Thick Composite Cylinders Research Articles

Buckling and fracture analysis of thick and long composite cylinders with cutouts under axial Compression: An experimental and numerical campaign

This article reports on the manufacturing, experimental testing, and finite element analysis of very thick and long carbon-fiber-reinforced polymers (CFRP) tubes under uniaxial compression (radius-to-thickness ratio ∼ 10 and length-to-radius ratio ∼ 21). Herein, long and hollow axisymmetric composite cylinders were produced through bladder molding. The CFRP tubes have two oppositely located cutouts in the middle of the structures. Three test specimens with different cutout diameters (5, 10, and 15 mm) were experimentally tested until failure. The experimental testing campaign was supported by digital image correlation, acoustic emission, and infrared thermographic measurements to investigate the damage propagation and failure analysis. The CFRP tubes failed at the cutout location due to fiber fracture. Linear static and geometrically non-linear analyses were performed using ABAQUS to analyze the CFPR tubes under axial compression. In general, numerical and experimental results are in good agreement if the maximum stress or Hashin criteria are applied.

Sound Radiation Characteristics of Acoustically Thick Composite Cylinders and Their Experimental Verification

Cylindrical shells made of composite material form one of the major structural parts in aerospace structures. Many of them are acoustically thick, in which the ring frequencies are much higher than their critical frequencies. In this work, sound radiation behaviour of acoustically thick composite cylinders is presented. Based on the structural and acoustic wave number diagrams, the modal average radiation resistances in the frequency band of interest are theoretically determined. The structural wavenumbers are determined considering transverse shear deformation. The results show lesser sound radiation between the critical and ring frequencies, and significant sound radiation near the ring frequency and beyond. In the absence of the present results the radiation efficiency is considered to be unity at all frequencies beyond the critical frequency, including near the ring frequency. The radiation resistances of the same cylinder are determined experimentally and they are in very good agreement with the theoretical estimates. As part of this investigation, an expression for determining the ring frequency of composite cylinder is also presented.

Creep analysis in thick composite cylinder considering large strain

Cylindrical vessels are widely used in petroleum or aerospace industry. In these applications, the cylinders have to work under harsh mechanical and thermal loadings where creep plays an important role. The present paper analyzes creeps behavior of an Al–SiCp composite cylinder under internal pressure. The strains are assumed to be large which necessitate the use of finite strain theory. Threshold creep law is used for analysis because the creep rate in aluminum-based composites using Norton’s law was not approved due to apparently high stress exponent and high apparent activation energy. Such analysis will help the designers in the prediction of correct creep rate and stresses in cases where large creep deformation of a cylinder is permissible. With the use of finite strain theory, it is found that design of the cylinder based on small strain theory leads to unsafe cylinder design.

Interlaminar stress analysis in general thick composite cylinder subjected to nonuniform distributed radial pressure

ABSTRACTInterlaminar stresses in thick a composite cylinder with general layer stacking subjected to uniform and nonuniform distributed radial pressure are studied. The layerwise theory of Reddy is employed for formulation of the problem. An analytical method is presented for solving the governing equations. To increase accuracy, interlaminar stresses are obtained by integrating the equilibrium equation of elasticity. After a convergence study, the accuracy of the layerwise laminate theory is investigated using the predictions of finite element method. Predictions of Hooke's law and integration method for interlaminar stresses are compared. Uniform and nonuniform internal and external loads are considered and a parametric study is done for various cylinders.

Edge stresses analysis in laminated thick sandwich cylinder subjected to distributed hygrothermal loading

The boundary layer hygrothermal stresses in the thick sandwich cylinder with laminated face are investigated. Uniform and through the thickness steady-state distribution for temperature and moisture content can be considered in the analysis. A displacement based layer-wise formulation is presented for analysis of thick sandwich composite cylinders subjected to hygrothermal loading conditions. Considering a general displacement field and employing a displacement based layer-wise theory, the governing equations of thick laminated sandwich cylinder are obtained. The displacement based formulation is derived for thick sandwich cylinder, which is subjected to non-uniform hygrothermal loading conditions. The faces of the sandwich cylinder are made of laminated composite with general layer stacking. The governing equations of the system include a set of coupled differential equations on the displacement components of the numerical surfaces. A semi-analytical solution is developed and the governing equations are solved for free edge boundary conditions. The accuracy of the numerical results is validated by the results of the finite element simulation and good agreements are seen between the predicted results. The free edge interlaminar stresses distributions are presented for thin and thick sandwich composite cylinders for uniform and non-uniform loading conditions. It is concluded that the presented layer-wise formulation is efficient and accurate method for analysis of thermal and hygroscopic stresses in thick and thin sandwich cylinders with general layer stacking.

