Zichen Deng

Northwestern Polytechnical University | NWPU · Department of Engineering Mechanics

The rheological properties and limited flow velocities of solvent-free nanofluids are crucial for their technologically significant applications. In particular, the flow in a solvent-free nanofluid system is steady only when the flow velocity is lower than a critical value. In this paper, we establish a rigid-flexible dynamic model to investigate t...

This study introduces a novel underground subwavelength seismic metamaterial (SM) designed to attenuate ultra-low-frequency surface waves. The SM comprises a three-component column featuring rubber embedded within a steel resonator. Through calculations utilizing the Bloch theorem and the sound cone method, we investigate the dispersion relations a...

In this study, circumferential taper wedges are proposed to reduce broadband vibrations reduction in a circular cylindrical shell. The structural damping characteristics and vibration response of the circular cylindrical shell with circumferential taper wedges are analyzed based on an analytical wave propagation model developed using the symplectic...

This work presents the longitudinal and transverse coupling vibrations of a deployable Telescopic Tubular Mast (TTM), a multi-stepped structure integrated into a spacecraft system, while considering the rigid-flexible coupling phenomenon. The model is derived using the principle of virtual work and discretized via the variable separation method. Th...

Mechanical metamaterials are highly versatile structures capable of achieving unconventional mechanical properties. Of particular interest are mechanical metamaterials with the ability to tune bandgaps, offering potential applications in vibration control tailored to specific requirements. In this study, a new type of metamaterial is introduced to...

Acoustic black holes (ABHs) have recently been revealed as an effective vibration-control technology. However, owing to their disadvantages such as low stiffness, structural discontinuity and manufacturing difficulties, ABHs are limited in terms of their practical application. Therefore, a multilayer composite sandwich plate with filled imperfect-A...

This work presents the longitudinal and transverse coupling vibrations of a deployable Telescopic Tubular Mast (TTM), a multi-stepped structure integrated into a spacecraft system, while considering the rigid-flexible coupling phenomenon. The model is derived using the principle of virtual work and discretized via the variable separation method. Th...

In recent years, due to the excellent vibration reduction performance of the acoustic black hole (ABH), its application in engineering has become increasingly widespread. This paper proposes an analytical method which combines the symplectic method with the impedance method, for solving the forced response of the rectangular thin plates attached by...

Multistable metamaterials are artificially engineered materials that possess microarchitectures capable of maintaining multiple stable configurations. However, the realization of mechanical metamaterials with numerous programmable stable configurations using Double-Curved Beam (DCB) elements remains an ongoing challenge. In this study, we exploit t...

Designing options for aircraft frame plate repair often relies on experience. Development of optimization technique is necessary to obtain optimal design for aircraft frame plate structure. In this paper, a method to optimize the repair parameters using genetic algorithm is proposed for the structural repair of aircraft frame plate. In the design p...

In order to explore the fault characteristics and failure mechanism of the sensor, staring from the working principle and structural characteristics of the piezoelectric acceleration sensor, the problems affecting the quality of the collected signal due to the fault of the component of the sensor are systematically studied. Firstly, according to th...

In comparison to conventional hexagonal honeycomb structures, auxetic metamaterials with re-entrant configurations have exhibited superior mechanical properties in terms of energy absorption. To further enhance the energy absorption capacity of these materials, a novel re-entrant honeycomb configuration, named novel auxetic re-entrant honeycomb (NA...

A recent topic of interest in dynamics research is bi-stable negative stiffness (NS) mechanical metamaterials that allow for the efficient control of wave propagation and bandgap (BG) tuning. In this study, a three-dimensional (3D) bi-stable NS mechanical metamaterial based on fan-shaped inclined beams was developed. It has BGs in multiple directio...

Auxetic metamaterials, which exhibit the negative Poisson’s ratio (NPR) effect, have found wide applications in many engineering fields. However, their high porosity inevitably weakens their bearing capacity and impact resistance. To improve the energy absorption efficiency of auxetic honeycombs, a novel vertex-based hierarchical star-shaped honeyc...

Considering the manipulators applied in the space missions, a flexible hub-beam model with a hollow tapered cross section is concerned based on the classic hub-beam model in this paper. The dynamic equations describing the coupling behaviors between the rotation of the hub and the vibration of the flexible beam with a hollow tapered cross section a...

