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Volume 15, Number 4, April 2023

The vibrational behavior of nanoelements is critical in determining how a nanostructure behaves. However, combining vibrational analysis with stability analysis allows for a more comprehensive knowledge of a structure's behavior. As a result, the goal of this research is to characterize the behavior of nonlocal nanocyndrical beams with uniform and nonuniform cross sections. The nonuniformity of the beams is determined by three distinct section functions, namely linear, convex, and exponential functions, with the length and mass of the beams being identical. For completely clamped, fully pinned, and cantilever boundary conditions, Eringen's nonlocal theory is combined with the Timoshenko beam model. The extended differential quadrature technique was used to solve the governing equations in this research. In contrast to the other boundary conditions, the findings of this research reveal that the nonlocal impact has the opposite effect on the frequency of the uniform cantilever nanobeam. Furthermore, since the mass of the materials employed in these nanobeams is designed to remain the same, the findings may be utilized to help improve the frequency and buckling stress of a resonator without requiring additional material, which is a cost-effective benefit.

Key Words
cross-section effect; dynamic analysis; optimization; stability analysis; truncated conical tubes

(1) Qiuyang Cheng:
School of Civil, Architecture and Environment, Hubei University of Technology, Wuhan 430068, Hubei, China;
(2) H. Elhosiny Ali:
Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha, Saudi Arabia;
(3) Ibrahim Albaijan:
Mechanical Engineering Department, College of Engineering at Al Kharj, Prince Sattam Bin Abdulaziz University, Al Kharj 11942, Saudi Arabia.

Anti-tank weapons are among the infantry weapons used by the armies of many countries. Anti-tank rockets and explosives such as TNT, generally used for armour piercing, are also frequently used in terrorist attacks. These attacks damage the protection facilities built from reinforced concrete. Rockets or similar explosives' rapid speed and burst temperatures pierce reinforced concrete during strikes, resulting in casualties and damage to crucial strategic structures. This study aimed to devise an economic and applicable reinforced concrete plate that could absorb the impact of anti-tank rockets and Trinitrotoluene (TNT) type explosives. Therefore, 5 different samples, produced from C50 reinforced concrete and 150 × 150 cm in size, were formed by combining plates of different numbers and thicknesses. Also, a sample, which was a single thick plate, was prepared. In destructive testing, Rocket Propelled Grenade (RPG-7) was used as the anti-tank rocket launcher. As a result of this study, the impact damage was reduced with hollow concrete plate geometries, and recommendations were developed for complete prevention.

Key Words
anti-tank; bomb; concrete; explosion; impact; Rpg-7; shape charge; TNT

(1) Berivan Yilmazer Polat:
Department of Architecture, Faculty of Fine Arts, Design and Architecture, Munzur University, 62100, Turkey;
(2) Sedat Savaş:
Department of Civil Engineering, Faculty of Engineering, Firat University, 23000, Turkey;
(3) Alper Polat:
Department of Civil Engineering, Faculty of Engineering, Munzur University, 62100, Turkey.

The unsteady mixed convection Casson type MHD nanofluid flow in the stagnation point with motile microorganism around a spinning sphere is investigated. Time dependent flow dynamics is considered. Similarity transformations have been employed to transfer the governing partial differential structure into ordinary differential structure. The impact of distinct parameters is examined via tables and graphs. The impact of rotational parameter (spin) on profiles of velocity profiles, temperature and concentration is revealed for unsteady mixed convection Casson type MHD nanofluid flow. It is observed that it is clear that rotational parameter has a great effect on non-dimensional primary velocity component but rotational parameter has a slight impact on non-dimensional secondary velocity component. The validity of the current investigation is authorized through comparing the existing outcomes with previous published literature.

Key Words
casson type MHD nanofluid; non-dimensional secondary velocity component; unsteady mixed convection; velocity profiles

