Analysis Of Composite Cylinder Research Articles

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.

Residual Stress Analysis of an Orthotropic Composite Cylinder under Thermal Loading and Unloading

Elastoplastic analysis of a composite cylinder, consisting of an isotropic elastic inclusion surrounded by orthotropic matrix, is conducted via numerical parametric studies for examining its residual stress under thermal cycles. The matrix is assumed to be elastically and plastically orthotropic, and all of its material properties are temperature-dependent (TD). The Hill’s anisotropic plasticity material model is adopted. The interface between the inclusion and matrix is perfectly bonded, and the outer boundary of the cylinder is fully constrained. A quasi-static, uniform temperature field is applied to the cylinder, which is analyzed under the plane-strain assumption. The mechanical responses of the composite cylinder are strongly affected by the material symmetry and temperature-dependent material properties. When the temperature-independent material properties are assumed, larger internal stresses at the loading phase are predicted. Furthermore, considering only yield stress being temperature dependent may be insufficient since other TD material parameters may also affect the stress distributions. In addition, plastic orthotropy inducing preferential yielding along certain directions leads to complex residual stress distributions when material properties are temperature-dependent.

Parametric Analysis of Composite Cylinders with an Embedded Exponentially Graded Piezoelectric Layer

An exact solution is obtained for a sandwich cylinder composed of two homogeneous elastic layers and an embedded exponentially graded piezoelectric (EGP) layer under the radial deformation. Based on the displacement method, the governing equations for both the elastic and piezoelectric layers are derived. Frobenius series method is employed to solve the governing equation of EGP layer, which is a second-order nonhomogeneous ordinary differential equation with variable coefficients. With the aid of the obtained solution, the parametric analysis is extensively investigated for a sandwich cylinder subjected to radial mechanical loads at the internal and external surfaces coupled with the applied voltages on the piezoelectric layer. Numerical results show that the Young’s moduli of the elastic layers, the inhomogeneity parameter of the EGP layer, as well as the external applied voltages have significant effects on the mechanical and electric fields in a sandwich cylinder.

Viscoelastic Analysis of Composite Cylinders Subjected to Rotation

A viscoelastic analysis has been developed to investigate stress relaxation and creep in a multi-layered composite cylinder subjected to rotation. The analysis accounts for ply-by-ply variation of material properties, fiber orientations, and density gradients through the thickness of cylinders. A closed form solution based on the corresponding elastic problem is derived for a generalized plane strain state in a thick-walled multi-layered cylinder. Laplace transform is then applied to obtain the numerical solution of the viscoelastic problem. The paper illustrates the derivation of the analytical model and solution procedure. A numerical simulation shows substantial creep and stress relaxation in thick-walled cylinders at an elevated temperature. Viscoelastic effects of composite can result in a drastic change of stress and strain profiles in a cylinder over a period of time, which is critical in terms of structural durability for application suchas energy storage flywheels.

Torsional Buckling Analysis of Composite Cylinders

A buckling analysis of composite cylinders under torsion is performed by using the geometrically nonlinear e nite element analysis. A nine-node assumed strain shell-element model with six degrees of freedom per node is used for the analysis. The buckling load of a composite cylinder is found by searching for a bifurcation point on the geometrically nonlinear deformation path. The corresponding buckling mode is obtained from the eigenvalue analysis at the bifurcation point. Numerical results show good agreement with linear solutions for isotropic and most composite cylinders, but large discrepancies in some cases. This discussion focuses on the pinpoint of the bifurcation point on the nonlinear path and the differences of torsional buckling loads between the nonlinear and linear solutions for various types of composite cylinders.

Stresses and Deformations Induced during Manufacturing. Part I: Theoretical Analysis of Composite Cylinders and Shells

Composite cylinders and cylindrical shells are important structural members. It has been observed that during the manufacture of these components, residual stresses build up. In composite cylinders, the state of residual stresses may lead to defects such as micro-cracking, fibre waviness, delamination, and wrinkling, which might degrade the final mechanical performance of the cylinders. In the case of cylindrical segments, the residual stresses also lead to a reduction in the enclosed angle where the out-of-plane contraction is higher than the in-plane contraction. This phenomenon (of the reduction in the enclosed angle) is referred to as spring-in. In this paper, a simple mechanics-based model is developed using modified shell theory that predicts the degree of spring-in in anisotropic cylindrical shells and determines the residual stresses, strains and displacements in both anisotropic laminated composite cylinders and shells with arbitrary lay-ups subjected to random temperature gradients. The model accounts for the resin shrinkage occurring during curing and also includes the effect of moisture gradients. The effects of various factors such as geometry of the component, the ply stacking sequence, the part thickness and the tool radius are examined. The accuracy of the present analysis is investigated by comparing predicted results with previously published results.