Showing papers in "Mechanics Based Design of Structures and Machines in 2023"
TL;DR: In this article , the static bending and free vibration response of organic nanoplates based on the combination of nonlocal theory with various shear strain theories, where the theory of shear deformation of the plate has the advantage of requiring no shear correction factor.
Abstract: This is the first study of the static bending and free vibration response of organic nanoplates based on the combination of nonlocal theory with various shear strain theories, where the theory of shear deformation of the plate has the advantage of requiring no shear correction factor. The equilibrium equation of the plate is derived using Hamilton’s principle, the analytic solution is derived using the Navier solution form, and the finite element technique is implemented using a quadrilateral element with four nodes and six degrees of freedom for each node. Moreover, this is the first work to calculate for nanoplates with a nonlocal parameter whose value varies with plate thickness. This study’s credibility has been established by comparing it to previously published findings, which are utilized to validate the results of analytical and numerical calculations, respectively. In addition, the study investigates how a range of components impact the displacement and stress response of organic nanoplates. The findings of the study indicate that there are some circumstances in which it is not feasible to disregard the nonlocal parameter while doing calculations for organic nanostructures.
7 citations
TL;DR: In this paper , the effects of cooling on the cutting temperature, surface roughness and tool wear are investigated by using the developed virtual machining system, which can accurately calculate the cutting forces during turning operations of Ti6Al4V alloy.
Abstract: The titanium alloys are widely used in aeronautical engineering and medical device materials due to exceptional mechanical properties such as tensile resistance and toughness of fractures. High thermo-mechanical loads occur in metal cutting of Titanium alloy Ti6Al4V, which can decrease life of cutting tool and increase cost of part production. In this paper, the coolant effects on the cutting temperature, surface roughness and tool wear are investigated by using the developed virtual machining system. The cutting forces during turning operations of Ti6Al4V alloy are accurately calculated in order to be used in calculation of cutting temperature and tool wear. The modified Johnson–Cook methodology is utilized to obtain the cutting temperatures along machining paths. Then, the Coupled Eulerian-Lagrangian (CEL) approach is investigated to predict and evaluate the effects of coolants on the cutting temperature in turning operations of Ti6Al4V alloy. The finite element approach is employed to predict tool wear by using the Takeyama–Murata analytical model and modifying the cutting tool geometry during the chip production process. To verify the developed methodology in the study, the results of experiments for the measured cutting temperatures, surface quality and wear rate are compared to the results of virtual machining system obtained by the finite element simulation. Thus, utilizing the proposed virtual machining system in the study, cutting temperatures, surface quality and tool wear during the turning operations of Ti6Al4V alloys with and without coolant can be accurately predicted to enhance the accuracy as well as productivity in the CNC machining operations.
3 citations
TL;DR: In this article , a flexible tool for hole hemming between dissimilar materials with very different mechanical properties is presented, which can be used for creating hole-hemmed joints between different materials.
Abstract: This research work presents the development of a flexible tool for performing the new joining process, called hole hemming, between dissimilar materials with very different mechanical properties. This work includes the design, fabrication, and assembly of the structural, active and passive components of the hole hemming tool and the evaluation of their performance. The tool is designed to have adjustable structural and passive tool components as well as easily interchangeable active tool components. The tool is evaluated for joining the AA6082-T4 aluminum sheet with 2 mm thickness to the AZ31 magnesium sheet with 0.9 mm thickness by experimental tests. The maximum force measured during the hole flanging and hemming stages is about 55 kN and 70 kN, respectively. The experimental data is also compared to the numerical results obtained from the finite element analysis of an ideal design. The results in both stages allow concluding the developed tool meets the considered requirements and can be efficiently used for creating hole-hemmed joints between dissimilar materials.
3 citations
TL;DR: In this article , a numerical axisymmetric elastic stress wave propagation analysis of the 2D-FGM hollow thick finite cylinder has been performed, where a non-uniform impulsive pressure has been applied on the one-third of the top inner cylinder wall.
Abstract: In this paper, a numerical axisymmetric elastic stress wave propagation analysis of the 2D-FGM hollow thick finite cylinder has been performed. The new accurate material distribution model based on Mori-Tanaka scheme and third-order transition function for 2D-FGMs has been implemented in the graded finite element method with higher-order quadrilateral elements. A non-uniform impulsive pressure has been applied on the one-third of the top inner cylinder wall. Consequently, different wave velocities and reflections from the boundaries have been observed due to the graded distribution of material along with two directions. Moreover, the effects of two-dimensional material property distributions on the stress wave propagations and displacements through the cylindrical wall at different locations have been studied systematically. Normalized effective stresses based on von-Mises criteria has been performed in comparison with the internal impulsive pressure amplitude to provide a measure of the cylinder wall response to the mechanical impact loading, the effective stresses are nearly 2.5 times the internal pressure loading amplitude, closed to the impact location. According to the results, 2D material property gradations has effected the stresses significantly. Alternatively, desired stress values can be achieved through optimal design and appropriate choice of property distribution.
