Abstract
This paper introduces a methodology that combines Multivariate Adaptive Regression Splines (MARS) modelling
and Monte Carlo Simulation to investigate the natural frequencies of porous functionally graded material (FGM) plates along with the frequency response function (FRF) analysis. The MARS model captures the nonlinear relationship between natural frequencies and different parameters, while the FRF approach provides insights into the plate's frequency response. The proposed methodology is accurate and helpful in studying the impact of porosity, power law index, temperature, and plate thickness on the first three natural frequencies, considering the stochastic variations in material properties caused by manufacturing errors. The porous FGM plate is subjected to a traditional finite element (FE) analysis with random material properties. The power law distribution is used to ascertain the material characteristics of porous functionally graded plates. The
effects of critical material characteristics, such as elastic Young's modulus, shear modulus, Poisson's ratio, and mass density, on the natural frequencies of porous FGM are examined. The results show that MARS-based finite element analysis has better computational efficiency than Monte Carlo simulations-based finite element analysis.
Key Words
frequency response function; functionally graded materials; Monte Carlo simulation; multivariate adaptive regression splines; stochastic analysis; uncertainty quantification
Address
Himanshu P. Raturi: Department of Mechanical Engineering, National Institute of Technology Silchar, India
Pradeep K. Karsh: Department of Mechanical Engineering, Parul Institute of Engineering and Technology, Parul University, Vadodara, India
Ravi R. Kumar: Department of Mechanical Engineering, National Institute of Technology, Arunachal Pradesh, India
Sudip Dey: Department of Mechanical Engineering, National Institute of Technology Silchar, India
Abstract
Curved hexahedral finite elements based on the hybrid-mixed stress formulation are proposed for structural dynamic analysis of three-dimensional solids. The stress and displacement in the domain of an element and the displacement on its boundary are simultaneously and independently approximated using sets of complete and linearly independent non-nodal Legendre polynomials. The element geometry is given in terms of its corner and mid-edge points using the same interpolation functions of the traditional isoparametric 20-node brick element. Symmetric, highly sparse and well conditioned solving systems are obtained. Numerical tests are carried out using h- and p-refinements to assess the behavior of these new hexahedrons.
Key Words
curved hexahedral; finite element; hybrid-mixed; structural dynamics; vibration
Address
Eliseu Lucena Neto, Flávio Luiz de Silva Bussamra: Instituto Tecnológico de Aeronáutica, São José dos Campos, SP, 12228-900, Brazil
Giorgio Paciarotti: Capgemini Engineering, Munich, 81829, Germany
Felipe Rodrigo Cardoso: Empresa Brasileira de Aeronáutica, São José dos Campos, SP, 12227-901, Brazil
Abstract
An Earthquake is a natural phenomenon that causes the destruction of structures. For many years, various methods
have been proposed to control this phenomenon. In modern times, a new method called active and passive control has been developed. Isolator systems are among the methods to control the structure's response. Instead of increasing the strength and capacity of the structure, these systems react to earthquakes. In this paper, a nonlinear rhombus shaped spring combined with the pendulum column isolation system was introduced that caused the piers to be flexible. The behavior of this isolator with flexible bases has been investigated. The studied system mathematical equations were derived, solved with MATLAB software, and compared with ABAQUS results. Later on, the isolator system was investigated under different earthquakes, and FFT analysis
was performed on the results. The results demonstrate that this mechanism is suitable as an isolator because it reduces
earthquake effects. It was observed that in the flexible piers form, the period was increased. The flexible piers have an effective role - in the response of the system-by reducing the system's stiffness considerably. Among the different damping ratios, those with ratios greater than 10% showed better results.
