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CONTENTS
Volume 11, Number 4, December 2024
 

Abstract
In this work, it would be very interesting to study the post-buckling response of FG beams with relatively simple boundary conditions, i.e., simply supported. The material properties of the beams are considered to vary continuously in the thickness direction according to the power-law form. The formulations used are based on the classical beam theory (CBT), and two higher order theories, such as, the hyperbolic shear deformation theory of beams (HSDBT) and the Aydogdu shear deformation theory (ASDBT). On the one hand, in this context, we examine the effects of two parameters, such as the slenderness ratio and material variations presented by the power index on the critical buckling load via the two formulations of beam theories. The results in the tables can be useful and can be considered as a reference with which other researchers can verify the accuracy of their results.

Key Words
ASDBT; beams, functionally graded materials; HSDBT; postbuckling CBT

Address
Mokhtar Bouazza: Department of Civil Engineering, University Tahri Mohammed of Bechar, Bechar 08000, Algeria; Laboratory of Materials and Hydrology (LMH), University of Sidi Bel Abbes, Sidi Bel Abbes 2200, Algeria
Khaled Amara: Engineering and Sustainable Development Laboratory, University of Ain Temouchent, Ain Temouchent 46000, Algeria; Department of Civil Engineering, University of Ain Temouchent, Ain Temouchent 46000, Algeria
Mohamed Zidour: Laboratory of Geomatics and Sustainable Development, University of Tiaret, BP 78 Zaaroura, 14000 Tiaret, Algeria; Department of Civil Engineering, University of Tiaret, BP 78 Zaaroura, 14000 Tiaret, Algeria

Abstract
Various components of mechanisms and devices that are extensively used in a variety of aerospace and aeronautical applications frequently perform different kinds of movement with acceleration. According to D'Alembert's principle, the acceleration induces forces of inertia that have to be taken into account when analyzing various problems in the area of strength, fracture, stability, durability, reliability, etc. of components of load-bearing engineering structures, machines, mechanisms and devices. Having in mind that functionally graded materials are widely applied for manufacturing of high performance structures in modern aerospace industry, analyzing fracture behaviour of functionally graded structural members represents a problem of the present day. The goal of this paper is to analyze longitudinal fracture in functionally graded rods which perform non-uniform rotational movement around a pinned support. Non-linear viscoelastic rods that are functionally graded along the thickness and length are considered. The problem of determination of the strain energy release rate (SERR) in rods with a longitudinal crack under the action of distributed forces of inertia induced by the normal and tangential acceleration is treated generally (in essence, this is a dynamic problem). The distribution of the forces of inertia in the rod is analyzed. An application of the general approach for solving a particular problem is presented. The solution is confirmed by the integral J. The influence of various parameters of the model is studied. For instance, the influence of the ratio of the values of material parameters on the upper and lower surface of the rotating beam on the SERR is studied in detail. It is found that the SERR is very sensitive with respect to these ratios. A practical application of the solution for determining the boundary value of the parameter involved in the rotation law and the boundary crack length is presented.

Key Words
forces of inertia; functionally graded rod; longitudinal fracture; non-uniform rotational movement; viscoelastic behaviour

Address
Victor I. Rizov: Department of Technical Mechanics, University of Architecture, Civil Engineering and Geodesy,
1 Chr. Smirnensky Blvd., 1046, Sofia, Bulgaria

Abstract
This study aims to develop a numerical simulation model that investigates the load response of the low velocity impact for curved plates with different layup configurations using unidirectional carbon fiber-reinforced polymer (CFRP). At first, the commercial explicit finite element code LS-DYNA is used to develop the numerical simulation model to validate the experimental finding of a published work. A 2D modeling approach with a single shell element is adopted. The plies thickness and fiber orientations are defined using PART_COMPOSITE. The elasto-plastic composite material model MAT54, based on the failure criteria, is used to define the unidirectional composite material, while MAT20 is used to define the impactor material as a rigid body. The numerical simulation results show a strong agreement with the experimental results in terms of absorbed energy, impact force, and deflection plots. Consequently, the developed model is used to study the impact response and resistance of different curved plates (R0 (Flate), R500, R750, and R1500), and different layup configurations (Unidirectional (UD), Cross-Ply (CP), Quasi-Isotropic (QI), Linear bio-inspired Helicoidal (LH), and nonlinear bio-inspired Fibonacci-Helicoidal (FH)). The designed CFRP plate consist of 32-plies with overall dimensions of 300x150x3.6 mm. The CFRP plate is impacted by a hemispherical steel impactor of 25.4 mm diameter and 6.5 m/s speed to generate 40 J of impact energy. Each layup configuration is analyzed separately with different plate curvatures to discover the advantages of the curved plates over the flat plate in order to improve the low velocity impact resistance. The curved plates showed excellent behavior in reducing the impact force and deflection during the low velocity impact simulation for all layup configurations. It can be concluded from this study that the curved plates can be effective in enhancing structural impact resistance under low velocity impact conditions, while the following numerical simulation model can be effectively utilized for the purpose of designing and analyzing innovative bio-inspired composite structures in various configurations under different impact scenarios to study the load response.

Key Words
bio-inspired; composite structures; curved plates; low velocity impact; LS-DYNA

Address
Faisal K. Baakeel: Mechanical Engineering Department, Faculty of Engineering, King Abdulaziz University, Jeddah, Saudi Arabia
Mohamed A. Eltaher: Mechanical Engineering Department, Faculty of Engineering, King Abdulaziz University,
Jeddah, Saudi Arabia; Mechanical Design and Production Department, Faculty of Engineering, Zagazig University, Egypt
Muhammad A. Basha: Mechanical Engineering Department, Faculty of Engineering, King Abdulaziz University, Jeddah, Saudi Arabia

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