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CONTENTS
Volume 95, Number 4, August25 2025
 

Abstract
Magneto-electro-elastic (MEE) materials, due to their unique magneto-electric coupling effect, exhibit the capability of rapidly converting between magnetic, electric, and mechanical energies. This distinctive property makes them indispensable for the fabrication of fundamental electronic components such as sensors and energy harvesters. This paper focuses on an MEE plate with initial geometric imperfections, delving into its response under moving loads and the comprehensive influence of multiple physical fields, including electric, magnetic, and thermal effects. Utilizing the classical theory, displacement formulations for the MEE plate with initial geometric imperfections are established, and the von Kármán nonlinear straindisplacement relations were adopted to describe the large deformation effects. Simultaneously, with the aid of Maxwell's equations, the constitutive equations for the MEE plate encompassing electric, magnetic, and thermal fields are derived, and the nonlinear motion equations are formulated using the Euler-Lagrange principle. Subsequently, the Runge-Kutta method is employed to solve for the vibration deflection at the center of the plate. To validate this study, comparative analyses and convergence verifications are provided. Finally, this paper thoroughly examines the specific impacts of various factors, such as initial geometric imperfections, BaTiO3 volume fraction, electric potential, magnetic potential, temperature, and load magnitude, on the dynamic behavior of the MEE plate.

Key Words
initial geometric imperfections; magneto-electro-elastic plate; moving loads; nonlinear dynamic response; vibration disturbance

Address
Ying Cai and Gui-Lin She: College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing, 400044, China

Abstract
This paper attempts to provide an insight into studies of Machine learning regression and Optimal Neural Network models for the prediction of compressive strength of high-strength self-compacting concrete using project site testing results. We use these models, as they are time and cost-effective to gather data and to predict the incident itself, or, more likely, because the incident will occur in some future time. Prediction of Compressive Strength of High Strength Self-Compacting Concrete (HSSCC) for 7 days, 28 days, 56 days, and 90 days based on design mix parameters is implemented in this work by adopting an Optimal Neural Network model. An Information Criterion (AIC) algorithm, along with the golden search algorithm, was applied progressively till the optimal network with a minimum AIC was found. Machine learning Multiple Regression models are also developed to predict compressive strength of concrete from one or more design mix variables. The Regression equations are developed for computing the compressive strength of concrete based on the 9 input design mix parameters. The results of the models were encouraging and found to be reliable.

Key Words
compressive strength; concrete; machine learning; optimal neural network; regression learner

Address
Siddesha Hanumanthappa, D.S Rajendra Prasad, Pavan Kumar Emani and H.D. Sharma: Department of Civil Engineering, Siddaganga Institute of Technology, B.H. Road, Tumakuru – 572 103, Karnataka, India

Abstract
This study investigated the low-velocity impact behavior of glass fiber-reinforced polymer (GFRP) composite laminates embedded with shape memory alloy (SMA) wires, using a drop-weight impact testing machine. Three types of specimens were evaluated: (1) laminates without SMA wires, (2) laminates with embedded SMA wires, and (3) laminates containing 3% pre-strained SMA wires. The measured parameters included impact force, maximum displacement at the middle point of the laminates, absorbed impact energy, and damage area. The results indicated that embedding SMA wires longitudinally within the mid-layer improved load distribution and enhanced the composite's performance under impact loading. Furthermore, the presence of SMA wires significantly enhanced the impact force response and contributed to maintaining structural integrity through improved energy dissipation. The incorporation of SMA wires also led to reduced maximum displacement and damage area, while effectively preventing the propagation of irregular and uncontrolled cracks.

