard plastic shell, we can cast objects of unprecedented complexity. An innovative algorithm based on a volumetric analysis defines the layout of the internal cuts in the silicone mold part. Our approach can robustly handle thin protruding features and intertwined topologies that have caused previous methods to fail. We compare our results with state of the art techniques, and we demonstrate the casting of shapes with extremely complex geometry.

Tungsten filled 3D printed field shaping devices for electron beam radiation therapy

PurposeElectron radiotherapy is a labor-intensive treatment option that is complicated by the need for field shaping blocks. These blocks are typically made from casting Cerrobend alloys containing lead and cadmium. This is a highly toxic process with limited precision. This work aims to provide streamlined and more precise electron radiotherapy by 3D using printing techniques.MethodsThe 3D printed electron cutout consists of plastic shells filled with 2 mm diameter tungsten ball bearings. Five clinical Cerrobend defined field were compared to the planned fields by measuring the light field edge when mounted in the electron applicator on a linear accelerator. The dose transmitted through the 3D printed and Cerrobend cutouts was measured using an IC profiler ion chamber array with 6 MeV and 16 MeV beams. Dose profiles from the treatment planning system were also compared to the measured dose profiles. Centering and full width half maximum (FWHM) metrics were taken directly from the profiler software.ResultsThe transmission of a 16MeV beam through a 12 mm thick layer of tungsten ball bearings agreed within 1% of a 15 mm thick Cerrobend block (measured with an ion chamber array). The radiation fields shaped by ball bearing filled 3D printed cutout were centered within 0.4 mm of the planned outline, whereas the Cerrobend cutout fields had shift errors of 1–3 mm, and shape errors of 0.5–2 mm. The average shift of Cerrobend cutouts was 2.3 mm compared to the planned fields (n = 5). Beam penumbra of the 3D printed cutouts was found to be equivalent to the 15 mm thick Cerrobend cutout. The beam profiles agreed within 1.2% across the whole 30 cm profile widths.ConclusionsThis study demonstrates that with a proper quality assurance procedure, 3D-printed cutouts can provide more accurate electron radiotherapy with reduced toxicity compared to traditional Cerrobend methods.

Progress on observations of interspecies ion separation in inertial-confinement-fusion implosions via imaging x-ray spectroscopy

We report on the analyses of x-ray-imaging spectroscopy data from experiments to study interspecies ion separation in direct-drive inertial-confinement-fusion experiments on the Omega laser facility. This is a continuation of recent, related research [S. C. Hsu et al., Euro Phys. Lett. 115, 65001 (2016); T. R. Joshi et al., Phys. Plasmas 24, 056305 (2017)]. The targets were argon (Ar)-doped, deuterium (D2)-filled spherical plastic shells of varying D2-Ar relative and total gas pressures. We used a time- and space-integrated spectrometer, streaked crystal spectrometer, and up to three time-gated multi-monochromatic x-ray imagers (MMIs) fielded along different lines of sight to record x-ray spectral features obtained from the implosions. The MMI data were recorded between first-shock convergence and slightly before the neutron bang time. We confirm the presence of interspecies ion separation as reported in our recent work. Extensions to the previous work include (a) the inclusion of shell mix in the data analysis, which slightly changes the amount of inferred species separation, (b) observation of species separation closer to the neutron bang time, and (c) fielding of the particle x-ray temporal diagnostic (PXTD) [H. Sio et al., Rev. Sci. Instrum. 87, 11D701 (2016)] to infer the relative timing between the neutron bang time and peak x-ray emission. Experimentally inferred species separation is compared with radiation-hydrodynamic simulations that include a multi-ion-species transport model.

Radiometric Characterization of a Water-Based Conical Blackbody Calibration Target for Millimeter-Wave Remote Sensing

In this paper, we present the design and radiometric characterization of a water-based conical blackbody calibration target to be applied as a precise reference source in laboratories and for the accurate calibration of ground-based microwave instruments. The concept of aqueous blackbody targets circumvents the conflict between the electromagnetic and thermal properties of traditional calibration target designs. The temperature controllable target consists of a conical low loss plastic shell, which has been manufactured using a stereolithography three-dimensional printer to define the water–air interface. An advanced exponential profile of the shell is used to compensate the comparatively high refractive index of water and to obtain a high emissivity. Simulations and active measurements of the coherent backscattering S11 have been performed verifying its excellent electromagnetic properties. Furthermore, radiometric measurements at 110 GHz demonstrate the outstanding thermal performance at various target temperatures between 10 and 60 °C. The differences between the brightness temperature and the water temperature are measured to be less than 40 mK and therefore significantly smaller in comparison to traditional calibration targets. In addition, the measured baseline ripples in the spectra caused by the water-based calibration target are small compared to established blackbody concepts.

