Journal of Theoretical and Applied Mechanics-Bulgaria has been selected for

coverage in Thomson Reuter’s products and services. Beginning with Vol. 46(1)

MAR 2016, this publication will be indexed and abstracted in

Emerging Sources Citation Index

AL . CHEREMENSKY

Institute of Mechanics, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria

[Received 25 November 2016. Accepted 08 October 2018]

Institute of Mechanics, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria

[Received 25 November 2016. Accepted 08 October 2018]

MECHANICAL
SYSTEMS OF COSSERAT–ZHILIN

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).

KEY WORDS: classical mechanics, continuum mechanics, mechanical measures, foundations of mechanics, screw theory.

KEY WORDS: classical mechanics, continuum mechanics, mechanical measures, foundations of mechanics, screw theory.

Full Article | Times
Downloaded: 00123 |

HARSH SARDANA , MAHAVIR SINGH

Technosoft, Sec 16 Noida, UP-201301, India

[Received 19 March 2017. Accepted 08 October 2018]

Technosoft, Sec 16 Noida, UP-201301, India

[Received 19 March 2017. Accepted 08 October 2018]

REDUCTION OF DRAG OF SUV SIMILAR TO
TATA SUMO

USING VORTEX GENERATOR

USING VORTEX GENERATOR

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.

KEY WORDS : aerodynamics, Ahmed body, computational fluid dynamics, SUV, drag reduction.

KEY WORDS : aerodynamics, Ahmed body, computational fluid dynamics, SUV, drag reduction.

Full Article | Times
Downloaded: 00175 |

SANDHYARANI BANDARI ^{1} , ANAND
RAO JAKKULA ^{1},

MALLA REDDY PERATI^{2}

1 Department of Mathematics, Osmania University, Hyderabad 500007, India

2 Department of Mathematics, Kakatiya University, Warangal 506009, India

[Received 28 November 2017. Accepted 08 October 2018]

MALLA REDDY PERATI

1 Department of Mathematics, Osmania University, Hyderabad 500007, India

2 Department of Mathematics, Kakatiya University, Warangal 506009, India

[Received 28 November 2017. Accepted 08 October 2018]

STUDY OF RADIAL VIBRATIONS IN AN INFINITELY LONG

FLUID-FILLED TRANSVERSELY ISOTROPIC THICK-WALLED

HOLLOW COMPOSITE POROELASTIC CYLINDERS

FLUID-FILLED TRANSVERSELY ISOTROPIC THICK-WALLED

HOLLOW COMPOSITE POROELASTIC CYLINDERS

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.

KEY WORDS: poroelasticity, radial vibrations, composite poroelastic cylinder, fluid, anisotropic ratios, frequency, ratio of radii.

KEY WORDS: poroelasticity, radial vibrations, composite poroelastic cylinder, fluid, anisotropic ratios, frequency, ratio of radii.

Full Article | Times
Downloaded: 00100 |

A. MALEKI
, A. AHMADI

Department of Mechanical Engineering,

Malek Ashtar University of Technology, Iran

[Received 30 November 2017. Accepted 08 October 2018]

Department of Mechanical Engineering,

Malek Ashtar University of Technology, Iran

[Received 30 November 2017. Accepted 08 October 2018]

BUCKLING
ANALYSIS OF ORTHOTROPIC THICK

CYLINDRICAL SHELLS CONSIDERING GEOMETRICAL

IMPERFECTION USING DIFFERENTIAL QUADRATURE

METHOD (DQM)

CYLINDRICAL SHELLS CONSIDERING GEOMETRICAL

IMPERFECTION USING DIFFERENTIAL QUADRATURE

METHOD (DQM)

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.

KEY WORDS : orthotropic material, thick cylindrical shells, buckling load, geometrical imperfections, differential quadrature method.

KEY WORDS : orthotropic material, thick cylindrical shells, buckling load, geometrical imperfections, differential quadrature method.

Full Article | Times
Downloaded: 00111 |

VICTOR RIZOV

Department of Technical Mechanics, University of Architecture, Civil

Engineering and Geodesy, 1 Chr. Smirnensky blvd, Sofia, Bulgaria

[Received XXX. Accepted 08 October 2018]

Department of Technical Mechanics, University of Architecture, Civil

Engineering and Geodesy, 1 Chr. Smirnensky blvd, Sofia, Bulgaria

[Received XXX. Accepted 08 October 2018]

ANALYTICAL
STUDY OF ELASTIC-PLASTIC FRACTURE IN

THE CRACK-LAP SHEAR MULTILAYERED BEAM

CONFIGURATION

THE CRACK-LAP SHEAR MULTILAYERED BEAM

CONFIGURATION

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.

KEY WORDS : fracture, multilayered beam, material non-linearity, J-integral, analytical modelling.

KEY WORDS : fracture, multilayered beam, material non-linearity, J-integral, analytical modelling.

Full Article | Times
Downloaded: 00097 |

NAMAN JAIN

Department of Mechanical Engineering, G. B. Pant University of Agriculture and Technology, Pantnagar, India

[Received XXX. Accepted 08 October 2018]

Department of Mechanical Engineering, G. B. Pant University of Agriculture and Technology, Pantnagar, India

[Received XXX. Accepted 08 October 2018]

EFFECT
OF HIGHER ORDER ELEMENT ON NUMERICAL

INSTABILITY IN TOPOLOGICAL OPTIMIZATION OF

LINEAR STATIC LOADING STRUCTURE

INSTABILITY IN TOPOLOGICAL OPTIMIZATION OF

LINEAR STATIC LOADING STRUCTURE

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.

KEY WORDS : topology optimization; pseudo-densities; optimality criterion; SIMP; checkerboarding.

KEY WORDS : topology optimization; pseudo-densities; optimality criterion; SIMP; checkerboarding.

Full Article | Times
Downloaded: 00092 |