Composite Shells Research Articles

Dynamic performance of multi‐layered composite sandwich open cylindrical shells with double‐layered soft cores

AbstractIn this paper, the dynamic performance of Multi‐layered Sandwich Composite Cylindrical Open Shells (MSCCOS) with double‐layered soft cores is analyzed for the first time by adopting the First‐order Shear Deformation Theory (FSDT). For accomplishing this aim, vibration differential equations of MSCCOS are derived based on Hamilton's variance principle. Then, the closed‐form Navier solution is introduced to obtain the numerical results of differential equations. Subsequently, the effectiveness and accuracy are discussed by several comparisons. Ultimately, the dramatic effect of different structural and material parameters on natural frequencies and associated loss factors is investigated and described vividly. Because shear deformation and rotary inertia of all layers are considered in vibration differential equations, thin and moderately thick MSCCOS could be researched, and some interesting discoveries for the dynamic performance of MSCCOS are derived.Highlights A vibration model of five‐layered composite open shell was obtained. The optimal structure parameters maximizing the damping properties are shown. Dynamics properties of five‐layered composite open shell are presented.

Coalescence of liquid marbles on oil-infused surface

While droplets typically merge instantly in an air medium, alterations to the outer medium can complicate the coalescence process. This study investigates droplet coalescence dynamics when encapsulated by a uniform liquid–solid composite shell, aiming to understand its implications for mechanical stability and merging behavior. The uniform shell around a sessile droplet is produced by using liquid marble on oil-infused surfaces (LMOI). The coalescence dynamics was studied under two different conditions: droplet with LMOI and LMOI with LMOI. In contrast to merging of bare droplets, coalescence involving at least one LMOI reveals a three-step process, including spreading, depletion, and eventual merging phases. Higher oil viscosity influences the merging process, with increased viscosity leading to delayed merging with longer spreading and depletion phases. LMOI exhibits significant resistance to merging with another LMOI, necessitating external triggers like pressure or electric fields for coalescence. These findings provide insights into designing microreactor systems based on LMOI, contributing to the comprehension of their dynamics and functionalities.

Bending Analysis of Laminated Composite and Sandwich Cylindrical Shells Using Analytical Method and Ansys Calculations

Bending Analysis of Laminated Composite and Sandwich Cylindrical Shells Using Analytical Method and Ansys Calculations

A unified framework for equivalent single layer theories of composite beams, plates, and shells: a review

This article presents a comprehensive review of the unified framework for the equivalent single layer theories of composite beams, plates and shells. First, the approach to unified displacement fields has two main categories: one is to start from the assumption of linear displacement field variables. And the another is to start from the assumption of transverse strains and transverse displacement variable. In terms of unified shape functions, the shape function is defined as the function that exist in the transverse strain rather than the in-plane displacement variables. Moreover, the basic requirements for the choose of shape functions are also given and analysed in this paper. The unified shape functions are introduced in terms of the several functions and the unified polynomial model. In addition, a construction method for new shear strain shape functions is described in this review. Finally, the current research progress and future prospects are also given.

Grey wolf optimizer based-natural frequency optimization of laminated composite shells carrying distributed mass

In this study, a grey wolf optimizer is proposed to find the optimum stacking sequence to maximize the fundamental frequency of shells. The vibration analysis of the shells is done using first-order shear deformation theory and a nine-node isoparametric element with five degrees of freedom per node. A mass lumping scheme with rotary inertia is considered in the finite element formulation to include the rotary inertia effect. The design variable considered is the fiber angle orientation of the shells. The present approaches are compared with previously published results using layerwise optimization theory, the Ritz method, and classical lamination theory. A comparison study is also performed, comparing the GWO-based finite element model against six different metaheuristic approaches, and it demonstrates that the Grey Wolf Optimizer consistently outperforms these competing algorithms. The optimum fiber angle orientation of shells carrying distributed mass for various boundary conditions and shell types is analyzed for the first time, to the best of the author’s knowledge. This novel discovery will benefit future studies.

