Composite Conical Shells Research Articles

Nonlinear vibrations of three-phase composite truncated conical shells affected by complex factors under 1:1 internal resonance

The investigation into the nonlinear vibrations of the three-phase composite truncated conical shell structure is still in its early stages, which limits its practical implementation. This paper involves calculating equivalent physical property parameters for the three-phase composite materials and establishing a nonlinear dynamic model for the truncated conical shells. The study examines the nonlinear vibration characteristics of the shells under various conditions, considering factors such as temperature, humidity, reinforcement components, and external excitation. It is observed that temperature and humidity changes have significant influences on the structure's resonant responses, with varying effects for the driving mode and accompanying mode. The addition of GPLs or carbon fiber as reinforcement components weakens the resonant response amplitude with an increase in their content. External excitation is identified as a noteworthy energy input source that significantly impacts the nonlinear vibration characteristics of the three-phase composite conical shell structure, thereby amplifying the resonant responses and complicating the nonlinear dynamic behaviors. The findings hold significant value for guiding the design of advanced composite structures in future engineering.

Analysis of the deformation of conical shells made by 4D Printing of composites

4D printing of composites (4DPC) is a technique that allows the manufacturing of composite structures to shape without the use of a complex-shaped mold. Instead, only a flat mold is utilized. This innovative technique has been employed to make composite leaf springs with performance comparable to metallic springs, omega stiffeners, and corrugated core for flexible wings. Recently, this technique was applied to fabricate composite conical shells. While experimental work has successfully demonstrated the transformation from flat to conical shape, the development of a numerical method to replicate this transformation is highly desirable. The availability of such method not only provides theoretical support for the experimental result, it also provides means to develop other shapes. The lay-up sequence for transforming flat to conical shapes involves curvilinear fibers. Most if not all finite elements currently available deal only with straight fibers (even though the boundaries of the element may be curved). The objective of this research is to examine the efficiency of the analysis for the deformation of composite from flat to curve made by 4DPC by special finite elements containing curved fibers. The developed finite elements were used to determine the shapes of conical shells made using multiple distinct lay-up sequences. The direction of bending in curvilinear fiber structures is significantly influenced by the orientation of the fibers. This highlights the critical role of fiber orientation and layer composition in achieving desired shapes in 4D printed composites.

Thermal buckling analysis of reinforced composite conical shells in acidic environments: Numerical and experimental investigation on the effects of nanoparticles

This study investigates the effects of acid penetration and temperature on the buckling behavior of conical composite shells, to enhance structural integrity and longevity in corrosive environments. The study explores the impact of acid exposure on thermal properties and examines the efficacy of incorporating nano-silica and nano-clay in preventing buckling. Additionally, it analyzes the influence of nanoparticles on the thermal, moisture, and mechanical properties of the composite material. Experimental assessments are conducted to measure material properties during exposure to a sulfuric acid solution, providing a comprehensive understanding of the material's behavior under extreme conditions. However, due to the complexity of investigating the combined effects of temperature, acid, and nanoparticles on composite shell buckling, a combined numerical and experimental approach is adopted to predict the critical buckling load. To this end, equations of conical shells under hygrothermal loading are derived, and the critical buckling load is determined through pre-buckling analysis. The Generalized Differential Quadrature (GDQ) method is employed to solve the hygrothermal buckling of the composite shell using experimentally obtained material properties. Comparative results are presented for different nanoparticles, shell geometries, and exposure times in acidic environments. The experiments reveal that adding nanoparticles enhances mechanical properties and reduces thermal and moisture expansion coefficients. Conversely, the acidic conditions deteriorate these properties. Numerical analysis demonstrates that incorporating nanoparticles significantly increases the critical buckling temperature, with nano-silica and nano-clay particles resulting in an 11.5 % and 34.2 % increase, respectively. However, acidic environments decrease the critical buckling temperature, with reductions of 32 % for unreinforced, 29 % for nano-silica reinforced, and 46 % for nano-clay reinforced composites after three months of exposure.