In recent years, acoustic black holes (ABHs) have been revealed as an effective bending wave control technology and widely used to regulate the vibration and noise reduction performance of plate structure. However, the isolation effect of most traditional ABH plate can only be aroused at frequencies above the cut-off frequency. In order to widen th...

Based on the symplectic and higher-order WKB theory, a semi-analytical method is developed for the forced vibration of a built-up system comprising rectangular thin plate terminated by multiple acoustic black hole beams. The analytical waves are used to describe the vibration of the plate and ABH beam components. The dynamic flexibility matrix and...

Recently, acoustic black holes (ABHs) have been widely used for vibration and noise reduction. Compared with a single ABH, multiple ABHs embedded in a structure can achieve better vibration suppression. However, most of the current research focuses on embedding a single ABH. In this study, a symplectic space wave propagation method was proposed for...

Higher-order topological insulators (HOTIs) have attracted considerable attention because of their topological properties of low-dimensional topological corner states and edge states that exist in bandgaps. High-frequency edge states and corner states can be realized by controlling the interface configuration. However, most studies on HOTI focus on...

An analytical method, called the symplectic mathematical method, is proposed to study the wave propagation in a spring-mass chain with gradient arranged local resonators and nonlinear ground springs. Combined with the linearized perturbation approach, the symplectic transform matrix for a unit cell of the weakly nonlinear graded metamaterial is der...

By introducing the concept of a graded structure to seismic metamaterials, a new type of graded seismic metamaterial assembled using four steel sections with different graded levels is proposed to investigate its attenuation performance for surface waves. The dispersion curves and vibration modes are obtained using the finite element method and the...

Origami inspires various designs of foldable prismatic structures with zero-thickness facets. However, there is a difficulty in directly applying them to thick materials. This paper presents a novel design of the foldable prismatic structure inspired by the zigzag pattern, which can accommodate the thickness of materials easily by placing hinges on...

In this study, an analytical closed-form expression was developed based on the beam-column theory for the buckling strength of octagonal honeycombs without and with defects under additive manufacturing, and an analytical expression of the critical relative density of the octagonal honeycomb was also proposed. Plateau borders and wavy cell walls wer...

In this chapter, symplectic approaches for the finite-dimensional Hamiltonian systems are discussed. Firstly, the foundations of the symplectic method are reviewed, which include the symplectic map, the symplectic matrix, the symplectic structure, and so on. Then, two typical symplectic discretization methods are presented. One is the symplectic Ru...

The small damping, the complex constraints and the long-term running are the main characteristics of the space structures. Inspired by the excellent long-time numerical stability and the perfect structure-preserving ability of the generalized multi-symplectic method, the orbit-attitude-vibration coupling dynamic problems of the space structures are...

For the extremely small size of micro/nano systems, the experiments and the numerical simulations on which are challengeable. Taking the nano-injection as an example, the nonlinear behaviors of the nanotube’s vibration contained in the nano-injection system are difficult to be reproduced, which is crucial for the stable operation of the nano-inject...

Based on the multi-symplectic theory proposed by Bridges and Marsden, the mathematical formulations for the multi-symplectic method are reviewed and several applications of which are presented in this chapter. Generalizing the concept of reversibility to high-dimensional systems, the bisymplectic structure, named as the multi-symplectic structure o...

Inspired by the Noether symmetry theory, the mapping relationship between the dynamic symmetry breaking and the local energy dissipation of the infinite-dimensional system is proposed. Then, focusing on the residuals of the local conservative quantities of the infinite-dimensional system with the dynamic symmetry breaking, the generalized multi-sym...

Aiming to reveal the fundamental mechanisms of large dynamic deformation and failure of structures/materials under impact loading to establish analytical models and effective tools to deal with various complex issues prompted by engineering, the generalized multi-symplectic method is employed to investigate the energy loss in the pulse detonation e...

The fascinating liquid-like behavior of the Fe 3 O 4 /polyaniline (Fe 3 O 4 /PANI) solvent-free nanofluid permits some important applications of which. However, for the lack of the investigation on the magnetic response mechanism of the Fe 3 O 4 /PANI solvent-free nanofluid, the precise magnetic control on the liquid-like behaviors of the Fe 3 O 4...

PurposeThe excellent numerical behaviors of the structure-preserving method had been illustrated in the applications on the orbit-attitude-vibration space coupling dynamic problems. In this paper, the generalized multisymplectic method, a typical structure-preserving approach for the infinite-dimensional non-conservative systems, is employed to stu...

