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In the present study, a discrete layer model was established to explore the vibration performance of Functionally Graded Carbon Nanotube‐Reinforced Composite (FG‐CNTRC) open cylindrical shells with damping film embedded based on the first‐order shell theory. There are four configurations of stacking arrangements considered for FG‐CNTRC open cylindrical shells with damping film embedded. The equivalent structural parameters of the top and bottom FG‐CNTRC panels are generated by implementing the extended mixing rule. Governing equations are derived based on the Hamilton principle and solved with the Naiver solution. Subsequently, after verifying the validity of this paper's solution by comparing it with the published literature, a parametric elaborated investigation discloses the variation patterns of vibration performance of four FG‐CNTRC open cylindrical shells with damping film embedded. The conclusions of the study can be used as a useful guide about open cylindrical composite shell structures with the design of high strength and damping. Highlights: Discrete layer vibration model was bulit based on first‐order shell theory.Vbration performance of FG‐CNTRC open sandwich shells was studied.Variation patterns of frequency and loss factor was disclosed. [ABSTRACT FROM AUTHOR]

In this paper, the thermomechanical buckling and vibration analysis are investigated for carbon nanotube‐reinforced composite sandwich doubly curved shells (CNCSDS) under the action of both thermal loads and in‐plane compressive loads. Based on the von‐Karman non‐linear kinematic relations, First Order Shear Theory, and Hamilton's principle, the vibration and stability equations for CNCSDS under thermomechanical loads are deduced. For obtaining the critical thermomechanical buckling load and vibration frequency, an exact method is adopted. Subsequently, the results are validated by comparing with the finding in published literature and simulation results. At last, the influence of system parameters on critical thermomechanical buckling load and vibration frequency is studied and displayed graphically. Meanwhile, some new results about thermomechanical buckling and vibration analysis of CNCSDS are proposed for the first time. Highlights: Thermomechanical buckling and vibration of carbon nanotube‐reinforced composite sandwich doubly curved shells was studied.Vibration and stability equations under thermomechanical loads was deduced.The change rules of thermomechanical buckling load and frequency were obtained. [ABSTRACT FROM AUTHOR]

Composite sandwich double‐curved shells (CSDCS) have been extensively employed in the engineering domain of variable temperature environments; consequently, it becomes very significant and essential to present the thermal buckling characteristics of CSDCS to supply some valuable numerical results. The no‐linear strain–displacement relationship due to temperature variation has been taken into consideration based on the Von‐Karman non‐linear strain theory, and Hamilton's principle is adapted to derive the buckling differential equations of the CSDCS. The Navier method is employed to solve the eigenvalue problem for obtaining the critical buckling temperature. Finally, through studying the variation rule of thermal buckling temperature (CBT), several interesting findings on thermal buckling of the CSDCS are shown, as follows: As the h3/h1 rises, the CBTs of CSDCS first decrease then increase. With the increase of radius value, the CBTs of spherical shells decline, the CBTs of models (1,1) and (2,2) of hyperbolic paraboloidal shells are essentially unchanged, but the ones of models (1,2) and (2,1) decrease. As the h2 increases, the CBT progressively grows after the initial reduction. With the increase in aspect ratio, the CBTs for modes (1,1) and (2,1) of CSDCS gradually increase, and the ones of modes (1,2) and (2,2) shows an increase after an initial decrease. The CBTs of CSDCS gradually increase as the shear module of damping layer increases. Highlights: Thermal buckling of composite doubly‐curved sandwich shells was studied.A solution was proposed to derive the buckling differential equations.The change rules of critical buckling temperature were obtained. [ABSTRACT FROM AUTHOR]

In this paper, for reducing the number of independent generalized displacements of the traditional piecewise model to decrease the number of vibration equations, a refined piecewise shear deformation model considering the effect of rotary inertias and shear deformation for vibration analysis of laminated composite and sandwich plates is presented. Unlike the conventional piecewise model, the significant novelty of the proposed theory is that the new proposed piecewise theory reduces the number of independent generalized displacements from 9 to 8. Some relevant assumptions, dividing the transverse displacement into bending and shear parts, are introduced into the traditional piecewise model, and the displacement fields of the refined piecewise shear deformation theory are obtained. Next, the governing equations are derived by employing Hamilton's principle and solved by the closed-form Navier method. Then, the present solutions are compared with those available in the previous literature for confirming their validity. Finally, the variations of frequencies and loss factors with system parameters are evaluated and presented graphically. [ABSTRACT FROM AUTHOR]

In this paper, we present an experimental study on the surface frictional wear mechanism of the high-strength aluminum alloy after high-speed milling. We use a surface profilometer and an X-ray stress tester to characterize the milled surface integrity of the material, and UMT-3 friction testing machine to obtain its surface roughness, oxygen content, hardness, and wear morphology during different wear stages. The results show that milling-induced residual tensile stress makes the cut surface more prone to fatigue cracking and consequently abrasive wear in the initial wear stage. The larger the angle between the friction pair movement direction, the greater the chance of adhesive wear and abrasive wear. A complete friction stage pattern can be obtained at a high load (15 N) and a low sliding speed (0.6 mm/s). The friction pair enters a stable wear stage after 20 sliding cycles. Work hardening constitutes the main driver of stable wear. [ABSTRACT FROM AUTHOR]

A new type of damping composite structure was fabricated by embedding polymer materials into the phenolic resin matrix fiberglass-reinforced laminates. The damping layer of novel damping composites shows the characteristics of anti-aging and strong adhesion compared with the traditional damping composites. The ingredients of the polymer material were studied according to the orthogonal test method. The curing mechanism of resin matrix and vulcanized characteristics of polymer damping material were combined in the design process. The damping composite structures were researched by single cantilever beam vibration and modal analysis techniques to determine its damping characteristics. The least square method was used to calculate the loss factor of the damping composites. It was observed that the damping performance of co-cured composites was significantly enhanced compared to traditional damping composites. When the thickness of damping layer is only 0.1 mm, the composite loss factor increases by as much as 49%. The embedding of damping layer has a positive effect on structural stiffness. The work indicates that the low-temperature co-cured phenolic resin matrix damping composite has broad application prospects in vibration reduction. [ABSTRACT FROM AUTHOR]

In this work, a first-order discrete layer model is performed to deal with the free vibration and buckling analysis of composite sandwich plates in thermal environment. Owing to considering the effect of rotary inertias and shear deformation, thin-to-moderately thick shells can be analyzed. The differential equations of motion are derived from Hamilton's principle, and account for the nonlinear variation of the in-plane and transverse displacements through the thickness due to temperature variation. These equations are solved by means of the closed-form Navier method, and validated by comparing the numerical results obtained by the present method with the findings published in literatures. Finally, the variation tendency of critical buckling temperature with material parameters is evaluated and shown graphically. [ABSTRACT FROM AUTHOR]

The aim of this paper is to perform a structural optimization of composite beams with multilayered viscoelastic cores based on the first-order shear deformation theory. First, the numerical model of vibration governing equations is derived by employing the Hamilton's principle, and these vibration equations are solved by means of the closed-form Navier method. Then the calculated results are compared with the findings of previous literatures, and a good agreement is observed. Finally, structural optimization of composite sandwich beams is obtained by numerical analysis. [ABSTRACT FROM AUTHOR]