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Open access

Sandhyarani Bandari, Anand Rao Jakkula and Malla Reddy Perati

Abstract

In this paper, radial vibrations of an infinitely long fluid-filled transversely isotropic thick-walled hollow composite poroelastic cylinder are investigated in the framework of poroelasticity. The cylinder consists of two concentric cylindrical layers namely, core (inner one) and coating (outer one), each of which retains its own distinctive properties. A comparative study has been made between the thick-walled hollow composite poroelastic cylinder and that of fluid-filled one. Frequency is computed against the ratio between the thickness to inner radius of the composite cylinder at various anisotropic ratios. Another comparative study is made between the results of current case and that of isotropic case by making Young’s modulus and Poisson ratio values of isotropic and that of transversely isotropic in the transverse direction equal. Numerical results are depicted graphically and then discussed.

Open access

Harsh Sardana and Mahavir Singh

Abstract

The aim of this research paper is to reduce the drag of SUV by using a vortex generator and to calculate the pressure and turbulence profile across the vehicle. The Ahmed Reference Model is taken as a benchmark test. Computational fluid dynamics (CFD) simulation with and without vortex generator is performed at different velocities across the SUV similar to TATA Sumo. The performance of Vortex generator is analyzed at different velocities to obtain the particular velocity at which it will have the minimum value of drag. The end results are henceforth analyzed and a comparative study has been performed with the experimental data given by Gopal and Senthikumar on SUV. And finally it is found that the 10 % of drag reduction is achieved using vortex generator.

Open access

Al. Cheremensky

Abstract

Mechanical systems of Cosserat–Zhilin are introduced as the main object of rational (non-relativistic) mechanics on the base of new notions of vector calculus—sliders and screw measures (bi-measures).

Open access

Naman Jain

Abstract

This paper presents the mathematical model to solve the topological optimization problem. Effect of higher order element on the optimum topology of the isotropic structure has been studied by using 8-node elements which help in decreasing the numerical instability due to checkerboarding problem in the final topologies obtained. The algorithms are investigated on a number of two-dimensional benchmark problems. MATLAB code has been developed for different numerical two dimensional linear isotropic structure and SIMP approach is applied. Models are discretized using linear quadratic 4-node and 8-node elements and optimal criteria method is used in the numerical scheme. Checkerboarding instability in the final topology is greatly reduces when incorporated 8-node element instead of 4-node element which can be confirmed through comparing the final topologies of the structure.

Open access

A. Maleki and A. Ahmadi

Abstract

This paper presented a three dimensional analysis for the buckling behavior of an imperfect orthotropic thick cylindrical shells under pure axial or external pressure loading. Critical loads are computed for different imperfection parameter. Both ends of the shell have simply supported conditions. Governing differential equations are driven based on the second Piola–Kirchhoff stress tensor and are reduced to a homogenous linear system of equations using differential quadrature method. Buckling loads reduction factor is computed for different imperfection parameters and geometrical properties of orthotropic shells. The sensitivity is established through tables of buckling load reduction factors versus imperfection amplitude. It is shown that imperfections have higher effects on the buckling load of thin shells than thick ones. Results show that the presented method is very accurate and can capture the various geometrical imperfections observed during the manufacturing process or transportation.

Open access

Victor Rizov

Abstract

This paper reports an analytical study of delamination fracture in the Crack-Lap Shear (CLS) multilayered beam configuration with taking into account the material non-linearity. A delamination crack was located arbitrary along the beam height. It was assumed that the CLS mechanical response can be described by using a power-law stress-strain relation. It should be mentioned that each layer may have different material constants in the stress-strain relation. Besides, the thickness of each layer may be different. The classical beam theory was applied in the present study. The non-linear fracture behaviour was analyzed by the J-integral. Analytical solutions of the J-integral were obtained for homogeneous as well as for multilayered CLS beams. In order to verify the solutions obtained, analyses of the strain energy release rate were developed with considering material non-linearity. Material properties and crack location effects on the non-linear fracture behaviour were investigated. The analysis revealed that the J-integral value increases when the material non-linearity is taken into account. It was found also that the J-integral value decreases with increasing the lower crack arm thickness. The approach developed here is very convenient for parametric fracture analyses. The solutions derived can be used for optimization of the CLS multilayered beams with respect to their fracture performance.

