De-qing Yang - Academia.edu (original) (raw)

Papers by De-qing Yang

Research paper thumbnail of The load criteria for ship mechanical noise prediction in low frequencies and experimental validation

Journal of Ocean Engineering and Science, 2022

Research paper thumbnail of Vibroacoustics Analysis And Reduction of Liquid-filled Pipeline

The characteristics of pipeline model construction for vibroacoustic analysis are investigated. T... more The characteristics of pipeline model construction for vibroacoustic analysis are investigated. The establishment of fluid-structure coupling numerical models with FE model and FE-SEA hybrid model in pipeline vibroacoustics analysis was proved to be suitable for the whole frequency domain. Experimental investigations compared with the numerical results showed the effectiveness of the presented technology. Finally, vibration reduction design of pipeline with application of different damping materials were evaluated by the proposed technology.

Research paper thumbnail of Numerical Simulation of Vibration and Noise for Ship Collision

The correct use of nonlinear finite element analysis enables increased confidence in the results ... more The correct use of nonlinear finite element analysis enables increased confidence in the results and better utilization of the actual structural capacity compared with simplified methods, which has rapidly become a widely adopted tool for the simulation of such accidental impacts. By applying structural dynamic finite element numerical simulation technology and acoustic numerical simulation technology, taking an actual ship collision accident as an example, detailed vibration and acoustic ship models through the finite element method are constructed in this paper. Collision process, structure damages, vibration of ship structure and noise resulting from collision are calculated, according to the loading condition and the navigation status of accident ships. Comparison of the results shows a good agreement between the accident structure damages and numerical simulation results. Moreover, acceleration vibration level difference and average sound pressure level of the wheelhouse are ob...

Research paper thumbnail of Sensitivity Analysis of Non-Linear Air Gap and Wave Slamming Load with Respect to Current for Semi-Submersible Platform Design

A design of offshore platform is mainly based on the extreme response analysis due to the critica... more A design of offshore platform is mainly based on the extreme response analysis due to the critical environment condition. It is important to predict accurately air gap and wave slamming load in order to check the strength of local structures which withstand the wave slamming due to negative air gap. Due to the factors of working depth, the size of mooring system model, sizes of experimental tank and the equipment of tank, it is difficult to simulate the wave, wind and current loads at the same time, accurately. When the platform suffers the rough wave condition, the current is also harsh. The main aim of this paper is to present sensitivity analysis results of non-linear air gap and wave slamming load with respect to the current load for the design of semisubmersible platform. In this paper, the wind tunnel test and the seakeeping model test have been performed. The linear air gap analysis can be carried out in frequency domain without the effects of wind and current. But the result...

Research paper thumbnail of Anti-Explosion Performance of Composite Blast Wall with an Auxetic Re-Entrant Honeycomb Core for Offshore Platforms

Journal of Marine Science and Engineering, 2020

To improve the anti-explosion performance of blast wall in offshore platforms, an auxetic re-entr... more To improve the anti-explosion performance of blast wall in offshore platforms, an auxetic re-entrant blast wall (ARBW) was proposed and designed based on the indentation resistance effect of an auxetic structure. Based on the numerical nonlinear dynamic analysis method verified by the explosion experiment of a conventional steel corrugated blast wall (CBW), the failure mechanisms of ARBW, steel honeycomb sandwich blast wall (HSBW) and CBW were investigated under distributed impulse loads. Computational results demonstrated the excellent anti-explosion performance of the proposed ARBW design. Concerning the minimal deformation at the mid-point of the proposed protective structures, the ARBW performed best. As regards the minimal deformation at the connection, both ARBW and HSBW worked well. The stress distribution of the connection illustrated the different energy absorption and transmission modes of the three blast walls.

Research paper thumbnail of Impact resistance performance and optimal design of a sandwich beam with a negative stiffness core

Journal of Mechanical Science and Technology, 2019

Numerical analyses were carried out to investigate the response of a sandwich beam with a negativ... more Numerical analyses were carried out to investigate the response of a sandwich beam with a negative stiffness (NS) core under quasistatic compression and low-velocity impact at the center. By varying the thicknesses of face sheets and interlayers and the lengths of segments, a parametric study on the impact resistance of the sandwich beam is conducted. The maximal deflection of the top face sheet and the strain energy stored in the NS beam were recorded at the moment when the impactor's velocity decreased to zero. Based on the impact simulation, a multi-objective optimization problem on the beam configuration was set up to find out the most efficient antideformation design at the impact velocity of 2500 mm/s. To solve the problem with the surrogate model method, an optimal Latin hypercube sampling (OLHS) technique and a two-phase differential evolution (ToPDE) algorithm were utilized to generate calculation points in the design space, respectively. Then different surrogate models including the RSM model, the Kriging model and the RBF model, were compared to give the best approximation of the original problem. In the end, the genetic algorithm (GA) dealing with discrete optimization problems was employed to obtain the optimum solutions. Results indicate that different parts of the NS beam dominate the resistance to deformation under different levels of impact intensity. The largest portion of the strain energy is stored in the four curved plates. In the obtained optimization solution, the longest segment is near the two ends and the flat plates near the top are thicker, which is instructive to the beam design on improving impact resistance.

