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CONTENTS
Volume 99, Number 3, August10 2026
 

Abstract
Surrogate models have been widely used in structural reliability evaluation. However, the high construction cost of a surrogate model is often unacceptable in practical engineering. This paper presents the largest contribution function (LCF) to reduce the construction cost of a surrogate model used for estimating structural system reliabilities. The LCF identifies the best sample that has the greatest contribution to the variance of the system failure probability. A learning stopping criterion for the LCF is established using the confidence level and the allowable relative error. Expressions of the LCF are provided for single failure, series system, parallel system, and seriesparallel system, and the general expression of the LCF is also given. In this study, a multi-output Kriging model is selected as the surrogate model, and the structural system reliability is estimated using the Kriging model based on the LCF and Monte Carlo simulation. Numerical examples demonstrate that the proposed method achieves a satisfactory balance between accuracy and efficiency for structural system reliability assessment.

Key Words
failure probability; Kriging; largest contribution function; learning function; structural reliability

Address
Weitao Zhao: College of Aerospace Engineering, Shenyang Aerospace University, Shenyang 110136, China
Hai An: College of Aerospace and Civil Engineering, Harbin Engineering University, Harbin 15001, China

Abstract
Vibrational behaviour of cylindrical shell filled with fluid using spline method is analysed to find out the frequency of the shell. The shell is made up of isotropic or specially orthotropic materials and the non-uniform thickness are assumed to be linear, exponential and sinusoidal along the axial direction of the cylinder. The equations of motion are coupled with fluid terms, by assuming irrotational and inviscid fluid. The equations which are in terms of longitudinal, circumferential and transverse displacement functions are derived from Love's first approximation theory. The equations are solved using Bickley-type splines of suitable order, which are cubic and quintic, by applying the point collocation method. This results in the generalized eigenvalue problem by combining suitable boundary conditions. This study examines the frequency parameter and its corresponding eigenvector of the spline coefficients, considering parameters such as relative layer thickness, length parameter, material characteristics, and thickness variation coefficients, under clamped–clamped and simply supported–simply supported boundary conditions.

Key Words
cylindrical shell with fluid interaction; free vibration; laminated composite shell; love's first approximation theory; non-uniform thickness; spline method

Address
M.D. Nurul Izyan: Faculty of Entrepreneurship and Business, Universiti Malaysia Kelantan, 16100 Kota Bharu, Kelantan, Malaysia
D.F.K. Omonova: Department of Mathematical Modeling, Samarkand State University, 15, University Boulevard, Samarkand, 140104, Uzbekistan
A.K. Nor Hafizah: Kolej Genius Insan, Universiti Sains Islam Malaysia, 71800, Nilai, Negeri Sembilan, Malaysia
J.M. Makhmudov: Department of Mathematical Modeling, Samarkand State University, 15, University Boulevard, Samarkand, 140104, Uzbekistan
K.K. Viswanathan: Department of Mathematical Modeling, Samarkand State University, 15, University Boulevard, Samarkand, 140104, Uzbekistan; University of Economics and Pedagogy, Karshi, Uzbekistan

Abstract
In this study, synthesis and investigation of PVDF/CNT nanocomposite has been conducted and then it has been used to design and optimize a castor bean vibrating harvester. Polyvinylidene fluoride (PVDF) was used as the matrix polymer and multi-walled carbon nanotubes (MWCNT) were used as the reinforcing agent. Nanocomposites with various weight percent of CNT (1, 3 and 5 wt%) were prepared by solution mixing and casting. In order to investigate the structural, thermal, mechanical and dynamic properties of the samples, SEM, FTIR, XRD, TGA, DMA analyses and mechanical tests were performed. The results showed that the addition of CNT increased the crystallinity, improved the B phase, increased mechanical strength and improved the piezoelectric response of the nanocomposite. The thermal stability, vibration and dynamic properties were optimal in the sample with 3 wt% CNT. Next, the synthesized nanocomposite was used in the vibrating part of a castor bean harvester. The performance tests indicated that PVDF/CNT could harvest the efficiency from 78% to 93%, reduce crop loss from 14% to 5% and decrease the consumption of machine energy. Furthermore, the vibration transmitted in a more uniform manner, thus minimizing plant branch damage. Based on the findings of this research, the PVDF/CNT nanocomposite material can be considered as a good material for the manufacturing of smart harvest machines with light weight and low energy consumption in agriculture.