Key Words
GFRP composite; low-velocity impact; nitinol; SMA wires; superelastic

Address
Mohammad Mostafa Makhtoomi Aghdam, Omid Rahmani, Mohammad Javad Ramezani: Smart Structures and Advanced Materials Laboratory, Department of Mechanical Engineering, University of Zanjan, Zanjan, Iran
Masoud Osfouri: Institute of Ceramics and Polymer Engineering, Faculty of Materials Science and Engineering, University of Miskolc, Miskolc-Egyetemvaros, Hungary

Abstract
Structures that are partly in contact experience considerable torsional vibrations during earthquakes. This phenomenon is referred to in the literature as asymmetric pounding. The present paper deals with the effects of asymmetric pounding on the rotational seismic response of reinforced concrete buildings. In particular, the study aims to identify the influence of several parameters that have never been addressed in the past, such as the masonry infills distribution, the buildings' structural system and the seismic excitation directionality. Moreover, the effects of asymmetric pounding on the overall building response are evaluated through the calculation of representative response quantities. Based on the mean storey drifts, an approximate estimation of the earthquake economic losses due to asymmetric pounding is also attempted. For this purpose, two 8-storey reinforced concrete frame buildings which are sequentially considered in partial contact with an adjacent 6-, 3- or single-storey structure, are analyzed for three natural seismic excitations. Crucial aspects of the topic are highlighted: the unfavorable pilotis effect, the importance of ground motion directionality and the economic implications of the phenomenon.

Key Words
asymmetric pounding; floor-to-column pounding; floor-to-floor pounding; pilotis configuration; reinforced concrete structures; torsional vibration

Address
Grigorios E. Manoukas and Chris G. Karayannis: Department of Civil Engineering, Aristotle University of Thessaloniki, University Campus, 54124, Thessaloniki, Macedonia, Greece

Abstract
This study investigates the nonlinear vibration of a symmetrically laminated composite beam with a tip mass, subjected to uniform airflow and planar excitation forces. The beam is excited at its primary resonances, with auto-parametric internal resonance conditions between the flapwise-torsional and chordwise modes. The influence of uniform airflow in the flapwise direction on the beam's response is examined, extending previous research to include base excitation and tip mass. The multiple scales method is employed to analyze the non-linear equations and determine the stability of the steady-state amplitudes in both frequency and forced responses. The results show that the introduction of airflow significantly alters the system's behavior, eliminating Hopf bifurcations and reducing hardening-type behavior. Additionally, airflow induces a jump phenomenon at lower excitation frequencies and amplifies the effects of reduced damping on the system's amplitude. The findings demonstrate the importance of considering airflow in the analysis of vibration systems, particularly those with complex non-linear behavior.

Key Words
airflow; composite beam; flapwise and chordwise vibration; nonlinear vibration; tip mass

Address
Malihe Eftekhari: Department of Mechanical Engineering, Sirjan University of Technology, Sirjan 78137-33385, Iran

Abstract
This paper presents a study on the free vibrations of a new concept of functionally graded beams (FGM) resting on an elastic foundation under various boundary conditions employing the higher-order shear deformation theory (HDT). In classical FGM beam models, the variation of mechanical properties typically occurs from the top to the bottom surface. However, in this new concept, a novel variation has been proposed where the mechanical properties evolve from the exterior to the interior of the beam. This new variation is accounted for using a novel power-law mixing rule based on the constituents' volume fractions. The theoretical approach relies on the application of Hamilton's principle to derive the governing equations, which are solved using the state-space method. A parametric analysis is carried out to examine the influence of several parameters on the natural frequencies, including the power-law index, the slenderness ratio, and the Winkler and Pasternak parameters associated with the elastic foundation.

Key Words
boundary conditions; elastic foundation; exterior-to-interior variation; FGM beam; free vibrations

Address
Radim Ghelamallah, Benferhat Rabia, Hassaine Daouadji Tahar: Department of Civil Engineering, University of Tiaret, Algeria; Laboratory of Geomatics and Sustainable Development, University of Tiaret, Algeria
Tlidji Youcef: Department of Civil Engineering, University of Tiaret, Algeria; Materials and Structures Laboratory, Civil Engineering Department, University of Tiaret, Algeria

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