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CONTENTS
Volume 35, Number 6, June25 2020
 

Abstract
The homotopy perturbation method (HPM) to predict the pre- and post-buckling behaviour of simply supported steel beams with rectangular hollow section (RHS) is presented in this paper. The non-linear differential equations solved by HPM derive from a kinematics where large twist and cross-sections distortions are considered. The results (linear and non-linear paths) given by the present HPM are compared to those provided by the Newton–Raphson algorithm with arc length and by the commercial FEM code Abaqus. To investigate the effect of cross-sectional distortion of beams, some numerical examples are presented.

Key Words
post-buckling; homotopy; RHS; distortion; Newton–Raphson

Address
Noureddine Benmohammed, Noureddine Ziane and Sid Ahmed Meftah: Laboratoire des Structures et Matériaux Avancés dans le Génie Civil et Travaux Publics,
Université de Djillali Liabes, Sidi Bel Abbes, Algeria
Giuseppe Ruta: Department of Structural & Geotechnical Engineering, University \'La Sapienza\',
Rome, and National Group for Mathematical Physics, Italy



Abstract
The goal of this study is to investigate dynamic responses of laminated composite beams under a moving load with thermal effects. The governing equations of problem are derived by using the Lagrange procedure. The transverse-shear strain and rotary inertia are considered within the Timoshenko beam theory. The material properties of laminas are considered as the temperature dependent physical property. The differential equations of the problem are solved by the Ritz method. The solution step of dynamic problem, the Newmark average acceleration method is used in the time history. A compassion study is performed for accuracy of used formulations and method. In the numerical results, the effects of velocity of moving load, temperature values, the fiber orientation angles and the stacking sequence of laminas on the dynamic responses of the composite laminated beam are investigated.

Key Words
laminated composites; moving load problems; temperature effect; ritz method

Address
Şeref D. Akbaş: Department of Civil Engineering, Bursa Technical University, Yildirim Campus, Yildrim, Bursa 16330, Turkey

Abstract
This paper aims to investigate cyclic plasticity of a new type of high-performance austenitic stainless steel with both high strength and high ductility. The new stainless steel termed as QN1803 has high nitrogen and low nickel, which leads to reduction of cost ranging from 15% to 20%. Another virtue of the new material is its high initial yield strength and tensile strength. Its initial yield strength can be 40% to 50% higher than conventional stainless steel S30408. Elongation of QN1803 can also achieve approximately 50%, which is equivalent to the conventional one. QN1803 also has a corrosion resistance as good as that of S30408. In this paper, both experimental and numerical studies on the new material were conducted. Full-range true stress-true strain relationships under both monotonic and cyclic loading were obtained. A cyclic plasticity model based on the Chaboche model was developed, where a memory surface was newly added and the isotropic hardening rule was modified. A user-defined material subroutine was written, and the proposed cyclic plasticity model can well evaluate full-range hysteretic properties of the material under various loading histories.

Key Words
Chaboche model; memory surface; cyclic plasticity; high strength; stainless steel QN1803

Address
yi Zhou and Jiang-Yue Xie: Department of Structural Engineering, School of Civil Engineering and Architecture,
Changzhou Institute of Technology, 213000, China
Kim Eng Chouery, Jiang-Yue Xie and Liang-Jiu Jia: Department of Disaster Mitigation for Structures, College of Civil Engineering, Tongji University, Siping Road,
Tongji University, Shanghai, 200092, China


Abstract
In this article, the influence of fuzzified uncertain composite elastic properties on non-linear deformation behaviour of the composite structure is investigated under external mechanical loadings (uniform and sinusoidal distributed loading) including the different end boundaries. In this regard, the composite model has been derived considering the fuzzified elastic properties (through a triangular fuzzy function, a cut) and the large geometrical distortion (Green-Lagrange strain) in the framework of the higher-order mid-plane kinematics. The results are obtained using the fuzzified nonlinear finite element model via in-house developed computer code (MATLAB). Initially, the model accuracy has been established and explored later to show the dominating elastic parameter affect the deflection due to the inclusion of fuzzified properties by solving a set of new numerical examples.

