Wyniki wyszukiwania - Biblioteka Nauki

1

Analytical evaluation of the influence of adding rubber layers on free vibration of sandwich structure with presence of nano-reinforced composite skins

100%

Al-Shablle M. , Al-Waily M. , Njim E. K.

|

2022

|

tom Vol. 116, nr 2

57--70

EN

Purpose: Developing structural designs that offer superior vibration properties is still a major challenge, but they stay solid and lightweight simultaneously. Composite faces are frequently used in insulating constructions as an alternative to sheet metal roofs. Rubber overlays have been added to reduce waves' natural frequency and fade time. Design/methodology/approach: The mechanical properties and the natural frequency calculation of the materials that make up the composite structural panels designed for structural applications with the addition of rubber layers were studied in this study. Findings: The results showed the addition of rubber layers with SiO2 nanoparticles with a density of 1180 kg m3, and the optimal decrease (VF = 2.5%) is 38.5% in the natural frequency while at a density of 1210 kg/m3, it is 40.2% in the natural frequency. While the addition of rubber layers with Al2O3 nanoparticles shows a density of 1180 kg/m3, the optimum reduction (VF = 2.5%) is 41% in HF while at a density of 1210 kg/m3 36.8% in an NF 41% during a density of 1210 kg/m3 38.4%. Research limitations/implications: Certain hypotheses were used to apply Kirchhoff's theory to solve the mathematical model of the structure. Practical implications: The work was carried out on the faces of nanocomposites made of SiO2/epoxy and Al2O3/epoxy with different densities and polylactic acid core. The inclusion of nanoparticles as a percentage of the fraction size ranges from 0% to 2.50%. Originality/value: This study's results shed light on the fundamental behaviour of the components that make up the sandwich in the presence of rubber layers.

2

Analytical and numerical investigation of the free vibration of functionally graded materials sandwich beams

100%

Bakhy S. H. , Al-Waily M. , Al-Shammari M. A.

|

tom Vol. 110, nr 2

72--85

EN

Purpose: In this study, the free vibration analysis of functionally graded materials (FGMs) sandwich beams having different core metals and thicknesses is considered. The variation of material through the thickness of functionally graded beams follows the power-law distribution. The displacement field is based on the classical beam theory. The wide applications of functionally graded materials (FGMs) sandwich structures in automotive, marine construction, transportation, and aerospace industries have attracted much attention, because of its excellent bending rigidity, low specific weight, and distinguished vibration characteristics. Design/methodology/approach: A mathematical formulation for a sandwich beam comprised of FG core with two layers of ceramic and metal, while the face sheets are made of homogenous material has been derived based on the Euler–Bernoulli beam theory. Findings: The main objective of this work is to obtain the natural frequencies of the FG sandwich beam considering different parameters. Research limitations/implications: The important parameters are the gradient index, slenderness ratio, core metal type, and end support conditions. The finite element analysis (FEA), combined with commercial Ansys software 2021 R1, is used to verify the accuracy of the obtained analytical solution results. Practical implications: It was found that the natural frequency parameters, the mode shapes, and the dynamic response are considerably affected by the index of volume fraction, the ratio as well as face FGM core constituents. Finally, the beam thickness was dividing into frequent numbers of layers to examine the impact of many layers' effect on the obtained results. Originality/value: It is concluded, that the increase in the number of layers prompts an increment within the frequency parameter results' accuracy for the selected models. Numerical results are compared to those obtained from the analytical solution. It is found that the dimensionless fundamental frequency decreases as the material gradient index increases, and there is a good agreement between two solutions with a maximum error percentage of no more than 5%.

3

Analytical and numerical free vibration analysis of porous functionally graded materials (FGPMs) sandwich plate using Rayleigh-Ritz method

100%

Njim E. K. , Bakhy S. H. , Al-Waily M.

|

2021

|

tom Vol. 110, nr 1

27--41

EN

Purpose: This study introduces a new approximated analytical solution of the free vibration analysis to evaluate the natural frequencies of functionally graded rectangular sandwich plates with porosities. Design/methodology/approach: The kinematic relations are developed based on the classical plate theory (CPT), and the governing differential equation is derived by employing the Rayleigh-Ritz approximate method. The FGM plate is assumed made of an isotropic material that has an even distribution of porosities. The materials properties varying smoothly in the thickness direction only according to the power-law scheme. Findings: The influences of changing the gradient index, porosity distribution, boundary conditions, and geometrical properties on the free vibration characteristics of functionally graded sandwich plates are analysed. Research limitations/implications: A detailed numerical investigation is carried out using the finite element method with the help of ANSYS 2020 R2 software to validate the results of the proposed analytical solution. Originality/value: The results with different boundary conditions show the influence of porosity distribution on the free vibration characteristics of FG sandwich plates. The results indicated a good agreement between the approximated method such as the Rayleigh-Ritz and the finite element method with an error percentage of no more than 5%.

4

Hyperelastic modelling of rubber with multi-walled carbon nanotubes subjected to tensile loading

88%

Jweeg M. J. , Alazawi D. A. , Jebur Q. H. , Al-Waily M. , Yasin N. J.

|

tom Vol. 114, nr 2

69--85

EN

Purpose: This study thoroughly examined the application of inverse FE modelling and indentation tensile tests to identify nanotubes' rubber material properties. indentation tensile tests to identify nanotubes' rubber material properties. Design/methodology/approach: Carbon nanotubes with various percentages of multi-walled carbon nanotubes exposed to high tensile stress were used to enhance the mechanical qualities of N.R. rubber. Findings: In this work, carbon nanotubes have been added to natural rubber. By using a solvent casting technique, toluene was used to make nanocomposites. 0.2%, 0.4%, 0.6%, 0.8%, and 1%. In this article, rubber and multi-walled carbon nanotubes interact in practical ways. Mechanical features of carbon nanotubes in NR have been researched. The results will lead to rubber products with improved mechanical qualities compared to present nanocomposite rubber containing various percentages of multi-walled carbon nanotubes exposed to large tensile test loading. The relative fitness error for significant stresses is reasonable with a second or third-order deformation model in numerical results. Research limitations/implications: Non-linear finite element analysis is widely used to optimise complicated elastomeric components' design and reliability studies. However, accurate numerical results cannot be achieved without using rubber or rubber nanocomposite materials with reliable strain energy functions. Practical implications: The indentation tensile tests of rubber samples have been simulated and confirmed using a parametric FE model. An inverse materials parameter identification algorithm was used to calculate the hyperelastic material properties of rubber samples evaluated in uniaxial tensile. Using ABAQUS FE software, material parameters and force-displacement data may be automatically updated and extracted. Originality/value: The numerical data for the inverse method of material property prediction has been successfully established by developing simulation spaces for various material characteristics. The force-displacement curve can be represented using technical methods. The results demonstrate that the inverse FE modelling process might be simplified by using these curve fitting parameters and plot equations to build a mathematical link between curve coefficients and material properties. The first, second, and third-order deformation models were tested using FE simulations for the tensile test.