Composite Cylinders Research Articles

The probabilistic dynamic stability analysis of fluid-filled porous cylindrical shells reinforced with graphene platelets

The aim of the current paper is the probabilistic dynamic stability analysis of graphene-reinforced functionally graded porous cylindrical shells under dynamic axial loads. For this purpose, various sources of uncertainty including the material and geometrical properties of the cylinder and loading are considered. By combining a Lagrangian solution method and a semi-analytical method, some formulations are developed for determining the dynamic buckling loads of the cylindrical shells. In order to model the fluid–reservoir interaction, a semi-analytical boundary solution is used. The functionally graded porous shells reinforced with graphene platelets (FGP-GPL) are modeled with three porosity distributions and three GPL dispersions in the shell thickness based on the Halpin–Tsai formulation. The kinetic equilibrium equations of the shells are derived based on Sanders’ nonlinear theory and the higher order shear theory. Moreover, in order to solve the nonlinear dynamic equations of motion, the Newton–Raphson and the Newmark methods are combined. Finally, the results are presented in terms of the probabilistic density functions (PDFs) and cumulative density functions (CDFs) of the buckling loads. In addition, a parametric study is conducted for the effects of the different material and physical conditions on the probabilistic dynamic buckling loads of the composite cylinders. As a result, in the probabilistic dynamic stability analysis of the composite shells, the distributions of the different buckling loads may have overlaps with each other. This phenomenon indicates that in probabilistic cases, the first buckling mode of a structure is not necessarily always the dominant failure mode.

Defect and damage detection in filament wound carbon composite cylinders: A new numerical-experimental methodology based on vibrational analyses

Due to its high efficiency, carbon fibre reinforced composite materials are used in many applications, including aeronautical, automotive, and civil structures. A wide range of manufacturing processes are used in composites production and each of these processes is marked by many processing parameters. However, because of the variations that are inherent to the manufacturing method, the final properties of the structure can be strongly affected, mainly the strength values. On the other hand, Vibration-Based Methods (VBM) has the advantage of simplicity and low cost, although it is very sensitive to variations in geometry and material properties. Therefore, it is strategic to deepen the research in this line to generalize the method, allowing its use in the industry as a solution to complicated real-life problems. Thus, this work presents a new numerical-experimental methodology to evaluate the effect of design parameter variations on the dynamic response of laminated composite cylinders. Numerical dynamic analyses are run via a Finite Element code, which is complemented with subroutines written in Python. A Design of Experiments (DoE) strategy is developed to reduce the number of experiments and to evaluate the effect of the design parameter variations. Three sets of nominally different composite cylinders are investigated [(90/60/-60)2/90]s, [(90/30/-30)2/90]s and [90/30/-60/60/-60/30/-30]s. System natural frequencies as taken as the primary response quantities. Frequency Response Functions (FRF) enrich the data set for more elaborate analysis. A DoE strategy is set up to deal with the range of design parameters and process parameters, a full factorial design is selected. Afterward, the results are discussed with proper attention for the potential and limitations of the proposed methodology from the perspective of usage to detect defects in real laminated composite cylinders. Finally, damage indices are calculated using the experimental FRFs magnitudes to quantify the influence of the undamaged and impact damage structure. The general conclusion is that the new methodology provides the foundations for the next generation of software systems for detecting defects from the manufacturing process and damage caused in-service of real composite structures.

Failure analysis of fiberglass‐vinyl ester composite cylinders subjected to fire and asymmetric transient pressure

AbstractA hybrid numerical method is developed for failure prediction of glass fiber reinforced vinyl ester (GRV) composite cylinders subjected to fire and asymmetric transient pressure. The method is composed of layerwise theory, differential quadrature method, Fourier series expansion, and Newmark's time integration method. To achieve high‐accuracy solution, the char formation, resin decomposition, volatile convection, and temperature‐dependent material properties are considered. By comparing the developed results with the experimental and numerical results presented in the available literatures, the precision of this method is confirmed. The results reveal that although the polymeric composites are flammable, they are also strong thermal insulators compared to conventional metals, which reduces the flame spread rate from one section to another.

Effect of Different Surface Treatments and Pressure Conditions on Shear Bond Strength of Zirconia Ceramic to Composite Resin.

