Fiber Winding Angles Research Articles

Deformability of filament-wound GFRP tubes filled with lightweight aggregate concrete: Experimental and improved analytical studies

Previous research indicates that lightweight aggregate (LWA) concrete exhibits more brittle failure under compression than conventional normal density (ND) concrete. In contrast, angle-ply fiber-reinforced polymer (FRP) filament-wound tubes filled with ND concrete show significant improvements in strength and deformability compared to hollow tubes. This study evaluates the impact of these tubes on LWA concrete to mitigate its brittle behavior. Sixteen concrete-filled FRP filament-wound tubes (CFFTs) made of ±55° filament-wound glass FRP (GFRP) were tested under axial compression. The GFRP tube’s mechanical properties and fiber winding angle of ±55° allowed for a compressive strength enhancement factor ranging from two to five for the CFFTs compared to unconfined specimens. Results also revealed substantial nonlinearity and deformability in the LWA-CFFTs due to the angle-ply tube orientation. An iterative analytical model predicted the CFFT’s nonlinear response, validated by experimental data. The findings demonstrate that angle-ply FRP tubes effectively enhance the bearing capacity and deformability of inherently brittle unconfined LWA concrete.

Design and Calculation of Products from Composite Materials Using Software

This article analyzes six types of composite pipes that are good replacements for corrosive steel and metal pipes for oil, gas, and water. The analysis of the six samples of composite pipes was done using the software program Hoffman Engineering, which is intended for the design and calculation of various types of products made of composite materials. For the analysis of the six composite pipes, the same diameter and the same length were taken, and variable parameters are: the type of material from which the composite pipes are made (carbon/epoxy, carbon-glass/epoxy and glass/epoxy), and the angle of winding of the fibers (10º and 90º degrees). Using the Hoffman Engineering software package, an analysis of the durability of the six differently designed composite pipes at high internal pressure was performed. The same conclusion was obtained from all analyses: the high internal pressure resistance of composite pipes is highly dependent on the fiber winding angle and the type of fibers used. Composite pipes obtained with a fiber winding angle of 90º have twice the internal pressure resistance compared to composite pipes obtained with a fiber winding angle of 10º. Composite pipes based on carbon fibers have the highest resistance to internal pressure, then composite pipes based on hybrid materials (glass and carbon fibers) and finally composite pipes based on glass fibers. Finally, a comparison was made with the obtained laboratory results for the same composite pipes. The same conclusion was obtained from all analyses: the high internal pressure resistance of composite pipes is highly dependent on the fiber winding angle and the type of fibers used. The composite pipes obtained by this process are durable and resistant to very high pressures.

Bending energy absorption performance of composite fender piles with different winding angles

Abstract In recent years, there has been an increase in accidents involving vessels colliding with bridge piers. These ship–bridge collisions can result in tragic loss of life and severe damage to the bridge structure. To address this issue, a type of fender pile made of winding-formed glass fiber-reinforced polymer (GFRP) was proposed as a solution. In this article, three- and four-point bending tests were performed to compare and analyze the damage modes and load-carrying capacity of the fender piles at two different winding angles, namely 45° and 75°. Vertical impact test was simulated using ANSYS/LS-DYNA to verify finite element models. The results revealed variations in damage patterns and bending performance of GFRP piles under the two fiber winding angles. The simulation results suggest that GFRP fender piles can effectively increase the impact time of ship–bridge collisions and reduce the collision forces, thereby significantly improving the protection of bridge piers.

On the inflation, bulging/necking bifurcation and post-bifurcation of a cylindrical membrane under limited extensibility of its constituents