2 citations
TL;DR: In this article , the unconventional tensors of nonlocal stress and couple stress are incorporated simultaneously in the in-plane nonlinear stability analysis of functionally graded (FG) multilayer shallow micro/nano-arches under thermomechanical loading conditions.
Abstract: In the present exploration, the unconventional tensors of nonlocal stress and couple stress are incorporated simultaneously in the in-plane nonlinear stability analysis of functionally graded (FG) multilayer shallow micro/nano-arches under thermomechanical loading conditions. For this purpose, the nonlocal couple stress (NCS) mechanics of continuum is implemented into the third-order shear flexible arch theory incorporating the von Karman kinematical nonlinearity. The nanocomposite material of FG multilayer shallow micro/nano-arches is reinforced with graphene nanofillers in accordance with different patterns of FG lamination. The generalized differential quadrature numerical strategy in conjunction with the pseudo arc-length continuation procedure are employed to deduce the roles of unconventional nonlocal and couple stress tensors in the NCS-based nonlinear stability paths of thermomechanical loaded FG multilayer shallow micro/nano-arches. It is found that for all patterns of the lamination, the contributions associated with the nonlocality and couple stress small scale effects on the value of the upper limit as well as the first bifurcation compressive loads are less than those on the lower limit and the second bifurcation ones. Also, it is demonstrated that by combining a temperature rise with the applied compressive lateral load, the upper limit lateral load increases, while the lower limit one decreases. Furthermore, it is seen that by applying a temperature rise, an initial lateral deflection is induced in the shallow micro/nano-arch before applying the compressive lateral load.
2 citations
TL;DR: In this article , the seismic behavior of a cable-arch bridge as a new type of bridge with a hybrid system of an arch and stay cables was studied considering the effect of seismic hazard probabilities and vertical excitations.
Abstract: There are many parameters that affect the seismic behavior of the bridge, especially in the new type of bridges. In this research, the seismic behavior of a cable-arch bridge as a new type of bridge with a hybrid system of an arch and stay cables has been studied considering the effect of seismic hazard probabilities and vertical excitations. By considering these parameters, the seismic analysis was investigated in three steps: Response spectrum analysis to obtain general seismic behavior of the bridge, time-history analysis using seismic ground motion records to capture dynamic responses, and pushover analysis to determine the capacity of the bridge. The performance of the bridge was monitored, and the significance of considering seismic hazard probabilities and vertical excitations was investigated. Pointing out the effects of these parameters on the seismic behavior of the bridge, the results indicated a requirement for considering them to provide the seismic safety of the bridge.
2 citations
TL;DR: In this article , the effects of porosity and its geometry on tensile features of concrete were investigated, using the Brazilian test and three dimensions PFC model, and the results showed that porosity geometry plays an important role in the fracturing pattern.
Abstract: In this article, the effects of porosity and its geometry on tensile features of concrete were investigated, using the Brazilian test and three dimensions PFC model. In the first step, the PFC sample was calibrated by indirect tensile lab outcomes and uniaxial compression test outputs. In the next step, indirect tensile tests were done on the models consisting of various pore shapes. Cylindrical models consisted of internal pores with different shapes such as rectangular, circular, horizontal notch, and vertical notch. The diameter and or the length of these porosity changes in various values, i.e., 10 mm, 20 mm, and 30 mm. Twelve different configurations of samples were prepared by varying the porosity shapes. The mechanical behavior of samples has been provided in form of stress–strain curves at a constant and slow loading rate of 0.05 mm/min for ensuring the static condition based on Newton’s first law. Concurrent with numerical simulation, an experimental test was done on the concrete slabs containing different pores. The outcomes showed that porosity geometry plays an important role in the fracturing pattern. It was found that the porosity geometry has potent consequences on fracturing process stress and the value of the UCS for rocks. Numerical simulation shows that fracture energy decreased by increasing the dimension of the defect. Crack initiation stress was close to final stress in vertical notch configuration while the difference between the final stress and crack initiation stress has a high value for horizontal notch configuration. The sharper the hole tip, the faster the progressive failure occurred.
1 citations
TL;DR: In this paper , an approach for thermal analysis of articulated systems subject to boundary and motion constraints (BMC) is proposed to capture large temperature fluctuations, significant change in geometry due to reference configuration and deformations, and geometric nonlinearity due to articulated mechanical systems (AMS) large displacements and spinning motion.