Research on the Crashworthiness of Regular Centurion 2M Barrier Based on the Arbitrary Lagrange-Euler Method

In this study, the crash-worthiness of a regular Centurion 2M barrier, which is a type of portable water-filled barrier (PWFB), is evaluated under different collision conditions. A numerical model of the regular Centurion 2M barrier, consisting of a plastic shell and water, was developed and validated. The validity of the numerical model is demonstrated by comparisons to experimental results. During the establishment of the finite element numerical model, the ALE (Arbitrary Lagrange-Euler) method was used to solve the problem of the fluid-structure interaction of the PWFB system. This model can be extended to a series of impact cases including an actual pick-up truck. Impact cases set six collision conditions according to different collision speeds and angles. The dynamic response of the collision between the pick-up truck and the PWFB process was investigated. From the analysis, we find that the greater the collision angle is, the greater the impact is on the collision result. According to the actual accident collision angle, setting the collision angle above 50° is satisfactory in most situations. In addition, a regular Centurion 2M barrier is just suitable for use on roads when the speed of vehicles is 20 km/h or less.

Thermal treatment of flame retardant plastics: A case study on a waste TV plastic shell sample

In this work, the combustion and pyrolysis characteristics of a waste TV plastic shell sample were investigated using a powerful Thermogravimetric-Fourier Infrared Spectrum-Mass Spectrum (TG-FTIR-MS) technique. The decomposition mechanisms of plastic waste and fate of bromines in both thermal processes were probed as well. The TG analysis revealed that the combustion rate was larger than that of pyrolysis at temperature of 456 °C below, whereas it decreased at temperature of 456–605 °C. As a result, the total weight loss was equivalent at temperature of 605 °C for both processes. The FTIR analysis indicated the plastic combusted vigorously at 300–500 °C and 800–900 °C. As a comparison, it decomposed drastically at 300–400 °C and 500–900° in pyrolysis. The MS analysis showed that the release of brominated products HBr, CH3Br, C2H5Br, C3H5Br, C3H7Br and C3H5BrO increased with an increase of temperature and reached maximum at 400–600 °C in both thermal processes. The release intensities of larger molecules C6H5Br, C6H5BrO and C6H4Br2 were in the descending order of C6H5Br > C6H4Br2 > C6H5BrO. It was not significant in the evolved products and decomposition pathway for both thermal processes. The entire decomposition of TV plastic shell sample could be divided into three stages, taking account of the evolved products. The backbone in acrylonitrile butadiene styrene resin and tetrabromobisphenol A first broke at 350 °C below, resulting in the form of 2-bromophenol, styrene, acrylonitrile and polybutadiene. Subsequently, the resulted 2-bromophenol debrominated forming HBr, which further reacted with hydrocarbons resulting in various brominated derivates. In addition, many small molecules, including CO2, CO and CH4 were generated in this stage. Further increasing temperature to 550 °C above, larger brominated derivates decomposed and smaller molecules predominated.

Multi-species plasma transport in 1D direct-drive ICF simulations

A multi-species plasma ion transport model has been added to the adaptive mesh refinement radiation hydrodynamics code, xRage, to include kinetic transport effects when the particle distributions are near Maxwellian, with deviations proportional to a Knudsen number smaller than one. The model is first verified against self-similar solutions reported previously for the pressure equilibrium case, and next shown to be relatively insensitive to the choice of equation of state for the ions. Simulations are then used to examine Inertial Confinement Fusion dynamics in a 1D spherical geometry characteristic of an Omega implosion with a plastic (CH) shell containing a deuterium-tritium (DT) fuel, and with an added heavy ion impurity, argon. Even in this simplified 1D geometry, several interesting results are apparent. Ion stratification occurs similarly to that reported previously in purely kinetic simulations. The hydrogen in the plastic shell is transported radially inward, carried with the main drive shock, and thus migrates away from the C ions. The fuel D and T ions show the expected stratification with an increase in the lighter species concentration during the shock implosion and a reversal, with heavier species concentrations enhanced after shock expansion from the center. This stratification during burn yields different burn weighted ion temperatures, Ti, for the reactions, Ti[DD] < Ti[DT] < Ti[TT], consistent in their ordering with experiments. The mix widths per ion, measured where concentrations fall to 10% of their interfacial value, are evaluated as a function of time, and these are seen to be significant (of order 10 μm) even at early times, well before the main shock converges and before the shell deceleration. The 1D geometry may be a reasonable approximation for this early time mix and implies that this transport may play a role in reducing or modifying the instabilities driven by initial perturbations, ablation, and Rayleigh-Taylor unstable deceleration. An apparent depletion of the heavier ions seen at the incoming ion shock front warrants further investigation.

