Optimal design of density gradient is a vibrant research topic in the realm of sandwich structure due to its potential benefits of enhancing mechanical performance. Herein, we propose a general yield criterion for functionally graded sandwich structures that accounts for the continuously varying yield strength distribution and the interaction of plastic bending and stretching in large deflection regime

The present study deals with the rheological behavior modeling of a dielectric elastomeric (DE) material class. The DE materials are commonly used to develop soft actuators and energy harvesters in soft robotics. DE is a class of electroactive polymers that produces large strains with an electrically induced load application. In this article, a micro mechanics-based thermodynamically consistent rheological

Two-phase flows are common in large-scale power systems and petroleum industry. During upstream oil and gas productions, crude oil, gas and sand eroded from formation zones are often conveyed as a mixture through horizontal pipes up to the well heads and between well heads and flow stations. In this work, governing equations and boundary conditions (BCs) for the motion of vibrating pipe conveying two

This paper presents the nonlinear static analysis of circular cylindrical sandwich shells using a higher-order thickness and shear deformation theory with nine kinematic parameters. The sandwich shell consists of a functionally graded porous core perfectly bonded with two carbon nanotubes (CNT) reinforced composite face sheets. The gradation is done in the thickness direction using three different

The continuously density-graded cellular materials have great potential to mitigate the impact damage of structures under intensive loading. In this article, we theoretically and numerically investigate the uniaxial crushing of continuously density-graded cellular cores in sandwich plates subjected to impulsive loading. Four types of core density distribution are investigated: positive, negative, middle-high

In this paper we present a density based topology optimization approach to the synthesis of industrially relevant MEMS resonators. The methodology addresses general resonators employing suspended proof masses or plates, where the first structural vibration modes are typically of interest and have to match specific target eigenfrequencies. As a significant practical example we consider MEMS gyroscope

A new three-dimensional temperature-dependent viscoelastic constitutive model for unidirectional fiber reinforced, polymer composite materials subjected to small strains is developed in this work. The key point is to introduce the viscoelastic behavior only where appropriate, based on the constitutive behavior of the underlying constituents: in particular, the matrix deviatoric response is considered

The sintered nano-silver has been popularly selected as die attachment and interconnection material in the next generation of high-power electronics packaging due to its low-temperature sintering and high-temperature operation. Considering the high temperature application condition, the temperature-dependent mechanical behaviors of sintered nanoscale silver have become one of reliability concerns in

Nonlinear vibration of suspension bridge is a topic requiring comprehensive investigation. This study is focused on the internal resonance of the suspension bridge consisting of spatially inclined main cables and hangers by proposing a mathematic full bridge model. The vertical vibration of the bridge deck is studied. Specifically, the dynamic governing functions of this model can consider the geometric

Quasicrystals have attracted the tremendous attention of researchers for their unusual properties. In this paper, an analytical treatment is presented for the static response and free vibration of a multilayered three-dimensional, cubic quasicrystal rectangular simply supported plate with bonding imperfections. Based on the basic elasticity equation of three-dimensional quasicrystals, we construct

A fast and robust stress-integration algorithm is the key to full exploitation of advanced anisotropic yield functions in computational mechanics. Poor global convergence of a direct application of the Newton-Raphson scheme has been rectified by applying line search strategies during the Newton iterations. In this work the line-search approach is further improved by a better first guess. The new algorithm

We derive explicit expressions for the three 2 × 2 generalized Barnett-Lothe tensors S, H and L associated with the anti-plane deformations of monoclinic piezoelectric materials with symmetry plane at x3 = 0 and with poling in the x3-direction. The resulting generalized Barnett-Lothe tensors contain four independent components which are, in turn, expressed explicitly in terms of the ten electroelastic

This paper aims to propose an equivalent cylinder radius for the buckling behavior of relatively thick steel conical shells subjected to axial compression. This is both experimental and numerical/theoretical work. Test data on this subject is scarce and the existing design recommendations have not been validated experimentally, especially in the plastic buckling region. In order to authenticate the

A new theoretical and numerical tool, comprising of a novel cubic Hermite spline layerwise theory and a time-domain spectral strip finite element with integration points collocated to its nodes and high-order polynomial shape functions, is evaluated regarding its capability to predict intralaminar and interlaminar stresses in laminated and sandwich composite strips. Stress predictions in various laminated

An innovative technique, called conversion, is introduced to model circumferential cracks in thin cylindrical shells. The semi-analytical finite element method is applied to investigate the modal deformation of the cylinder. An element including the crack is divided into three sub-elements with four nodes in which the stiffness matrix is enriched. The crack characteristics are included in the finite

