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CONTENTS
Volume 3, Number 2, April 2018
 

Abstract
This paper presents the vibration and harmonic analysis of orthotropic laminated composite plate. The response of plate is determined using Finite Element Method. The eight noded shell 281 elements are used to analyze the orthotropic plates and results are obtained so that the right choice can be made in applications such as aircrafts, rockets, missiles, etc. to reduce the vibration amplitudes. Initially the model response for orthotropic plate and harmonic response for isotropic plate is verified with the available literature. The results are in good agreement with the available literature. Numerical results for the natural frequency and harmonic response amplitude are presented. Effects of boundary conditions, thickness to width ratio and number of layers on natural frequency and harmonic response of the orthographic plates are also investigated. The natural frequency, mode shape and harmonic analysis of laminated composite plate has been determined using finite element package ANSYS.

Key Words
finite element method; orthotropic plate; free vibration; harmonic response

Address
Manoj Narwariya and Achintya Choudhury: Department of Mechanical Engineering, Sir Padampat Singhania University Bhatewar Udaipur 313 601, India
Avadesh K. Sharma: Rajkiya Engineering College, Mainpuri, India


Abstract
The paper discusses numerical analysis of tensile notched specimens with the use of Gurson – Tvergaard – Needleman (GTN) material model. The analysis concerned S235JR and S355J2G3 steel grades, subjected to medium stress state triaxiality ratio, amounting 0.739. A complete procedure for FEM model preparation was described, paying special attention to the issue of determining material constants in the GTN model. An example of critical void volume fraction (fc) experimental determination procedure was presented. Finally, the results of numerical analyses were discussed, indicating the differences between steel grades under investigation.

Key Words
steel; static tensile tests; Gurson–Tvergaard–Needleman model; determination of model parameters; numerical simulation

Address
Pawel G. Kossakowski and Wiktor Wciślik: Department of Strength of Materials and Concrete Structures, Kielce University of Technology,
Al. Tysiąclecia Państwa Polskiego 7, 25-314 Kielce, Poland


Abstract
Cementitious composites are multiphase heterogeneous materials with distinct dissimilarity in strength under compression and tension (high under compression and very low under tension). At macro scale, the phenomenon can be well-explained as the material contains physical heterogeneity and pores. But, it is interesting to note that this dissimilarity initiates at molecular level where there is no heterogeneity. In this regard, molecular dynamics based computational investigations are carried out on cement clinkers and calcium silicate hydrate (C-S-H) under tension and compression to trace out the origin of dissimilarity. In the study, effect of strain rate, size of computational volume and presence of un-structured atoms on the obtained response is also investigated. It is identified that certain type of molecular interactions and the molecular structural parameters are responsible for causing the dissimilarity in behavior. Hence, the judiciously modified or tailored molecular structure would not only be able to reduce the extent of dissimilarity, it would also be capable of incorporating the desired properties in heterogeneous composites. The findings of this study would facilitate to take step to scientifically alter the structure of cementitious composites to attain the desired mechanical properties.

Key Words
Molecular dynamics; C-S-H; cement clinkers; mechanical properties

Address
B.S. Sindu and Saptarshi Sasma: Academy of Scientific and Innovative Research, India;
CSIR-Structural Engineering Research Centre, Taramani, Chennai-600113, India
Aleena Alex : Academy of Scientific and Innovative Research, India



Abstract
In this article, the static behavior of non-prismatic sandwich beams composed of functionally graded (FG) materials is investigated for the first time. Two types of beams in which the variation of elastic modulus follows a power-law form are studied. The principle of minimum total potential energy is applied along with the Ritz method to derive and solve the governing equations. Considering conventional boundary conditions, Chebyshev polynomials of the first kind are used as auxiliary shape functions. The formulation is developed within the framework of well-known Timoshenko and Reddy beam theories (TBT, RBT). Since the beams are simultaneously tapered and functionally graded, bending and shear stress pushover curves are presented to get a profound insight into the variation of stresses along the beam. The proposed formulations and solution scheme are verified through benchmark problems. In this context, excellent agreement is observed. Numerical results are included considering beams with various cross sectional types to inspect the effects of taper ratio and gradient index on deflections and stresses. It is observed that the boundary conditions, taper ratio, gradient index value and core to the thickness ratio significantly influence the stress and deflection responses.

Key Words
static analysis; Ritz method; tapered sandwich beam; functionally graded material; Chebyshev polynomials

Address
M. Rezaiee-Pajand, Amir R. Masoodi and M. Mokhtari: Department of Civil Engineering, Ferdowsi University of Mashhad, Iran

Abstract
Establishment of an efficient routing technique in multiple-input-multiple-output (MIMO) based mobile ad hoc network (MANET) is a new challenge in wireless communication system to communicate in a complex terrain where permanent infrastructure network implementation is not possible. Due to limited power of mobile nodes, a minimum power consumed routing (MPCR) algorithm is developed which is an integration of cooperative transmission process. This algorithm select relay node and support short distance communication. The performance analysis of proposed routing algorithm increased signal to noise interference ratio (SNIR) resulting effect of cooperative transmission. Finally performance analysis of the proposed algorithm is verified with simulated result.

Key Words
MIMO; MANET; propagation loss; signal strength; routing

Address
Swati Chowdhuri: ECE Department, Techno India Batanagar B7-360/New, Ward No.30, Putkhali,
Maheshtala Kolkata - 700141, West Bengal, India
Pranab Banerjee and Sheli Sinha Chaudhuri: ETCE Department, Jadavpur University, Kolkata-700032, India


Abstract
Decrease in availability of suitable subbase and base course materials for highway construction leads to a search for economic method of converting locally available troublesome soil to suitable one for highway construction. Present study insights on evaluation of benefits of stabilization of subgrade soils in term of extension in service life (TBR) and layer thickness reduction (LTR). Laboratory investigation consisting of Atterberg limit, Compaction, California Bearing Ratio, unconfined compressive strength and triaxial shear strength tests were carried out on two types of soil for varying percentages of stabilizers. Vertical compressive strains at the top of unstabilized and stabilized subgrade soils were found out by elasto-plastic finite element analysis using commercial software ANSYS. The values of vertical compressive strains at the top of unstabilized and stabilized subgrade, were further used to estimate layer thickness reduction or extension in service life of the pavement due to stabilization. Finite element modeling of the flexible pavement layered structure provides modern technology and sophisticated characterization of materials that can be accommodated in the analysis and enhances the reliability for the prediction of pavement response for improved design methodology. If the pavement section is kept same for unstabilized and stabilized subgrade soils, pavement resting on lime, fly ash and fiber stabilized subgrade soil B will have service life 2.84, 1.84 and 1.67 times than that of unstabilized pavement respectively. The flexible pavement resting on stabilized subgrade is beneficial in reducing the construction material. Actual savings would depend on the option exercised by the designer for reducing the thickness of an individual layer.

Key Words
stabilization; finite element analysis; layer thickness reduction; traffic benefit ratio; vertical compressive strain

Address
Prashant P. Nagrale: Sardar Patel College of Engineering, Andheri, Mumbai, India, 400058
Atulya Patil: Datta Meghe College of Engineering, Airoli, Navi Mumbai, India, 400708


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