(1) Mohamed A. Khadimallah:
Department of Civil Engineering, College of Engineering in Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj, 11942, Saudi Arabia;
(2) Imene Harbaoui:
Laboratory of Applied Mechanics and Engineering LR-MAI, University Tunis El Manar- -ENIT BP37- Le belvedere, 1002, Tunisia;
(3) Sofiene Helaili:
Carthage University, Tunisia Polytechnic School, LASMAP (LR03ES06), La Marsa, Tunisia;
(4) Sofiene Helaili:
Carthage University, ISTEUB, Tunis, Tunisia;
(5) Abdelhakim Benslimane:
Laboratoire de Mécanique Matériaux et Énergétique (L2ME), Département Génie Mécanique, Faculté de Technologie, Université de Bejaia, 06000 Bejaia, Algérie;
(6) Humaira Sharif, Muzamal Hussain, Muhammad Nawaz Naeem:
Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan;
(7) Mohamed R. Ali:
Faculty of Engineering and Technology, Future University in Egypt New Cairo 11835, Egypt;
(8) Mohamed R. Ali:
Basic Engineering Science Department, Benha Faculty of Engineering, Benha University, Benha, Egypt;
(9) Aqib Majeed:
Department of Mathematics, The University of Faisalabad, Sargodha Road, University Town Faisalabad, 38000, Pakistan;
(10) Abdelouahed Tounsi:
YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea;
(11) Abdelouahed Tounsi:
Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia.

In this paper, an experimental investigation is carried out to assess the inherent self-compacting properties of geopolymer mortar and its impact on flexural strength of thin-walled ferro-geopolymer box beam. The inherent self-compacting properties of the optimal mix of normal geopolymer mortar was studied and compared with self-compacting cement mortar. To assess the flexural strength of box beams, a total of 3 box beams of size 1500 mm × 200 mm × 150 mm consisting of one ferrocement box beam having a wall thickness of 40 mm utilizing self-compacting cement mortar and two ferro-geopolymer box beams with geopolymer mortar by varying the wall thickness between 40 mm and 50 mm were moulded. The ferro-cement box beam was cured in water and ferro-geopolymer box beams were cured in heat chamber at 75°C - 80°C for 24 hours. After curing, the specimens are subjected to flexural testing by applying load at one-third points. The result shows that the ultimate load carrying capacity of ferro-geopolymer and ferro-cement box beams are almost equal. In addition, the stiffness of the ferrogeoploymer box beam is reduced by 18.50% when compared to ferro-cement box beam. Simultaneously, the ductility index and energy absorption capacity are increased by 88.24% and 30.15%, respectively. It is also observed that the load carrying capacity and stiffness of ferro-geopolymer box beams decreases when the wall thickness is increased. At the same time, the ductility and energy absorption capacity increased by 17.50% and 8.25%, respectively. Moreover, all of the examined beams displayed a shear failure pattern.

Key Words
box beam; ferro-cement; ferro-geopolymer; flexural behavior; self-compacting mortar

(1) Dharmar Sakkarai:
Department of Civil Engineering, Ramco Institute of Technology, Rajapalayam, Tamilnadu, India;
(2) Nagan Soundarapandian:
Department of Civil Engineering, Thiagarajar College of Engineering, Madurai, Tamilnadu, India.

In the present study, we aim to utilize the numerical solution frequency results of functionally graded beam under thermal and dynamic loadings to train and test an artificial neural network. In this regard, shear deformable functionally-graded beam structure is considered for obtaining the natural frequency in different conditions of boundary and material grading indices. In this regard, both analytical and numerical solutions based on Navier's approach and differential quadrature method are presented to obtain effects of different parameters on the natural frequency of the structure. Further, the numerical results are utilized to train an artificial neural network (ANN) using AdaGrad optimization algorithm. Finally, the results of the ANN and other solution procedure are presented and comprehensive parametric study is presented to observe effects of geometrical, material and boundary conditions of the free oscillation frequency of the functionally graded beam structure.

Key Words
AdaDelta, vibration; atificial intelligence (AI); functionally graded beams; numerical analysis; optimizations

(1) Yong Cao, Wei Qi:
School of Rail Transit, Chengdu Vocational & Technical College of Industry, Chengdu 610200, Sichuan, China;
(2) Ruizhe Qiu:
School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, China.

Hockey games attracts many fans around the world. This game requires a specific type of ball and a stick for controlling the motion and trace of the ball. This control of motion involves hitting the ball which is a direct intensive dynamic loading. The impact load transferred directly to the hand of the player and in the professional player may cause long term medical problems. Therefore, dynamic motion of the stick should be understood. In the current study, we analyze the dynamic motion of a hockey stick under impact loading from a hockey ball. In doing so, the stick geometry is simplified as a beam structure and quasi-2D relations of displacement is applied along with classical linear elasticity theory for isotropic materials. The governing equations and natural boundary condition are extracted using Hamilton's principle. The final equations in terms of displacement components are solved using Galerkin's numerical method. The results are presented using indentation and contact force values for variations of different parameters.

Key Words
dynamics; Hamilton's principle; hockey stick; impact loading; various boundary conditions

Physical Education Institute, Institutes of Hulunbuir, Hulunbuir 021008, Inner Mongolia, China.

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