In the present paper, a new generalized strain energy density-based life prediction model was proposed by analyzing the drawbacks of the commonly-used fatigue life prediction criteria. In the proposed model, the critical plane was defined as the maximum shear strain energy density plane with the larger normal strain energy density. A weight index was introduced in this model to take into account the

In this study, the high-velocity impact behavior of new designed sandwich structures with syntactic foam core and FML skins is investigated by experimental and numerical approaches. An appropriate numerical model is developed in order to modelling of the impact behavior of sandwich structures using the finite element software ABAQUS/Explicit. In this model, two VUMAT subroutine are presented to simulate

The analytical investigation for the nonlinear thermal dynamic buckling of smart sandwich plate subjected to mechanical, thermal and electric loadings is presented. The sandwich plate is composed of a porous homogeneous core, two carbon nanotube reinforced composite (CNTRC) layers and two piezoelectric face sheets. Basic equations are derived based on the Reddy's higher order shear deformation plate

In this work, an innovative two-dimensional (2D) hybrid auxetic elastic metamaterial (MODEL I) with reentrant triangular and chiral structures is proposed to open the broaden bandgap for vibration attenuation. Furthermore, the hybrid reentrant-chiral lattice with embedded resonators (MODEL II) shows multiple bandgaps at ultra-low frequency. Based on theoretical lumped mass-in-mass method and finite

Constitutive relations of two classes are proposed for nonlinear elastic isotropic materials, which, in case of purely volumetric deformation, are reduced to the Murnaghan’s equation of state. Exact analytical solution of the Lame problem of the radially symmetric deformation of a hollow sphere is obtained for one of these material classes. Nonlinear effects are studied. The non-uniqueness of solution

The spectral kurtosis (SK) is a useful tool for locating the non-stationary component in the single source signal. It has been verified by the mechanical fault diagnosis. The fast kurtogram (FK) is an improvement method based on the SK. However, for the signals with lower signal noise ratio (SNR), FK is not able to locate the chatter. In this paper, an on-line chatter monitoring using the FK and the

In phase-field models the damage evolution problem is considered as a minimisation problem of a Griffith-like energy functional, governed by the principles of irreversibility, stability and energy balance. Herein, we consider phase-field models characterised by different degradation and energy dissipation functions. With a proper choice for the characteristic functions in phase-field models, it is

A frictional receding contact problem of an infinitely long layer pressed by different finite pressure distributions onto a half-plane of the same linear elastic material is solved with the distributed dislocation technique. Solutions are obtained for when the layer is subject to three different pressure distributions: finite patch of constant pressure, square-root bounded (Hertzian) pressure and square-root

Void interaction, leading to coalescence, is the mechanism leading to ductile failure under intense shearing. Published unit cell model studies have demonstrated that micron-size voids collapse to form micro-cracks while continuous elongation and rotation of the voids thin the intervoid ligaments. At a final stage, the deformation leads to plastic flow localization in the ligament, and the material

In this paper, we investigate the asymptotic crack tip fields in a neo-Hookean sheet reinforced by two families of nonlinear fibers, where the fibers are characterized by the standard reinforcing model. In the asymptotic analysis, the fibers with stronger stiffening compared to the matrix dominate the mechanical behavior at the crack tip, which simplifies the analysis. A hodograph transformation is

Non-prismatic beams are widely employed in several engineering fields, e.g., wind turbines, rotor blades, aircraft wings, and arched bridges. While analytical solutions for variable cross-section beams are desirable, a model describing all stress components for beams with general variation of their cross-section under generalised loading remains an open and important problem to solve. To partly address

The addition of nanofillers to composites has attracted great attention since it adds multifunctional potential. However, the presence of nanofillers inside a composite may cause a more complex response in many situations, e.g. damage accumulation processes, and this response poses extra challenges in the development of reliable numerical approaches. In this work, a three-step multiscale modelling

The Mori–Tanaka (MT) scheme is a well-established mean-field model that combines simplicity and good predictive capabilities. The additive tangent MT scheme is a popular variant of the method that is suitable for elastic–viscoplastic composites. This work is concerned with the analysis of some intrinsic features of the additive tangent MT scheme, in particular, of spurious softening in the macroscopic

Large-deformation pure bending of a straight beam of uniform rectangular cross-section in plane strain is re-visited and generalised to an orthotropic linear-elastic material and the case of plane stress. The beam is bent into a completely shearless state by means of normal surface traction of a specific profile. For a linear-elastic material expressed in terms of Biot strain and stress tensors (orthotropic