We consider the bifurcation and post-bifurcation of an extended and inflated circular cylindrical membrane under limited extensibility of its constituents. First, for illustration of the limited extensibility effect, a membrane made of the (isotropic) Gent model is briefly analyzed. Second, the membrane is considered to be made of an isotropic ground substance reinforced with fibers symmetrically arranged in two helically distributed families which are mechanically equivalent. The mechanical behavior of the fibers in a similar way to the (isotropic) Gent model is taken to reflect fiber limited extensibility. In particular, the materials under consideration are NH models augmented with two functions called reinforcing models, each one accounting for unidirectional reinforcement. For a specific material, since both families are mechanically equivalent, the reinforcing models are equal. The nature of the anisotropy considered, i.e., the reinforcing model, can depend only on the stretch in the fiber direction or can depend on the fiber stretch and also can have an influence on the shear response of the material (i.e., it also captures shearing in the fiber direction). The limitation associated with the material anisotropic deformability as well as the arrangement of the material constituents is discussed with respect to the initiation of bulging and necking for the membrane. The subsequent consequences for configurations in equilibrium during post-bifurcation are also studied in detail and a variety of results are given in terms of the limited extensibility (deformability) of the fibers as well as their mechanical response and arrangement (fiber winding angle).

Influence of winding angles on hoop stress in composite pressure vessels: Finite element analysis

Various pressure vessels from Type I to Type IV are used to store hydrogen and compressed natural gas (CNG) at high pressures. The polymeric liner in Type IV composite pressure vessels (CPVs) does not share the load, unlike those with metallic liners (Type III); hence, the composite layers share the entire load. The winding angles play a crucial role in tailoring the pressure-bearing properties of CPVs. This study investigated the effect of fiber winding angles on the hoop stress in Type IV CPVs using finite element (FE) analysis, and the advantage of multi-angle winding was realized. Stress analysis is vital to ensure that the vessel can withstand the intended operating conditions without undergoing failure. A series of finite element analyses (FEA) was carried out using the Abaqus FE simulation software to study the behavior of an anisotropic fiber-reinforced CPV with varied winding schemes. A stress analysis was performed, and various winding schemes were compared for different cases. The hoop stress in various configurations was documented to assess and compare various winding configurations.

Compressive behavior of circular GFRP tube-confined UHPC-filled steel-encased stub columns

Using ultra-high-performance concrete with coarse aggregate (UHPC-CA) instead of plain concrete, the mechanical performance of FRP tube-confined concrete-filled steel-encased columns (FUSCs) can be significantly improved with controllable cost. In this study, the axial compressive behavior of FUSCs was investigated, in which the thickness and fiber winding angle of FRP tube, section size of profile steel, and substitution rate of coarse aggregate were the variables considered. The failure mode and the load-deformation relation were analyzed, upon which the interaction mechanism between the profile steel, UHPC, and FRP tube was uncovered. The results showed that FUSCs mainly failed in two distinct failure modes, i.e., shear failure and crush failure respectively, depending on the magnitude of FRP confinement and the size of profile steel. Meanwhile, the incorporation of coarse aggregate could enhance the constraint effect of FRP tube, resulting in an increase in the strength index and peak strain up to 16.2% and 38.2%, respectively. With extra restraint after the peak load, the profile steel provided a significant contribution to the FUSCs’ ductility, leading to a transition of FRP confinement effect from non-uniform to uniform. The research outcome serves as a reference for design of FUSCs and promotes the application of FUSC structure.

Theoretical prediction for the torsional stiffness of reinforced thermoplastic pipes (RTPs) based on the strain energy-work equivalence of anisotropic cylinders

Torsional characteristics must be considered in the mechanical analysis of offshore pipelines. However, there is no specific theoretical model for RTPs to predict the torsional behavior due to the multilayered helically winding laminates. To address the problem, a theoretical model using the energy method is constructed, in which the governing equation is based on the strain energy-work equivalence of helically anisotropic hollow cylinders instead of homogenous structures in previous studies on unbonded flexible risers. The strain energy of RTPs is firstly obtained by the stress analysis of helically anisotropic elements, while the work is derived by the torsion-deformation relationship. It gives a concise theoretical expression of torsional stiffness of RTPs for the first time and greatly improves the computation efficiency. Another improvement is that it could consider the coexistence of the isotropic and orthotropic materials due to the symmetry of isotropic materials. To verify the proposed model, quasi-static torsion tests and numerical simulations were conducted on two RTP specimens. The proposed model could give accurate torsional stiffness predictions in both twisting directions. Besides, the stress distributions, the effect of thickness-radius ratios and fiber's winding angles were also investigated, in which the applicability of the proposed model was further discussed.