Abstract: Abstract This paper proposes an approach for thermal analysis of articulated systems subject to boundary and motion constraints (BMC). The solution framework is designed to capture large temperature fluctuations, significant change in geometry due to reference configuration and deformations, and geometric nonlinearity due to articulated mechanical systems (AMS) large displacements and spinning motion. Thermal-expansion displacements, which do not contribute to rigid-body translations, are determined from thermal stretch of position-gradient vectors using a new sweeping matrix technique designed to eliminate dependence on translational rigid-body modes. A new quadratic thermal-energy kinetic form is defined and used to formulate a dynamic force vector that accounts for thermal transient and inertia effects. Nodal thermal displacements are used in formulating AMS differential/algebraic equations (DAEs), and consequently, thermal stresses due to BMC equations are automatically accounted for based on integration of thermal analysis and Lagrange-D’Alembert principle, which is the foundation of computational multibody system (MBS) algorithms. The approach used in this study for large-displacement constrained and unconstrained thermal expansions is based on multiplicative decomposition of position-gradient matrix, instead of strain additive decomposition, for solution of thermo-elasticity problems. Four configurations are used to define continuum geometry and displacements: straight configuration, reference configuration, thermal-expansion configuration, and current configuration. The proposed approach allows applying thermal loads during constrained large displacements, does not impose restrictions on the choice of thermal coefficients, captures reference-configuration geometry and change in inertia forces due to temperature fluctuations, accounts for thermal displacement in formulating AMS nonlinear constraint equations, and allows for integration with MBS algorithms for the study of a wide range of thermo-elasticity problems.
1 citations
TL;DR: In this paper , the thermally induced vibrations of FGM joined spherical-conical shells are analyzed and the total functional of the shells are obtained under the assumptions of uncoupled thermoelasticity laws, first order shear deformation shell theory, and the von Kármán type of geometrical nonlinearity.
Abstract: Geometrically non-linear thermally induced vibrations of functionally graded material (FGM) joined spherical-conical shells are analyzed in the current research. Thermo-mechanical properties of the shells are assumed to be temperature and position dependent. The system of joined spherical-conical shells is subjected to thermal shock on the ceramic-rich surface, whereas the metal-rich one is kept at reference temperature. The one-dimensional transient heat conduction equation is established and solved via the generalized differential quadrature (GDQ) and Crank-Nicolson methods. This equation is non-linear since the thermo-mechanical properties of the shells are temperature dependent. The total functional of the shells is obtained under the assumptions of uncoupled thermoelasticity laws, first order shear deformation shell theory, and the von Kármán type of geometrical non-linearity. Non-linear coupled equations of motion are solved via the iterative Picard method accompanied with the β-Newmark time approximation technique. Numerical results are well-validated with the available data for the case of single FGM spherical shell. Parametric studies are conducted to examine the influences of conical and spherical shell geometries, material composition, temperature dependence, in-plane and out-of-plane mechanical boundary conditions, various configuration of conical/spherical shell system, and thermal boundary conditions. It is highlighted that thermally induced vibrations indeed exists.
1 citations
TL;DR: In this article , the buckling of multilayered CNT/GPL/Fibre/Polymer hybrid composite Levy-type nanoplates resting on Winkler-Pasternak support is investigated using modified nonlocal first-order plate theory.
Abstract: In the following research, the buckling of multilayered CNT/GPL/Fibre/Polymer hybrid composite Levy-type nanoplates resting on Winkler–Pasternak support is investigated using modified nonlocal first-order plate theory. The different layers of the plate are assumed to be reinforced with functionally graded carbon nanotube composite or functionally graded graphene platelets composite. Modified nonlocal first-order plate theory is used to capture the molecular effects at nanoscale and extract the buckling equations. The along-thickness variation of reinforcing nanocomposites may be uniform or functionally graded, and functionality can be linear or nonlinear based on specific functions presented by scientists. Using a closed-form analytical solution, these partial differential governing equations are changed to a set of coupled ordinary differential equations that may be solved for the Levy-type boundary conditions (i.e., two opposite edges with simply supported and two other with edges arbitrary). The obtained results may be used as a useful benchmark for validation of other works developed in the future.
1 citations
TL;DR: In this article , the impact of different volume fraction distributions on the buckling and bending response of a bidirectional functionally graded (BDFG) beam with general boundary conditions is investigated via a quasi-3D solution.
Abstract: This article considers a bidirectional functionally graded (BDFG) beam with various distributions of volume fraction. The impact of these distributions on the buckling and bending response of BDFG beam with general boundary conditions is investigated via a quasi-3D solution. It is assumed that the beam is exposed to a set of in-plane varying compressive loads and there mechanical characteristics change in both directions. Also, the BDFG beam is considered to be exposed different external mechanical loads. Hamilton’s principle is employed to derive the governing equations, which are then solved using analytical solution to obtain buckling and bending characteristics. The precision of the current formulation is investigated via a comparison with available data in literature. Some numerical results are presented and discussed to assess the effect of different parameters such type of volume fraction, boundary condition, varying load, and beam geometry on the buckling and bending of BDFG beam.