Objectives: The aim of this study was to assess the shear bond strength (SBS) of zirconia ceramic to composite resin with various surface treatments following pressure changes. Materials and Methods: Totally, 135 zirconia blocks were prepared by computer-aided design/computer-aided manufacturing technology. The samples were divided into 9 groups (n=15). Three surface treatments including sandblasting, tribo-chemical preparation, and laser application were used. For each method, 45 samples were considered and tested under different pressure conditions. Z-Prime Plus primer was used for bonding of all samples to composite cylinders. All specimens were stored in water for 24 h, underwent thermocycling, and were then placed in a pressure chamber under normal-, high-, and low-pressure conditions. Then, the SBS test was performed for each sample. Data were analyzed by two-way and one-way ANOVA (α=0.05). Results: The SBS was significantly higher in sandblasting and tribochemical preparation compared with laser irradiation (P<0.05). There was no statistically significant difference in SBS of sandblasting and tribochemical preparation methods (P>0.05). Sandblasting, tribochemical preparation, and laser methods did not show a significant difference in SBS at different pressures (P>0.05). Conclusion: Sandblasting and tribochemical preparation yielded a higher SBS than laser. Different pressures had no effect on SBS, irrespective of surface preparation method.

Stress analysis of multi-layered composite cylinders subjected to various loadings

Composite cylinders are widely used in many applications, common examples for these applications are power drive shafts, chemical storage tanks, rocket motor cases and pressure vessels used in aerospace vehicles. The structure of the composite cylinder can be represented as a cylinder composed of coaxial orthotropic layers. In this paper, an analytical method is used to calculate stresses, strains and displacements through the wall thickness of multi-layered composite cylinder made of orthotropic material. The method is based on the theory of elasticity of bodies having cylindrical anisotropy. This method permits accurate stress analysis of thin and thick-walled composite cylinders subjected to axial load, torsional load and bending moment. The analytical method is modified to incorporate internal and external pressure loads beside the prescribed load cases. A numerical example is presented for a composite cylinder subjected to internal pressure load with a tensile axial load. The resulted stresses and strains are used to validate 3-dimensional finite element model. A parametric study has been performed using the analytical method to investigate the influencing parameters on stress distribution within the cylinder thickness and the results are found to be beneficial to look into during the preliminary design phase.

Composite shell of toroidal balloons of breathing apparatus with meridional winding of threads

The prospects of using toroidal composite high-pressure cylinders for breathing apparatus, which are more ergonomic in comparison with similar cylindrical cylinders, are described. Through the analytical solution of the equilibrium equations, the cross-sectional shape of the composite shells of toroidal balloons, which are intersecting loop-like curves, is determined. A constructive diagram of a toroidal composite balloon, formed by the intersection of the upper and lower branches of the shell reinforced along the meridians, and the profiled annular layer of threads, installed at the point of their intersection, is proposed.

Тороидальная равнонапряженная оболочка сосуда давления, образованная меридиональной и окружной намоткой нитей

The paper outlines the prospects for the use of composite toroidal high-pressure cylinders for the breathing apparatus of the Ministry of Emergency Situations, fire brigades, industrial workers, which are more ergonomic in comparison with their cylindrical counterparts. Relying on the analytical solution of the equilibrium equations, we determined the shape of the cross-section of toroidal shells reinforced along the meridians and representing intersecting loop-like curves that form an infinitely long corrugated pipe. The study introduces a solution for a toroidal composite pressure vessel formed by the intersection of the upper and lower branches of the shell, reinforced along the meridians, and a profiled ring layer of filaments installed at the point of their intersection. The parameters of the toroidal uniformly stressed pressure vessel shell made by ring and meridian filament winding are calculated.

The shear bond measurement of two self-adhesive composite resins to both enamel and dentin (An in vitro study)

Background and objectives: The aim of this study is to measure the shear bond strength of two self-adhesive composite resins (Vertise Flow, Kerr and Constic, DMG) to both enamel and dentin and compared it to that of conventional flowable composite (used with self-etching bonding system).Methods: Sixty freshly extracted human third molar teeth were chosen for this study (thirty for enamel samples and thirty for dentin samples). The teeth were mounted horizontally, in blocks of self-cured acrylic resin to leave only buccal surfaces exposed. Then 0.5 and 2mm were cut from the buccal surface to obtain flat enamel and dentin surfaces successively. Thirty enamel samples were divided into three groups; group E1: Vertise Flow, group E2: Constic and group E3: conventional composite with self-etching bonding. Also the thirty dentin groups were divided into three groups, group D1, D2 and D3 with the same corresponding composites as in enamel groups. For all the specimens composite cylinders (4mm height and 4 mm in diameter) were built of the flat surface of the sample then subjected to shear bond testing in a universal testing machine. Results: Group E3 (conventional flowable composite bonded to enamel) had the highest bond strength while group D1 ( Vertise Flow bonded to dentin) had the lowest bond.Conclusion: Both self-adhesive composites provided insufficient shear bond strength less than that required for using in most clinical conditions.Keywords: Shear bond strength, self-adhesive, Vertise Flow, Constic.