Elastic field in composite cylinders made of functionally graded coatings

In this paper, the elastic field is studied in a composite cylinder made of heterogeneous coatings. The coating layers are such that the mechanical properties of the entire composite structure change across the radius. Thus, both Young’s modulus and Poisson’s ratio vary continuously in coatings across the radius. The effect of varying Young’s modulus has been shown to be significant on the elastic field in these types of composites. Herein, it is shown that varying Poisson’s ratio also plays an important role in the stress and strain distribution and should be considered in the design process especially in carbon coated titanium cylinders, where Poisson’s ratio changes between zero and a half in the structure. In addition, variation of Poisson’s ratio across the radius not only changes the elastic field, but also different spatial variations of Poisson’s ratio lead to distinct hoop stresses and radial displacements for a coated cylinder. The effects of Poisson’s ratio variation on the elastic field in thick composite cylinders are also studied. Two closed form expressions are derived for the normalized hoop stresses at the inner and outer surfaces of thick-walled coated cylinders. It is found that the effect of varying Poisson’s ratio on the normalized hoop stress in thick-walled coated cylinders is also important and the maximum hoop stress changes dramatically for thicker cylinders.

FE modeling of creep in linear and non-linear FGM cylinder under internal pressure

Purpose – The purpose of this paper is to investigate creep in an internally pressurized thick-walled, closed ends cylinder made of functionally graded composite, having linear and non-linear distribution of reinforcement, using finite element (FE) analysis. Design/methodology/approach – FE-based Abaqus software is used to investigate creep behavior of a functionally graded cylinder. The cylinder is made of composite containing linear and non-linearly varying distributions of reinforcement along the radius. The creep behavior has been described by Norton's power law. The creep stresses and strains have been estimated in linear and non-linear functionally graded materials (FGM) cylinders and compared with those estimated for a similar composite cylinder but having uniform distribution of reinforcement. Findings – The radial stress in the composite cylinder is observed to decreases over the entire radius upon imposing linear or non-linear reinforcement gradients. However, the tangential stress in the cylinder increases near the inner radius but decreases toward the outer radius, on imposing linear or non-linear reinforcement gradients. The creep strains in the FGM cylinders are significantly lower than those observed in a uniform composite cylinder. Originality/value – The creep strains in an internally pressurized functionally graded thick composite cylinder could be reduced significantly by employing non-linear distribution of reinforcement along the radial direction.

Analysis of Steady State Creep in Whisker Reinforced Functionally Graded Thick Cylinder Subjected to Internal Pressure by Considering Residual Stress

The steady state creep behavior of a functionally graded thick composite cylinder subjected to internal pressure has been analyzed in the presence of residual stress. To study the effect of residual stress, the yielding of composite material is described by Hoffman's yield criterion. The results obtained are compared with a similar cylinder but yielding according to von Mises yield criterion, which ignores the presence of residual stress. The cylinder is made of functionally graded composite containing a linearly varying amount of silicon carbide whisker in a matrix of 6061Al. It is revealed that the presence of residual stress in the FG cylinder having linearly varying whisker content in the radial direction, the radial stress decreases slightly over the entire radius of the cylinder, whereas the tangential and axial stresses increase considerably near the inner radius but show a significant decrease towards the outer radius. In the presence of residual stress, the effective stress also increases in the cylinder, except for some decrease observed near the inner radius. The presence of thermal residual stress in the cylinder leads to increase the tangential as well as radial strain rate throughout the cylinder. The increase observed in strain rate increases with increasing radial distance.

Modeling Steady State Creep Behavior of Functionally Graded Thick Cylinder in the Presence of Residual Stress

Abstract The steady state creep behavior in a functionally graded thick composite cylinder subjected to internal pressure has been investigated in the presence of residual stress. Hoffman's yield criterion is used, to describe the yielding of the cylinder material in order to account for residual stress. The results obtained are compared with a similar cylinder but yielding according to von Mises criterion. The cylinder is made of functionally graded material containing linearly varying silicon carbide whiskers in a matrix of 6061aluminum. The study shows that in the presence of residual stress in composite cylinder the radial stress decreases slightly over the entire cylinder, whereas the tangential and axial stresses increase significantly near the inner radius but show considerable decrease towards the outer radius. The effective stress in the cylinder increases in the presence of residual stress and the maximum increase near the outer radius. The study also reveals that the creep rates are strongly influenced by the presence of residual stress in the cylinder material.