TL;DR: In this article , the two-way coupled thermoelastic behavior of axially graded composite plate and doubly-curved (cylindrical, spherical, hyperbolic, and elliptical) panels is examined under conductive-convective boundary and uniformly distributed loading conditions.
Abstract: In this article, the two-way coupled thermoelastic behavior of axially graded composite plate and doubly-curved (cylindrical, spherical, hyperbolic, and elliptical) panels is examined under conductive-convective boundary and uniformly distributed loading conditions. Here, the material properties of the axial functionally graded panel are computed by employing the power-law-based Voigt’s scheme. The material and geometric nonlinearities are incorporated using the cubic-polynomial-based temperature-dependent constitutive model and higher-order kinematics-based Green-Lagrange strain, respectively. The temperature profile is obtained through thermally nonlinear theory associated with high temperature, which is used to extract the energy equations obtained from the first law of thermodynamics and deformation-dependent entropy relation. The weak forms of motion and heat-transfer equations are derived using Galerkin’s method and further combined into the two-way coupled field equation through 2D-finite element approximation via Lagrangian elements. The transient responses are computed via the Newmark and the Crank-Nicolson schemes, whereas the nonlinear iterations are executed through Picard’s iteration technique. The performance of the fully coupled model for an axially graded (metal/ceramic) structure is verified with analytical, numerical, and experimental results and tested through a variety of numerical illustrations under various sets of conditions.
TL;DR: In this paper , the authors analyzed rectangular functionally graded material plates with rectangular cutouts of diverse sizes, numbers, and positions for free vibration using Mindlin's first-order shear deformation theory (FSDT).
Abstract: This article aims to analyze rectangular functionally graded material plates with rectangular cutouts of diverse sizes, numbers, and positions for free vibration using Mindlin’s first-order shear deformation theory (FSDT). Isoparametric plate elements of nine nodes and five degrees of freedom at each node were used for the present finite element formulation. The Poisson ratio is assumed to be constant throughout the plate. At first, results piled up from the present finite element formulation were compared with existing results collected from various previous journals for different isotropic plates and functionally graded material plates. After verification of finite element formulation, some new results (nondimensional fundamental frequency) were obtained considering various shapes, sizes, numbers, positions of cutouts, thickness ratio, aspect ratio, FGM power law index, and different edge conditions. Dynamic analysis of FGM plate with interior support along rectangular cutout edges is an integral part of this study.
TL;DR: In this paper , the authors employed Mindlin's first-order shear deformation theory to analyze the dynamic behavior of laminated composite shells with various geometries, featuring central cutouts and cracked corners that carry concentrated and distributed mass.
Abstract: This article employs Mindlin’s first-order shear deformation theory to analyze the dynamic behavior of laminated composite shells with various geometries, featuring central cutouts and cracked corners that carry concentrated and distributed mass. The formulation considers an isoparametric element with nine nodes and five degrees of freedom per node. Both in-plane and transverse effects of mass are addressed by incorporating lumped mass with rotational inertia in the formulation. The obtained results are compared to previously published data, showing an excellent agreement with a variation of less than ±2.5% for all cases. Following validation, the study examines shell vibration for various geometries carrying concentrated mass, distributed mass, and distributed patch mass. Additionally, the dynamic analysis of shell panels with central cutouts and cracked corners with different cracked dimensions is conducted. Unique boundary conditions are introduced by applying them to both the outer and cutout edges (i.e., SSSS-CCCC, FFFF-CCCC).
TL;DR: In this paper , a multi-roller beam-bar-spring (MR-BBS) model was developed that incorporates axial load, radial load, turning torque and thread modification.
Abstract: Obtaining the load distribution and radial deformations of planetary roller screw mechanism (PRSM) for the load carrying capacity design under complex loading conditions (multi-directional loads) is beneficial to decelerate fatigue and wear of threads. However, the combined effects of axial load, radial load and turning torque (overturning moment) were ignored in previous studies due to the complicated structure of PRSM. This paper presents a multi-roller beam-bar-spring (MR-BBS) model that incorporate radial load, turning torque and thread modification. The proposed model extended the theoretic method for calculating bending behavior of screw and rollers, which can more precisely describe the locus of the threads and roller axis. The load distribution of threads and load sharing among rollers of a PRSM under different external loads and cycling process are analyzed. The results show that the load distribution is more sensitive to turning torque of screw but relatively insensitive to the radial load. Moreover, the load distribution moderately changes with the variation of modification factor. Based on thread modification, the variable lead PRSM is proposed so that the uniformity of load sharing with complex load can be optimized. HighlightsA multi-roller beam-bar-spring (MR-BBS) model is developed that incorporate axial load, radial load, turning torque and thread modification.The load distribution of threads and load sharing among rollers of a PRSM under different external loads and cycling process are analyzed.The load distribution is more sensitive to turning torque of screw but relatively insensitive to the radial load.The variable lead PRSM is proposed so that the uniformity of load sharing with complex load can be optimized.