Key Words
nonlinear bending; Green-Lagrange; laminated composite; fuzzy-FEM; Uncertain properties

Address
B.K. Patle: Department of Mechanical Engineering, CVR College of Engineering, Hyderabad, India
Chetan K. Hirwani: Department of Mechanical Engineering, National Institute of Technology Patna, Bihar, India
Subrata Kumar Panda, Pankaj V. Katariya and Hukum Chand Dewangan: Department of Mechanical Engineering, National Institute of Technology Rourkela, Odisha, India
Nitin Sharma: School of Mechanical Engineering, KIIT Bhubaneswar, Odisha, India

Abstract
In the context of classic conical shell formulation, nonlinear forced vibration analysis of truncated conical shells and annular plates made of multi-scale epoxy/CNT/fiberglass composites has been presented. The composite material is reinforced by carbon nanotube (CNT) and also fiberglass for which the material properties are defined according to a 3D Mori-Tanaka micromechanical scheme. By utilizing the Jacobi elliptic functions, the frequency-deflection curves of truncated conical shells and annular plates related to their forced vibrations have been derived. The main focus is to study the influences of CNT amount, fiberglass volume, open angle, fiber angle, truncated distance and force magnitude on forced vibrational behaviors of multi-scale truncated conical shells and annular plates.

Key Words
forced vibration; annular plate; conical shell; multi-scale composite; carbon nanotube; annular sector

Address
Seyed Sajad Mirjavadi and AMS Hamouda: Department of Mechanical and Industrial Engineering, Qatar University, P.O. Box 2713, Doha, Qatar
Masoud Forsat: Department of Civil and Architectural Engineering, Qatar University, Doha, Qatar
Mohammad Reza Barati: Fidar project Qaem Company, Darvazeh Dolat, Tehran, Iran

Abstract
Multi-Walled Carbon nanotubes (MWCNT) coupled with Silicone Rubber (SR) can represent applicable strain sensors with accessible materials, which result in good stretchability and great sensitivity. Employing these materials and given the fact that the combination of these two has been addressed in few studies, this study is trying to represent a low-cost, durable and stretchable strain sensor that can perform excellently in a high number of repeated cycles. Great stability was observed during the cyclic test after 2000 cycles. Ultrahigh sensitivity (GF>1227) along with good extensibility (e>120%) was observed while testing the sensor at different strain rates and the various number of cycles. Further investigation is dedicated to sensor performance in the detection of human body movements. Not only the sensor performance in detecting the small strains like the vibrations on the throat was tested, but also the larger strains as observed in extension/bending of the muscle joints like knee were monitored and recorded. Bearing in mind the applicability and low-cost features, this sensor may become promising in skin-mountable devices to detect the human body motions.

Key Words
multi-walled carbon nanotubes; silicone rubber; stretchablity; strain sensors; piezoresistive sensor; body movement monitoring

Address
Mohammadbagher Azizkhani, Javad Kadkhodapour, Ali Pourkamali Anaraki and Reza Kolahchi: Department of Mechanical Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran
Behzad Shirkavand Hadavand: Department of Resin and Additives, Institute of Color Science and Technology, Tehran, Iran
Reza Kolahchi: Institute of Research and Development, Duy Tan University, Da Nang 550000, Viet Nam