THE STATIC RESPONSE OF AN AXISYMMETRIC FUNCTIONLLY GRADED PIEZOELECTRIC/PIEZOMAGNETIC CYLINDER

For infinite-length functionally graded piezoelectric/piezomagnetic (FGPEPM) hollow cylinders, the statics of the electro-magnetic-elastic coupling for an axisymmetric hollow cylinder is studied. In the cylindrical coordinate system, assuming that the material parameters are distributed along the radial direction as a power function, analytical solutions of the physical fields such as displacement, stress, electric and magnetic potentials in the hollow cylinder under external excitation are derived. In the numerical discussions, for the BaTiO3-CoFeO4 composite material hollow cylinder, the distribution of stress, electric and magnetic potentials for the hollow cylinder with different gradient parameters and different thicknesses are obtained under different boundary conditions. The results show that the material failure is mainly caused by the circumferential stress for the FGPEPM hollow cylinder, and that the cylindrical thickness has a significant influence on the circumferential stress. In addition, the gradient parameters strongly affect the electrical/magnetic output and the mechanical properties for FGPEPM sensors/actuators. The results have a certain guiding effect on the design and analysis for FGPEPM cylindrical sensors/actuators.

MODELING OF OPERATING MODES GAS COMPOSITE CYLINDERS

Statement of the problem. The emergence of composite cylinders on the market offers a range of technological and operational advantages in comparison with metal cylinders of liquefied hydrocarbon gas. At the same time, the absence of substantiated recommendations for determining the vapor capacity of cylinders by modes of their operation in the scientific literature limits their wide implementation into gas practice. Results. A mathematical model considering the operation of the cylinder in the mode of periodic gas consumption is developed, the coefficient of non-uniformity of gas consumption during the day is calculated, the values of the heat transfer coefficient of the composite cylinder wall are identified, the approximate dependence of the heat transfer coefficient is obtained. Conclusions. As a result of the research, the criteria influencing steam productivity of compositecylinders of the liquefied hydrocarbon gas in various operating modes are found.

Do Chemical-Based Bonding Techniques Affect the Bond Strength Stability to Cubic Zirconia?

This study evaluated the effectiveness of chemical-based adhesive techniques on promoting immediate and aged bond strength between zirconia and luting cement. A total of 128 discs of zirconia were divided into 4 groups (n = 32) according to the adhesive treatment: tribochemical silica-coating followed by silane (Silane Primer, Kerr) and bonding (Optibond FL, Kerr), Signum Zirconia Bond (Hereaus), Z-Prime Plus (Bisco), and All-Bond Universal (Bisco). Composite cylinders were cemented on the zirconia sample with Duo-Link Universal (Bisco). Eight specimens per group were subjected to 10,000 thermocycles and subsequently bond strength was tested with shear-bond strength test. ANOVA test showed that artificial aging significantly affected the bond strength to zirconia. Bonferroni test highlighted a significant influence of adhesive treatment (Signum) on bond strength after thermocycling. It was concluded that 10-MDP-based bonding systems showed no improvement in initial bond strength compared with tribochemical treatment. All chemical bonding techniques tested in this study were influenced by thermocycling.

Buckling of composite cylindrical shells with ovality and thickness variation subjected to hydrostatic pressure

The initial geometric imperfection is one of the primary factors affecting the buckling behaviors of composite cylindrical shells under hydrostatic pressure. In this study, ovality and thickness variations as two representative types of the geometric imperfections are considered. After measuring the geometric imperfections, a typical carbon fiber reinforced polymers (CFRP) cylindrical shell is tested to obtain the buckling pressure. The buckling behaviors of the shell sample are analyzed in combination with the strain responses. By using the nonlinear numerical analysis, the buckling shapes of the CFRP cylinder shells with different combinations of ovality and thickness variation are firstly discussed. The rules of influence of such imperfections on the buckling pressure are then obtained by nonlinear regression method. Finally, an empirical formula is proposed to predict the buckling pressure of the composite cylinder shells, and the calculated results from the formula are in good agreement with the numerical results.