Probabilistic analysis of the mechanical response of thick composite pipes under internal pressure

In the present work an analytical method is developed to study the mechanical response of thick composite pipes under internal pressure. The present method considers that the surface tension must satisfy, on the interface between two adjacent layers, all the boundary conditions imposed on the radial and hoop stresses, which are computed using a specific model for thick multi-layered composite cylinders suggested by Tsai. This model uses the plane strain states of cylindrical tubes under internal pressure containing a number of cylindrical sub-layers, each of which is cylindrically orthotropic. Such analytical method is considered as simple, fast and precise compared to other analytical and numerical methods. Thereafter, the effects of random design variables on the pipe behavior are quantified by probabilistic analysis. Using these stress components for each ply, the Monte Carlo method is used to predict the distribution function of the mechanical response, in addition to the failure probability. Five random design variables are considered, namely, the composite elastic constants, the ply angles, the inner and outer diameters, thickness and the mechanical loading. The improvement of multi-layered filament-wound composite pipes design based on the probabilistic analysis is also discussed. According to the obtained results, we note that the thickness of the pipe and the internal pressure variation are the principal factors influencing the scatter of stress distribution.

Buckling analysis of filament-wound thick composite cylinder under hydrostatic pressure

Underwater vehicles that operate in deep waters require a pressure hull to maintain the sufficient strength and stiffness against external hydrostatic pressure. We investigated the validity of the finite element method (FEM) that is applied to a buckling analysis of the filament-wound composite cylinder, subjected to an external hydrostatic pressure. Two methods were suggested for the buckling analysis of a filament-wound thick composite cylinder under hydrostatic pressure: using the equivalent properties of the composite, and using stacking sequence. The hydrostatic pressure test was conducted to verify the FEA. Test results were compared with the previous results obtained by FEM on the buckling of a filament-wound composite cylinder under hydrostatic pressure. FEM analysis results were in good agreement with the test results. The difference between FEM results and the test results was approximately 1∼5%.

Modeling creep in a thick composite cylinder subjected to internal and external pressures

AbstractA mathematical model to describe secondary creep in a thick composite cylinder made of Al–SiCpand subjected to both internal and external pressures has been developed. The creep behavior of the composite has been described by a threshold stress based creep law with a stress exponent of 5. The model developed has been used to investigate the effect of varying size and content of the SiCpdispersoid on the stresses and strain rates in a composite cylinder. It is observed that the stress distributions in the cylinder do not have significant variation with varying size and content of the SiCp. Unlike stresses, the strain rates in the cylinder are reduced to a significant extent by decreasing the size of SiCpand increasing the content of SiCp.

Effect of Material Parameters on Steady State Creep in a Thick Composite Cylinder Subjected to Internal Pressure

The steady state creep in Al- SiCP composite cylinder subjected to internal pressure was investigated. The creep behavior of the material were described by threshold stress based creep law by assuming a stress exponent of 5. The effect of size and content of the reinforcement (SiCP ), and operating temperature on the stresses and strain rates in the composite cylinder were investigated. The stresses in the cylinder did not have significant variation with varying size and content of the reinforcement, and operating temperature. However, the tangential as well as radial strain rates in the cylinder could be reduced to a significant extent by decreasing size of SiCP, increasing the content of SiCP and decreasing operating temperature.

외부 수압을 받는 필라멘트 와인딩 후판 복합재 원통의 좌굴 연구

The buckling and failure of filament wound thick composite cylinders under external hydrostatic pressure were investigated by the finite element analysis and test. ACOS, MSC.NASTRAN, and MSC.MARC were used for finite element analysis. T700 carbon-epoxy filament wound composite cylinders were fabricated to have winding angles of , , , , and tested to verify the finite element analysis. Among the softwares, ACOS predicted buckling load the best with about 1.7~14.3% deviation from test. Analysis and test shows cylinders do not recover the initial buckling pressure after buckling and directly lead to final failure.

Scale and Size Effects on Dynamic Response and Damage of Glass/Epoxy Tubular Structures

The impact behavior of composite materials has been extensively studied but interest has been centered on flat plates. For underwater applications, thick composite cylinders are employed and several questions must be addressed concerning the influence of accidental impact. The aim of this work is to study the dynamic response of tubular structures. Such structures find many applications but the damage upon impact is not taken into account during their dimensioning. However, at the time of their handling or in service the damage introduced by accidental impact can compromise their capacity to fulfill their function. The cylinders are thick and consist of epoxy matrix and glass fiber reinforcement. After having observed the nature of the damage related to the static and dynamic loading, the scale and size effects on dynamic response and damage are examined. The studies reveal that the dynamic responses show a satisfactory correlation with predictions based on rules of similitude.