Forced and post-forced responses of multi-stepped composite cylindrical shell under general moving excitations

For the first time, this work presents a comprehensive analysis of the forced and post-forced vibration responses for the multi-stepped composite cylindrical shell (MSCCS) subjected to moving excitation with the general distribution. Based on the method of reverberation-ray matrix (MRRM) of the general connection conditions, the investigated structural system composed of several cylindrical shells having different lengths and thicknesses is modeled analytically by the inhomogeneous dynamic equations with introduced the continuous acting mechanism of the moving excitations precisely. In order to address the discontinuity problem of the moving excitation at the multi-stepped connections, a coupling technique involving the recombination of wave numbers and a matrix excitation coordinate transfer scheme is adopted. This approach allows for a flexible span of axial loading and arbitrary circumferential distribution. The verification results exhibit excellent accuracy for dealing with the transient responses under various moving excitations of the MSCCS. The novel parameters examples reveal that the post-forced vibration phenomenon can be eliminated within a certain parametric range instead of changing the load velocity. Furthermore, the thickness ratio, axial loading span and circumferential distribution also play an important role in the dynamic responses under moving excitations.

Собственные колебания композитных эллиптических цилиндрических оболочек с жидкостью

Собственные колебания композитных эллиптических цилиндрических оболочек с жидкостью

Dynamic Analysis of Shape-Memory-Alloy-Reinforced Damaged Layered Panel: Reversal of Structural Stiffness

This research investigates the dynamic analysis of a shape-memory-alloy-reinforced laminated composite shell panel (SMARLCSP) with and without damage. The potential of SMA reinforcement against the internally defected composite structural panel has been explored by enhancing the parent structural stiffness and the corresponding dynamic responses. To ensure the accuracy of the proposed model, convergence studies, experimental tests, and numerical validations are performed. The theoretical and mathematical modeling of the study employs the higher-order shear deformation theory, offering improved accuracy for modeling the complex behavior of the SMARLCSP. The transient responses are determined using Newmark’s average acceleration steps via MATLAB computer code. The functional material effect has been included in this analysis via the marching technique to compute the numerical outcomes presented in detail. The study comprehensively evaluates geometric and SMA-relevant parameters for intact and damaged Laminated Composite Spherical Shell Panel (LCSSP) cases. The findings exhibit positive results, highlighting significant enhancements in structural stiffness and improved dynamic responses when SMA reinforcement is incorporated into the composite shell panel.

The competition between buckling and stress failure of degraded composite cylindrical shell under combined axial compression and external pressure loads

When thin-walled composite cylindrical shells are subjected to combined loads, not only will they buckle, but they could fail under overstressing. Buckling-failure and stress-failure are two types of failure that compete mutually, and if one of them occurs, the structure loses its ability to carry the load. However, there is a lack of study, and very little attention was paid to the competitive-failure of the composite cylindrical shells under combined loads. To bridge this research gap, a competitive failure analysis framework of degraded composite cylindrical shells exposed to combined axial compression and external pressure loads was developed, considering the nonlinear buckling-failure interacting curve approach for buckling-failure analysis and the Tsai-Wu failure criterion for stress-failure analysis. The material degradation model was adopted to modify the properties of the failed ply based on two degrading philosophies. The proposed framework agrees well with the published results. Extensive parametric studies are accomplished and presented to detect the failure mode of composites. For material parametric study, the variation of material properties does not significantly affect the shape of the normalized buckling-failure interacting curve, while it appreciably affects the behavior of the stress-failure interacting curve. Moreover, it is found that as the proportions of the longitudinal compressive strength to longitudinal modulus and transverse tensile strength to transverse modulus of composite materials increase, the tendency for buckling-failure increases; otherwise, stress-failure happens. For a geometric parametric study, decreasing the radius-to-thickness ratio leads to an increase in the shape of the buckling-failure interacting curve and the possibility of stress-failure.