Composite Overwrapped Pressure Vessel Design Optimization Using Numerical Method

Composite Overwrapped Pressure Vessels (COPVs) are widely used in fields including aeronautics and by companies such as SpaceX to hold high pressure fluids. They are favored for these applications because they are far lighter than all-metal vessels, although they demand special design, manufacturing, and testing requirements. In this study, finite element modeling was used to conducted stress and damage assessments on a composite overwrapped pressure vessel that has a 4 mm thick aluminum core cylinder. To develop the optimum COPV, the lamina sequences, thickness, and fiber winding angle were considered. The relationship between these variables and the composite-overwrapped structure’s maximum burst pressure bearing capacity was assessed. The ABAQUS composite modeler was used to design and generate 14 models of COPVs from carbon fiber/epoxy plies with a consistent thickness of 6.5 mm and various fiber angle orientations. The effects of the ply stacking order were analyzed by the finite element analysis approach for all designed models, which had 13 layers of uniform thickness but a varying fiber orientation. A ply stacking sequence of [55°, −55°] PP winding pattern had an optimum COPV design profile, with a burst pressure bearing capacity of 24 MPa. The stress–strain distribution along the geometry of the COPV was also obtained using the finite element method, and it was found that the distribution is uniform over the surface of the COPV and that its peak values are found towards the polar boss section of the COPV. Extreme stress gradients were noticed when the boss nears its geometrical transition to the dome phase. This factor is evident from the change in the ply thickness caused by the overlapped fiber orientation. The results obtained from this study are useful for the design and application of composite overwrapped pressure vessels.

Effect of Basalt Intraply Fiber Hybridization on the Compression Behavior of Filament Wound Composite Pipes

Abstract The current study deals with the effect of basalt fiber hybridization on the compressive properties of composite pipes reinforced with glass fiber and carbon fiber. Hybrid and non-hybrid fiber reinforced pipes (FRPs) were fabricated through wet filament winding technique. Intraply fiber winding structure in which different fiber types were simultaneously wound at the layer was employed for the hybridization. The FRP samples wound by different fiber winding angles (± (40°), ± (55°), ± (70°)) were prepared in order to gain a better insight on the influence of basalt intraply fiber hybridization. The compression properties of FRP samples were experimentally determined by quasi-static compression tests using external parallel-plates for both the axial and radial directions. The non-hybrid carbon FRP pipes showed the maximum axial compression strength in parallel to the highest strength and lowest ductility of carbon fibers, while the minimum axial compression strength was obtained for the non-hybrid pipes reinforced with basalt fibers that, in comparison, exhibit much less strength and higher ductility. The pipes submitted to the axial compression tests predominantly failed due to the development of cracks and buckling along the fiber direction. While the inclusion of basalt fiber reduced the axial compression behavior of the non-hybrid carbon and glass FRP samples, it improved that behavior in the radial compression tests. Delamination was determined as the major failure mode for the damaged FRPs under radial compression. It is found that the incorporation of basalt fiber provides improvements in radial compression properties as opposed to axial compression properties and in the same manner the increment in fiber winding angle makes a positive contribution to radial compression properties.

An analytical model for the progressive failure prediction of reinforced thermoplastic pipes under axial compression

AbstractAn analytical model is presented to predict the progressive failure of reinforced thermoplastic pipes (RTPs) under axial compression, in which the existing homogenization method and a nonlinear stiffness degradation model are combined to predict the continuum damage mechanical response in an iterative and cyclic way. As the homogenization method ignores the effect of the cross‐sectional curvature on the damage sequence, a stress correction factor is defined to consider this effect. Once corrected stresses satisfy Hashin‐Yeh failure criteria, the nonlinear stiffness degradation model is adopted to update the constitutive relationship established by the homogenization method. The proposed model is capable of identifying the damage location and failure mode, analyzing damage accumulation and predicting the ultimate compression. Meanwhile, ABAQUS Explicit quasi‐static analyses calling a user‐defined subroutine were conducted to capture the progressive failure mechanisms in 3D composites and verify the proposed model. The proposed model was found to give accurate prediction on the elastic stiffness, first ply failure, the damaged stiffness, the ultimate compression, and stress distributions. Furthermore, the effects of fiber's winding angles and the thickness‐radius ratios have been discussed, which illustrate that tensile failure mode would appear even when RTPs are under axial compression.