Research paper thumbnail of Design Method of Lightweight Metamaterials with Arbitrary Poisson’s Ratio

Materials, 2018

A heuristic approach to design lightweight metamaterials with novel configurations and arbitrary ... more A heuristic approach to design lightweight metamaterials with novel configurations and arbitrary Poisson’s ratio is studied by using the functional element topology optimization (FETO) method. Mathematical model of the optimization problem is established, where the minimization of the mass is set as the objective, then a series of metamaterials with Poisson’s ratio ranging from −1.0 to +1.0 are designed by solving this model. The deformation resistance and vibration reduction performance of the novel metamaterials and conventional honeycomb are compared by numerical simulations. Specific stiffness analysis shows that the novel metamaterials are 5.6 to 21.0 times more resistant to deformation than that of the honeycomb, and frequency response shows about 60% improvement in vibration reduction performance. Finally, the lightweight effects of the novel metamaterials on deformation resistance and vibration reduction performance are analyzed, and further analysis reflects that the lightw...

Research paper thumbnail of Vibration and Sound Transmission Performance of Sandwich Panels with Uniform and Gradient Auxetic Double Arrowhead Honeycomb Cores

Shock and Vibration, 2019

Auxetic mechanical metamaterials that exhibit a negative Poisson’s ratio (NPR) can be artificiall... more Auxetic mechanical metamaterials that exhibit a negative Poisson’s ratio (NPR) can be artificially designed to exhibit a unique range of physical and mechanical properties. Novel sandwich structures composed of uniform and gradient auxetic double arrowhead honeycomb (DAH) cores were investigated in terms of their vibration and sound transmission performance stimulated by nonhomogeneous metamaterials with nonperiodic cell geometries. The spectral element method (SEM) was employed to accurately evaluate the natural frequencies and dynamic responses with a limited number of elements at high frequencies. The results indicated that the vibrating mode shapes and deformations of the DAH sandwich models were strongly affected by the patterned gradient metamaterials. In addition, the sound insulation performance of the considered DAH sandwich models was investigated regarding the sound transmission loss (STL) from 1 Hz to 1500 Hz under a normal incident planar wave, and this performance was ...

Research paper thumbnail of Modelling theory of functional element design for metamaterials with arbitrary negative Poisson's ratio

Computational Materials Science, 2018

Metamaterials with arbitrary negative Poisson's ratio(NPR) can be designed by functional element ... more Metamaterials with arbitrary negative Poisson's ratio(NPR) can be designed by functional element topology optimization method, but modelling theory of this method is not investigated thoroughly, including functional element, volume fraction ration, the definition of objective functions and NPR constraints. In this paper, functional element with different shapes (triangle and rectangle), method of evaluating macroscopic NPR value, and three categories of objective functions: maximum compliance, minimum mass, minimum compliance, are conducted. A series of metamaterials structures with arbitrary NPR (the ratio range is −0.3 to −6.0) are designed, and the NPR values of these metamaterials structures are verified. Static analysis shows that the Poisson's ratio between single functional element and macroscopic metamaterials structure are consistent with each other (error rate is 3.3%). Dynamic analysis to explore the vibration reduction performance of the metamaterials structure. All our works provide a method and theory for the design of novel metamaterials structure with arbitrary specified NPR.

Research paper thumbnail of Mechanical Performance of Multidirectional Buckling-Based Negative Stiffness Metamaterials: An Analytical and Numerical Study

Materials, 2018

Unidirectional, bidirectional and tridirectional Buckling-based Negative Stiffness (BNS) lattice ... more Unidirectional, bidirectional and tridirectional Buckling-based Negative Stiffness (BNS) lattice metamaterials are designed by adding prefabricated curved beams into multidimensional rigid frames. Finite Element Analysis models are built, and their mechanical performance is investigated and discussed. First, geometric parameters of the curved beam were systematically studied with numerical analyses and the results were validated by theoretical solutions. Next, within unidirectional designs of different layer numbers, the basic properties of multilayer BNS metamaterials were revealed via quasi-static compressions. Then, the bidirectional and tridirectional designs were loaded on orthogonal axes to research both the quasi-static and dynamic behaviors. For dynamic analysis conditions, simulation scenarios of different impact velocities were implemented and compared. The results demonstrate that the proposed numerical analysis step has accurately predicted the force-displacement relations of both the curved beam and multilayer designs and the relations can be tuned via different geometric parameters. Moreover, the macroscopic performance of the metamaterials is sensitive to the rigidity of supporting frames. The shock force during impact is reduced down below the buckling thresholds of metamaterial designs and sharp impact damage is avoided. The presented metamaterials are able to undergo multiaxial stress conditions while retaining the negative stiffness effect and energy-absorbing nature and possess abundant freedom of parametric design, which is potentially useful in shock and vibration engineering.

Research paper thumbnail of Pitch Channel Control of a REMUS AUV with Input Saturation and Coupling Disturbances

Applied Sciences, 2018

The motion of an underwater vehicle is prone to be affected by time-varying model parameters and ... more The motion of an underwater vehicle is prone to be affected by time-varying model parameters and the actuator limitation in control practice. Adaptive control is an effective method to deal with the general system dynamic uncertainties and disturbances. However, the effect of disturbances control on transient dynamics is not prominent. In this paper, we redesign the L 1 adaptive control architecture (L1AC) with anti-windup (AW) compensator to guarantee robust and fast adaption of the underwater vehicle with input saturation and coupling disturbances. To reduce the fluctuation of vehicle states, the Riccati-based AW compensator is utilized to compensate the output signal from L1AC controller via taking proper modification. The proposed method is applied to the pitch channel of REMUS vehicle's six Degrees Of Freedom (DOF) model with strong nonlinearities and compared with L1AC baseline controller. Simulations show the effectiveness of the proposed control strategy compared to the original L1AC. Besides, the fluctuation in roll channel coupled with pitch channel is suppressed according to the performances of control tests.

