The paper considers dimensional synthesis of a path generator four-bar linkage by applying the modified Differential Evolution (DE) algorithm. During the search of the space, the DE algorithm may skip the right solution and lead to premature convergence. If the step is reduced, the search space is reduced as well, so that convergence becomes slower. Search efficiency may be achieved by including Lévy Flight in the DE algorithm. Namely, when the DE algorithm identifies the space of best solution, then a Levý Flight step is used for local search in that region, which significantly increases the exploitation capability and allows obtaining a very efficient solution of the optimization problem. The algorithm was tested with three examples of dimensional synthesis of a path generator four-bar linkage. The proposed algorithm can be very efficiently applied to solving very complex optimization problems.

Sandwich panel structures are widely used for light-weight applications due to their high strength and stiffness to density ratios. They are composed of two main parts: the skins and the core. This paper investigates a Miura-ori structural sandwich core with open cells that can be used as an alternative to the existing honeycomb structures. A fully parametric design approach, starting from drawing to Finite Element Analysis (FEA), is presented to efficiently analyze the effect of different geometries on the resulting structure. The geometric model was built based on the kinematic model, which can represent the folding process of the foldcore using the Matlab script. The obtained coordinates of the vertices of the folding pattern were exported to ANSYS APDL where the surfaces were automatically created and meshed. The created mesh was imported to LS-Dyna where explicit compression analyses were performed to evaluate the compression stiffness and strength of the studied geometries. The developed parametric model aims to find the best configuration for a given application, based on three sets of geometric parameters that define the shape of the Miura Ori folding pattern. Therefore, in the range of the studied geometries, the best parameter combination for specific compression stiffness and specific compression strength was found. To evaluate the performance of the foldcore and to validate the FE model, experimental quasi-static compression tests were undertaken with two kinds of specimens (‘strip’ and “panel”), and the measured force-displacement curves were obtained. The result of the test agrees with that of the FE simulations, with an error of <6.6% in the elastic region.

This investigation explores the vibrational response of a sandwich plate with material parameter nonhomogeneity and a viscoelastic core, incorporating Pasternak foundations. The study views the equation of motion from an anti-plane shear perspective, presenting a generalized exact dispersion relation (GEDR). It analyzes the impact of parameters like material nonhomogeneity, viscoelasticity, and Pasternak foundation properties on the dimensionless phase velocity against wave number. Findings reveal decreasing phase velocity with increasing wave number, with nonhomogeneity and Pasternak parameters exerting substantial influence. The study offers valuable insights into composite material wave behavior, benefiting design methodologies for diverse applications.

In this research article, an investigation into the natural frequencies of functionally graded porous curved beams is presented, covering both deterministic and stochastic domains. The stochastic finite element analysis is based on a three-node, C0 continuous element, and higher-order shear deformation theory, utilizing the first-order perturbation technique (FOPT). The study includes a comparative analysis of three porosity distribution models, including a recently proposed sinusoidal model. Additionally, the study examines the influence of various factors, such as porosity distributions, boundary conditions, volume fraction indices, and geometric configurations, on the natural frequencies. The analysis encompasses uncertain natural frequencies in functionally graded curved beams, accounting for material stochasticity through FOPT. Monte Carlo simulation (MCS) is used to validate the accuracy of the FOPT model, increasing the approach’s reliability. Potential future research in this area could investigate the effects of stochastic variations in geometric parameters, including dimensions and boundary conditions.

The current research introduces a multilayer functional structure along with its corresponding multi-objective optimization design strategy intended to improve the design efficiency of materials exhibiting remarkable properties in both load-bearing and electromagnetic wave absorption. The composite structure contains several layers of graphite oxide reinforced epoxy resin, each of which has a different thickness and volume fraction of fillers. The proposed strategy employs the volume fraction of fillers and thickness of each layer as the design variables, with the electromagnetic wave absorption bandwidth and bending stiffness of the entire structure serving as objectives. The multi-objective model was derived using the Maxwell-Garnett Model, Halpin-Tsai Model, Transmission Line Theory and Classical Laminate Theory. To efficiently optimize the multilayer structure, the JAYA, an evolutionary algorithm is employed as optimizer. The results indicate that the optimized structure exhibits a considerable increase in electromagnetic wave absorbing capacity and a slight increase in load-bearing performance relative to the original structure, while the total thickness remains constant. In addition, the whole process takes only a few seconds.