TL;DR: In this paper , a gripper for pipe climbing is presented, where the gripper is alternately actuated between gripped and ungripped states using a camshaft and lever mechanism powered by a single DC motor.
Abstract: The article presents the design of Complibot, a robot with a novel gripper for pipe climbing. The mechanism of the gripper involves the use of a bistable buckled beam, which is a type of bistable compliant mechanism. The bistable buckled beam in the gripper is alternately actuated between its gripped and ungripped states using a camshaft and lever mechanism, which is powered by a single DC motor. The design parameters associated with the gripper are obtained both experimentally and numerically. A proper selection of design parameters helps in the efficient functioning of the gripper. After the design of the gripper, two such grippers are fabricated and attached to each other by two stepper motor-driven lead screws to make a pipe climbing robot with inchworm locomotion. The mobility of the robot is controlled by an Arduino Uno microcontroller after the electronic components have been integrated. Finally, Complibot is subjected to a series of tests to establish its maximum load-carrying capacity when climbing a polyvinyl chloride (PVC) pipe. Complibot is found to perform satisfactorily without slipping while climbing a PVC pipe with a diameter of 105–115 mm, a velocity of 0.2 m/min, a power consumption of 18.58 W, a maximum load-carrying capacity of 114.64 N, and a payload to weight ratio of 0.52.
TL;DR: In this article , a dual number formalism was proposed to compute all kinematic quantities up to the fourth order, including the jerk and jounce/snap, automatically once the position vector is constructed.
Abstract: In the analysis of robots and mechanisms, the computation of velocities and accelerations is frequently needed. In other cases, higher-order kinematic formulas such as the jerk and the jounce/snap—the third and fourth-order time derivative of the position vector, respectively—are also needed. While procedures for computing velocity and accelerations can be found elsewhere in the literature, the computations of the jerk and especially of the jounce/snap are not so common. In this study, a novel formulation to compute all kinematic quantities up to the fourth order, based on the dual number is presented. In dual number formalism, kinematic analysis equations are computed automatically once the position vector is constructed. This provides a concise and efficient method to conduct kinematic analysis. To prove the validity of the implemented formulation, we compute the velocity, acceleration, jerk, and jounce/snap for the end effector of the RC robot manipulator. In addition, we compute the jerk and the jounce/snap for the coupler point of the spherical 4 R mechanism.
TL;DR: In this paper , a mathematical approach is proposed to apply strain-driven and stress-driven two-phase local/nonlocal integral models (TPNIMs) with discontinuity of variable fields.
Abstract: A mathematical approach is proposed to apply strain-driven (εD) and stress-driven (σD) two-phase local/nonlocal integral models (TPNIMs) with discontinuity of variable fields. The equivalently differential form together with constitutive boundary conditions and constitutive continuity conditions is derived explicitly. Compare to constitutive boundary conditions, constitutive continuity conditions have one more integral item, and the discontinuity plays no role on differential constitutive relation and constitutive boundary conditions. εD- and σD-TPNIMs are applied to formulate the Mode I and II fracture problem of double cantilever Euler-Bernoulli microbeams subjected symmetric and anti-symmetrical end moment and force loads. It is found that constitutive continuity conditions play no role on Mode I fracture problem since that the flexible deformation disappears for intact microbeam under symmetry loads. The bending deflections under different loads are solved analytically, and the energy release rate (ERR) and stress intensity factor (SIF) are derived explicitly. On the basis of the superposition principle, SIF for edge-cracked Euler-Bernoulli microbeams subjected generally end moment and force can be calculated. The influence of nonlocal parameters and the intact microbeam length on the size-dependent fracture behavior is investigated numerically. The obtained results can explain the superior fracture performance of nanomaterials.
TL;DR: In this article , a four-node quadrilateral element with eleven degrees of freedom per node is approximated using the C1-order non-conforming Hermite and Lagrange functions and the novel refined Quasi-3D plate hypothesis for buckling and free vibration analysis of non-uniform thickness bi-directional functionally graded sandwich porous (BFGSP) plates resting on variable elastic foundations (VEF) in a hygro-thermal environment.