Research paper thumbnail of Sensitivity analysis of air gap motion with respect to wind load and mooring system for semi-submersible platform design

China Ocean Engineering, 2016

A design of semi-submersible platform is mainly based on the extreme response analysis due to the... more A design of semi-submersible platform is mainly based on the extreme response analysis due to the forces experienced by the components during lifetime. The external loads can induce the extreme air gap response and potential deck impact to the semi-submersible platform. It is important to predict air gap response of platforms accurately in order to check the strength of local structures which withstand the wave slamming due to negative air gap. The wind load cannot be simulated easily by model test in towing tank whereas it can be simulated accurately in wind tunnel test. Furthermore, full scale simulation of the mooring system in model test is still a tuff work especially the stiffness of the mooring system. Owing to the above mentioned problem, the model test results are not accurate enough for air gap evaluation. The aim of this paper is to present sensitivity analysis results of air gap motion with respect to the mooring system and wind load for the design of semi-submersible platform. Though the model test results are not suitable for the direct evaluation of air gap, they can be used as a good basis for tuning the radiation damping and viscous drag in numerical simulation. In the presented design example, a numerical model is tuned and validated by ANSYS AQWA based on the model test results with a simple 4 line symmetrical horizontal soft mooring system. According to the tuned numerical model, sensitivity analysis studies of air gap motion with respect to the mooring system and wind load are performed in time domain. Three mooring systems and five simulation cases about the presented platform are simulated based on the results of wind tunnel tests and sea-keeping tests. The sensitivity analysis results are valuable for the floating platform design.

Research paper thumbnail of Vibration of thermally postbuckled carbon nanotube-reinforced composite beams resting on elastic foundations

International Journal of Non-Linear Mechanics, 2017

This paper investigates the small-and large-amplitude vibrations of thermally postbuckled carbon ... more This paper investigates the small-and large-amplitude vibrations of thermally postbuckled carbon nanotube-reinforced composite (CNTRC) beams resting on elastic foundations. For the CNTRC beams, uniformly distributed (UD) and functionally graded (FG) reinforcements are considered where the temperature-dependent material properties of CNRTC beams are assumed to be graded in the thickness direction and estimated through a micromechanical model. The motion equations are derived based on a higher order shear deformation beam theory with including the beam-foundation interaction. The initial deflection caused by thermal postbuckling is also included. The numerical illustrations concern small-and large-amplitude vibration characteristics of thermally postbuckled CNTRC beams under uniform temperature field. The effects of carbon nanotube (CNT) volume fraction and distribution patterns as well as foundation stiffness on the vibration characteristics of CNTRC beams are examined in detail.

Research paper thumbnail of Thermal postbuckling analysis of anisotropic laminated beams with tubular cross-section based on higher-order theory

Ocean Engineering, 2016

Buckling of composite riser assumed beam structure is one of numerous engineering challenges in d... more Buckling of composite riser assumed beam structure is one of numerous engineering challenges in deep water pipeline design. Thermal postbuckling analysis of shear deformable anisotropic laminated composite beams with tubular cross-section subjected to uniform, linear and non-linear temperature distribution through the thickness resting on a two-parameter elastic foundation is presented. The material of each layer for the composite beam with tubular section is assumed to be linearly elastic and fiberreinforced. The governing equations are introduced by using high-order shear deformation beam model with a von Kármán-type of kinematic nonlinearity. Composite beams with clamped-clamped, clampedhinged, and hinged-hinged boundary conditions are considered. A numerical solution for nonlinear partial-integral differential form in terms of the transverse deflection by using Galerkin's method is employed to determine the buckling temperatures and postbuckling equilibrium paths of anisotropic laminated beams with different types of temperature distribution through the thickness. The numerical illustration concern the thermal postbuckling response of laminated beams with different types of boundary conditions, ply arrangements (lay-ups), geometric and physical properties. The results reveal that the geometric and physical properties, temperature dependent properties, initial geometry imperfection, boundary conditions and elastic foundation have a significant effect on thermal postbuckling behavior of anisotropic laminated composite tubular beams.

Research paper thumbnail of Ship appearance optimal design on RCS reduction using response surface method and genetic algorithms

Journal of Shanghai Jiaotong University (Science), 2008

Radar cross section (RCS) reduction technologies are very important in survivability of the milit... more Radar cross section (RCS) reduction technologies are very important in survivability of the military naval vessels. Ship appearance shaping as an effective countermeasure of RCS reduction redirects the scattered energy from one angular region of interest in space to another region of little interest. To decrease the scattering electromagnetic signals from ship scientifically, optimization methods should be introduced in shaping design. Based on the assumption of the characteristic section design method, mathematical formulations for optimal shaping design were established. Because of the computation-intensive analysis and singularity in shaping optimization, the response surface method (RSM) combined genetic algorithm (GA) was proposed. The polynomial response surface method was adopted in model approximation. Then genetic algorithms were employed to solve the surrogate optimization problem. By comparison RCS of the conventional and the optimal design, the superiority and effectiveness of proposed design methodology were verified.