Existing conventional materials are usually difficult to achieve multiple tunable stress plateau characteristics, which hinders their multifunctional applications. This study proposes a multiple stable stress plateau metamaterial. A theoretical model for predicting stress plateaus was established, and its accuracy was verified by experimental and n...

Decreasing the vibration amplitude of the manipulator in the Space Manipulator Systems (SMS) with a given mass limitation is an effective way to reduce the control costs for the SMS. In this paper, the dynamic response of the SMS modeled by a flexible hub-beam with a step-variable cross-section excited by an external torque is investigated employin...

This paper studies the dynamic properties of a 3D chiral mechanical metamaterial, which largely depend on tacticity describing the connection forms of the chiral unit. Based on the finite element theory and Bloch's theorem, a dynamic model of the 3D chiral mechanical metamaterial is established to analyze the band structures and transmission respon...

The dynamic behavior of a piezoelectric-graphene compound asymmetric nanoplate resting on a viscoelastic foundation is investigated in this paper, considering both exposure to thermal environment and transverse harmonic excitation. First, according to the Hamilton principle and nonlocal elastic theory, a dynamic model of the composite nanoplate is...

Solvent-free nanofluids hold promise for many technologically significant applications. The liquid-like behavior, a typical rheological property of solvent-free nanofluids, has aroused considerable interests. However, there has been still lack of efficient methods to predict and control the liquid-like behavior of solvent-free nanofluids. In this p...

The effects of cracks on the dynamic behavior of engineering structures affect the structure safety. In this paper, a generalized multi-symplectic approach is developed to investigate the effects of crack on a dynamic behavior of a simply supported beam in detail. First, the effect of the crack on the bending stiffness of the simply supported beam...

Negative-stiffness mechanical metamaterials that can achieve bandgap tuning are a novel area of intense interest, enabling vibration control as well as a wide range of mechanical properties. In this paper, a negative-stiffness mechanical metamaterial consists of beam elements that can be reconfigured for large deformations and the bandgap can be tu...

The coupling dynamic problems, such as the vehicle-bridge interaction problem, are difficult to be analyzed. In this paper, the generalized multi-symplectic approach is employed to investigate the coupling dynamic behaviors in the vehicle-bridge interaction system. A simply-supported damping beam model carrying a moving mass is considered and the g...

In this paper, an analytical homogenization formula is derived based on the numerical representative volume element (RVE) method and asymptotic homogenization (AH) method for the effective elastic properties of truss lattice materials. Compared with the numerical homogenization method, the analytical homogenization formula can treat the geometric p...

In this paper, we report the frequency comb response experimentally and analytically in a rhombic micro-resonator with paramet- rical modulation. When the electrostatically actuated rhombic micro-resonator is modulated axially by a low-frequency periodic excitation, a comb-like vibration response with few equidistant positioned fingers in the frequ...

The concept of a space solar power station (SSPS) was proposed in 1968 as a potential approach for solving the energy crisis. In the past 50 years, several structural concepts have been proposed, but none have been sent into orbit. One of the main challenges of the SSPS is dynamic behavior prediction, which can supply the necessary information for...

This paper aims to study the effect of the interaction of adjacent unit-cells in coupled mass-in-mass metamaterial on wave behaviors, which enables us to achieve a wavy dispersion relationship. Elastic wave propagation in a coupled mass-in-mass metamaterial is investigated to clarify the effect of the interaction of adjacent unit-cells on the dispe...

The spider web is a multifunctional structure with vibration transmission performance and excellent mechanical properties. In this study, a spider web-inspired resonator is designed to adjust the band gaps of periodic lattices with different topologies. The spider web-inspired resonator can increase the relative density of periodic lattice and gene...

A symplectic stiffness method, based on Hamiltonian variational principle and symplectic eigen expansion, is presented to investigate the buckling of honeycomb structures under a general macroscopic stress state. The analytical closed-form expressions of critical forces are obtained for the possible buckling modes, which satisfy the deformation com...

This work investigates the elastic wave propagation in origami-inspired lattice which is a space network established by the beams at the mountain lines and valley lines in Miura-origami. The eigenvalue equation describing the dispersion relation is established by the finite element method and Bloch theorem, and the band structure is obtained by usi...

Frequency comb in microelectromechanical systems has attracted many concerns, which is expected to realize great achievements analogous with the optical frequency comb. Previous frequency combs are generated by mode coupling in a single micro-resonator. To pursuit more excellent tunability and robustness, it is impending to create a frequency comb...