A semi-analytical spectral element model for guided wave propagation in composite laminated conical shells

The conical shell is a typical non-uniform waveguide with its circumferential radius varies linearly. This work aims to provide physical insights for the composite laminated conical shell in terms of waves. A semi-analytical spectral element model is presented, which adopts the Fourier series in the circumferential direction and the higher-order shape functions in the axial direction. The first-order shear deformation theory and Hamilton principle are employed to derive the energy functions of the conical shell, and they are discretized using the spectral elements to achieve a weak-form variational problem. The dispersion equation and the group velocity expression are derived via the piecewise approximation concept and Bloch's periodic theorem. The accuracy of the developed spectral element is verified by comparison with published results. The deformation evolution mechanisms of the composite conical shell are revealed, and the wave propagation characteristics of uniform and ply drop-off composite conical shells are investigated. The results demonstrated that wavenumber distribution at 0–5 kHz is spatially dependent, and wavenumber becomes cut off and bifurcate near the cone vertex. When the frequency exceeds 2 kHz, the deformation of conical shell changes from rigid to flexible, and the structure tends to be a uniform waveguide. Compared to the geometric curvature effect, the asymmetric lay-up leads to more significant mode coupling.

Optimization Modeling for Vibration of Composite Conical Shell Suitable for A Wide Range of Complex Boundaries: Used for Discontinuous Winding Structure

Optimization Modeling for Vibration of Composite Conical Shell Suitable for A Wide Range of Complex Boundaries: Used for Discontinuous Winding Structure

Modeling and vibration analysis of bolted composite conical-conical shells with flanges

This paper proposes a general semi-analytical modeling method of bolted composite conical-conical shells with flanges based on the first-order shear deformation theory. The coupling connections between conical shells and flanges are achieved by using the penalty function method. A bolted joint model that considers the non-uniform distribution of interface pressure is proposed, which can efficiently simulate any number of bolt connections between flanges and boundaries and between flanges and flanges. The correctness and effectiveness of the proposed modeling method are confirmed through step-by-step comparisons with finite element analysis and experimental testing. Then, the influence of various parameters on the frequency trajectories and modal shapes of bolted composite conical-conical shells with flanges is analyzed, with a particular focus on frequency veering and modal coupling vibration behaviors in these structures. The analyses indicate that the proposed modeling method can flexibly adjust structural geometric parameters, material parameters, bolt parameters, fiber layer parameters, and so on, which can efficiently guide the dynamic design of bolted composite conical shell structures with flanges.

Adjusting dynamic and damping performance in fiber-reinforced magnetorheological elastomer composite conical shells subjected to compressive loads

This study explores the dynamic behavior of axially loaded conical shells composed of magnetorheological elastomer composites (MRECs). The investigation focuses on analyzing the impact of compressive loads on the frequencies and loss factors of these composites. The MRECs consist of laminates reinforced with fibers, enabling tunable viscoelastic properties through the utilization of magnetic fields. The equivalent mechanical characteristics of the MREC are calculated using the modified Voigt and Halpin–Tsai micromechanical rules. By employing the first-order shear deformation theory and Sanders-based strains, the kinematics of the conical shell are accurately modeled. A semi-analytical analysis, combining trigonometric expansion and the generalized differential quadrature (GDQ) methods, is employed to solve the system's highly coupled partial differential equations. Two consecutive analyses are performed. Firstly, the critical buckling load of the MREC conical shell is obtained through a stability analysis. Subsequently, the frequencies and loss factors of the shell in the pre-buckling zone are computed. Parametric analyses are conducted to study the impact of key factors, including magnetic field strength, compressive load magnitude, composite properties, geometric parameters, and boundary conditions. The proposed methodology is rigorously validated through meticulous accuracy and convergence analysis. The outcomes provide valuable insights into the dynamic response of axially loaded magnetorheological elastomer composite conical shells, highlighting their potential in adjustable dynamic and damping systems.

The rigid-flexible coupling vibration of assembled disk-composite conical shell structure of electric aircraft in hygrothermal circumstance

A novel theoretical formulation for addressing the coupling vibration of the rigid disc and flexible composite conical shell structure (RDFCCSs) in hygrothermal circumstances is established to investigate the vibration evolution of the rigid-flexible composite thin-walled coupled structure of new energy electric aircraft. According to Donnell's thin shell theory, the potential energy of the composite conical shell under hygrothermal load is calculated. A uniform mass model and a set of artificial springs distributed on the interface of the shell and disk are imported to simulate the RDFCCSs. The governing equation of the RDFCCSs with arbitrary foundations in hygrothermal circumstances is deduced according to the Rayleigh-Ritz variational procedure. Systematic experiments and finite element simulations have been demonstrated to confirm the accuracy of the proposed method. Three new rigid-flexible coupling vibration modes of the RDFCCSs that differ from the traditional single thin-walled conical shell element due to the influence of the disk have been revealed. After that, the unique vibration characteristics of RDFCCSs under various masses, axial loads, hygrothermal environments and interface connection stiffnesses are discussed in detail.