Abstract
The effect of Chitosan (CS), Carbon Nanotube (CNT) and hybrid (CS-CNT) fillers on the natural frequency of drilled composite plate is investigated by experimentally in this study. The numerical validation is also made with a program based on Finite Element Method (SolidWorks). Nine types filled and one neat composite plates are used in the study. The fillers ratios are 1% CS, 2% CS, 3% CS, 0.1% CNT, 0.2% CNT, 0.3% CNT, 1% CS+0.3% CNT, 2% CS+0.3% CNT, 3% CS+0.3% CNT. The specimens cut to certain sizes by water jet from the plates 400 mm x 400 mm in dimensions. Some of them are drilled in certain dimensions with drill. The natural frequency of each specimen is measured by the vibration test set up to determine the vibration characteristic. The vibration test set up includes an accelerometer, a current source power unit, a data acquisition card and a computer. A code is written in Matlab program for the signal processing. The study are investigated and discussed in four main points to understand the effect of the fillers on the natural frequency of the composite plate. These are the effect of fillers contents and amounts, orientation angles of fibers, holes numbers and holes sizes. As results, the natural frequency of the plate with 1% CS and 0.1% CNT hybrid filler is lower than those of the plates with other fillers ratios for 45 orientation angle. Besides, in the composite plate with 0 orientation angle, the natural frequency increases with increasing the filler ratio. Moreover, the natural frequency increases until a certain hole number and then it decreases. Furthermore, the natural frequency is not affected until a certain hole diameter but then it decreases.

Key Words
composite plate; carbon nanotube; chitosan; filler; vibration

Address
n Demir, Hasan Çallioglu and Metin Sayer: Pamukkale University, Mechatronics Engineering Department, Kinikli Campus, 20160, Denizli, Turkey
Furkan Kavla: Pamukkale University, Graduate School of Natural and Applied Sciences, Kinikli Campus, 20160, Denizli, Turkey

Abstract
Fatigue cracks of rib-to-deck (RD) joints have been frequently observed in the orthotropic steel decks (OSD) using conventional U-ribs (CU). Thickened edge U-rib (TEU) is proposed to enhance the fatigue strength of RD joints, and its effectiveness has been proved through fatigue tests. In-depth full-scale tests are further carried out to investigate both the fatigue strength and fractography of RD joints. Based on the test result, the mean fatigue strength of TEU specimens is 21% and 17% higher than that of CU specimens in terms of nominal and hot spot stress, respectively. Meanwhile, the development of fatigue cracks has been measured using the strain gauges installed along the welded joint. It is found that such the crack remains almost in semi-elliptical shape during the initiation and propagation. For the further application of TEUs, the design curve under the specific survival rate is required for the RD joints using TEUs. Since the fatigue strength of welded joints is highly scattered, the design curves derived by using the limited test data only are not reliable enough to be used as the reference. On this ground, an experiment-numerical hybrid approach is employed. Basing on the fatigue test, a probabilistic assessment model has been established to predict the fatigue strength of RD joints. In the model, the randomness in material properties, initial flaws and local geometries has been taken into consideration. The multiple-site initiation and coalescence of fatigue cracks are also considered to improve the accuracy. Validation of the model has been rigorously conducted using the test data. By extending the validated model, large-scale databases of fatigue life could be generated in a short period. Through the regression analysis on the generated database, design curves of the RD joint have been derived under the 95% survival rate. As the result, FAT 85 and FAT 110 curves with the power index m of 2.89 are recommended in the fatigue evaluation on the RD joint using TEUs in terms of nominal stress and hot spot stress respectively. Meanwhile, FAT 70 and FAT 90 curves with m of 2.92 are suggested in the evaluation on the RD joint using CUs in terms of nominal stress and hot spot stress, respectively.

Key Words
orthotropic steel deck; rib-to-deck joint; thickened edge U-rib; probabilistic fatigue assessment

Address
Junlin Heng: Department of Bridge Engineering, School of Civil Engineering, Sou thwest Jiaotong University, Chengdu, China;Department of Civil Engineering, School of Engineering, University of Birmingham, Birmingham, UK
Kaifeng Zheng and Jin Zhu: Department of Bridge Engineering, School of Civil Engineering, Sou thwest Jiaotong University, Chengdu, China
Sakdirat Kaewunruen and Charalampos Baniotopoulos: Department of Civil Engineering, School of Engineering, University of Birmingham, Birmingham, UK



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