Contents of Journal of Mechanical Engineering 57, 6 (2006) 




ATTIA, H. A.: Numerical study of unsteady MHD Couette flow 
of a viscoelastic fluid with temperature dependent viscosity 
in the presence of exponential decaying pressure gradient              309

AUDY, J.: Exploring the role of computer modeling and image 
analysis in assessing drill design features and performance            322

HASAN, A., KHAN, R. A., MOHD, A.: Isomorphism in kinematic 
chains using Joint-Joint matrix                                        339

KADRY, S.: Multi-dimensional transformation method for 
reliability analysis                                                   348

Abstracts



Numerical study of unsteady MHD Couette flow of a viscoelastic fluid with temperature
dependent viscosity in the presence of exponential decaying pressure gradient

HAZEM A. ATTIA

The unsteady Couette flow of a conducting, viscoelastic fluid between two horizontal porous plates in the presence of a transverse magnetic field is studied. The plates are assumed to be non-conducting and maintained at two fixed but different temperatures. The fluid viscosity is assumed to be temperature dependent and the fluid is subjected to a uniform suction from above and injection from below. The motion of the fluid is produced by a uniform horizontal exponential decaying pressure gradient. The equation of motion and the energy equation are solved numerically to yield the velocity and temperature distributions.

Exploring the role of computer modeling and image analysis
in assessing drill design features and performance

JAROMÍR AUDY

Present study was set up to explore the role and efficiency of computer modeling and image analysis in assessing design features with respect to predicted performance measures of a general type twist drill and a point modified-web profile ground-drill. Computer assisted modeling and predictive approaches involved analysis of rake angle distributions along the lip and chisel edge regions for both drill designs followed by study of the effects of individual drill geometrical features on drilling forces and power. The results demonstrated that the computer assisted modeling and predictions were successful in predicting and comparing the performance trends for different design features of the experimental drills examined in this study. The predictive model for web profile ground drills showed that the normal rake angles along the lip were more positive and therefore more favorable than those for the corresponding general purpose twist drills. Similarly point thinning of the web profile ground drill design seemed to be superior in terms of less negative rake angle distribution along the chisel edge to that of the general purpose twist drill. The web profile ground drill design was found to reduce the thrust and torque values, respectively, by about 13 % and 15 % 'on average', compared to the corresponding values for the general purpose twist drill design. In addition, it was also possible to establish comprehensive 'empirical type' thrust and torque equations using multivariable regression analysis to curve fit the predicted thrust and torque data from the computer simulation studies.

Isomorphism in kinematic chains using Joint-Joint matrix

ALI HASAN, RASHEED A. KHAN, AAS MOHD

The present work deals with the problem of detection of isomorphism, which is frequently encountered in structural synthesis of kinematic chains. A new method based on theoretic approach, easy to compute and reliable, is suggested in this paper. It is capable of detecting isomorphism in planar kinematic chains having simple joints.

Multi-dimensional transformation method for reliability analysis

SEIFEDINE KADRY

In this work, a new method is proposed to evaluate the reliability of stochastic mechanical systems. This technique is based on the combination of the probabilistic transformation methods for multiple random variables and the finite element method (FEM). The transformation technique evaluates the Probability Density Function (PDF) of the system response by the use of the Jacobian of the inverse mechanical function. This approach has the advantage of giving directly the whole density function of the response in a closed form, which is very helpful in reliability analysis.