Chaos and bifurcation analyses of functionally graded composite spherical shallow shells reinforced with graphene nanoplatelets

Functionally graded (FG) graphene nanoplatelets reinforced composite (FG-GPLRC) structures are expected to be greatly developed in engineering due to their excellent mechanical properties. The nonlinear dynamic behaviors such as chaos and bifurcation are particularly important. This article explores the nonlinear dynamics of FG-GPLRC shallow shells with three different GPL distribution patterns under the transverse and the in-plane excitation. The effective material properties of the composite material were calculated using an improved Halpin-Tsai model and the mixture rule. Using the Hamilton's principle and the high-order shear deformation theory (HSDT) to design a nonlinear mathematical model of simply supported spherical shallow shells. Numerical analysis shows that the weight fraction, the layer number, and the length-to-thickness ratio of GPL have significant effects on the mechanical behavior. These parameters have varying sensitivities to different GPL distribution patterns. The X-shaped distribution is more capable of withstanding larger external excitation compared to the U-shaped and O-shaped. The O-type distribution is more sensitive to the layer number. The mechanical behavior of the two modes also different after exceeding the critical value. This article focuses on providing effective theoretical guidance for practical engineering by simulating the mechanical behavior of structures under complex excitations.

Precast-Monolithic Reinforced Concrete Large-Span Shells of Unique Buildings from Enlarged Elements

The stress-strain state of precast monolithic reinforced concrete shells from enlarged elements taking into account the installation conditions. The results of experimental-theoretical studies of precast monolithic reinforced concrete shells of complex geometry assembled from enlarged elements are given. The studies were carried out on full-scale composite shells 48x48 m and diameter 96m, its enlarged elements 3x18m and 3x24m as well as on the shell model on a scale of 1:10 and 1: 4. The stress-strain state of shells of a similar type was studied with different mounting and splitting designs. Recommendations are given on rational methods for the construction of shells from enlarged elements for public buildings.

Nonlinear bending examination of nanocomposite cylindrical shell exposed to mechanical loads using dynamic relaxation method

In the current context, the nonlinear bending examination of a carbon nanotube reinforced composite (CNTRC) shell exposed to mechanical loading using the first-order shear deformation shell model via the dynamic relaxation (DR) procedure, is perused. The composite shell is assumed to be reinforced in the longitudinal axis. The curved morphology distribution of CNTs is considered to be functionally graded (FG) or uniform along the shell thickness. Mechanical properties of the constituents are gathered based on the modified rule of the mixture. For verification, the present numeric outcomes are compared with available references and ABAQUS finite element package. Finally, the roles of effective items including carbon nanotubes (CNTs) distributions, thickness-to-radius and length-to-radius ratios, boundary conditions, and the volume fraction of CNTs are investigated on the maximum non-dimension deflection.

G-code generation for deposition of continuous glass fibers on curved surfaces using material extrusion-based 3D printing

Improving the mechanical properties of 3D printed parts produced through a material extrusion-based 3D printer with continuous fibers (carbon, glass, and aramid) has been a focal point for numerous researchers. Given the layered nature of additive manufacturing (AM) processes, wherein parts are built up layer by layer, most studies involve the deposition of continuous fibers onto a 2D surface. Cases involving curved surfaces have employed robots with high degrees of freedom. This research introduces a method for depositing continuous glass fibers onto curved surfaces, implemented on a cost-effective material extrusion-based 3D printer. The presented approach involves G-code modification, the incorporation of a rotating axis for the nozzle, and the application of computer-aided design and manufacturing techniques. Experimental results affirm the efficacy of this method for depositing continuous fibers onto curved surfaces. The developed technique enables the production of free-form composite shells with a thermoplastic matrix and continuous fiber reinforcement. Lastly, through 3D scanning of the printed sample and subsequent comparison with the 3D model, the degree of surface form deviation and tolerance is determined. The maximum deviation identified in this study is 0.1 mm, a tolerable amount considering the inherent characteristics and behaviors of thermoplastic materials (shrinkage and warpage) during production processes.