The Effect of GaAlAs Laser, Sandblasting, and Primers on Bond Strength between Zirconia Ceramic and Direct Resin Composite after Thermocycling

Objective: This study was conducted to evaluate the shear bond strength (SBS) of resin composite on zirconia ceramic after different surface treatments and thermocycling. Material and Methods: Two hundred and seven zirconia specimens were divided into 9 groups and treated as follows: Group C-no treatment (served as the control); Group PC-Clearfil Ceramic primer (CP); Group PZ-Z-Prime Plus primer (ZP); Group A-sandblasted with 50 µm Al2O3 at 0.25 MPa for 20 s at a distance of 10 mm; Group AC-sandblasted and coated with CP; Group AZ-sandblasted and coated with ZP; Group L-GaAlAs diode laser with 808±5 mm wavelength, 3 watts power, and 10 Hz frequency; Group LC-GaAlAs diode laser coated with CP; and Group LZ-GaAlAs diode laser coated with ZP. All specimens were directly bonded with a resin composite cylinder using Adper Scotchbond Multi-purpose. Specimens were stored at 37ºC for 30 days and subjected to 2,500 thermocycles from 5ºC and 55ºC before the SBS was performed. One-way ANOVA and Tukey’s HSD test (=0.05) were performed. Surface topography changes were evaluated with a scanning electron microscope (SEM). Results: Sandblasting combined with CP or ZP (25.08±0.86 and 24.78±0.13 MPa, respectively) yielded the highest SBS and was significantly different from other methods (p&lt;0.05). SEM showed various degrees of changes depending on different surface treatments. Conclusion: Surface treatment by sandblasting combined with a CP or ZP significantly provide the highest SBS between zirconia and resin composite. KEYWORDS Bond strength; Resin composite; Surface treatment; Zirconia ceramic.

Stress Distribution and Fracture Toughness of Underground Reinforced Plastic Pipe Composite.

Reinforced composite materials have many applications in the aerospace, marine, and petroleum industries. Glass fiber-reinforced pipes are of considerable importance as pressurized vessels, infrastructure materials, and petroleum wastewater pipelines. The stress intensity factor due to through-thickness discontinuities is a major parameter in fracture mechanics to understand the failure mechanisms in glass fiber-composite pipes. The stress intensity factor is calculated for a composite cylinder subjected to internal pressure using the linear extended finite element method based on the law of energy release evaluation of surface damage. The analytical model needs two material properties; they are the tensile strength and the fracture toughness; therefore, a standard tensile test was carried out on a standard specimen taken from the pipe’s wall thickness. Moreover, the compact tension test specimen was manufactured from the pipe’s wall thickness to obtain the fracture toughness. The average tensile strength was measured as 21.5 MPa with a standard deviation of 5.59 MPa, moreover, the average Young’s modulus was measured as 32.75 GPa with a standard deviation of 6.64 GPa. The fracture toughness was measured as 2322 () with a standard deviation of 142.5 (), whereas the average surface release energy () was 153.6 kJ/m2 with a standard deviation of 22.53 kJ/m2. A valuable design equation was extracted from the finite element model to measure the effect of cracks on the hoop stress of the cylinder wall thickness based on a nonlinear model. Moreover, an acceptable equation was used to calculate the correction and shape factor of a cylinder with movable and unmovable through-thickness cracks. This study provides useful tools and guidance for the design and analysis of composite cylinders.

Analytical Solution for Buckling Analysis of Composite Cylinders with Honeycomb Core Layer

In this study, an analytical solution is presented to determine the buckling load of composite cylindrical shells with an auxetic honeycomb layer under a uniform axial load. The composite shell consists of three layers in which the core layer is made of the auxetic honeycomb structure with a negative Poisson’s ratio and the internal and external layers have been made of elastic and isotropic materials. The first-order shear deformation theory has been used as the displacement field. The equilibrium equations are determined by considering the von Kármán theory, and they are coupled nonlinear differential equations that are solved by employing the perturbation technique. The buckling load has been determined analytically by solving the stability equations, which are a system of coupled differential equations with variable coefficients. By conducting a parametric study, the effects of the honeycomb structure and the aspect ratios on the buckling load have been investigated. It is seen that by changing the geometrical parameters of the honeycomb structure, the Poisson ratio can be adjusted and the mechanical behavior of the composite shell has been modified. The results are compared with some other references and the finite element analysis.