Research paper thumbnail of Nonlinear vibration of functionally graded fiber-reinforced composite laminated cylindrical shells in hygrothermal environments

Applied Mathematical Modelling, 2015

ABSTRACT The effect of hygrothermal conditions on the linear and nonlinear free flexural vibratio... more ABSTRACT The effect of hygrothermal conditions on the linear and nonlinear free flexural vibration of anisotropic shear deformable laminated cylindrical shells is investigated. The cylindrical shell is made of fiber-reinforced composites (FRCs) with the reinforcement being distributed either uniformly (UD) or functionally graded (FG) of piece-wise type along the thickness of the shells. The motion equations are based on a higher order shear deformation shell theory with a von Kármán-type of kinematic nonlinearity. The hygrothermal effects are also included, and the material properties of FRCs are estimated through a micromechanical model and are assumed to be temperature dependent and moisture-dependent. The equations of motion are solved by a singular perturbation technique along with a two-step perturbation approach to determine the linear and nonlinear frequencies of the FRC laminated cylindrical shells. Detailed parametric studies are carried out to investigate effects of material property gradient, the temperature change, the degree of moisture concentration, shell geometric parameter, stacking sequence, as well as the end conditions on the vibration characteristics of FRC shells with polymer matrix. The results show that the temperature/moisture variation has a moderately effect on the natural frequencies of the FRC cylindrical shells, but only has a small effect on the nonlinear to linear frequency ratios of the same shell.

Research paper thumbnail of Nonlinear vibration of anisotropic laminated cylindrical shells with piezoelectric fiber reinforced composite actuators

Ocean Engineering, 2014

This paper deals with the small and large amplitude flexural vibrations of anisotropic shear defo... more This paper deals with the small and large amplitude flexural vibrations of anisotropic shear deformable laminated cylindrical shells with piezoelectric fiber reinforced composite (PFRC) actuators in thermal environments. Two kinds of fiber reinforced composite (FRC) laminated shells, namely, uniformly distributed and functionally graded reinforcements, are considered. The motion equations are based on a higher order shear deformation shell theory with a von Karman-type of kinematic nonlinearity and including the extension-twist, extension-flexural and flexural-twist couplings. The thermo-piezoelectric effects are also included, and the material properties of both FRCs and PFRCs are estimated through a micromechanical model and are assumed to be temperature dependent. A boundary layer theory and associated singular perturbation technique are employed to determine the linear and nonlinear frequencies of hybrid laminated cylindrical shells. The numerical illustrations concern the cross-ply and angle-ply laminated cylindrical shells with fully covered or embedded PFRC actuators under different sets of thermal and electric loading conditions. Detailed parametric studies are carried out to investigate effects of material property gradient, temperature variation, applied voltage, shell geometric parameter, stacking sequence, as well as the shell end conditions on the linear and nonlinear vibration characteristics of the hybrid laminated cylindrical shells.

Research paper thumbnail of Postbuckling of shear deformable stiffened anisotropic laminated cylindrical shell under axial compression

Ocean Engineering, 2011

ABSTRACT A postbuckling analysis is presented for a shear deformable anisotropic laminated cylind... more ABSTRACT A postbuckling analysis is presented for a shear deformable anisotropic laminated cylindrical shell with stiffener of finite length subjected to axial compression. The material of each layer of the shell is assumed to be linearly elastic, anisotropic and fiber-reinforced. The governing equations are based on a higher order shear deformation shell theory with von Kármán-Donnell-type of kinematic nonlinearity and including the extension/twist, extension/flexural and flexural/twist couplings. The ‘smeared stiffener’ approach is adopted for the beam stiffeners. This arrangement allows the beam stiffeners to be assembled directly into the global stiffness matrix. The nonlinear prebuckling deformations and initial geometric imperfections of the shell are both taken into account. A singular perturbation technique is employed to determine the buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling response of perfect and imperfect, grid, axial, ring stiffened, and unstiffened shells. The results confirm that there exists a compressive stress along with an associate shear stress and twisting when the anisotropic shell is subjected to axial compression. The postbuckling equilibrium path is unstable for the moderately thick cylindrical shell under axial compression and the stiffened shell structure is imperfection-sensitive.

Research paper thumbnail of Postbuckling Behavior of Shear-Deformable Anisotropic Laminated Cylindrical Panels under External Lateral Pressure

Journal of Engineering Mechanics, 2011

A postbuckling analysis for a shear-deformable anisotropic laminated cylindrical panel of finite ... more A postbuckling analysis for a shear-deformable anisotropic laminated cylindrical panel of finite length is presented, subjected to external lateral pressure based on a boundary-layer theory of shell buckling. The material properties of each layer of the panel are assumed to be linearly elastic. The governing equations are based on a higher-order shear-deformation shell theory with a von Karman–Donnell type of kinematic nonlinearity and including extension/twist, extension/flexural, and flexural/twist couplings. The nonlinear prebuckling deformations and initial geometric imperfections of the panel are both taken into account. A singular perturbation technique is employed to determine the buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling behavior of perfect and imperfect moderately thick, anisotropic laminated cylindrical panels under different values of panel parameters and stacking sequence. The new finding reveals that a circumferential stress exists along with an associate shear stress and twisting when the moderately thick anisotropic laminated cylindrical panel is subjected to external lateral pressure.

Research paper thumbnail of Numerical and Experimental Studies of a Light-Weight Auxetic Cellular Vibration Isolation Base

Shock and Vibration, 2016

This paper presents a preliminary study of the dynamic performance of a novel light-weight auxeti... more This paper presents a preliminary study of the dynamic performance of a novel light-weight auxetic (negative Poisson’s ratio) cellular vibration isolation base constituted by reentrant hexagonal honeycombs. Numerical and experimental analyses were conducted to reveal the effects of Poisson’s ratio (cell angle) and relative density (cell thickness) of these reentrant honeycombs on the dynamic performance of this novel base and to propose design guidelines for the best use of the auxetic cellular vibration isolation system. By doing numerical analysis, we found that, by decreasing the relative density of reentrant honeycombs and increasing Poisson’s ratio of them, excellent vibration isolation performance of the auxetic cellular base will be achieved. This analysis was followed by static, modal, and frequency response tests, which verified the results of the numerical analysis.