Transient response of doubly-curved bio-inspired composite shells resting on viscoelastic foundation subject to blast load using improved first-order shear theory and isogeometric approach

Investigating natural-inspired applications is a perennially appealing subject for scientists. The current increase in the speed of natural-origin structure growth may be linked to their superior mechanical properties and environmental resilience. Biological composite structures with helicoidal schemes and designs have remarkable capacities to absorb impact energy and withstand damage. However, there is a dearth of extensive study on the influence of fiber redirection and reorientation inside the matrix of a helicoid structure on its mechanical performance and reactivity. The present study aimed to explore the static and transient responses of a bio-inspired helicoid laminated composite (B-iHLC) shell under the influence of an explosive load using an isomorphic method. The structural integrity of the shell is maintained by a viscoelastic basis known as the Pasternak foundation, which encompasses two coefficients of stiffness and one coefficient of damping. The equilibrium equations governing shell dynamics are obtained by using Hamilton's principle and including the modified first-order shear theory, therefore obviating the need to employ a shear correction factor. The paper's model and approach are validated by doing numerical comparisons with respected publications. The findings of this study may be used in the construction of military and civilian infrastructure in situations when the structure is subjected to severe stresses that might potentially result in catastrophic collapse. The findings of this paper serve as the foundation for several other issues, including geometric optimization and the dynamic response of similar mechanical structures.

Dynamic characteristics of novel damping sandwich composite open cylindrical shell: From theory to simulation

Based on the first-order shear deformation shell theory, the free vibration model of Multilayer Damping Sandwich Composite Open Cylindrical Shell (MDSCOCS) under different lay-up angles is established. The Navier double series and Rayleigh-Ritz method are used to solve the free vibration equation under four sided simply supported boundary conditions. The theoretical solutions are compared with the existing literature and finite element simulation results respectively to verify the validity of theoretical calculation model. The influences of the thickness, position, shell opening angle, composite lay-up angle and other factors on the natural frequency and loss factor of the structure under different number of core layers are investigated in detail. The analysis shows that the damping loss factor of the composite structure is greatly improved by the addition of multilayer damping sandwich, and the dynamic performance of the composite structure is optimized, compared with that of single-layer damping sandwich composite structure. It provides a theoretical basis for the design of multilayer damping sandwich composite open cylindrical shell.

Carrera Unified Formulation (CUF) for the composite plates and shells of revolution. Layer-wise models

Here, higher order layer-wise models of elastic composite multilayer plates and shells of revolution are developed using the variational principle of virtual power for the 3-D linear anisotropic theory of elasticity and generalized series in the thickness coordinates. Following the Unified Carrera Formulation (CUF), the stress and strain tensors, as well as the displacement vector, were expanded into series in terms of the coordinates of the shell thickness. The higher-order rectangular plate and cylindrical shell supported on the edges under sinusoidal loading, are considered and solved analytically using a Navier close form solution method. Also, composite axisymmetric conical, spherical, elliptical and catenoidal shell fixed at the ends are considered. Numerical calculations were performed using the computer algebra software Mathematica. The resulting equations can be used for theoretical analysis and calculation of the stress–strain state, as well as for modeling thin-walled structures used in science, engineering, and technology. The results of calculation can be used as benchmark examples for finite element analysis of the higher order composite laminate shells.

Gegenbauer-Ritz method for free vibration analysis of rotating functionally graded graphene reinforced porous composite stepped cylindrical shells with arbitrary boundary conditions

In this paper, a semi-analytic method with Gegenbauer polynomials as an admissible function is presented. Free vibration analysis of rotating functionally graded graphene reinforced porous composite (FG-GPLRPC) stepped cylindrical shells with arbitrary boundary conditions is analyzed by using the unified Gegenbauer-Ritz method. The effective material properties of rotating FG-GPLRPC stepped cylindrical shells are obtained with Halpin-Tsai micromechanical model and the open-cell body theory. The boundary conditions at both ends of the structure and the continuous coupling between the shell segments are simulated with the artificial spring technique. Then, based on the first-order shear deformation theory (FSDT), the Rayleigh-Ritz method is employed to derive the equations of rotating FG-GPLRPC stepped cylindrical shells. Finally, the influences of several factors on dimensionless frequency of the shell are also assessed. The results show that this method has excellent convergence and higher computational efficiency. Furthermore, the traveling wave frequencies of different modes show different trends with the increase of rotating speed under elastic boundary conditions. In high-order modes, the influence of porosity coefficient is smaller than that of rotating speed.

