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CONTENTS
Volume 76, Number 5, December10 2020
 

Abstract
The present work addresses the surface integrity and chip morphology in finish hard turning of AISI D3 steel under nanofluid assisted minimum quantity lubrication (NFMQL) condition. The surface integrity aspects include microhardness, residual stress, white layer formation, machined surface morphology, and surface roughness. This experimental investigation aims to explore the feasibility of low-cost multilayer (TiCN/Al2O3/TiN) coated carbide tool in hard machining applications and to assess the propitious role of minimum quantity lubrication using graphene nanoparticles enriched eco-friendly radiator coolant based nano-cutting fluid for machinability improvement of hardened steel. Combined approach of central composite design (CCD) - analysis of variance (ANOVA), desirability function analysis, and response surface methodology (RSM) have been subsequently employed for experimental investigation, predictive modelling and optimization of surface roughness. With a motivational philosophy of “Go Green-Think Green-Act Green”, the work also deals with economic analysis, and sustainability assessment under environmental-friendly NFMQL condition. Results showed that machining with nanofluid-MQL provided an effective cooling-lubrication strategy, safer and cleaner production, environmental friendliness and assisted to improve sustainability.

Key Words
hard turning; AISI D3 steel; NFMQL; surface integrity; chip morphology; economic analysis; sustainability assessment

Address
Department of Production Engineering, Veer Surendra Sai University of Technology, Burla 768018, India

Abstract
This paper’s objective is to investigate the effect of gravity on a micropolar thermoelastic medium with voids. The problem is assessed according to the three-phase-lag model. An analysis of the resulting non-dimensional displacement, temperature variation, and internal stress of the study material is carried out and presented graphically. The non-dimensional displacement, temperature, micro-rotation, the change in the volume fraction field and stress of the material are obtained and illustrated graphically. Comparisons are made with the results predicted by different theories for different values of gravity, the phase-lag of the heat flux and the phase-lag of the temperature gradient. The numerical results reveal that gravity and relaxation times have a significant influence on the distribution of the field quantities. Some notable insights of interest are deduced from the investigation.

Key Words
thermoelasticity; micropolar; voids. Green-Naghdi theory; gravity; three-phase-lag

Address
Amnah M. Alharbi and Al-Anoud M. Kh. Al-Autabi: Department of Mathematics, Faculty of Science, Taif University, P.O. Box 11099, Taif 21944, Taif, Saudi Arabia
Mohamed I.A. Othman: Department of Mathematics, Faculty of Science, Zagazig University, P.O. Box 44519, Zagazig, Egypt

Abstract
Ultrasonic waves provide a non-destructive and sensitive way to monitor the concrete hydration. However, limited works are reported to monitor the evolution of the mechanical parameter at early ages. In this study, modified piezoelectric aggregates are embedded inside a concrete beam to excite and receive primary waves. A hydration index, namely, the variation of ultrasonic waveform (VUW) is developed to characterize the variation of the transmitted waves during the hydration process. The recorded hydration indices are compared with the compressive strength measured by destructive test at different ages. The results show that the VUW is closer to the compressive strength than the other two traditional hydration indices, ultrasonic velocity and wave packet energy. The proposed VUW provides a simple and accurate way to monitor the concrete hydration at early ages.

Key Words
compressive strength; early age; hydration monitoring; piezoelectric aggregate; ultrasonic waveform; P-waves; wavelet packet analysis

Address
Li Wei, Maosen Cao and Ronghua Fu: School of Mechanics and Materials, Hohai University, Nanjing 210024, China
Zijian Wang: Key Laboratory of C&PC Structures, Ministry of Education, Southeast University, Nanjing 211189, China

Abstract
A state-space method is developed to investigate the time-dependent behaviors of an angle-ply cylindrical shell in cylindrical bending with surface-bonded piezoelectric layers. Both the interfacial diffusion and sliding are considered to describe the properties of the imperfect interfaces. Particularly, a matrix reduction technique is adopted to establish the transfer relations between the elastic and piezoelectric layers of the laminated shell. Very different from our previous paper, in which an approximate numerical technique, i.e. power series expansion method, is used to deal with the time-dependent problems, the exact solutions are derived in the present analysis based on the piezoelasticity equations without any assumptions. Numerical results are finally obtained and the effects of imperfect interfaces on the electro-mechanical responses of the laminated shell are discussed.

Key Words
laminated shell; interfacial imperfection; state-space formulation; matrix reduction technique; exact solution

Address
Faculty of Architectural, Civil Engineering and Environment, Ningbo University, Ningbo 315211, China

Abstract
Exhausting oil resources and increasing pollution around the world are forcing researchers to look for new, renewable, biodegradable materials to lead sustainable development. The use of fiber reinforced composites based on natural fibres has increasingly begun as prospective materials for various engineering applications in the automotive, rail, construction and aerospace industries. The natural fiber chosen to make the composite material is plant-based fibre, e.g. jute fibre, and hemp fibre. Thermosetting polymer based Epoxy (LY556) was utilized as matrix material and The composites were produced using hand lay-up technique. The fabricated composites were tested for acoustic testing, thermo-gravimetric analysis (TGA) and flammability testing to asses sound absorption, thermal decomposition and fire resistivity of the structures. Hemp fibre composites have shown improved thermal stability over Jute fibre composites. However, the fire resistance characteristics of jute fibre composites are better as compared to hemp fibre composites. The sound absorption coefficient of composites was found to enhance with the increase of frequency.