Development of Computed Tomography Head and Body Phantom for Organ Dosimetry

Introduction: Quality assurance in Computed tomography (CT) centers in developing countries are largely hindered by the unavailability of CT phantoms. The development of a local CT phantom for the measurement of organ radiation absorbed dose is therefore requisite. Material and Methods: Local CT phantoms were designed to meet the standard criteria of 32 cm diameter for body, 16 cm diameter for head, and 14 cm in length respectively. The outer plastic shell was made using poly (methyl methacrylate [PMMA]) sheet. The developed CT phantoms were validated against a standard phantom. Radiation absorbed dose was determined by scanning the setup with the same protocol used for the standard phantom. The local phantoms were then verified for organ radiation absorbed dose measurement using bovine tissues. The set up was CT-scanned, and Hounsfield units (HU) for bovine tissues were obtained. Results: There was no significant difference between the local and standard head phantoms (P=0.060). Similarly, no difference was noted between the local and standard body phantoms (P=0.795). The percentage difference in volume CT dose index (CTDIvol) between the body (local and standard) phantoms was higher than that for the head phantoms. There were no significant differences in HU between bovine and human brain, liver, kidney and lung tissues (P=0.938). Conclusion: The local phantoms showed good agreement with the standard ones. The developed phantoms can be used for CT organ radiation absorbed dose measurement in radiology departments in Nigeria.

Numerical Simulation of the Effect of Deformation Rates on the Dynamic Strength of GFRP Cylindrical Shells

A technique for the numerical analysis of nonlinear dynamic deformation and progressive failure of cylindrical glass-fiber plastic shells is developed with account of their strain-rate-dependent strength characteristics. The kinematic model of deformation of a layer package is based on a nonclassical theory of shells. The geometrical relations are constructed using the simplest quadratic variant of nonlinear elasticity theory. The relationship between the stress and strain tensors in a composite macrolayer is established on the basis of Hooke’s law for an orthotropic body, with account of volatility of the stiffness and strength characteristics of the multilayer package due to a local failure of some elementary layers of the composite and the strain-rate dependence of strength characteristics. An energy-consistent resolving system of dynamics equations for composite cylindrical shells is obtained as a result of minimization of the functional of total energy of the shell as a three-dimensional body. The numerical method for solving the initial boundary-value problem is based on an explicit variationaldifference scheme. The reliability of the technique developed was confirmed by a satisfactory agreement of calculation results with experimental data. For different shell reinforcement structures, qualitative differences in the character and size of failure zones were found, which were calculated by the model considering the strain-rate dependence of strength or their constancy.

Buckling and free vibration study of variable and constant-stiffness cylindrical shells

The ability to steer carbon fibre tapes, varying the tow angle, can widen the designs possibilities of cylindrical shells that are one of the main components of aerospace structures. This research presents experimental and numerical investigation of two carbon fibre reinforced plastic cylindrical shells – a cylinder with conventional layup made of unidirectional prepreg and a variable-stiffness cylinder manufactured by applying fibre placement technology. The shells were tested in compression until buckling and later subjected to a vibration analysis. Load-shortening curves and buckling shapes were acquired during the compression tests, while the natural frequencies and the mode shapes were measured during the vibration tests. Both tests provide a useful data set of the mechanical response of the cylinders which can be applied for further validation of models. The acquired experimental results were compared to a simple, approximated numerical model of the variable-stiffness cylinder showing good correlation with the test results.