A smeared stiffener model for vibration analysis of anisogrid-stiffened composite conical shells using differential quadrature method

A smeared stiffener model for vibration analysis of anisogrid-stiffened composite conical shells using differential quadrature method

Free Vibration and Dynamic Analysis on Free-Constrained Layer of Graphene Based on Composite Conical Shell via Jacobi–Ritz Method

Excessive vibration has always been a serious problem for conical shell structures, while the application of the graphene-based free-constrained layer (GFCL) based on carbon fiber-reinforced composite (CFRC) structure is a novel way to improve structural performance. An analytical model for vibration and dynamic characteristics of the GFCL-CFRC conical shell resting on the Winkler–Pasternak elastic foundation with arbitrary boundary conditions is constructed, and four types of GFCL porosity distribution and GFCL dispersion pattern are considered in this model. The multi-segment technique and virtual spring technique are utilized to simulate arbitrary boundary conditions. Then, the first-order shear deformation theory (FSDT) and Hamilton’s principle are employed to obtain the motion equation of the GFCL-CFRC conical shell, and the motion equation of the GFCL-CFRC conical shell is solved by the Ritz method. In conclusion, the dispersion mode of GFCL, thickness ratio of GFCL, and fiber angle have influence on the dynamic performance. With a reasonable design, the dynamic performance of the GFCL-CFRC conical shell can be further improved.

Thermal Postbuckling Characteristics Of Angle-ply Laminated Truncated Circular Conical Shells

Here, the nonlinear thermoelastic pre- and post-buckling characteristics of angle-ply laminated composite conical shells subjected to uniform temperature rise are studied using semi-analytical finite element approach. The finite element formulation is based on first-order shear deformation theory and field consistency principle. The nonlinear governing equations, considering geometric nonlinearity based on von Karman’s assumption for moderately large deformation, are solved using Newton-Raphson iteration procedure coupled with displace- ment control method to trace the prebuckling followed by postbuckling equilibrium path. The presence of asymmetric perturbation in the form of small magnitude load spatially proportional to the linear buckling mode shape is assumed to initiate the bifurcation of the shell deformation. The study is carried out to highlight the influences of semi-cone angle, ply-angles, number of layers and number of circumferential waves on the nonlinear prebuckling/postbuckling thermoelastic response of the laminated circular conical shells. The participation of axisymmetric and asymmetric modes in the total response of the shells is brought out through the deformation shape analysis.

Postbuckling of Laminated Composite Circular Conical Shells Under Combined Thermo-Mechanical Loads

In this paper, the postbuckling characteristics of cross- and angle-ply laminated composite conical shells subjected to combined thermo-mechanical loading are studied using shear deformable semi-analytical finite element. The nonlinear governing equations, considering geometric nonlinearity based on Sanders type of kinematic approximations, are solved using Newton-Raphson iteration procedure coupled with adaptive displacement control method to trace the postbuckling equilibrium path. It is brought out from the study that the inward displacement in the postbuckling region is significantly higher as compared to the outward one. The ratio of the lowest load in the postbuckling path and the bifurcation load increases with the increase in the pressure loading proportion and decreases with the increase in the axial loading proportions. The relative load carrying capacity of shells under different set of loading combinations changes with the increase in the maximum postbuckling displacement. It is also observed that the nonlinearity in the load interaction relation corresponding to lowest load in the postbuckling path is less compared to that for bifurcation load.

Transient Behaviour and Impact Induced First-Ply Failure of Delaminated Composite Conical Shells

Transient Behaviour and Impact Induced First-Ply Failure of Delaminated Composite Conical Shells

Vibration evolution of laminated composite conical shell with arbitrary foundation in hygrothermal environment: experimental and theoretical investigation

This contribution addresses on a systematic experimental and theoretical investigations on the vibration of laminated composite conical shell with hygrothermal environment and arbitrary supports. The Donnell’s thin shell assumption is employed to derive the elastic potential energy, and the hygrothermal potential energy due to the thermal and humid environment is considered at the same time. A series of linear artificial springs are imported on the free boundaries of the conical shell to approximate the possible arbitrary support. The governing equations of motion of laminated composite conical shell in hygrothermal environment with arbitrary foundation have been derived in frame of Rayleigh-Ritz approach by utilizing a series of improved orthogonal polynomials as the admissible displacement functions. Particularly, the mechanical parameters of composite material were determined via the thermomechanical and mechanical parameter analysis instruments. Then, the convergence of the present analytical formulation was confirmed via comparing the experiment and finite element results. Finally, the influence of hygrothermal environment and boundaries stiffness on the vibration of laminated composite conical shell was investigated in detail and several interesting phenomena have been confirmed by theoretical analysis, experiment and finite element method.

