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Volume 11, Number 1, March 2022

In this paper, the nonlocal integral Timoshenko beam model is employed to study the free vibration characteristics of singled walled carbon nanotubes (SWCNTs) including the thermal effect . Based on the nonlocal continuum theory, the governing equations of motion are formulated by considering thermal effect. The influences of small scale parameter, the chirality of SWCNTs, the vibrational mode number, the aspect ratio of SWCNTs and temperature changes on the thermal vibration properties of single-walled nanotubes are examined and discussed. Results indicate significant dependence of natural frequencies on the nonlocal parameter, the temperature change, the aspect ratio and the chirality of SWCNTs. This work should be useful reference for the application and the design of nanoelectronics and nanoelectromechanical devices that make use of the thermal vibration properties of SWCNTs.

Key Words
nonlocal continuum theory; nonlocal integral Timoshenko beam model; singled walled carbon nanotubes (SWCNTs); small-scale effect; thermal effect; vibration characteristics

(1) Mohamed Liani, Noureddine Moulay:
Departement de physique, Faculte des Sciences Exactes, Université Djilali Liabès de Sidi Bel Abbès 22000, Algérie;
(2) Fouad Bourada, Farouk Yahia Addou, Mohamed Bourada, Abdelouahed Tounsi:
Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
(3) Fouad Bourada:
Département des Sciences et de la Technologie, Université de Tissemsilt, BP 38004 Ben Hamouda, Algérie;
(4) Abdelouahed Tounsi:
YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea;
(5) Muzamal Hussain:
Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan.

This work deals with the two-dimensional deformation in a homogeneous isotropic nonlocal magnetothermoelastic solid with two temperatures under the effects of inclined load at different inclinations. The mathematical model has been formulated by subjecting the bounding surface to a concentrated load. The Laplace and Fourier transform techniques have been used for obtaining the solution to the problem in transformed domain. The expressions for nonlocal thermal stresses, displacements and temperature are obtained in the physical domain using a numerical inversion technique. The effects of nonlocal parameter, rotation and inclined load in the physical domain are depicted and illustrated graphically. The results obtained in this paper can be useful for the people who are working in the field of nonlocal thermoelasticity, nonlocal material science, physicists and new material designers. It is found that there is a significant difference due to presence and absence of nonlocal parameter.

Key Words
concentrated load; Eringen model of nonlocal theories; inclined load; magnetic field; nonlocal theory of thermoelasticityl; nonlocality; rotation; thermoelasticity; two temperatures

(1) Parveen Lata:
Department of Basic and Applied Sciences, Punjabi University Patiala, India;
(2) Sukhveer Singh:
Punjabi University APS Neighbourhood Campus, Dehla Seehan, India.

This paper is focused on delamination analysis of a multilayered inhomogeneous viscoelastic beam subjected to linear creep under constant applied stress. The viscoelastic model that is used to treat the creep consists of consecutively connected units. Each unit consists of one spring and two dashpots. The number of units in the model is arbitrary. The modulus of elasticity of the spring in each unit changes with time. Besides, the modulii of elasticity and the coefficients of viscosity change continuously along the thickness, width and length in each layer since the material is continuously inhomogeneous in each layer of the beam. A time-dependent solution to the strain energy release rate for the delamination is derived. A time-dependent solution to the J-integral is derived too. A parametric analysis of the strain energy release rate is carried-out by applying the solution derived. The influence of various factors such as creep, material inhomogeneity, the change of the modulii of elasticity with time and the number of units in the viscoelastic model on the strain energy release rate are clarified.

Key Words
analytical study; creep; delamination; inhomogeneous material; multilayered beam

Department of Technical Mechanics, University of Architecture, Civil Engineering and Geodesy, 1 Chr. Smirnensky blvd., 1046 - Sofia, Bulgaria.

In the construction industry, thin-walled frame elements with very slender open cross-sections and low torsional stiffness are often subjected to a complex loading condition where axial, bending, shear and torsional stresses are present simultaneously. Hence, these often fail in instability even before the yield capacity is reached. One of the most common instability conditions associated with thin-walled structures is Lateral Torsional Buckling (LTB). In this study, a first order Generalized Beam Theory (GBT) formulation and numerical analysis of cold-formed steel lipped channel beams (C80×40×10×1, C90×40×10×1, C100×40×10×1, C80×40×10×1.6, C90×40×10×1.6 and C100×40×10×1.6) subjected to uniform moment is carried out to predict pure Lateral Torsional Buckling (LTB). These results are compared with the Finite Element Analysis of the beams modelled with shell elements using ABAQUS and analytical results based on Euler

Key Words
finite element analysis; generalized beam theory; instability failure; lateral torsional buckling; light gauge steel; lipped channel beams

Department of Civil Engineering, Dr. B R Ambedkar National Institute of Technology, Jalandhar, Punjab-144011, India.

In this paper, functionality of soft computing algorithms such as Group method of data handling (GMDH), Random forest (RF), Random tree (RT), Linear regression (LR), M5P, and artificial neural network (ANN) have been looked out to predict the compressive strength of concrete mixed with marble powder. Assessment of result suggests that, the overall performance of ANN based model gives preferable results over the different applied algorithms for the estimate of compressive strength of concrete. The results of coefficient of correlation were maximum in ANN model (0.9139) accompanied through RT with coefficient of correlation (CC) value 0.8241 and minimum root mean square error (RMSE) value of ANN (4.5611) followed by RT with RMSE (5.4246). Similarly, other evaluating parameters like, Willmott's index and Nash-sutcliffe coefficient value of ANN was 0.9458 and 0.7502 followed by RT model (0.8763 and 0.6628). The end result showed that, for both subsets i.e., training and testing subset, ANN has the potential to estimate the compressive strength of concrete. Also, the results of sensitivity suggest that the water-cement ratio has a massive impact in estimating the compressive strength of concrete with marble powder with ANN based model in evaluation with the different parameters for this data set.

Key Words
artificial neural network; coefficient of correlation; compressive strength; marble powder; Nash-Sutcliffe coefficient; root mean square error; Willmott's index

(1) Nitisha Sharma, Ankita Upadhya, Mohindra S. Thakur:
Department of Civil Engineering, Shoolini University, Solan, Himachal Pradesh, 173229, India;
(2) Parveen Sihag:
Department of Civil Engineering, Chandigarh University, Ajitgarh, Punjab, 140413, India.

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