Rapid Design of Fully Soft Deployable Structures Via Kirigami Cuts and Active Learning

AbstractSoft deployable structures – unlike conventional piecewise rigid deployables based on hinges and springs – can assume intricate 3‐D shapes, thereby enabling transformative soft robotic and manufacturing technologies. Their virtually infinite degrees of freedom allow precise control over the final shape. The same enabling high dimensionality, however, poses a challenge for solving the inverse problem: fabrication of desired 3D structures requires manufacturing technologies with extensive local actuation and control, and a trial‐and‐error search over a large design space. Both of these shortcomings are addressed by first developing a simplified planar fabrication approach that combines two ingredients: strain mismatch between two layers of a composite shell and kirigami cuts that relieves localized stress. In principle, it is possible to generate targeted 3‐D shapes by designing the appropriate kirigami cuts and the amount of prestretch (without any local control). Second, a data‐driven physics‐guided framework is formulated that reduces the dimensionality of the inverse design problem using autoencoders and efficiently searches through the “latent” parameter space in an active learning approach. The rapid design procedure is demonstrated via a range of target shapes, such as peanuts, pringles, flowers, and pyramids. Experiments and our numerical predictions are found to be in good agreement.

Programmable Photoswitchable Microcapsules Enable Precise and Tailored Drug Delivery from Microfluidics.

The development of precision personalized medicine poses a significant need for the next generation of advanced diagnostic and therapeutic technologies, and one of the key challenges is the development of highly time-, space-, and dose-controllable drug delivery systems that respond to the complex physiopathology of patient populations. In response to this challenge, an increasing number of stimuli-responsive smart materials are integrated into biomaterial systems for precise targeted drug delivery. Among them, responsive microcapsules prepared by droplet microfluidics have received much attention. In this study, we present a UV-visible light cycling mediated photoswitchable microcapsule (PMC) with dynamic permeability-switching capability for precise and tailored drug release. The PMCs were fabricated using a programmable pulsed aerodynamic printing (PPAP) technique, encapsulating an aqueous core containing magnetic nanoparticles and the drug doxorubicin (DOX) within a poly(lactic-co-glycolic acid) (PLGA) composite shell modified by PEG-b-PSPA. Selective irradiation of PMCs with ultraviolet (UV) or visible light (Vis) allows for high-precision time-, space-, and dose-controlled release of the therapeutic agent. An experimentally validated theoretical model was developed to describe the drug release pattern, holding promise for future customized programmable drug release applications. The therapeutic efficacy and value of patternable cancer cell treatment activated by UV radiation is demonstrated by our experimental results. After in vitro transcatheter arterial chemoembolization (TACE), PMCs can be removed by external magnetic fields to mitigate potential side effects. Our findings demonstrate that PMCs have the potential to integrate embolization, on-demand drug delivery, magnetic actuation, and imaging properties, highlighting their immense potential for tailored drug delivery and embolic therapy.

Internal pressure testing of open-ended filament-wound cylinders using radial expansion of elastomeric inserts

A novel approach for generating internal pressure in filament-wound cylinders using the compressed elastomer method is investigated. Pressure is exerted on the inner surface of the cylinder by radially expanding elastomeric discs inside the composite cylindrical shell. This is accomplished by applying a uniaxial compressive load to the discs with the aid of rigs placed between compression platens in an ordinary universal testing machine. The digital image correlation (DIC) technique is employed to assist the tests in mapping both strain and displacement fields during the entire testing process. Cylinders with six different winding angles (±35°, ±45°, ±55°, ±65°, ±75°, and ±90°) are prepared and analysed. Their load-carrying capacity increases up to an angle of ±75°, accompanied by systematic changes in deformation and failure mechanisms. The suggested testing setup offers benefits in evaluating the impact of processing parameters on the internal pressure strength of filament-wound cylinders. It serves as a secure and cost-efficient laboratory-scale alternative to conventional hydrostatic pressure testing.