Iraqi journal of mechanical and material engineering

A variation method for potential and kinetic energy of the beam system was presented to simulation and solve the problems of free and forced vibrations. Rayleigh-Ritz method was used to solve the free vibration, while Newmark method was used to solve the forced vibration in the truss system, which has concentrated mass moves slowly on it, with a speed less than the vibrated speed of the structure system elements. The advantage of these methods is that the special approximating functions are added and used to solve the mathematical model of the beams system, which doesn't demand splitting of a beam into a large number of elements as is usual in finite elements analysis software .Every beam has considered as one element with two points, start and end point respectively, and in this situation allows for easy connection between beams and satisfy the geometric boundary conditions . The finite elements analysis has used in the computational model analysis of the all system, which has programmed by a Fortran programming language, and the solution process and the results are given numerically.

Jet impingement cooling is critical in many industrial applications (such as manufacturing process, gas turbine blades, etc), since it yields high local or averaged heat transfer coefficient, so a large amount of heat is extracted from hot surface. In this work the thermal characteristic of confined impinging air jet on a hot plate is evaluated experimentally and computationally. The parameters studied were , jet Reynolds number (ranged from 14000 to 70000), angle of impingement jet (0o to 50o measured from vertical axis on the hot plate), and the heat flux subjected on the hot plate (ranged from 1500 to 6000 W/m2). The two – dimensional continuity, Navier-Stockes, energy equations with (k-ε) turbulence model have been solved using finite volume method. The effect of covering the hot plate by a layer of Aluminum metal foam have on the impinging jet cooling of this plate is investigated experimentally for the same studied parameters. The experimental and computational results show that increasing the jet angle decreases the Nussetl no. , while increasing Re no. increases Nusselt no. Utilizing a layer of metal foam on the hot plate enhances the heat transfer by jet cooling by 33 % compared with jet cooling of bare hot plate under the same conditions. A comparison of the present results with the available reported data shows good agreement.

In this research, a free vibration of unidirectional composite laminated plate with different holes shape effect investigation is done experimentally and numerically. The natural frequency and deflection response of a unidirectional composite plate are studied with different holes shape effect as (rectangular or triangular or square or ellipse or circular shape, for simply supported and clamped composite laminated plate boundary conditions. This effect is studied for different shape cutout with the same area of different cutout shapes. The results of natural frequency evaluated by experimental work are compared with those evaluated by numerical method using a finite element method, (ANSYS program Ver. 14). The deflection of composite laminated plate with different holes effect is evaluated using finite element method. The results showed that the maximum natural frequency of unidirectional composite plate occurs at the clamped supported boundary composite plate with circular cutout. The experimental results of natural frequency of composite plate with different cutout shape are compared with those obtained using FEM. The comparison of results showed that the maximum discrepancy between experimental and numerical natural frequency is about (14.85%).

This study suggests a new theoretical analysis for the thermal bubble pump system. The main application of this system is to replace the mechanical pump in vapor absorption refrigeration system. The analysis is based on utilizing one-dimensional slug flow model to describe the void fraction in the riser tube of the pump, and adopting an appropriate method to evaluate the two-phase frictional pressure drop. The model is capable to predict the maximum pumping capacity of the pump in terms of the operation and configuration parameters. Three tube diameters (6.5,10, and 14mm) with four submergence ratios (0.5, 0.6, 0.7, and 0.8) were experienced using water as a working fluid. Results indicate that the maximum pumping capacity is positively increased with increasing the submergence ratio and tube diameter at a fixed riser tube length. The maximum pumping capacity is found to be independent of the liquid temperature at the inlet to the generator under the assumption of stable operation of the pump. It is obtained that the slip ratio decreases with the increasing of the submergence ratio and slightly decrease with the decreasing of the tube diameter.

In the present study mechanical properties of pure epoxy and hybrid composites were studied. Pure epoxy and hybrid composites were prepared by Hand lay-up molding and investigated. The composites constituents were epoxy resin as the matrix, 4% and 8% volume fractions of glass fibers as reinforcement and 4% and 8% of silicon carbide as filler particles. The investigated mechanical properties were hardness, tensile properties (ultimate tensile strength (UTS), fracture strength), and impact properties (impact strength, fracture toughness). The experimental results showed that the mechanical properties, Hybrid composite with (Epoxy +8%GF+8% SiC) has the maximum hardness of (82) shore D, Hybrid composites with (Epoxy +8%GF+4% SiC) has the maximum (UTS), fracture strength, impact strength (Gc) & fracture toughness (Kc) of (107) MPa, (108) MPa, (9900) J/m2, (27. 487) MPa.m-1/2 respectively

The research aim is to evaluate the properties of Ferro Cement mortar and the effect of the Wire Mesh strengthening layers number from(1-6) layers on the compressive and flexural strength with cement decreasing ability of the wall finishing mortar with one mesh layer. (127) samples were required, samples for reference cement paste standard consistency ,reference mortar compressive and flexural strength tests in addition to that a Samples for the strengthened mortar compressive and flexural strength tests with one mesh layer up to (6)layers ,another samples also for the strengthened mortar tests with one mesh layer and reducing the cement. Results showed that the strengthened mortar by (5) mesh layers was increased in compressive strength by (61.5%) and flexural strength by(205.21%) more than their reference mortar strengths. When strengthening the walls finishing mortar by one mesh layer we can decreasing the mortar cement content by a ratio of(20%) of its weight in reference mortar and the mortar properties are satisfied the requirements of the Iraqi specifications with good workability.