This study describes the wave propagation in a periodic lattice which is formed by a spring-mass two-dimensional structure with local Duffing nonlinear resonators. The wave propagation characteristics of the system are evaluated by using the perturbation method to determine the dispersion relationships and wave propagation characteristics in the no...

It is common to fold a hollow 3D Archimedean solid flat using paper folding. However, little has been done to create 3D cellular assemblies of polyhedrons consisting of rigid facets that can be folded flat with a single degree of freedom. Inspired by both origami and kirigami, we present two groups of foldable truncated octahedrons composed of rigi...

In this study, we propose valley phononic crystals that consist of a hexagonal aluminum plate with six chiral arrangements of ligaments. Valley phononic crystals were introduced into a topological insulator (TI) system to produce topologically protected edge waves (TPEWs) along the topological interfaces. The implementation of chiral topological ed...

The Earth orbit becomes more and more crowded with the space launch missions one after the other. Most of the spacecrafts launched will stay in the orbit when the mission completed and a large number of the orbital debris will be produced in the hypervelocity impact, the high-intensity explosion or the dysfunctional satellites. Nowadays, developing...

Although the complex structure-preserving method presented in our previous studies can be used to investigate the orbit–attitude–vibration coupled dynamic behaviors of the spatial flexible damping beam, the simulation speed still needs to be improved. In this paper, the infinite-dimensional dynamic model describing the orbit–attitude–vibration coup...

The longitudinal wave propagating in an elastic rod with a variable cross-section owns wide engineering background, in which the longitudinal wave dissipation determines some important performances of the slender structure. To reproduce the longitudinal wave dissipation effects on an elastic rod with a variable cross-section, a structure-preserving...

The coupling effect between the vibration of the electric components and the wave propagation is the critical factor that should be considered in the optimization on the layout of the electric components in the spacecrafts. Different from the case considered in our previous job, the layout of the electronic components on the spacecraft is always as...

To avoid structural failure, the issue of the dynamic reliability of a wrinkled-film-substrate structure has become one of the most key problems for the design of the film-substrate-type flexible electronics. In this paper, an improved theoretical model of such a structure with finite deformation is established, which takes the shear stress at the...

Periodic lattices have unusual physical and mechanical properties that can be used to control elastic wave propagation and design smart wave devices. In this study, a lattice design strategy is proposed that considers chirality and tacticity to realize a low-frequency band gap. The design of elastic wave logic gates is also investigated. In the des...

As one of the potential active debris removal approaches, removal of space debris by a tether tow may be applied to perform the large space debris removal mission. To remedy the omissions of the current references, including effects of the initial state and the considerable elongation of the tether on the evolution of the tumbling angle of the targ...

Fractal lattice is a kind of lattices with multifunctional physical characteristics and superior mechanical properties. The wave propagation of the triangular lattice with Koch fractal is calculated by the finite element method and Bloch theorem. The effects of the iteration number on the band gaps and the band edge modes are studied. The finite el...

Purpose This study aims to focus on the effect of interlayer bonding and thermal decomposition on the mechanical properties of fused filament fabrication-printed polylactic acid specimens at high extrusion temperatures. Design/methodology/approach A printing process, that is simultaneous manufacturing of contour and specimen, is used to improve th...

The liquid-like property of solvent-free nanofluids under room temperature can be harnessed to achieve various advanced functions with significant applications. However, the determination of the critical flow conditions of solvent-free nanofluid is yet an unsolved issue. In this paper, we establish a mechanoelectrical flexible hub-beam model of ion...

Compound lattice structures are novel lattice structures with high stiffness and strength and their anisotropy can be easily controlled. In this study, two elastically equivalent compound truss lattice materials, BCS-I and BCS-II, are designed, and their anisotropic elastic properties and strength, such as the initial yield strength and elastic buc...

The coupling between the plane motion and transverse vibration is a challenge for the dynamic analysis of space structures. The coupling dynamic behavior of the on-orbit space flexible hollow beam is studied in this paper. As a common configuration of spacecraft and their components, the space structure with a large slenderness ratio and hollow str...

We investigate two-dimensional phononic metaplates consisting of a periodic array of cups on a thin epoxy plate that is perforated with periodic cross holes. The cups are individually filled with water or remain empty, in view of creating reconfigurable phononic waveguides. Phononic band gaps exist for empty or filled epoxy cups, leading to wavegui...