Based on convolutional neural network (CNN) and improved long short-term memory (LSTM) neural network, a deep learning model CPINet is proposed for instant and accurate identification of path-dependent constitutive model parameters with excellent denoising performance. The elastic-plastic constitutive model with isotropic hardening is taken as an example for illustration. The results show that the

The paper is focused on the stability computation of a rotating system affected by parametric excitation, by using a frequency based computational method. The test case is a Jeffcott rotor excited by the unbalance of the disk and by the parametric excitation due to varying compliance of the rolling bearing elements of the supports. The stability of a system is typically studied using Floquet's theory

Due to the influence of various factors in the planar linkage mechanism, clearances will occur at the kinematic pair unavoidably. The existence of clearances will reduce the kinematic accuracy of mechanisms and have a great influence on reliability of mechanisms. At present, most of researches focus on static reliability of mechanisms or dynamic accuracy reliability of simple mechanisms with a single

Rotating machinery are present in many engineering applications. Such rotor systems often subjected to high vibration loads that can be at the origin of noise or failure. For these reasons, it is of main importance to predict with accuracy the critical speeds and the dynamic response amplitude of such structures. However, they are often subjected to many potential uncertainties that may rise from environmental

A buckling solution capable of accounting for prebuckling stress field heterogeneities is proposed. Oftentimes the same structural elements that restrict the out-of-plane displacement of the edges of a plate may also constrain their in-plane movements and cause heterogeneous prebuckling stress fields. The effect of these constraints and the consequent prebuckling stress field heterogeneity is vastly

The scattering of guided waves through a complex structure is of great importance in predicting vibration energy transmission and reflection across structures. Multi-scale models based on generalized continuum theory have been developed recently to investigate the vibration behavior of complex media in the frame of continuum mechanics. In this study, models based on the second strain gradient theory

Rubber components usually exhibit changes in their mechanical properties that accumulate over their service life and often determine the need for replacement. This article deals with chemical ageing coupled with mechanical loading. During chemical ageing, changes in the chemical structure of the material lead to alterations in its stiffness and gradual evolution of permanent deformations. The dynamic

The superposition theory is adopted to study the boundary value problem of needle domains in barium titanate single crystals, which decomposes into an infinite-medium solution and a complementary solution. The model of an equivalent edge dislocation and line charge is adopted to calculate the fields due to the discrete needle domains in an infinite medium. The complementary solutions are obtained from

In this paper, the bending behaviour of small-scale Bernoulli–Euler beams is investigated by Eringen’s two-phase local/nonlocal theory of elasticity. Bending moments are expressed in terms of elastic curvatures by a convex combination of local and nonlocal contributions, that is a combination with non-negative scalar coefficients summing to unity. The nonlocal contribution is the convolution integral

This paper experimentally and numerically investigates the nonlinear vibrations and dynamic snap-through behaviors of the bistable asymmetric carbon fiber-reinforced [90n/0n] composite laminated shallow shell. In the experimental research, in order to produce the dynamic snap-through phenomena, the center of a bistable asymmetric composite laminated shallow shell is clamped on an electromechanical

Thermoelastic vibration of micro and nano-beam resonators is described by the Euler-Bernoulli beam theory in context with two-temperature generalized thermoelasticity theory. The amplitude of deflection and thermal moment in the case of simply supported and the isothermal beam are obtained by the Laplace transform method along with the finite Fourier sine transform method and the vibration frequency

In the present paper a mathematical model able to reproduce the mechanical response of a shape memory alloy (SMA) helical spring is presented. The proposed model is based on a simplified but effective theory of the helix that assumes small strains and large displacements. The kinematics of the helix and the related generalized strain measures are introduced, with stress resultants conjugated to them

Torsion of an elastic half-space with a vertical cylindrical cavity by a coaxial punch bonded to a flat boundary and rotated under action of the torque about the axis is considered in this article by employing Weber–Orr integral transforms. We suggest two novel methods reducing the problem to the regular integral equations of the second kind, which are effective for different intervals of geometric

Crystalline metals are typically coated with materials such as natural oxides for engineering applications, wherein the coating surface has nanoscale roughness. Although the nanoscale asperities of material surfaces typically play a key role in the evolution of surface plasticity under contact loading, the dislocation activities interplaying with a nano-asperity coating and the resulting non-trivial

In this paper, we present polynomial varying modified polarization saturation models for semipermeable two unequal collinear cracks with coalesced interior zones in piezoelectric media. Under the influence of far-field electromechanical loadings, the cracks situated in an infinite arbitrary polarized piezoelectric media are opened in self-similar manner, forming a strip saturated zone in front of the