Key Words
sound absorption coefficients, natural fibres, thermal stability, TGA, flammability

Address
School of Mechanical Engineering, SASTRA Deemed University, Thanjavur, Tamilnadu 613402, India

Abstract
In current study, surface/interface effects for pull-in voltage and viscous fluid velocity effects on dimensionless natural frequency (DNF) of fluid-conveying piezoelectric nanosensor (FCPENS) subjected to direct electrostatic voltage DC with nonlinear excitation, harmonic force and also viscoelastic foundation (visco-pasternak medium and structural damping) are investigated using Gurtin–Murdoch surface/interface (GMSIT) theory. For this analysis, Hamilton’s principles, the assumed mode method combined with Lagrange–Euler’s are used for the governing equations and boundary conditions. The effects of surface/interface parameters of FCPENS such as Lame’s constants (λI,S, μI,S), residual stress (τ0I,S), piezoelectric constants (e31psk,e32psk) and mass density (ρI,S) are considered for analysis of dimensionless natural frequency respect to viscous fluid velocity ūf and pull-in voltage V̅DC.

Key Words
pull-in voltage; viscous fluid velocity; dimensionless natural frequency; piezoelectric nanosensor; Gurtin– Murdoch surface/interface theory; electrostatic force, harmonic excitation

Address
Department of Mechanical Engineering, Babol Noshirvani University of Technology, Shariati Street, Babol,
Mazandaran 47148-71167, Iran

Abstract
In the present work, an approach for the multiple time probabilistic characterization of the response of linear structural systems subjected to random non-Gaussian processes is presented. Its fundamental property is working directly on the multiple time probability density functions of the actions and of the response. This avoids of passing through the evaluation of the response statistical moments at multiple time or correlations, reducing the computational effort in a consistent measure. This approach is the extension to the multiple time case of a previously published dynamic Probability Transformation Method (PTM) working on a single evolution of the response statistics. The application to some simple examples has revealed the efficiency of the method, both in terms of computational effort and in terms of accuracy.

Key Words
stochastic analysis; evolutionary algorithm; simulation; dynamic analysis; parametric uncertainty

Address
Department of Engineering, University of Messina, Contrada Di Dio, 98166 Sant’Agata, Messina, Italy

Abstract
Generally, it is necessary to perform transient structural analysis in order to verify and improve the seismic performance of high-rise buildings and bridges against earthquake loads. In this paper, we propose the model order reduction (MOR) method using the Krylov vectors to perform seismic analysis for linear and elastic systems in an efficient way. We then compared the proposed method with the mode superposition method (MSM) by using the limited numbers of modal vectors (or eigenvectors) calculated from the modal analysis. In the calculation, the data of the El Centro earthquake in 1940 were adopted for the seismic loading in the transient analysis. The numerical accuracy and efficiency of the two methods were compared in detail in the case of a simplified high-rise building.

Key Words
model order reduction; seismic loading; Krylov subspace; mode superposition method; El Centro earthquake; transient analysis

Address
Department of Mechanical & Robotics Engineering, Andong National University, 1375 Gyeongdong-ro, Andong 36729, Korea

Abstract
The paper presents a study regarding rubber compressibility behavior. The objective is to analyze the effect of compression degree of rubber on its mechanical properties and propose a new methodology based on reverse engineering to predict compressibility degree based on uniaxial stretching test and Finite Element Analysis (FEA). In general, rubbers are considered to be almost incompressible and Poisson

Key Words
experimental investigation; finite element method (FEM); hyperelasticity; optimization; rubber

Address
Debora Francisco Lalo, Marcelo Greco: Graduate Program in Structural Engineering, Department of Structural Engineering, School of Engineering, Universidade
Federal de Minas Gerais, Belo Horizonte, Brazil
Matias Meroniuc: Fluid Mechanics Laboratory, Railway Engineering, National Technological University, Paris 532, Haedo, Buenos Aires, Argentina

Abstract
In this study, partially restrained beam-column moment joints in the weak-axis direction were examined using three large-scale specimens subject to cyclic loading in order to assess the seismic resistance of the joints of low-rise steel structures and to propose joint details based on the test results. The influence of different number of bolts on the moment joints was thoroughly investigated. It was found that the flexural capacity of the joints in the direction of weak axis was highly dependent on the number of high-tension bolts. In addition, even though the flexural connections subjected to cyclic loading was perfectly designed in accordance with current design codes, severe failure mode such as block shear failure could occur at beam flange. Therefore, to prevent excessive deformation at bolt holes under cyclic loading conditions, the holes in beam flange need to have larger bearing capacity than the required tensile force. In particular, if the thickness of the connecting plate is larger than that of the beam flange, the bearing capacity of the flange should be checked for structural safety.

Key Words
partially restrained beam-column weak-axis moment joints; cyclic loading tests; low-rise steel structures; high-tension bolts; bearing strength; block shear failure

Address
Woo-Young Lim: Department of Architectural Engineering, Wonkwang University, Iksan, Jeonbuk 54538, South Korea
Dongkeun Lee: Department of Civil Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
Young-Chan You: Department of Living and Built Environment Research, Korea Institute of Civil Engineering and Building Technology,Gyeonggi-Do 10223, South Korea


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