Abstract: A novel four-node quadrilateral element with eleven degrees of freedom per node is approximated using the C1-order non-conforming Hermite and Lagrange functions and the novel refined Quasi-3D plate hypothesis for buckling and free vibration analysis of non-uniform thickness bi-directional functionally graded sandwich porous (BFGSP) plates resting on variable elastic foundations (VEF) in a hygro-thermal environment. Material and mechanical properties that change in both the length and thickness directions with three different laws of porosity, which are made up of a fully ceramic core layer and two bi-directional functionally graded (2D-FG) material ones, may be used a lot in the aerospace engineering and military industries. In order to analyze the buckling and free oscillation behaviors shown by the plate with arbitrary boundary conditions, a series of mathematical methods created in Matlab’s software are used. The computation program’s correctness is verified by comparing numerical findings to dependable assertions. In addition, a comprehensive analysis of the impact of factors on the buckling and free oscillation responses is conducted. The findings reveal that the novel porosity patterns, the hygro-thermal environment, the elastic medium characteristics, and the boundary conditions have a substantial impact on the mechanical behaviors of the non-uniform thickness 2D-FG sandwich porous plates. The results of this article can be used as a useful reference for engineers when calculating and designing structures of this type in engineering practice.
TL;DR: In this article , a toroidal shell segment (TSS) made of functionally graded porous material (FGPM), exposed to elevated temperature and subjected to uniform torsion, is analyzed.
Abstract: This article aims to analyze the nonlinear instability of toroidal shell segment (TSS) made of functionally graded porous material (FGPM), exposed to elevated temperature and subjected to uniform torsion. The volume fraction of two material constituents is varied through the shell thickness according to a power-law function, while porous distribution into FGPM is modeled in forms of cosine functions. Governing equations in terms of deflection and stress function are established within the framework of classical shell theory incorporating geometrical nonlinearity. Two edges of the TSS are assumed to be simply supported and elastically restrained. Multi-term analytical solutions are assumed to satisfy boundary conditions and Galerkin method is applied to derive closed-form expressions of nonlinear load–deflection relations and buckling loads. Parametric studies are carried out to analyze the separate and combined influences of material and geometry properties, porous coefficient and distributions, degree of edge constraint and elevated temperature on the buckling resistance and postbuckling strength of torsionally loaded FGPM TSSs.
TL;DR: In this article , a first attempt to analytically determine the asymmetric dynamic transverse characteristics of thin to moderately thick viscoelastic functionally graded porous (VFGP) annular plates is presented.
Abstract: This research presents a first attempt to analytically determine the asymmetric dynamic transverse characteristics of thin to moderately thick viscoelastic functionally graded porous (VFGP) annular plates. Firstly, the material properties of the plate are assumed to have various nonlinear distributions in terms of porosity coefficient. Secondly, the motion equations are obtained through the first-order shear deformation theory (FSDT) of elasticity, the energy method, and the variations calculus. Thirdly, the standard linear solid (SLS) model is adopted to consider the viscoelastic behavior of the plate. Finally, the perturbation procedure together with Fourier series are utilized to solve the system of partial differential equations, and the asymmetrically dynamic response is found in a closed-form solution. To assess the veracity of the analytical findings, an algorithm based on the finite element (FE) method called the user-defined field (USDFLD) code is developed. In order to benchmark the present study, the dynamic response of VFGP annular plates is scrutinized under two types of excitations (impulsive and step), four different types of radial load profiles (such as constant, linear, parabolic, and sine distributions), and various asymmetric circumferential loads. Moreover, the influence of various geometrical and material characteristics on the dynamic response of VFGP annular plates is investigated.
TL;DR: In this paper , the kinematic hypothesis is used for modeling the disk springs with constant material thickness and the restricted radial movement of inner and outer edges of the disk washers.
Abstract: Actual manuscript examines the disk springs with constant material thickness. The kinematic hypothesis is used for modelling. Motivating feature is the possibility to calculate the disk springs of with free gliding edges and the edges with the constrained radial movement. Variation formulations are used for derivation. The developed equations are suitable for springs made of isotropic materials, as spring steel and light metal alloys. The advantage of the methodology is the derivation of closed form solutions with restrictions on radial movement of inner and outer edges. The developed formulas are recommended for industrial calculations of free and restricted Belleville washers.
TL;DR: In this paper , the additional inerter-based viscoelastic mass dampers (AIVMD) and additional viscoelsm damper inerters (AVMDI) are introduced to derive the optimal closed-form solutions for these novel dampers analytically.