Reliability-based multi-scale design optimization of composite frames considering structural compliance and manufacturing constraints

The paper proposes an efficient methodology for concurrent reliability-based multi-scale design optimization (RBMDO) of composite frames to minimize structural cost subjecting to compliance constraint. Two types of variables are systematically considered in RBMDO, which are deterministic design variables of the frame components, the discrete fiber winding angles at the two geometrical scales, and random parameters of material properties and loading conditions in both magnitude and direction. To overcome the difficulty of highly nonlinear compliance constraint when using fiber winding angles as design variables and improve efficiency and accuracy of RBMDO of composite frames, the improved single loop and single vector (SLSV) approach based on modified chaos control (MCC) scheme, which is abbreviated hereafter as SLSV-MCC, is proposed, and sensitivities at the current design point are utilized to further increase accuracy of the proposed SLSV-MCC. Six types of specific manufacturing constraints are explicitly considered in the proposed RBMDO to reduce the risk of local failure in the laminated composite. The deterministic multi-scale design optimization (DMDO) model is also presented and utilized for comparison to distinguish differences between deterministic and reliability-based optimization results. Efficiency and accuracy of the proposed SLSV-MCC are compared with the first-order reliability method (FORM) and conventional SLSV approach. Meanwhile, the Monte Carlo simulation (MCS) method is further utilized to validate the accuracy of the proposed RBMDO. The discrete material optimization (DMO) approach is utilized to couple two geometrical scales: macroscopic topology and microscopic material selection. Capabilities of the proposed RBMDO are demonstrated by optimization of 2D and 3D composite frames. Numerical study reveals that the uncertainties in material properties and loading conditions will lead to different macroscopic sizing and topology configurations for deterministic and reliability-based solutions.

A two-step optimization scheme based on equivalent stiffness parameters for forcing convexity of fiber winding angle in composite frames

For stiffness design optimization of composite frame structures, one of the major problems when using fiber winding angles as design variables directly is the lack of convexity of the objective function, which may lead to different local optima depending on initial designs when a traditional gradient-based optimization algorithm is applied. Therefore, the present paper adopts a gradient-based two-step optimization scheme to cope with the difficulty and search for a better optimal design of composite frames in which the fiber winding angles are taken as design variables. To realize the two-step optimization scheme, the equivalent stiffness parameters of a composite beam with circular cross-section are derived in explicit expressions and used to force the convexity of the design optimization of the composite frame. The stiffness matrices are linearly expressed in terms of the stiffness parameters, which guarantee the convexity of the design variable feasible region in the stiffness parameter space. The equivalent stiffness parameters are adopted to keep invariance of physical quantities between fiber winding angle and equivalent stiffness parameter spaces. In the two-step optimization scheme, the minimum identification problem with the constraint that the objective function at the new starting point is less than or equal to the previous objective function at the optimum point in fiber winding angle space is established. Then, the two-step optimization scheme can be implemented in the fiber winding angle and structural equivalent stiffness parameter spaces, respectively, until the minimum identification problem is not possible to identify a new starting point. The proposed two-step optimization scheme for composite frames fully takes advantage of the stiffness parameters in convexity and fiber winding angles as practically physical quantities, respectively. The sensitivity information of the objective function with respect to fiber winding angles and equivalent stiffness parameters is derived by the analytical sensitivity analysis method. Numerical examples show that the two-step optimization scheme can effectively force convexity of the optimization model and help to eliminate the initial design dependency. The effectiveness of the proposed two-step scheme is further verified through the particle swarm optimization (PSO) algorithm which is an evolutionary algorithm with global optimization capability.

Integrated design optimization of composite frames and materials for maximum fundamental frequency with continuous fiber winding angles

Fiber reinforced composite frame structure is an ideal lightweight and large-span structure in the fields of aerospace, satellite and wind turbine. Natural fundamental frequency is one of key indicators in the design requirement of the composite frame since structural resonance can be effectively avoided with the increase of the fundamental frequency. Inspired by the concept of integrated design optimization of composite frame structures and materials, the design optimization for the maximum structural fundamental frequency of fiber reinforced frame structures is proposed. An optimization model oriented at the maximum structural fundamental frequency under a composite material volume constraint is established. Two kinds of independent design variables are optimized, in which one is variables represented structural topology, the other is variables of continuous fiber winding angles. Sensitivity analysis of the frequency with respect to the two kinds of independent design variables is implemented with the semi-analytical sensitivity method. Some representative examples in the manuscript demonstrate that the integrated design optimization of composite structures can effectively explore coupled effects between structural configurations and material properties to increase the structural fundamental frequency. The proposed integrated optimization model has great potential to improve composite frames structural dynamic performance in aerospace industries.