Key Words
carbon nanotubes; castor harvesting machine; castor plant; piezoelectric materials; PVDF/CNT nanocomposite; vibratory harvesting

Address
Xv Liu, Hongchang Guan, Weijie Lin, Yixiao Zhang, Xiang Wang: College of Architecture and Urban Planning, Tongji University, 200092, Yangpu District, Shanghai, China
Yuming Fu: Department of Biomaterials, Saveetha Institute of Medical and Technical Sciences, Chennai, 600077, India
Mostafa Habibi: Department of Mechanical Engineering, Faculty of Engineering, Haliç University, Istanbul, Turkey; Department of Biomaterials, Saveetha Institute of Medical and Technical Sciences, Chennai, 600077, India

Abstract
Water storage tanks are vital infrastructure systems widely used for domestic, industrial, and emergency water supply. In addition to hydrostatic liquid pressure and self-weight, these tanks are subjected to external forces such as earthquakes, wind, and soil deformation. Among these effects, seismic-induced fluid sloshing and hydrodynamic interaction significantly influence tank performance and safety. This study presents a comprehensive review of the seismic behaviour of ground-supported and elevated water storage tanks by focusing on major research contributions available in the literature. Initially, the fundamental concepts of seismic response, sloshing behaviour, and interaction mechanisms are briefly introduced, followed by a discussion on analytical, numerical, experimental, and CFD-based modelling approaches. Subsequently, previous studies related to fluid-structure interaction (FSI), soil-structure interaction (SSI), and fluid-soil-structure interaction (FSSI) is systematically classified and reviewed. Experimental investigations and studies on seismic isolation and damping systems for reducing tank response are also discussed separately. Based on the review, major research trends, existing limitations, and potential areas for future investigation are identified.

Key Words
CFD; fluid-soil-structure interaction; fluid-structure interaction; hydrodynamic pressure; seismic response; sloshing; soil-structure interaction; water storage tanks

Address
Angadi Ravi: VTU Research Resource Centre (VTU RRC), Belagavi, Karnataka, India; Department of Civil Engineering, Jain College of Engineering, Belagavi, Karnataka, India
Nagraj S. Patil: Department of Civil Engineering, Visvesvaraya Technological University (VTU), Belagavi, Karnataka, India
K.G. Vishwanath: Department of Civil Engineering, Jain College of Engineering, Belagavi, Karnataka, India

Abstract
Lattice structures are open structures composed of a periodic array of beams or struts, frequently used in automotive and aerospace industries due to their potentials for better energy absorption ability and superior mechanical properties and yet lightweight. In this study, the authors created 900 lattice structures of cubic symmetry based on the crystallographic structural database and found 625 stretch-dominant lattice structures. The Young's modulus of the lattice structure was obtained by performing the FEM mechanical tests along different loading directions and with different porosity. The entire process was automated including structure modeling and FEM analysis via Python programming. Three stretch-dominated structures are found to have better isotropy and higher or comparable specific stiffness than the octet lattice structure.

Key Words
isotropy; lattice structure; stretch-dominated; specific stiffness

Address
Sang Joon Lee, Yongwoo Kim, SangHyuk Yoo: Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seoul, 03722, Republic of Korea
Sunil Moon: Memory Etch Technology Team, Samsung Electronics Co. Ltd., Pyeongtaek-si, Gyeonggi-do, 17786, Republic of Korea
Haryeong Choi: Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-ro, Seoul, 03722, Republic of Korea
Yoonjin Won: The Henry Samueli School of Engineering, University of California, Irvine, CA, 92697, U.S.A.
Keonwook Kang: Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seoul, 03722, Republic of Korea

Abstract
The main aim of this research article investigate the cracking behavior and damage assessment of steelreinforced concrete (steel-RC) and glass fiber-reinforced polymer-reinforced concrete (GFRP-RC) beams with varying tension reinforcement ratios. Beam specimens of dimensions (150x230x2100) mm were tested under fourpoint bending using a universal testing machine (UTM) integrated with an acoustic emission (AE) monitoring system. AE techniques were employed to detect and evaluate the progression of damage through parameters such as cumulative AE hits, average frequency, rise angle, amplitude, duration, and AE XY plots. These parameters enabled the identification of both micro- and macro-cracks during the flexural loading process. The results demonstrated that average frequency and rise angle are particularly effective in classifying crack types, distinguishing between flexural and shear cracks in both steel-RC and GFRP-RC beams. The study confirms the potential of AE-based techniques as a reliable tool for real-time crack monitoring, damage evaluation, and crack classification in reinforced concrete structures with varying reinforcement configurations.

Key Words
AE; crack classification; GFRP bars; hits; load-deflection; steel bars

Address
Gaurav Sharma: Civil Engineering Department, Lingaya

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