Research paper thumbnail of The load criteria for ship mechanical noise prediction in low frequencies and experimental validation

Journal of Ocean Engineering and Science, 2022

Research paper thumbnail of Vibroacoustics Analysis And Reduction of Liquid-filled Pipeline

The characteristics of pipeline model construction for vibroacoustic analysis are investigated. T... more The characteristics of pipeline model construction for vibroacoustic analysis are investigated. The establishment of fluid-structure coupling numerical models with FE model and FE-SEA hybrid model in pipeline vibroacoustics analysis was proved to be suitable for the whole frequency domain. Experimental investigations compared with the numerical results showed the effectiveness of the presented technology. Finally, vibration reduction design of pipeline with application of different damping materials were evaluated by the proposed technology.

Research paper thumbnail of Numerical Simulation of Vibration and Noise for Ship Collision

The correct use of nonlinear finite element analysis enables increased confidence in the results ... more The correct use of nonlinear finite element analysis enables increased confidence in the results and better utilization of the actual structural capacity compared with simplified methods, which has rapidly become a widely adopted tool for the simulation of such accidental impacts. By applying structural dynamic finite element numerical simulation technology and acoustic numerical simulation technology, taking an actual ship collision accident as an example, detailed vibration and acoustic ship models through the finite element method are constructed in this paper. Collision process, structure damages, vibration of ship structure and noise resulting from collision are calculated, according to the loading condition and the navigation status of accident ships. Comparison of the results shows a good agreement between the accident structure damages and numerical simulation results. Moreover, acceleration vibration level difference and average sound pressure level of the wheelhouse are ob...

Research paper thumbnail of Sensitivity Analysis of Non-Linear Air Gap and Wave Slamming Load with Respect to Current for Semi-Submersible Platform Design

A design of offshore platform is mainly based on the extreme response analysis due to the critica... more A design of offshore platform is mainly based on the extreme response analysis due to the critical environment condition. It is important to predict accurately air gap and wave slamming load in order to check the strength of local structures which withstand the wave slamming due to negative air gap. Due to the factors of working depth, the size of mooring system model, sizes of experimental tank and the equipment of tank, it is difficult to simulate the wave, wind and current loads at the same time, accurately. When the platform suffers the rough wave condition, the current is also harsh. The main aim of this paper is to present sensitivity analysis results of non-linear air gap and wave slamming load with respect to the current load for the design of semisubmersible platform. In this paper, the wind tunnel test and the seakeeping model test have been performed. The linear air gap analysis can be carried out in frequency domain without the effects of wind and current. But the result...

Research paper thumbnail of Anti-Explosion Performance of Composite Blast Wall with an Auxetic Re-Entrant Honeycomb Core for Offshore Platforms

Journal of Marine Science and Engineering, 2020

To improve the anti-explosion performance of blast wall in offshore platforms, an auxetic re-entr... more To improve the anti-explosion performance of blast wall in offshore platforms, an auxetic re-entrant blast wall (ARBW) was proposed and designed based on the indentation resistance effect of an auxetic structure. Based on the numerical nonlinear dynamic analysis method verified by the explosion experiment of a conventional steel corrugated blast wall (CBW), the failure mechanisms of ARBW, steel honeycomb sandwich blast wall (HSBW) and CBW were investigated under distributed impulse loads. Computational results demonstrated the excellent anti-explosion performance of the proposed ARBW design. Concerning the minimal deformation at the mid-point of the proposed protective structures, the ARBW performed best. As regards the minimal deformation at the connection, both ARBW and HSBW worked well. The stress distribution of the connection illustrated the different energy absorption and transmission modes of the three blast walls.

Research paper thumbnail of Impact resistance performance and optimal design of a sandwich beam with a negative stiffness core

Journal of Mechanical Science and Technology, 2019

Numerical analyses were carried out to investigate the response of a sandwich beam with a negativ... more Numerical analyses were carried out to investigate the response of a sandwich beam with a negative stiffness (NS) core under quasistatic compression and low-velocity impact at the center. By varying the thicknesses of face sheets and interlayers and the lengths of segments, a parametric study on the impact resistance of the sandwich beam is conducted. The maximal deflection of the top face sheet and the strain energy stored in the NS beam were recorded at the moment when the impactor's velocity decreased to zero. Based on the impact simulation, a multi-objective optimization problem on the beam configuration was set up to find out the most efficient antideformation design at the impact velocity of 2500 mm/s. To solve the problem with the surrogate model method, an optimal Latin hypercube sampling (OLHS) technique and a two-phase differential evolution (ToPDE) algorithm were utilized to generate calculation points in the design space, respectively. Then different surrogate models including the RSM model, the Kriging model and the RBF model, were compared to give the best approximation of the original problem. In the end, the genetic algorithm (GA) dealing with discrete optimization problems was employed to obtain the optimum solutions. Results indicate that different parts of the NS beam dominate the resistance to deformation under different levels of impact intensity. The largest portion of the strain energy is stored in the four curved plates. In the obtained optimization solution, the longest segment is near the two ends and the flat plates near the top are thicker, which is instructive to the beam design on improving impact resistance.