Assessment of approximate models to evaluate transient and cyclical hygrothermoelastic stress in composite plates

The present paper aims at assessing an approximate model to evaluate hygrothermoelastic stress in composite laminated plates. The approximate model is based on straight hypotheses (classical lamination theory of plates) and is able to simulate the effects of complex hygrothermal conditionings, such as those encountered in the life of real structures. For the purpose of the assessment, a 3D analytical solution for hygrothermally stressed plates is employed. The approximate model for plates is also compared to an analytical model for cylinders under transient and cyclical hygrothermal loads [Jacquemin, F., Vautrin, A., 2002a. Modelling of the moisture concentration field due to cyclical hygrothermal conditions in thick laminated pipes. European Journal of Mechanics – A/Solids 21, 845–855; Jacquemin, F., Vautrin, A., 2002b. A closed-form solution for the internal stresses in thick composite cylinders induced by cyclical environmental conditions. Composite Structures 58, 1–9]. This is done in order to assess the capabilities and the limits of a simplified model for plates to represent also the behaviour of cylinders.

Measurement of residual stresses in thick composite cylinders by the radial-cut-cylinder-bending method

Thick fabric composite cylinders for nozzle parts in solid rocket motors should be designed to endure the extreme temperature and pressure of combustion gas. As the thickness of the composite cylinder increases, fabricational residual stresses due to the anisotropic thermal expansion or shrinkage of fabric composites also increase, which induces inter-laminar failures. Therefore, the accurate estimation of the residual stresses is indispensable for the development of thick fabric composite cylinders. In this paper, the residual stresses in thick cylinders made of carbon fabric phenolic composites were measured by a new radial-cut-cylinder-bending method. To obtain the residual stresses from the measured relative strains during the radial-cut operation, a bending test of the cylinder with the radial-cut was performed instead of measuring the material properties with respect to radial positions. The thermal residual stresses were also calculated by finite element method considering shear deformation of fabric layers, and compared with the measured residual stresses by the new method, from which it was found that the new simple method estimated the residual stresses pretty well. Also the inter-laminar tensile strength at the position of maximum radial residual stress could be obtained from the bending test.

Analysis of multi-layered composite cylinders under hygrothermal loading

Abstract In this study, a general stress analysis is developed for thick or thin multi-layered composite cylinders under hygrothermal loadings. The layers are oriented symmetrically and antisymmetrically for [0°/90°] 2 , [30°/−30°] 2 , [45°/−45°] 2 and [60°/−60°] 2 orientations. The solution is carried out on composite cylinders for plane-strain, open end and closed end conditions. Uniform and parabolic temperature distributions are chosen for the thermal loads. All the integration constants are found from the radial stress and displacement in the normal direction of layers. The hygrothermal and other mechanical properties are measured on a glass-epoxy composite layer. Some analytical solutions are compared with the finite element solutions, in which commercial software ANSYS 7.0 is utilized, and close results are obtained between them.

Effects of Rotor Sizes and Epoxy System on the Process-Induced Residual Strains within Multi-Ring Composite Rotors

This paper discusses the effects of different rotor sizes and epoxy systems on the process-induced residual strains accumulated within multi-ring composite rotors. Thick composite cylinders were manufactured with wet impregnation of E-glass and graphite fibers in the epoxy resin systems. The radial stiffness and strength and the coefficients of thermal expansion were first measured. Hybrid two-ring composite rotors of glass and graphite fibers with equal thickness were manufactured for three different inner to outer radius ratios, i.e., 1.5, 2.0 and 2.5. A split ring method was then used to measure the radial and circumferential residual strains, following liquid penetration tests to detect delaminations on the surfaces. The measured residual strains are estimated using a two-dimensional stress analysis with an effective temperature drop. It is shown that the middle temperature-cured rotor attains as high strength as the high temperature-cured rotor while reducing significantly the residual strains.

A closed-form solution for the internal stresses in thick composite cylinders induced by cyclical environmental conditions

The paper presents a new semi-analytical model to assess the internal stress field in cylindrical pipes due to cyclical temperature and humidity conditions. The solution applies to both thin or thick laminated pipes composed of orthotropic plies following Fick's diffusion laws. The only restriction put on those diffusion laws is that the Arrhénius activation energy should be ply independent. Firstly, the resulting time and space dependent moisture concentration field within the interior of the pipe wall is calculated. It is the sum of the permanent solution, due to the mean relative humidity conditions imposed on the two lateral surfaces of the pipe, and a cyclical vanishing solution. Secondly, the mechanical problem is solved leading to the full stress field solution over the pipe interior and close to the lateral surfaces. The final solution can be implemented in a friendly-user software to assess the combined effects of the pipe thickness, ply stacking sequence and transient service conditions over the internal stress field.