Key Words
earthquake; isolator; non-linear; pendulum column; rhombus; vibration
Address
Abdallah Azizi and Majid Barghian: Department of Structural Engineering, University of Tabriz, 29 Bahman Boulevard, Tabriz, Iran
Abstract
This study investigates the free vibration behavior of functionally graded (FG) plates using trigonometric shear deformation plate theory. The novelty of this work lies in the incorporation of porosities, which are inherent in FG materials due to manufacturing processes, and their detailed impact on the vibrational performance of these plates. Unlike existing studies, this research comprehensively examines multiple porosity distribution patterns, including homogeneous, "O", "X", and "V" configurations, which are seldom analyzed together. The governing equations of motion are derived using Hamilton's principle and solved analytically with the Navier method for simply supported boundary conditions. A key contribution of this study is the exploration of how porosity levels, distribution types, and geometry parameters collectively influence the natural frequencies of FG plates. The results highlight the significant effect of different porosity patterns, with "X"-shaped porosity yielding the highest natural frequency and homogeneous distribution leading to the lowest. Furthermore, the findings reveal that increased porosity levels can either enhance or diminish the vibrational characteristics depending on the distribution pattern. These insights provide valuable guidance for optimizing the design of FG plates for various engineering applications, such as aerospace and biomedical industries.
Key Words
FG plate; free vibration; functionally graded (FG) materials; porosity; trigonometric shear deformation theory
Address
Vagelis Plevris: Department of Civil and Environmental Engineering, Qatar University, P.O. Box 2713, Doha, Qatar
Lazreg Hadji: Department of Civil Engineering, University of Tiaret, BP 78 Zaaroura, Tiaret, 14000, Algeria
Royal Madan: Department of Mechanical Engineering, Graphic Era (Deemed to be University), Dehradun 248002, India
Abstract
Micro-beams and micro-plates suffer from residual stress problems such as stiffening and curling. This affects the performance of these micro-structures in MEMS applications. It is found from previous literature that minimizing both stiffening and curling is a challenging issue. This paper proposes double corrugations in both longitudinal and transverse directions as a remedy to this problem. A Finite Element model is developed and validated with results in literature. A parametric study is implemented to study the effect of number of corrugations and corrugation height on the micro-plate performance as compared to a flat one with the same stiffness. Proposed corrugations result in reducing stiffening, and curling, by 90%, and 87%, respectively. The corrugations concept may be used to improve the performance of many MEMS applications such as pressure sensors, resonators, and RF switches. In the case of RF switches for instance, the proposed method achieved a reduction of 39%
in switching time.
Address
Bahi Bakeer: Design and Production Engineering Department, Ain Shams University, 1 Elsarayat St., Abbaseya, 11517 Cairo, Egypt, Department of Mechanical Engineering, Galala University, Galala City, Egypt
Adel Elsabbagh: Design and Production Engineering Department, Ain Shams University, 1 Elsarayat St., Abbaseya, 11517 Cairo, Egypt
Mohammed Hedaya: Design and Production Engineering Department, Ain Shams University, 1 Elsarayat St., Abbaseya, 11517 Cairo, Egypt
Abstract
In order to improve the seismic performance of reinforced concrete (RC) frame structure, high performance fiber reinforced concrete (HPFRC) energy dissipation walls were installed in RC frame to form a new aseismic structure. Two halfscale HPFRC energy dissipation wall-RC frame specimens were designed and constructed. Quasi-static tests were performed to study the failure mechanism, deformation performance, and energy dissipation performance. The test results indicate that HPFRC energy dissipation wall-RC frame structures can achieve the seismic fortification objective of being "repairable after major earthquake". Based on the incremental dynamic analysis (IDA) method, seismic fragility analysis of the HPFRC energy dissipation wall-RC frame structure was performed by using PERFORM-3D structural analysis software and 44 ground motion records. The results show that the HPFRC material has good tensile strain hardening performance, which can improve the damage resistance and energy dissipation capacity of the structure or components. When the structure collapses, the average spectral acceleration response corresponding to the fundamental period of the structure calculated by 44 ground motion records is greater than the spectral acceleration corresponding to the fundamental period of the structure duringa rare earthquake with a fortification intensity of 8 degree, so the HPFRC energy dissipation wall-RC frame structure has good anti-collapse ability. Under the action of a rare earthquake of magnitude 8, the exceeding probability of collapse of the HPFRC energy dissipation wall-RC frame structureis 0.03%, which meets the requirements forseismic protection of the structure under the action of a large earthquake.
