University of Thi-Qar Journal for Engineering Sciences

The aim of this work is to study the effect of the following parameters :reduction in thickness , length of contact, rolling radius, viscosity of lubricant oil, and roll speed on the lubricant film thickness which are pointed to as an independent variables. In order to illustrate the effect of these parameters, three types of lubricants ,A( Commercial rolling oil, known as Roll oil 981), B ( Forming cutting oil called Exx cut 225, with additive ) and C (Forming cutting oil called Exx cut 225 ). Were selected also three values for roll radius (55,65,and 75 mm), with three values for roll velocities (0.5, 1, and 1.5 m/s), and finally five values for reduction in thickness (75, 80, 85, 90, and 95%) were examined to cover all inquires in this work. The study shown that an increase in roll radius leads to increase in lubricant film thickness . At high reduction, the lubricant film thickness becomes very small, and requires the use of high viscosity lubricant.

A series of two-layered composite barriers filled with (10% carbon black) were produced, with their second layers loaded with foreign dispersion acting in aid of the microwave absorption process. Fixed weights of chopped copper wires with lengths (1,3,5) mm were dispersed in the above mentioned barriers. The resulting behavior indicates that these catalyst dispersion played a very useful role in enhancing the absorption of the barrier. Moreover, certain wire lengths exhibited an optimum behavior at various frequencies, suggesting that these wires act as short dipole antennas which convert the microwave signal into a leaked current. Mixing various wire lengths yielded a (100% bandwidth covering the whole of the X-band fore reflectivity level less than –11dB). Also various concentrations of AL-powders were dispersed in these second layers and an optimum concentration exhibited a low reflectivity level over the whole X-band. Intermixing of wires and powders produced a rather poor behavior suggesting that this might be due to the metallic over exceeded presence in the barrier.

A series of two-layered composite barriers filled with (10% carbon black) were produced, with their second layers loaded with foreign dispersion acting in aid of the microwave absorption process. Fixed weights of chopped copper wires with lengths (1,3,5) mm were dispersed in the above mentioned barriers. The resulting behavior indicates that these catalyst dispersion played a very useful role in enhancing the absorption of the barrier. Moreover, certain wire lengths exhibited an optimum behavior at various frequencies, suggesting that these wires act as short dipole antennas which convert the microwave signal into a leaked current. Mixing various wire lengths yielded a (100% bandwidth covering the whole of the X-band fore reflectivity level less than –11dB). Also various concentrations of AL-powders were dispersed in these second layers and an optimum concentration exhibited a low reflectivity level over the whole X-band. Intermixing of wires and powders produced a rather poor behavior suggesting that this might be due to the metallic over exceeded presence in the barrier

The aim of this study is to start a work about the bonding mechanism of tantalum -to- tantalum brazed by active filler metal alloy which basely stand on using copper or silver with active element such as titanium. Brazing will happen under inert gas (argon). Ag4Wt% Ti,Cu8wt %Ti , and the eutectic Ag 26wt% Cu 4 wt % Ti are the active filler metal which are used , and the bonding phases at the filler metal / tantalum interface line almost contain ( Ti Ta2 O7 ) and ( Ti0.51 Ta0.49 O2 ) . Which means that active element ( titanium ) shares oxygen with tantalum to make this bond as a cheap filler .

This paper investigates the nonstationary random excitations with a constraint on mean square value such that the response variance of a given linear system is minimized. It is also possible to incorporate the dominant input frequency into the analysis. The excitation is taken to be the product of a deterministic enveloping function and a zero mean Gaussian nonstationary random process. The power spectral density function of this process is determined such that the response variance is minimized. The numerical results are presented for multi-degree freedom system and modeled to predict the behavior of the gate of dike Structure under random water loading.

A theoretical analysis for the free , axisymmetric, vibrations of an isotropic thin oblate spheroid shell filled partially or completely with an incompressible, non-viscous, irrotational fluid is considered.The Rayleigh – Ritz's method is used to obtain an approximate solution which coincides with the exact solution for the cases of an empty or completely filled shell. The vibration of the shell is examined using the non – shallow shell theory. The analysis is based on considering the oblate spheroid as a continuous system constructed from two spherical shell elements matched at the continuous boundaries. Solutions are presented to show the effect of the angle of filling fluid on the shell natural frequencies. The effect of shell geometric parameters on the frequencies is also investigated. Natural frequencies are calculated for the shell in both empty and filled cases. It was found that their frequencies are decreased with the increase of fluid level in the shell. The analytical solution is compared with available test results. Good agreement is shown between test results found in the literature and predicted natural frequencies.

The aim of this work is to study the possibility of braze welding of austenitic steel AlSl316L , Low carbon steel A 283 Grade C , and austenitic stainless steel to low carbon steel by using Shielded Metal Arc Welding and oxyfuel gas welding equipment . Specimens with square-butt joint design and 2,5, and 7 mm gaps were joined using four different types of filler metal DIN SCuZn40Si , DIN ELCuSn7 , DIN ELCuSi3 , and DIN ENi-BG11. Other factors were kept constant at 100 A , 22 V , and 5 mm of metal thickness . Microstructures and mechanical tests ( Tensile test and Bending text ) were performed to study the properties of welding specimens . From microscopic examination , it was found that the bonding by braze using OFW with SCuZn40Si filler was similar to that of brazing process . On the other hand the bonding result from braze using SMAW with ELCuSi3 and ELCuSn7 were intermediate between brazing and electric are welding while the use of ENi-BG11 filler by SMAW shows a bond exactly as that of electric arc welding. Results show that maximum tensile strength and bending force can be achived by ENi-BG11 filler .

This work studies a new type of open curves which resulted from the non-slippery motion of an elliptic shape rolled on a specific path . This investigation was done by using cycloid drawing method which depends on rolling a cycle on a specific path . The curve was drawn by studying the motion of a stationary point on the ellipse circumference during one or more ellipse cycles . The percentages , of the resulted curve was studied by the analysis of a specific point on the ellipse circumference on both large and small axles . These two cases are taken in moving the ellipse on given length straight path equals to the ellipse circumference. The other studied case was rolling the ellipse on the outer circumference of the Laith-oid curve , which is a new case of curves that resulted from the motion of a stationary point on the outer circumference of a circle which rolls in a non-slippery motion on a straight line with a length equals to twice its diameter .The case of the ellipse rolling on one complete Laith-oid curve was studied . Another case was the rolling on two adjacent curves . The possibility of generating closed or open surfaces from the resulted curve was studied with their characteristics .