Filaman Sargılı Cam Elyaf Takviyeli Yarıklı Kompozit Tüplerin Burulma Yükleme Durumu Davranışları

The stress and strain behaviors of filament wound glass-fiber epoxy based cylindrical tube structures made of two different stacking sequences as [(±45°)5] and [(0/ 90)5] were numerically investigated under a constant torque value. The exterior surfaces of tubes were deliberately defected by longitudinally extending, rounded end, 0.6 mm deep, 2 mm wide but varying-length slots. Slot-less and full-length-slot structures were also included in the study. During torsional loading, the variations in stresses, strains and twisting angles of the specified thin-walled composite tube models were investigated, comparatively. Additionally, the effects of fiber winding angles and slot lengths on the specified quantities were parametrically examined. A considerable amount of stress accumulation around the slot tip of both type of tube model is measured which constitute a risk of damage progression. At the innermost laminas, slight fluctuations in the maximum stresses are observed in the slot lengths shorter than 140mm, whereas rapid increases are remarkable for exceeded lengths. On the other hand, the maximum stress changes in the outermost layer are quite uneven. From slot-less to full-length-slot, the change in slot dimensions provokes 8.32 and 9.11 % increments in twisting angles in the 45°/-45° angle-ply and 0°/90° cross-ply structures, respectively. Under the same loading condition, [(±45°)5] stacking sequence gives the structure averagely 0.66° lower total rotation at the specimen tip in comparison to [(0/ 90)5] fiber arrangement.

Concurrent multi-scale design optimization of composite frames with manufacturing constraints

This paper presents a gradient based concurrent multi-scale design optimization method for composite frames considering specific manufacturing constraints raised from the aerospace industrial requirements. Geometrical parameters of the frame components at the macro-structural scale and the discrete fiber winding angles at the micro-material scale are introduced as the independent design variables at the two geometrical scales. The DMO (Discrete Material Optimization) approach is utilized to couple the two geometrical scales and realize the simultaneous optimization of macroscopic topology and microscopic material selection. Six kinds of manufacturing constraints are explicitly included in the optimization model as series of linear inequalities or equalities. The capabilities of the proposed optimization model are demonstrated with the example of compliance minimization, subject to constraint on the composite volume. The linear constraints and optimization problems are solved by Sequential Linear Programming (SLP) optimization algorithm with move limit strategy. Numerical results show the potential of weight saving and structural robustness design with the proposed concurrent optimization model. The multi-scale optimization model, considering specific manufacturing constraints, provides new choices for the design of the composite frame structure in aerospace and other industries.

Concurrent multi-scale design optimization of composite frame structures using the Heaviside penalization of discrete material model

This paper deals with the concurrent multi-scale optimization design of frame structure composed of glass or carbon fiber reinforced polymer laminates. In the composite frame structure, the fiber winding angle at the micro-material scale and the geometrical parameter of components of the frame in the macro-structural scale are introduced as the independent variables on the two geometrical scales. Considering manufacturing requirements, discrete fiber winding angles are specified for the micro design variable. The improved Heaviside penalization discrete material optimization interpolation scheme has been applied to achieve the discrete optimization design of the fiber winding angle. An optimization model based on the minimum structural compliance and the specified fiber material volume constraint has been established. The sensitivity information about the two geometrical scales design variables are also deduced considering the characteristics of discrete fiber winding angles. The optimization results of the fiber winding angle or the macro structural topology on the two single geometrical scales, together with the concurrent two-scale optimization, is separately studied and compared in the paper. Numerical examples in the paper show that the concurrent multi-scale optimization can further explore the coupling effect between the macro-structure and micro-material of the composite to achieve an ultra-light design of the composite frame structure. The novel two geometrical scales optimization model provides a new opportunity for the design of composite structure in aerospace and other industries.