Research paper thumbnail of Design Method of Lightweight Metamaterials with Arbitrary Poisson’s Ratio

Materials, 2018

A heuristic approach to design lightweight metamaterials with novel configurations and arbitrary ... more A heuristic approach to design lightweight metamaterials with novel configurations and arbitrary Poisson’s ratio is studied by using the functional element topology optimization (FETO) method. Mathematical model of the optimization problem is established, where the minimization of the mass is set as the objective, then a series of metamaterials with Poisson’s ratio ranging from −1.0 to +1.0 are designed by solving this model. The deformation resistance and vibration reduction performance of the novel metamaterials and conventional honeycomb are compared by numerical simulations. Specific stiffness analysis shows that the novel metamaterials are 5.6 to 21.0 times more resistant to deformation than that of the honeycomb, and frequency response shows about 60% improvement in vibration reduction performance. Finally, the lightweight effects of the novel metamaterials on deformation resistance and vibration reduction performance are analyzed, and further analysis reflects that the lightw...

Research paper thumbnail of Vibration and Sound Transmission Performance of Sandwich Panels with Uniform and Gradient Auxetic Double Arrowhead Honeycomb Cores

Shock and Vibration, 2019

Auxetic mechanical metamaterials that exhibit a negative Poisson’s ratio (NPR) can be artificiall... more Auxetic mechanical metamaterials that exhibit a negative Poisson’s ratio (NPR) can be artificially designed to exhibit a unique range of physical and mechanical properties. Novel sandwich structures composed of uniform and gradient auxetic double arrowhead honeycomb (DAH) cores were investigated in terms of their vibration and sound transmission performance stimulated by nonhomogeneous metamaterials with nonperiodic cell geometries. The spectral element method (SEM) was employed to accurately evaluate the natural frequencies and dynamic responses with a limited number of elements at high frequencies. The results indicated that the vibrating mode shapes and deformations of the DAH sandwich models were strongly affected by the patterned gradient metamaterials. In addition, the sound insulation performance of the considered DAH sandwich models was investigated regarding the sound transmission loss (STL) from 1 Hz to 1500 Hz under a normal incident planar wave, and this performance was ...

Research paper thumbnail of Modelling theory of functional element design for metamaterials with arbitrary negative Poisson's ratio

Computational Materials Science, 2018

Metamaterials with arbitrary negative Poisson's ratio(NPR) can be designed by functional element ... more Metamaterials with arbitrary negative Poisson's ratio(NPR) can be designed by functional element topology optimization method, but modelling theory of this method is not investigated thoroughly, including functional element, volume fraction ration, the definition of objective functions and NPR constraints. In this paper, functional element with different shapes (triangle and rectangle), method of evaluating macroscopic NPR value, and three categories of objective functions: maximum compliance, minimum mass, minimum compliance, are conducted. A series of metamaterials structures with arbitrary NPR (the ratio range is −0.3 to −6.0) are designed, and the NPR values of these metamaterials structures are verified. Static analysis shows that the Poisson's ratio between single functional element and macroscopic metamaterials structure are consistent with each other (error rate is 3.3%). Dynamic analysis to explore the vibration reduction performance of the metamaterials structure. All our works provide a method and theory for the design of novel metamaterials structure with arbitrary specified NPR.

Research paper thumbnail of Mechanical Performance of Multidirectional Buckling-Based Negative Stiffness Metamaterials: An Analytical and Numerical Study

Materials, 2018

Unidirectional, bidirectional and tridirectional Buckling-based Negative Stiffness (BNS) lattice ... more Unidirectional, bidirectional and tridirectional Buckling-based Negative Stiffness (BNS) lattice metamaterials are designed by adding prefabricated curved beams into multidimensional rigid frames. Finite Element Analysis models are built, and their mechanical performance is investigated and discussed. First, geometric parameters of the curved beam were systematically studied with numerical analyses and the results were validated by theoretical solutions. Next, within unidirectional designs of different layer numbers, the basic properties of multilayer BNS metamaterials were revealed via quasi-static compressions. Then, the bidirectional and tridirectional designs were loaded on orthogonal axes to research both the quasi-static and dynamic behaviors. For dynamic analysis conditions, simulation scenarios of different impact velocities were implemented and compared. The results demonstrate that the proposed numerical analysis step has accurately predicted the force-displacement relations of both the curved beam and multilayer designs and the relations can be tuned via different geometric parameters. Moreover, the macroscopic performance of the metamaterials is sensitive to the rigidity of supporting frames. The shock force during impact is reduced down below the buckling thresholds of metamaterial designs and sharp impact damage is avoided. The presented metamaterials are able to undergo multiaxial stress conditions while retaining the negative stiffness effect and energy-absorbing nature and possess abundant freedom of parametric design, which is potentially useful in shock and vibration engineering.

Research paper thumbnail of Pitch Channel Control of a REMUS AUV with Input Saturation and Coupling Disturbances

Applied Sciences, 2018

The motion of an underwater vehicle is prone to be affected by time-varying model parameters and ... more The motion of an underwater vehicle is prone to be affected by time-varying model parameters and the actuator limitation in control practice. Adaptive control is an effective method to deal with the general system dynamic uncertainties and disturbances. However, the effect of disturbances control on transient dynamics is not prominent. In this paper, we redesign the L 1 adaptive control architecture (L1AC) with anti-windup (AW) compensator to guarantee robust and fast adaption of the underwater vehicle with input saturation and coupling disturbances. To reduce the fluctuation of vehicle states, the Riccati-based AW compensator is utilized to compensate the output signal from L1AC controller via taking proper modification. The proposed method is applied to the pitch channel of REMUS vehicle's six Degrees Of Freedom (DOF) model with strong nonlinearities and compared with L1AC baseline controller. Simulations show the effectiveness of the proposed control strategy compared to the original L1AC. Besides, the fluctuation in roll channel coupled with pitch channel is suppressed according to the performances of control tests.