Optimal design of trapezoid stiffeners of composite cylindrical shells subjected to hydrostatic pressure

Optimization of a composite cylindrical pressure hull subjected to hydrostatic pressure with trapezoidal stiffeners is considered in this paper. The composite cylindrical shell is fabricated with carbon fiber reinforced epoxy composite while the stiffener is made of aluminum alloy. First of all, the analytical buckling model for composite cylinders with stiffeners subjected to hydrostatic pressure is derived. Subsequently, the finite element method is used to verify the accuracy of the analytical solution through some examples. After verification, the analytical solution is coupled with the genetic algorithm and then used to optimize the cross-sectional shape of the stiffeners of the composite pressure hull to obtain the maximum buckling pressure. During the optimization process, the relationship between the buckling pressure and each geometrical parameter of the stiffener has been analyzed. The inertia moment of the stiffener section is found to have a good linear relationship with the buckling pressure. Therefore, the inertia moment is used as an objective function to optimize the cross-sectional shape of the stiffeners of the composite pressure hull, and the feasibility of this method has been proved by comparing the optimization results. With high efficiency, this method can be applied to the optimal design of the stiffener shape of a composite pressure shell.

Analytical Solutions for Transversely Isotropic Fiber Reinforced Composite Cylinders Under Internal or External Pressure

This paper deals with the elastic stresses of internally or externally pressurized long thick-walled composite cylinders with fixed ends. Cylinders are made of unidirectionally aligned transversely isotropic fibers and isotropic matrix. Axial and radial fiber alignments are considered, and analytical solutions are derived accordingly. Effects of fiber direction and fiber volume fraction alteration on the elastic limit stresses are analyzed. It is observed for both internal and external pressure cases that fiber direction and fiber volume fraction are important parameters which impact the elastic behavior of the cylinders.

A new hybrid analytical/numerical method for transient heat conduction in composite hollow cylinders applied to plug and abandonment of oil wells

This work presents a hybrid analytical/numerical approach for transient heat conduction through composite hollow cylinder structures applied for Plug and Abandonment (P&A). The Distribution Transfer Function Method (DTFM) is a mathematical framework able to solve both nonhomogeneous boundary conditions and a nonlinear partial differential equation with spatial-temporal source term, presenting good agreement with Finite Element Method (FEM) and other analytical approaches. A new technology of Thermal Plug and Abandonment (TP&A) devoted for P&A operation is studied in this work, where a heat generator is used to melt the first layer of the well structure. The heat source will be modeled using thermite within the oil well manifold structure, which must be descended to desirable depths along the borehole through a cylindrical container. After an exothermic reaction the temperature fields will be determined by means of DTFM method. A novel adaptative step-wise procedure applied for DTFM allows one to solve non-differentiable heat flux, thermal and volumetric heat source profiles which exact quadrature regression are not able to solve. This method provides simple replicability, which can be reproduced for many emerging fields where transient heat conduction is an important parameter to be accounted for. Using experimental data as input in DTFM provides insight that the temperature response overcame the design melting point of the production tube, being capable of melting down the production tubing wall, which is a valuable achievement for oil industries since not removing the production tubing can save a great amount of time, and hence save costs for oil industries.

Identification of Mode Shapes of a Composite Cylinder Using Convolutional Neural Networks.

The aim of the following paper is to discuss a newly developed approach for the identification of vibration mode shapes of multilayer composite structures. To overcome the limitations of the approaches based on image analysis (two-dimensional structures, high spatial resolution of mode shapes description), convolutional neural networks (CNNs) are applied to create a three-dimensional mode shapes identification algorithm with a significantly reduced number of mode shape vector coordinates. The CNN-based procedure is accurate, effective, and robust to noisy input data. The appearance of local damage is not an obstacle. The change of the material and the occurrence of local material degradation do not affect the accuracy of the method. Moreover, the application of the proposed identification method allows identifying the material degradation occurrence.

Demagnetization Effect on the Magnetoelectric Response of Composite Multiferroic Cylinders

Strain-mediated multiferroic composite structures are gaining scientific and technological attention because of the promise of low power consumption and greater flexibility in material and geometry choices. In this study, the direct magnetoelectric coupling coefficient (DME) of composite multiferroic cylinders, consisting of two mechanically bonded concentric cylinders, was analytically modeled under the influence of a radially emanating magnetic field. The analysis framework emphasized the effect of demagnetization on the overall performance. The demagnetization effect was thoroughly considered as a function of the imposed mechanical boundary conditions, the geometrical dimensions of the composite cylinder, and the introduction of a thin elastic layer at the interface between the inner piezomagnetic and outer piezoelectric cylinders. The results indicate that the demagnetization effect adversely impacted the DME coefficient. In a trial to compensate for the reduction in peak DME coefficient due to demagnetization, a non-dimensional geometrical analysis was carried out to identify the geometrical attributes corresponding to the maximum DME. It was observed that the peak DME coefficient was nearly unaffected by varying the inner radius of the composite cylinder, while it approached its maximum value when the thickness of the piezoelectric cylinder was almost 60% of the total thickness of the composite cylinder. The latter conclusion was true for all of the considered boundary conditions.