First-ply failure load prediction of delaminated pre-twisted rotating composite conical shells

First-ply failure load prediction of delaminated pre-twisted rotating composite conical shells

Free Vibration Responses of Functionally Graded CNT-Reinforced Composite Conical Shell Panels.

Functionally graded CNT (carbon nanotube)-reinforced composites (FG-CNTRCs) are intensively studied because the mechanical behaviors of conventional composites can be dramatically improved. Only a small amount of CNTs are appropriately distributed through the thickness. However, the studies on conical shell panels have been poorly reported when compared with beams, plates and cylindrical shells, even though more parameters are associated with the mechanical behaviors of conical shell panels. In this context, this study intends to profoundly investigate the free vibration of FG-CNTRC conical shell panels by developing an effective and reliable 2-D (two-dimensional) numerical method. The displacement field is expressed using the first-order shear deformation shell theory, and it is approximated by the 2-D planar natural element method (NEM). The conical shell surface is transformed into the 2-D planar NEM grid, and the approach for MITC3+shell element is employed to suppress the shear locking. The developed numerical method is validated through the benchmark experiments, and the free vibration responses of FG-CNTRC conical shell panels are investigated with respect to all the associated parameters. It is found from the numerical results that the free vibration of FG-CNTRC conical shell panels is significantly influenced by the volume fraction and distribution pattern of CNTs, the geometry parameters of the conical shell, and the boundary condition.

Vibration Analysis of Composite Laminated and Sandwich Conical Shell Structures: Numerical and Experimental Investigation

The use of composite conical shell structures across the globe in various applications concentrates on nose cones and incredibly complex vehicle components in the aerospace and automotive industries. This work investigates the free vibration analysis of laminated conical shell (LCS) and sandwich conical shell (SCS) structures with various foam cores. The sandwich construction is fabricated using the hand layup technique. The vibration characteristics of the fabricated LCS and SCS specimens are validated with the Finite element software (ANSYS). Very minimal variation was observed between the experimental and numerical simulations. The various parametric analyses were also studied for the LCS and SCS with length, ply orientation, and boundary conditions. Further, for SCS, vibration behaviors across multiple core materials and core thickness were also investigated.

Free Vibration Analysis of Cross-Ply Laminated Conical Shell, Cylindrical Shell, and Annular Plate with Variable Thickness Using the Haar Wavelet Discretization Method

This paper presents a unified solution method to investigate the free vibration behaviors of a laminated composite conical shell, a cylindrical shell, and an annular plate with variable thickness and arbitrary boundary conditions using the Haar wavelet discretization method (HWDM). Theoretical formulation is established based on the first-order shear deformation theory (FSDT), and displacement components are extended to the Haar wavelet series in the axis direction and trigonometric series in the circumferential direction. The constants generated by the integration process are disposed by boundary conditions, and thus the equations of the motion of the total system, including the boundary condition, are transformed into algebraic equations. Then, the natural frequencies of the laminated composite structures are directly obtained by solving these algebraic equations. The stability and accuracy of the present method are verified through convergence and validation studies. The effects of some material properties and geometric parameters on the free vibration of laminated composite shells are discussed and some related mode shapes are given. Some new results for laminated composite conical shell, cylindrical shell, and annular plate with variable thickness and arbitrary boundary conditions are presented, which may serve as benchmark solutions.

Free Vibration Response of Rotating Hybrid Composite Conical Shell Under Hygrothermal Conditions

Free Vibration Response of Rotating Hybrid Composite Conical Shell Under Hygrothermal Conditions

Nonlinear vibration response of a functionally graded carbon nanotube-reinforced composite conical shell using a stress function method

Nonlinear vibration response of a functionally graded carbon nanotube-reinforced composite conical shell using a stress function method