Research paper thumbnail of Sensitivity analysis of air gap motion with respect to wind load and mooring system for semi-submersible platform design

China Ocean Engineering, 2016

A design of semi-submersible platform is mainly based on the extreme response analysis due to the... more A design of semi-submersible platform is mainly based on the extreme response analysis due to the forces experienced by the components during lifetime. The external loads can induce the extreme air gap response and potential deck impact to the semi-submersible platform. It is important to predict air gap response of platforms accurately in order to check the strength of local structures which withstand the wave slamming due to negative air gap. The wind load cannot be simulated easily by model test in towing tank whereas it can be simulated accurately in wind tunnel test. Furthermore, full scale simulation of the mooring system in model test is still a tuff work especially the stiffness of the mooring system. Owing to the above mentioned problem, the model test results are not accurate enough for air gap evaluation. The aim of this paper is to present sensitivity analysis results of air gap motion with respect to the mooring system and wind load for the design of semi-submersible platform. Though the model test results are not suitable for the direct evaluation of air gap, they can be used as a good basis for tuning the radiation damping and viscous drag in numerical simulation. In the presented design example, a numerical model is tuned and validated by ANSYS AQWA based on the model test results with a simple 4 line symmetrical horizontal soft mooring system. According to the tuned numerical model, sensitivity analysis studies of air gap motion with respect to the mooring system and wind load are performed in time domain. Three mooring systems and five simulation cases about the presented platform are simulated based on the results of wind tunnel tests and sea-keeping tests. The sensitivity analysis results are valuable for the floating platform design.

Research paper thumbnail of Vibration of thermally postbuckled carbon nanotube-reinforced composite beams resting on elastic foundations

International Journal of Non-Linear Mechanics, 2017

This paper investigates the small-and large-amplitude vibrations of thermally postbuckled carbon ... more This paper investigates the small-and large-amplitude vibrations of thermally postbuckled carbon nanotube-reinforced composite (CNTRC) beams resting on elastic foundations. For the CNTRC beams, uniformly distributed (UD) and functionally graded (FG) reinforcements are considered where the temperature-dependent material properties of CNRTC beams are assumed to be graded in the thickness direction and estimated through a micromechanical model. The motion equations are derived based on a higher order shear deformation beam theory with including the beam-foundation interaction. The initial deflection caused by thermal postbuckling is also included. The numerical illustrations concern small-and large-amplitude vibration characteristics of thermally postbuckled CNTRC beams under uniform temperature field. The effects of carbon nanotube (CNT) volume fraction and distribution patterns as well as foundation stiffness on the vibration characteristics of CNTRC beams are examined in detail.

Research paper thumbnail of Thermal postbuckling analysis of anisotropic laminated beams with tubular cross-section based on higher-order theory

Ocean Engineering, 2016

Buckling of composite riser assumed beam structure is one of numerous engineering challenges in d... more Buckling of composite riser assumed beam structure is one of numerous engineering challenges in deep water pipeline design. Thermal postbuckling analysis of shear deformable anisotropic laminated composite beams with tubular cross-section subjected to uniform, linear and non-linear temperature distribution through the thickness resting on a two-parameter elastic foundation is presented. The material of each layer for the composite beam with tubular section is assumed to be linearly elastic and fiberreinforced. The governing equations are introduced by using high-order shear deformation beam model with a von Kármán-type of kinematic nonlinearity. Composite beams with clamped-clamped, clampedhinged, and hinged-hinged boundary conditions are considered. A numerical solution for nonlinear partial-integral differential form in terms of the transverse deflection by using Galerkin's method is employed to determine the buckling temperatures and postbuckling equilibrium paths of anisotropic laminated beams with different types of temperature distribution through the thickness. The numerical illustration concern the thermal postbuckling response of laminated beams with different types of boundary conditions, ply arrangements (lay-ups), geometric and physical properties. The results reveal that the geometric and physical properties, temperature dependent properties, initial geometry imperfection, boundary conditions and elastic foundation have a significant effect on thermal postbuckling behavior of anisotropic laminated composite tubular beams.

Research paper thumbnail of Ship appearance optimal design on RCS reduction using response surface method and genetic algorithms

Journal of Shanghai Jiaotong University (Science), 2008

Radar cross section (RCS) reduction technologies are very important in survivability of the milit... more Radar cross section (RCS) reduction technologies are very important in survivability of the military naval vessels. Ship appearance shaping as an effective countermeasure of RCS reduction redirects the scattered energy from one angular region of interest in space to another region of little interest. To decrease the scattering electromagnetic signals from ship scientifically, optimization methods should be introduced in shaping design. Based on the assumption of the characteristic section design method, mathematical formulations for optimal shaping design were established. Because of the computation-intensive analysis and singularity in shaping optimization, the response surface method (RSM) combined genetic algorithm (GA) was proposed. The polynomial response surface method was adopted in model approximation. Then genetic algorithms were employed to solve the surrogate optimization problem. By comparison RCS of the conventional and the optimal design, the superiority and effectiveness of proposed design methodology were verified.