Key Words
exceeding probability; fragility analysis; HPFRC energy dissipation wall; RC frame; spectral acceleration
Address
Penghui Yang: General Institute of Design and Research, Xi'an University of Architecture and Technology, Xi'an 710055, China; College of Civil Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
Xingwen Liang, Ren Xin, Huajing Zhao: eneral Institute of Design and Research, Xi'an University of Architecture and Technology, Xi'an 710055, China
Abstract
The analysis of elliptical cracks emanating from cavities in polymethyl-methacrylate (PMMA) surgical cement is crucial for understanding loosening in total hip prostheses, as cement failure is a primary cause of this issue. Understanding fracture mechanismsis vital for improving the durability of cemented prostheses. Predicting crack propagation paths can help identify high-risk areas using medical imaging. This study focuses on the behavior of cracks emanating from cavities within the orthopedic cement, using a realistic model. The crack behavior is analyzed in terms of the evolution of stress intensity factors (SIFs) in Modes I, II, and III, applying the maximum tangential stress criterion. The fracture analysis considers the crack size
relative to the cavity, its orientation, and its location in the orthopedic cement. The finite element method specifically examines elliptical cracks along the cement, focusing on the effect of the distance between cracks emanating from cavities and nearby defects on SIFs. The orientation of these cracks significantly influences SIF magnitudes and modes, affecting the direction and stability of crack propagation. The study reveals that the proximal lateral part experiences the highest stresses, with a notable increase in SIFs in Modes I and II, particularly where crack interaction occurs. The proximal medial part follows, while the distal part is predominantly subjected to compressive stresses.
Key Words
bone cement; elliptic crack; finite element method; interaction; stress; stress intensity factor
Address
Benouis Ali: Faculty of Technology, University of Dr Moulay Tahar, Saida BP138 Saida 20000, Algeria; Department of Mechanical Engineering, Laboratory Mechanics Physics of Materials (LMPM), University of Sidi Bel Abbes, BP 89, City Ben M'hidi, Sidi Bel Abbes 22000, Algeria
Zagane Mohammed El Sallah, Moulgada Abdelmadjid: Department of Mechanical Engineering, Laboratory Mechanics Physics of Materials (LMPM), University of Sidi Bel Abbes, BP 89, City Ben M'hidi, Sidi Bel Abbes 22000, Algeria; Department of Mechanical Engineering, University of Ibn Khaldoun, Tiaret, BP 78 Zaaroura Street, Tiaret 14000, Algeria
Ait Kaci Djafar: Department of Mechanical Engineering, University of Ibn Khaldoun, Tiaret, BP 78 Zaaroura Street, Tiaret 14000, Algeria; Department of Mechanical Engineering, University of Sidi Bel Abbes, BP 89, City Ben M'hidi, Sidi Bel Abbes 22000, Algeria
Zahi Rachid: Department of Mechanical Engineering, University of Relizane, Relizane BP 48000, Algeria
Cherfi Mohamed: Department of Mechanical Engineering, University of Ibn Khaldoun, Tiaret, BP 78 Zaaroura Street, Tiaret 14000, Algeria; Department of Mechanical Engineering, University of Sidi Bel Abbes, BP 89, City Ben M'hidi, Sidi Bel Abbes 22000, Algeria
Abstract
Pocket foundations are usually used under precast RC columns of steel or RC flyovers and industrial halls. Pocket foundations is a specific type of foundation in which, apart from standard calculations concerning the fulfilment of the limit states in the base of the footing, the problems related to the appropriate design of its walls in the pocket are also important. The aim of the article is, therefore, to draw attention to the specificity of pocket foundation design-which are part of the structural systems in the hall buildings-and to present the main problems that may arise during their construction at individual stages, including guidelines for checking the correctness of the conducted assembly works. The following article describes the main requirements for the construction of pocket foundations with particular attention to the type of surface present inside the pocket. The main problems related to the pocket foundations construction are also presented and the methodology of assembling the precast columns in the footings is described. In the manuscript, it was also discussed how to check and control the correctness of the skeleton installation works in hall buildings in order to prevent too large deviations in the assembled structure.
Key Words
assembly works; hall building, monolithic concrete; pocket foundation; prefabricated column; structural system
Address
Grzegorz Ludwik Golewski: Department of Structural Engineering, Faculty of Civil Engineering and Architecture, Lublin University of Technology, Nadbystrzycka 40 Street, 20-618, Lublin, Poland