Abstract: The additional inerter-based viscoelastic mass dampers (AIVMD) and additional viscoelastic mass damper inerters (AVMDI) are introduced in this article. H2 and H∞ optimization schemes are utilized to derive the optimal closed-form solutions for these novel dampers analytically. A parametric study performs to investigate the sensitivity of the optimal design parameters with other system parameters such as damper mass ratio, inerter mass ratio, and stiffness ratio. Thus, a higher damper mass ratio, a higher inerter mass ratio, and a higher stiffness ratio are recommended to design optimum novel dampers for achieving robust vibration reduction capacities. Therefore, H2 optimized AIVMD and AVMDI have 53.23% and 57.73% dynamic response reduction capacities while H∞ optimized AIVMD and AVMDI can provide 72.97% and 75.57% dynamic response reduction capacities subjected to harmonic excitation, respectively. In addition, random-white noise excitations are also applied instead of harmonic excitation to cross-check the accuracy of the optimal design parameters. The overall result shows that 74.24% and 82.17% dynamic response reduction capacities for H2 optimized AIVMD and AVMDI, furthermore, 92.14% and 94.36% dynamic response reduction capacities for H∞ optimized AIVMD and AVMDI. These optimal closed-form solutions are mathematically accurate and relevant for practical applications.
TL;DR: In this paper , a disk brake rotor optimization using parametric and topological optimizations considering three conflicting objectives: mass, temperature variation, and breaking time, was presented, where the Multi-objective Lichtenberg Algorithm (MOLA) was used to find the general rotor design parameters.
Abstract: Purpose: This work is dedicated to disk brake rotor optimization using parametric and topological optimizations considering three conflicting objectives: mass, temperature variation, and breaking time. The rotor had explicit equations modeled and the Multi-objective Lichtenberg Algorithm (MOLA), which is executable in Matlab®, performed a parametric optimization to find the general rotor design parameters. Several optimization techniques have been developed last few years, however, the ones that have presented better results are meta-heuristics associated with posteriori decision-making techniques. Thus, in this work, this powerful and recently created multi-objective meta-heuristic was applied. The MOLA found more than 3000 solutions and the TOPSIS was used for decision-making. Then, the rotor was designed in the SolidWorks® 3D software and the ANSYS software was applied to perform topological optimization, where more mass was removed and analysis regarding the work stresses was done. To the best author’s knowledge, this is the first work to consider multi-objective parametric and topological optimization for this structure at the same time in the literature. A considerable mass reduction was obtained. It was possible to find a rotor weighing only 164.8 g with the lowest safety factor across the entire rotor equals 2.02. Therefore, a rotor optimized with reliable, lightweight, and that allows a low braking time was found. Also, these results show that the methodology used can be applied in other structures with complex parameterization.
TL;DR: In this article , a new shear deformation plate theory is presented to formulate the displacement field and the nonlinear partial differential equations considering the small size effect are established via the principle of virtual work.
Abstract: Nonlinear bending of functionally graded metal/graphene (FGMG) sandwich rectangular plate with metal foam core resting on nonlinear elastic foundations is elucidated in this article. A new shear deformation plate theory is presented to formulate the displacement field. The nonlinear partial differential equations considering the small size effect are established via the principle of virtual work. The nonlinearity is considered by using Von Karman’s strain-displacement relations. While, the size effect is captured by employing the modified couple stress theory. The upper and lower layers are made of aluminum as a matrix that reinforced with graphene platelets (GPLs). The GPLs are functionally graded through the thickness of the face layers according to a new cosine rule. Moreover, the metal foam core is also made of aluminum containing porosities that uniformly distributed or functionally graded through the core thickness. The governing equations are solved based on the Galerkin and Newton’s methods. The obtained results are examined by introducing some comparison examples. In addition, several parametric examples are discussed including the effects of the porosity type, GPLs distribution type, core-to-face thickness, elastic foundation stiffness, side-to-thickness ratio, plate aspect ratio and material length scale parameter on the nonlinear deflection and stresses of FGMG sandwich plate with metal foam core.
TL;DR: In this paper , the transverse shear modulus of the sandwich core structure of 3D-printed materials is evaluated and replaced with the sandwich structure, which contains three layers; a core layer, upper and lower face sheets.
Abstract: In recent days, the sandwich structure has created significant evolutionary changes in world technology, which are used in many sectors like automobile, aeronautical, defence, etc., The structural-based studies are evaluated and replaced with the sandwich structure, which contains three layers; a core layer, upper and lower face sheets. This article evaluates the transverse shear modulus of the sandwich core structure of 3D-printed materials. Henceforth the bioinspired structural design is adopted as core structure which is bio-mimicked from the microstructural layer design of the woodpecker's beak. Forming the wavy patterns is incorporated with the conventional honeycomb shape. The edges of the structure’s waviness are modeled as champer edges with the required dimensions. The fused deposition modeling (FDM) process is carried out to bring out the expected sandwich core design. Here, the article speaks about the contest between the various types of materials like polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), high impact polystyrene (HIPS), carbon fiber-polylactic acid (CF-PLA), carbon fiber - acrylonitrile butadiene styrene (CF-ABS), carbon fiber-polyethylene terephthalate glycol (CF-PETG). Each material contains specific properties; Henceforth, each material property is validated by ASTM E1876 standard. The objective is to find the good effectiveness of transverse shear modulus by the Nondestructive process called alternative dynamic method among the 3D-printed Bioinspired materials. In this study, CF-PLA stands ahead to give efficient transverse shear modulus property values. These results can be carried forward to structural development, enhancing the structure's performance as the futuristic pathway.