Open access

F. Ebru Yildiz

Abstract

Burdur Lake is one of the largest lakes of Turkey consisting of about 23 700 ha. Unfortunately, Burdur Lake area and the lake depth decrease each year. Additionally, the salinity increased twice in 30 years because of the aridity. Burdur Municipality Drinking Water Pipeline had been constructed under Burdur Lake in 2002. Groundwater drained from deep wells was flowed to Burdur city under Burdur Lake. Burdur drinking water pipe line under Burdur Lake was broken to pieces during the storms in 2008, 2010 and 2013.

In this study, the stability analyses of Burdur Drinking Water Underlake Pipeline system were made for 2002-2008, 2008-2010 and 2010-2013 time periods by using the techniques of wave mechanics. Stability analysis was also made for the pipeline in the ditch with the gabions as a projection. Horizontal and vertical wave forces, weights of the cement bags and marble filled gabions were used at the calculations of wave mechanics. Soil mechanics parameters of the Burdur Lake and water hammer effect of the drinking water in the pipe line were also investigated in the content of this study.

Burdur Lake’s depth decreases every year because of the aridity, so the horizontal and vertical wave forces over the pipeline increase due to the decrease of the depth. Burdur Municipality could not use this pipeline system, so pipeline system must be placed in a ditch and suitable gabions that must be used in order to obtain the stability.

Open access

Rumiana Kotsilkova, Irena Borovanska, Peter Todorov, Evgeni Ivanov, Dzhihan Menseidov, Sudip Chakraborty and Chiranjib Bhattacharjee

Abstract

Mechanical properties of polymer membranes (strength, hardness and elasticity) are very important parameters for the application performance, e.g. water purification. We study the tensile and surface mechanical properties of hollow fiber and flat sheets mat membranes based on PES and PVDF polymers. Tensile test, nanoindentation and atom force microscopy are used for characterization at macro and nanoscale. Mechanical properties are correlated with pore structure of membranes. The reinforced PVDF HF hollow fiber membranes show 30-fold higher stiffness and 3-fold higher hardness compared to non-reinforced PES HF. Surface mechanical properties of flat sheet membranes are strongly improved by decreasing the pore size. The smoothest surface with 100–200 nm roughness has the best surface mechanical performance obtained by nanoindentation.

Open access

Linyue Guan, Mingjun Pang, Xuedong Jiang and Yongbin Zhang

Abstract

This paper presents an analysis for a micro/nano wedge-platform thrust slider bearing by using the flow factor approach model. The contact-fluid interfacial shear strength was taken into account for describing the inter-facial slippage. The carried load and friction coefficient of the bearing were calculated when different contact-fluid interactions were used. It was found that the interaction strength between the contact and the fluid has a significant contribution to the load-carrying capacity of the bearing, a weak contact-fluid interaction in the bearing inlet zone and its resulting interfacial slippage on the stationary contact surface is beneficial for both the load-carrying capacity and the friction coefficient of the bearing, while a strong contact-fluid interaction in the bearing outlet zone is contrarily harmful. The relative slip amount is linearly distributed in the bearing inlet zone, when the interfacial slippage occurs on the stationary surface in this subzone because of the low interfacial shear strength.

Open access

G. Stoilov, V. Kavardzhikov and D. Pashkouleva

Abstract

The review of progress in numerical synthesis and study of strain sensors patterns, which can be used for realization of digital image correlation (DIC) and its applications in engineering practice, is presented. Problems related to monitoring a large area of an objects surface while subsequently increasing the image scale and concentrating observation only to the area where the largest deformation has taken place are considered. An algorithm for numerical synthesizing of specialized strain sensor patterns is proposed. Results from a physical experiment are also reported.