In this contribution, the use of discrete simulations to formulate an anisotropic damage model is investigated. It is proposed to use a beam–particle model to perform numerical characterization tests. Indeed, this discrete model explicitly describes cracking by allowing displacement discontinuities and thus capture crack induced anisotropy of quasi-brittle materials such as concrete. Through 2D discrete

The impact resistance of single curvature semi-cylindrical shell targets of aluminum 1100-H12 was explored against hard steel cylindrical projectiles. Experimental as well as numerical investigations were carried out to observe the performance of shell targets against ogive, conical, blunt and hemispherical nosed projectiles. Effect of oblique impact was studied on the ballistic performance of the

Several beam and plate models have been recently developed in the literature to accommodate for size-dependence. These are usually obtained starting from a generalized continuum theory (such as the couple-stress, strain-gradient or non-local theory or their modifications) and then deducing the governing equations through Hamilton’s principle and ingenuous kinematical assumptions. This approach, originated

This study presents an efficient beam formulation for static and vibration analysis of 2D non-prismatic beams with the kinematic assumptions of the Timoshenko beam theory. Beams having complex configurations can be straightforwardly constructed by using B-spline basis functions, which are used for descriptions of the beam axis and the sectional height. This feature enables analysis of free-form non-prismatic

A finite element analysis of intergranular normal stresses is performed in order to identify a possible statistical correlation between the intergranular normal stresses and the corresponding grain boundary type within a polycrystalline aggregate. Elastic continuum grains of cubic lattice symmetry are assumed in the analysis. Meaningful results are obtained by analyzing the first two statistical moments

Perforated panels have gained much attention due to their acoustic performance. This paper, investigates the technical efficiency of the Multilayer Perforated Sound Absorber (MPSA) composed of perforated panel fabricated by three-dimensional (3D) printing. To this aim, perforated panels have been printed based on the vat photopolymerization method. In detail, standard resin (photopolymer) material

An original formulation is proposed in order to simulate molten metal deposition geometry with a very low CPU time. This new approach is based on the original technique proposed by Leblond et al. [C. R. Mecanique 341 (2013) 770–775] for the incorporation of surface tension in finite element calculations. The FEM simulation strategy is composed of a 2-step resolution algorithm at each time step of the

Eringen’s nonlocal theory has been widely used for the study of micro- and nano-structures exhibiting size effect phenomena. Eringen’s nonlocal differential constitutive equation has been employed to structural engineering applications, and a number of inconsistencies and paradoxes has been raised. This work centers on exploring static engineering benchmark problems of a nanobeam resting on a Pasternak-type

Foam materials are experiencing a great diffusion in the industrial field because of their numerous properties and adaptability to different purposes. At the same time, research efforts are addressed to define new fields of application and methodologies of foam simulation, capable of combining their behavior at macroscale to phenomena at microscale, i.e. ligaments level. In this paper, a FE beam modeling

Studies conducted in recent years have shown that the ultimate load-bearing and deformation capacity of weldments manufactured from ultra-high-strength steel is often impacted by the heat-affected zone. Thus, to assess the strength properties of these welds, in addition to the base material properties and weld metal, the heat-affected zone's mechanical properties must be analyzed. In this study, a

An investigation into the material stiffness design for enhancing the uniformity of the contact stress is conducted in this paper. A bidirectional evolutionary optimization design approach for interface material stiffness is developed, in which the standard deviation of the contact stress is defined as the objective function and the Young's modulus is treated as the design variable. A design case of

Torsional flexible links are essential for torque transmission in many industrial applications, such as automotive powertrains and turbomachinery. This work develops the formulation of a linear spring element attached between two rotating tracks. Then, the combination of elements is discussed, by generating torque curves that may present regions quasi-zero stiffness (QZS), negative stiffness, as well

In this paper, we present a geometrically nonlinear formulation for a nine-node shell finite element and demonstrate its performance. The total Lagrangian formulation is utilized to allow for large displacements and large rotations. The mixed interpolation of tensorial components (MITC) technique is applied to effectively reduce the membrane and shear locking phenomena without refining mesh, introducing

In this paper, shape transformers, a set of non-dimensional geometrical parameters that define beam cross-section efficiencies based on their size and shape, are employed in the wave propagation analysis of two-dimensional periodic lattice structures. Here, shape transformers of lattice unit-cell beams are used as design variables to tailor the frequency band gaps of the lattice structure, in the form

Clearance joint appears in the multibody system and it could cause the uncertainty of motion. A general method for dynamic modelling and analysis of slider-crank mechanism with multiple clearance joints is presented and discussed in this work. The contact-impact characteristics of clearance joint are described by the nonlinear continuous contact force model. With flexible link taken into account, the