Research paper thumbnail of Nonlinear vibration of functionally graded fiber-reinforced composite laminated cylindrical shells in hygrothermal environments

Applied Mathematical Modelling, 2015

ABSTRACT The effect of hygrothermal conditions on the linear and nonlinear free flexural vibratio... more ABSTRACT The effect of hygrothermal conditions on the linear and nonlinear free flexural vibration of anisotropic shear deformable laminated cylindrical shells is investigated. The cylindrical shell is made of fiber-reinforced composites (FRCs) with the reinforcement being distributed either uniformly (UD) or functionally graded (FG) of piece-wise type along the thickness of the shells. The motion equations are based on a higher order shear deformation shell theory with a von Kármán-type of kinematic nonlinearity. The hygrothermal effects are also included, and the material properties of FRCs are estimated through a micromechanical model and are assumed to be temperature dependent and moisture-dependent. The equations of motion are solved by a singular perturbation technique along with a two-step perturbation approach to determine the linear and nonlinear frequencies of the FRC laminated cylindrical shells. Detailed parametric studies are carried out to investigate effects of material property gradient, the temperature change, the degree of moisture concentration, shell geometric parameter, stacking sequence, as well as the end conditions on the vibration characteristics of FRC shells with polymer matrix. The results show that the temperature/moisture variation has a moderately effect on the natural frequencies of the FRC cylindrical shells, but only has a small effect on the nonlinear to linear frequency ratios of the same shell.

Research paper thumbnail of Nonlinear vibration of anisotropic laminated cylindrical shells with piezoelectric fiber reinforced composite actuators

Ocean Engineering, 2014

This paper deals with the small and large amplitude flexural vibrations of anisotropic shear defo... more This paper deals with the small and large amplitude flexural vibrations of anisotropic shear deformable laminated cylindrical shells with piezoelectric fiber reinforced composite (PFRC) actuators in thermal environments. Two kinds of fiber reinforced composite (FRC) laminated shells, namely, uniformly distributed and functionally graded reinforcements, are considered. The motion equations are based on a higher order shear deformation shell theory with a von Karman-type of kinematic nonlinearity and including the extension-twist, extension-flexural and flexural-twist couplings. The thermo-piezoelectric effects are also included, and the material properties of both FRCs and PFRCs are estimated through a micromechanical model and are assumed to be temperature dependent. A boundary layer theory and associated singular perturbation technique are employed to determine the linear and nonlinear frequencies of hybrid laminated cylindrical shells. The numerical illustrations concern the cross-ply and angle-ply laminated cylindrical shells with fully covered or embedded PFRC actuators under different sets of thermal and electric loading conditions. Detailed parametric studies are carried out to investigate effects of material property gradient, temperature variation, applied voltage, shell geometric parameter, stacking sequence, as well as the shell end conditions on the linear and nonlinear vibration characteristics of the hybrid laminated cylindrical shells.

Research paper thumbnail of Postbuckling of shear deformable stiffened anisotropic laminated cylindrical shell under axial compression

Ocean Engineering, 2011

ABSTRACT A postbuckling analysis is presented for a shear deformable anisotropic laminated cylind... more ABSTRACT A postbuckling analysis is presented for a shear deformable anisotropic laminated cylindrical shell with stiffener of finite length subjected to axial compression. The material of each layer of the shell is assumed to be linearly elastic, anisotropic and fiber-reinforced. The governing equations are based on a higher order shear deformation shell theory with von Kármán-Donnell-type of kinematic nonlinearity and including the extension/twist, extension/flexural and flexural/twist couplings. The ‘smeared stiffener’ approach is adopted for the beam stiffeners. This arrangement allows the beam stiffeners to be assembled directly into the global stiffness matrix. The nonlinear prebuckling deformations and initial geometric imperfections of the shell are both taken into account. A singular perturbation technique is employed to determine the buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling response of perfect and imperfect, grid, axial, ring stiffened, and unstiffened shells. The results confirm that there exists a compressive stress along with an associate shear stress and twisting when the anisotropic shell is subjected to axial compression. The postbuckling equilibrium path is unstable for the moderately thick cylindrical shell under axial compression and the stiffened shell structure is imperfection-sensitive.

Research paper thumbnail of Postbuckling Behavior of Shear-Deformable Anisotropic Laminated Cylindrical Panels under External Lateral Pressure

Journal of Engineering Mechanics, 2011

A postbuckling analysis for a shear-deformable anisotropic laminated cylindrical panel of finite ... more A postbuckling analysis for a shear-deformable anisotropic laminated cylindrical panel of finite length is presented, subjected to external lateral pressure based on a boundary-layer theory of shell buckling. The material properties of each layer of the panel are assumed to be linearly elastic. The governing equations are based on a higher-order shear-deformation shell theory with a von Karman–Donnell type of kinematic nonlinearity and including extension/twist, extension/flexural, and flexural/twist couplings. The nonlinear prebuckling deformations and initial geometric imperfections of the panel are both taken into account. A singular perturbation technique is employed to determine the buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling behavior of perfect and imperfect moderately thick, anisotropic laminated cylindrical panels under different values of panel parameters and stacking sequence. The new finding reveals that a circumferential stress exists along with an associate shear stress and twisting when the moderately thick anisotropic laminated cylindrical panel is subjected to external lateral pressure.

Research paper thumbnail of Numerical and Experimental Studies of a Light-Weight Auxetic Cellular Vibration Isolation Base

Shock and Vibration, 2016

This paper presents a preliminary study of the dynamic performance of a novel light-weight auxeti... more This paper presents a preliminary study of the dynamic performance of a novel light-weight auxetic (negative Poisson’s ratio) cellular vibration isolation base constituted by reentrant hexagonal honeycombs. Numerical and experimental analyses were conducted to reveal the effects of Poisson’s ratio (cell angle) and relative density (cell thickness) of these reentrant honeycombs on the dynamic performance of this novel base and to propose design guidelines for the best use of the auxetic cellular vibration isolation system. By doing numerical analysis, we found that, by decreasing the relative density of reentrant honeycombs and increasing Poisson’s ratio of them, excellent vibration isolation performance of the auxetic cellular base will be achieved. This analysis was followed by static, modal, and frequency response tests, which verified the results of the numerical analysis.