Iraqi journal of mechanical and material engineering

This work deals with effect of laser treatment of various positions on the fatigue specimens ,these positions were taken with respect to specimen for both cases of laser supplied (pulse and band) . beside , the steel reinforcement layer was added to improve fatigue properties .from S-N curve results ,the laser treatment improved properties approximately 23% while steel reinforcement improved it approximately 13% ,and the laser treatment contributed in improving properties 6% more than steel layer reinforcement

This research presents a SHM (Structural Health Monitoring) techniques that are based on static and modal analyses of cracked plate structure. Finite element models (FEMs) for the different cracked steel plate have been created by considering the length and the orientations of the crack, and a cantilever supported plates (parallel to the crack) are used. The finite element models are examined under the action of static concentrated lateral
load. It is found that the maximum deflections of cracked plate increases when there is an
increase in the crack length. The highest value of the maximum deflection is at (0.12 m) of
half-crack length. The reason of this behavior is attributed to the decrease in material's
stiffness causing structure deformation. However, this deflection decreases when the
orientation of crack increases until it reaches the minimum value at 90° of crack angle.
Modal analysis is also performed to each FEM to extract the values of the natural
frequencies. It is noticed that the values of natural frequencies decrease with an increasing
of crack length, and they increase with the increasing of crack orientation angle. An
experimental test has been done to check the validity of the intact plate. The results obtained
is the fundamental natural frequency. A comparison between the natural frequency and
finite element result is made an error of less than (10 %) is found. Finally, SHM analysis is
applied in order to predict the early behavior of the plates in accordance with the results
above. The extrapolation for certain symbols of the results is performed to derive numerical
formulas of the natural frequencies and static deflections. The natural frequencies and static
deflections' formulas are used as a function for the half-crack length, however, there is a
formula for each orientation angle.

Study on oblique angle of composite material bar by reinforcing with acetate fiber was conducted to estimate the stress strength at fatigue test, by using rotary bending tester. The specimens were used with 130mm length and 10mm diameter, which consist the basic material (Resin) and harder with oblique angles of (0°, 30°, 45°, 60°, and 90°), the cellulose acetate fiber has used with elastic mechanical properties. The results were converged with practical and theoretical result for the number of failure and the values of correction factor, as well as the values of fatigue strength were between (28-100 Mpa) and had directly proportional with vertical compounds material, while the maximum value of oblique angle was equal to zero.

Spinel nickel aluminate is an important industrial material, has been synthesized by a solid state reaction method from nano powders γ- Al2O3 and NiO represented as a theoretical batch. Sintering the raw materials was done at rate heating 4 OC/min in 1500 OC. The sintered specimens were investigated employing by X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy techniques (SEM). It is that the formation nickel aluminate spinel was completed in 1500 oC, at the following percent (20 wt % NiO and 30wt% NiO and 50 wt% NiO), thermal properties have been also investigated for sintered specimens. The new composite materials it high thermal expansion stability and resistant to thermal shock at 1200oC, especially with 30 wt % NiO.

Shape Memory Alloys (SMAs) have been considered as one of the most Promising smart materials. They can provide novel solution in several fields, for various applications. Shape Memory Alloys demonstrate a unique ability to recover their initial shape after deformation through a reversible thermo-elastic phase transformation, the effect of Cr addition on mechanical properties and biocompatibility of the Ti-Ta shape memory implant are investigated, many test was done on prepared samples that produced by powder metallurgy technique, and the results shows that all prepared sample consist of two phases α and β ,also the transformation temperature of the alloy decrease when Cr is added at different percentage, and there is a remarkable decrease in hardness (108.8Hv) due to the increase in porosity percentage(7.6%) when Cr is added ,finally the corrosion behavior of the alloy in general is improved as Cr content increase which mean that the alloy attractive to use in human body as implants.

Solar air heater (SAH) is more suitable for residential space heating in winter season and in drying crops. This work presents thermal performance of flat plate SAH with and without thermal storages. A forced convection solar collector (FCSC) integrated with different sensible heat storage materials (sand, concrete, pure cement) has been developed and tested to evaluate its performance under meteorological conditions of Baghdad, Iraq. System consists of three flat plate solar air heaters with different heat storage materials, and the fourth without storage heat material. All collectors are supplied with centrifugal blower. The experimental results indicated that the pure cement gives better thermal performance than other storage heat materials (sand, concert), the pure cement gives heat along (240 min) after (6:30 PM), but the duration was (170 min) and (65 min) for concrete and sand respectively. The air flow rate is more affect on both outlet air temperature storage heat times, where studied the effect of three air velocities (0.8m/s, 1.4m/s and 2.1m/s) on SAH performance with best thermal storage heat material (pure cement), the increase in outlet air
velocity leads to decrease in both outlet air temperature and storage time of thermal energy.
Keyword: Solar air heater, Thermal storage material, Flat plate solar collector.