TL;DR: In this article , a dexterity distribution design method for attitude adjustment of multi-joint robotics based on singularity-free workspace decomposition (SWD) is presented, where the requirement of attitude adjustment for platform is described by time-varying Euler angles, by which the structural prototyping of universal prismatic-spherical + spherical (UPS + S) parallel robot body can be generated via mechanism concept design.
Abstract: This paper presents a dexterity distribution design method for attitude adjustment of multi-joint robotics based on singularity-free workspace decomposition (SWD). The requirement of attitude adjustment for platform is described by time-varying Euler angles, by which the structural prototyping of universal-prismatic-spherical + spherical (UPS + S) parallel robot body can be generated via mechanism concept design. According to Kutzbach-Grubler formula regarding degree of freedom (DOF), the forward kinematics model is built, meanwhile, the reachable posture workspace of the robot can be depicted in 3D space by exploiting tilt-and-torsion method. The Jacobian matrix is extracted to reckon dexterous performance of the mechanism, including condition number, minimum singular value, manipulability and comprehensive evaluation index. The singularity degree within the design domain, from singularity-free to fully singularity, is comparatively ranked in polar coordinates, which constitutes the essence of SWD, the performance spectrum corresponding to the structural parameters can hereby be acquired for larger workspace and smaller singularity. The impedance control errors with parameter perturbation further validate the consistency of the singularity-free attitude from the perspective of dynamics. The physical experiments are carried out to verify the outcomes by virtue of multi-axis pose sensor array. Hence the presented SWD method has important application prospects regarding DOF coupling, especially in medical rehabilitation, industrial robotics, aerospace manufacturing and so forth.
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TL;DR: Wu et al. as mentioned in this paper retracted the following article:Xinyuan Wu, Wenling Yang, Heng Zhang, Yingchun Yue & Mingjun Yang (2020) On the dynamics of an ultra-fast-rotating-induced piezoelectric cantilevered nanodisk surrounded by viscoelastic foundation, Mechanics Based Design of Structures and Machines, DOI:10.1080/15397734.2020.1858870
Abstract: AbstractWe, the Editor and Publisher of Mechanics Based Design of Structures and Machines have retracted the following article:Xinyuan Wu, Wenling Yang, Heng Zhang, Yingchun Yue & Mingjun Yang (2020) On the dynamics of an ultra-fast-rotating-induced piezoelectric cantilevered nanodisk surrounded by viscoelastic foundation, Mechanics Based Design of Structures and Machines, DOI:10.1080/15397734.2020.1858870Since publication, concerns have been raised about the authorship of the article. When approached for an explanation, the authors have been unable to verify their original data.It has also come to our attention that the full authorship list for this manuscript was changed during the submission and publication process. As determining authorship is core to the integrity of published work and given our concerns regarding the data, we are therefore retracting this article.The authors listed in this publication have been informed.We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines.The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as ‘Retracted’.This article refers to:RETRACTED ARTICLE: On the dynamics of an ultra-fast-rotating-induced piezoelectric cantilevered nanodisk surrounded by viscoelastic foundation
TL;DR: In this article , the authors presented an analytical framework for magnetoelectroelastic analysis of a higher-order shear deformable sandwich cylindrical shell through a thickness-stretched model and piezomagnetoelasticity relations.
Abstract: This work presents an analytical framework for magnetoelectroelastic analysis of a higher-order shear deformable sandwich cylindrical shell through a thickness-stretched model and piezomagnetoelasticity relations. The sandwich cylindrical shell is subjected to a combination multifield loadings. Based on the thickness-stretched model, the transverse deflection is decomposed into bending, shear, and stretching parts where the third term is responsible for strain along the thickness direction. The sandwich cylindrical shell is fabricated from an elastic core sandwiched by two piezoelectric/piezomagnetic face-sheets subjected to an electromagnetic environment. The multifield equations are derived using the principle of virtual work. After performing a verification study, the comprehensive numerical results are presented in terms of multifield loading. The results indicate that the radial displacement is significantly improved using the thickness-stretched model.