The present article aims to develop a finite element formulation for FGM plates carrying concentrated and distributed mass. First-order shear deformation theory with consideration of physical neutral surface has been employed. Nine noded isoparametric element with five degrees of freedom at each node is used for this finite element analysis. To understand the effect of grading pattern under overhead mass carrying conditions, three types of FGMs have been analyzed. The effect of non-dimensional parameters such as aspect ratio, thickness ratio, power index, the intensity of mass etc. are extensively studied. It will bring new insights to the field of FGM structures.

In this paper, minimization of delamination effect on laminated composite plates using smart (piezoelectric and magnetostrictive) materials has been investigated. The static and dynamic responses of the smart composite plates with/without delamination have been obtained using the finite element method. The validation and comparison studies of the laminated composite plate have also been performed to show the level of accuracy of the presently adopted model by solving a few examples related to static and frequency cases. For control and minimization of delamination effect, smart materials have been introduced at the various layers of the laminated panel. Further, the influence of delamination size, location, orientation scheme, aspect ratio, modular ratio and different boundary conditions on the dynamic response of the smart delaminated composite plate has been analyzed. Finally, optimization study has been carried out to find the optimal value of these parameters by minimizing the difference between the frequency responses. Here, two optimization algorithms TLBO and PSO have been considered to carry out the optimization study and results obtained from both techniques are validated and compared.

This paper proposes a load distribution model for the ball screw feed system with the assembly errors of the guide rails, which is used to predict the variation law of the load distributions for the ball screws and carriage-guide rail systems. Firstly, under the action of the contact loads of the ball screws, the bending deformation of the screw axis corresponding to each ball is derived. Secondly, a static model of the machine tool bearing system with the assembly errors is established. Then, the load distribution model of the ball screw feed system is proposed based on the load balance and deformation compatibility equation, and the solution process of the proposed model including judging the ball-raceway contact state is given. In addition, the results are compared with those of the existing models to demonstrate the validity of the proposed model. Finally, the relation between the curve shape of the load distribution and the bending of the screw shaft axis is explored, and the variation law of the load distributions for the feed system under the effects of the axial, radial loads, and assembly errors is discussed.

This paper presents a study on modeling, analysis, and control of an over-constrained Cable-Driven Parallel Robot taking into account the deformation of the cable transmission system due to the elastic model of the transmission mechanism and the affection of tension distribution for cables. The Cable-Driven Parallel Robot is used for a virtual reality motion simulation system with a simulation cabin mounted on a moving platform. A nonlinear cable length controller with tension feedback is designed to control the cabin to move along a trajectory extracted from the virtual simulated environment. The tension distribution algorithm is integrated into the controller to compensate for the dynamic error caused by the two redundant cables and the elastic characteristic of the transmission mechanism. The tensions are calculated based on the constraints of the workspace, the structure of the system, and the force limits of actuators. The cable tension feedback control algorithm was tested on the concept Cable-Driven Parallel Robot, the experimental results show that the joint trajectories meet the desired moving trajectory with high accuracy, and the cable tensions are controlled in the optimal region to ensure safety and save energy, but still suitable for the control requirements of the virtual reality motion simulator system.

Contact mechanics analysis is crucial because such problems often arise in engineering practice. When examining contact mechanics, the material property of the contacting components is a crucially significant aspect. It is more complex to solve the contact mechanics of systems that are composed of materials that do not have a homogenous structure compared to materials that have homogeneous qualities throughout. While many studies on contact problems with homogeneous materials exist, those involving non-homogeneous materials are scarce in the literature. As material technology improves fast, there will be a greater need to solve such problems. In this respect, analytical and finite element method (FEM) solutions of the continuous and discontinuous contact problems of a functionally graded (FG) layer are carried out in this article. The FG layer in the problem rests on a rigid foundation and is pressed with a rigid punch. From the solutions, the contact length, contact stress, initial separation distance, and beginning and ending points of separation were determined, and the results were compared. It has been concluded that the FEM findings are consistent with the analytical results to a satisfactory degree. This study analyzes contact problem using different approaches and accounts for the influence of body force in a contact geometry that has yet to be reported.