Features of selecting a composite material for metal-composite high-pressure bottles

The paper considers matters of selecting a composite material as a part of metal-composite high-pressure bottles to be used in aero-space engineering. It is shown that glass-reinforced plastic, which is the most used now for these purposes, in combination with a steel liner favors the growth of low-cycle fatigue and corrosive cracking of materials under conditions of manufacturing and operating. It is shown that characteristics of metal-composite bottles can be improved by using high-strength and high-modulus carbon-fiber-reinforced plastic as a material of the load-bearing shell. The results of creating high-efficient superlight metal-composite bottles with the load-bearing carbon-reinforced plastic shell and the thin-walled welded stainless steel liner have been presented.

Iron X-ray Transmission at Temperature Near 150 eV Using the National Ignition Facility: First Measurements and Paths to Uncertainty Reduction

Discrepancies exist between theoretical and experimental opacity data for iron, at temperatures 180–195 eV and electron densities near 3 × 1022/cm3, relevant to the solar radiative-convective boundary. Another discrepancy, between theory and helioseismic measurements of the boundary’s location, would be ameliorated if the experimental opacity is correct. To address these issues, this paper details the first results from new experiments under development at the National Ignition Facility (NIF), using a different method to replicate the prior experimental conditions. In the NIF experiments, 64 laser beams indirectly heat a plastic-tamped rectangular iron-magnesium sample inside a gold cavity. Another 64 beams implode a spherical plastic shell to produce a continuum X-ray flash which backlights the hot sample. An X-ray spectrometer records the transmitted X-rays, the unattenuated X-rays passing around the sample, and the sample’s self-emission. From these data, X-ray transmission spectra are inferred, showing Mg K-shell and Fe L-shell X-ray transitions from plasma at a temperature of ~150 eV and electron density of ~8 × 1021/cm3. These conditions are similar to prior Z measurements which agree better with theory. The NIF transmission data show statistical uncertainties of 2–10%, but various systematic uncertainties must be addressed before pursuing quantitative comparisons. The paths to reduction of the largest uncertainties are discussed. Once the uncertainty is reduced, future NIF experiments will probe higher temperatures (170–200 eV) to address the ongoing disagreement between theory and Z data.

Using a 2-shock 1D platform at NIF to measure the effect of convergence on mix and symmetry

We describe the use of a robust new 1-D like implosion platform at the National Ignition Facility [G. H. Miller et al., Opt. Eng. 43, 2841 (2004)] to study the effect of convergence on mix and shape. Previous experiments suggest that nuclear yields and ion temperature degrade with increased convergence [M. D. Cable et al., Phys. Rev. Lett. 73, 2316 (1994)] due to enhanced perturbation growth and mix, but little has been reported on the distortion of the shape with time. The 2-shock platform was developed [S. F. Khan et al., Phys. Plasmas 23, 042708 (2016)] to maintain a high degree of sphericity during the whole implosion phase and has a thick, uniformly doped (1% Si) plastic CH shell to minimize the effect of mixing due to hydrodynamic feed-through from the outer ablator surface. An inner layer of deuterated plastic (CD) and hydrogen-tritium (DT) gas fill allows for the measurement of DT neutrons produced by the mix between the gas and ablator. DD neutrons provide information about the hot, unmixed CD region. By changing the fill gas density while keeping the capsule diameter, ablator thickness, and Au hohlraum conditions fixed, the x-ray hot spot convergence ratio was varied from 14 to 22. We find that the atomic mix (DT yield) grows linearly as a function of convergence, but since Tion changes as well, it does not necessarily mean that the amount or extent of mix grows linearly as well. We also find the DD yield, which is a measurement of the shell heating, saturates above a certain convergence.

Effects of the Plastic of the Realistic GeePS-L2S-Breast Phantom.

A breast phantom developed at the Supelec Institute was interrogated to study its suitability for microwave tomography measurements. A microwave measurement system based on 16 monopole antennas and a vector network analyzer was used to study how the S-parameters are influenced by insertion of the phantom. The phantom is a 3D-printed structure consisting of plastic shells that can be filled with tissue mimicking liquids. The phantom was filled with different liquids and tested with the measurement system to determine whether the plastic has any effects on the recovered images or not. Measurements of the phantom when it is filled with the same liquid as the surrounding coupling medium are of particular interest. In this case, the phantom plastic has a substantial effects on the measurements which ultimately detracts from the desired images.