Stochastic analysis of functional failure pressures in glass fiber reinforced polyester pipes

• Stochastic analysis of Functional Failure (FF) pressures in GRP pipes is conducted. • Both fiber volume fraction and winding angles are chosen as random parameters. • FF pressures are more significantly affected by fiber volume fraction variations. • Statistical analysis show that most probably FF pressure exceeds its mean value. The main objective of this study is to investigate the functional failure of Glass fiber Reinforced Polyester (GRP) pipes subjected to hydrostatic internal pressure implementing stochastic approach. In this regard, a progressive damage modeling is developed to evaluate the pressure at which weepage takes place throughout the pipe wall thickness. The functional failure implies on a certain pressure that the fluid finds a path through the pipe wall thickness as a consequence of weepage phenomenon. Fiber volume fraction and winding angles in cross plies are considered as the random parameters representing the most important uncertain parameters of filament winding production process. Sufficient numbers of samples are generated using Monte-Carlo technique on the basis of defined convergence criterion. The influence of random behavior of these parameters on the both first-ply-failure and functional failure of GRP pipes are analyzed in an integrated procedure. The results demonstrate that the effect of fiber volume fraction variation on the functional failure pressure is more crucial than that of winding angle variation. Finally, statistical analysis of obtained results is presented on obtained results from stochastic analysis in the form of Weibull probability density function.

Elastic response of water-filled fiber composite tubes under shock wave loading

We experimentally and numerically investigate the response of fluid-filled filament-wound composite tubes subjected to axial shock wave loading in water. Our study focuses on the fluid–structure interaction occurring when the shock wave in the fluid propagates parallel to the axis of the tube, creating pressure waves in the fluid coupled to flexural waves in the shell. The in-house-developed computational scheme couples an Eulerian fluid solver with a Lagrangian shell solver, which includes a new and simple material model to capture the response of fiber composites in finite kinematics. In the experiments and simulations we examine tubes with fiber winding angles equal to 45° and 60°, and we measure the precursor and primary wave speeds, hoop and longitudinal strains, and pressure. The experimental and computational results are in agreement, showing the validity of the computational scheme in complex fluid–structure interaction problems involving fiber composite materials subjected to shock waves. The analyses of the measured quantities show the strong coupling of axial and hoop deformations and the significant effect of fiber winding angle on the composite tube response, which differs substantially from that of a metal tube in the same configuration.

Variable stiffness property study on shape memory polymer composite tube

As a typical smart material, shape memory polymers (SMPs) have the capability of variable stiffness in response to external stimuli, such as heat, electricity, magnetism and solvents. In this research, a shape memory polymer composite (SMPC) tube composed of multi-layered filament wound structures is investigated. The SMPC tube possesses considerable flexibility under high temperature and rigidity under low temperature. Significant changes in effective engineering modulus can be achieved through regulating the environment temperature. Based on the classical laminated-plate theory and Sun’s thick laminate analysis, a 3D theory method is used to study the effective engineering modulus and modulus ratio of the SMPC tube. The tensile test is conducted on the SMPC tube to verify the accuracy of the theoretical method. In addition, the effective engineering modulus and modulus ratio are discussed under different fiber-winding angles and fiber volume fractions of the SMPC tube. The presented analysis provides meaningful guidance to assist the design and manufacture of SMPC tubes in morphing skin applications.

Fiber-Directed Conjugated-Polymer Torsional Actuator: Nonlinear Elasticity Modeling and Experimental Validation

Existing conjugated-polymer actuators typically take the form of benders or linear extenders. In this paper, a conjugated-polymer-based torsional actuator is proposed by embedding helically wound fibers into a conjugated polymer tube during the polymer-deposition process. Upon actuation, the electrolyte-soaked tube swells, and consequently, produces torsion and other associated deformations because of fiber-induced mechanical anisotropy of the composite material. A nonlinear elasticity-based model is presented to capture the torsion, elongation, and dilation of the tube. Experiments on tubular actuators with different thicknesses, fiber-winding angles, and diameters confirm the aforementioned deformation modes and validate the effectiveness of the proposed model.