Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : mechanical properties

The Influence of Quenching Media and Aging Time on Microstructure and Mechanical Behavior of 6061 Aluminum Alloy

Naser Korde Zedin

Engineering and Technology Journal, 2015, Volume 33, Issue 8, Pages 1757-1770

Aluminum-magnesium-silicon (Al-Mg-Si) alloys are medium strength, excellent formability, good corrosion resistance and widely used in extruded products and automotive body materials. The influence of quenching media with different aging time on microstructure and mechanical properties of 6061 aluminum alloy was investigated. The results show formation of (Mg2Si) and (CuAl2) phaseswhensolution treatmentwas applied (at 520°C for 2h,followed by quenching in water and oil at room temperature then aging (at 175°C for 2, 4and6h)) which resultimprovingof both the strength, hardness and decreases elongation. It can be noted that, the grains of samples which are quenching in water is finer than the structure of samples which are quenching in oil. The values of yield stress and ultimate tensile strength decrease respectively with increasing aging time to 6h as (258MPa) and (264MPa) for water quenching and (199MPa) and (235MPa) for oil quenching. In this piper were measured and discussedthe variation of the yield stress, ultimate tensile strength and elongation with different solution quenching and aging time.

Comparative Study of Some Properties of Two Groups’ Binary Polymer Blends Prepared By a Twin-Screw Extruder

Sihama I. Al-Shalchy; Kadhum M. Shabeeb; Rula F. Hasan

Engineering and Technology Journal, 2015, Volume 33, Issue 8, Pages 1971-1985

In this paper, the preparation and compare of some mechanical and physical properties of two groups of polymer blends consisting of polyvinyl chloride with polypropylene (PP-PVC) and poly-vinyl chloride with high-density polyethylene (HDPE-PVC). Using a twin-screw extruder, three weight percentages of PP and HDPE (5, 10 and 15%) were used to prepare the polymer blends. Experimental investigation was carried out for analyzing the mechanical properties liketensile strength, flexural strength, compression, impact, and hardnessand physical properties (thermal characteristics and melt flow index) for the polymer blend samples. The results show that the polymer blend (HDPE-PVC) get higher values than polymer blend (PP-PVC) in fracture strength, young´s modulus, elongation, flexural strength, creep resistantand maximum shear stress and thermal characteristics, whereas the polymer blends (PP-PVC) get higher values in impact strength, fracture toughness, hardnessand compression and melt flow index. Besides, the increment in PP or HDPE content weak the properties of the polymer blends and the samples with (5%PP:95%PVC) and (5%HDPE:95%PVC)were the best among the other polymer blends samples.

Nano-SiO2 Addition Effect on Flexural Stress and Hardness of EP/MWCNT

E.A.Al-Ajaj; A.Sh. Alguraby; M.K. Jawad

Engineering and Technology Journal, 2015, Volume 33, Issue 7, Pages 1248-1257

Nano-SiO2 with different weight percentage (1,2 ,3, 4 and 5) % wt. , and 3% MWCNT were usedto fabricate nano-SiO2/MWNT/epoxy composite samples by hand layup method. Ultrasonic mixing processwas used to disperse the nano additives into the resin system. scanning electron microscopy (SEM)where usedto carry out the characteristic of fracture surface. By both the high aspect ratio and the very high modulus ofnano fillers. The mechanical properties of the composite with different weight percentages of nano-SiO2 havebeen investigated and After examine, the Scanning Electron Microscopy (SEM) explains well dispersednanotubes and SiO2 nano particles in the matrix. No evidence of agglomeration of the nanotubes can be foundin this micrographs. By adding SiO2 nano particles to epoxy/MWCNT composite, this would dramaticallyimprove the bending properties and The Young’s modulus has been doubled and quadrupled for compositeswith respectively 2 and 4 wt.% nano SiO2, compared to the pure resin matrix samples (3.36 ,4.06 ,and 1.59 )GPa respectively .While flexural strength has been increased in random manner with maximum value for 2 wt%(111 MPa). The hardness of nano composite increased with increase of SiO2 filler loading, it can be seen thatthe SiO2 filler greatly increased the hardness, which can be attributed to the higher hardness and moreuniform dispersion of SiO2 filler. The higher hardness is exhibited by the 5 wt% SiO2 filled compared to othernanocomposites. The results show that at 5wt% nano SiO2 content there is 11% increase in hardness

Mechanical Properties of Tempered Nanobainite Steel

Dhafir S. Al-Fattal; Najmuldeen Y. Mahmood

Engineering and Technology Journal, 2013, Volume 31, Issue Issue1A [Engineering], Pages 107-119
DOI: 10.30684/etj.2013.71252

The mechanical properties of 62 SiMnCr 4 steel transformed isothermally at 280ºC for 5-hours were investigated. The hardness of nanobainite steel was equivalent to tempered martensite steel. The hardness decreases significantly at high tempering temperatures in excess of 500ºC. Yield strength of about 2GPa and ultimate tensile strength of 2.3GPa have been achieved for nanobainite steel. Furthermore, the high strength is frequently accompanied by relatively good percentage elongation of 8.25%. The strength decreases and the ductility increases with increasing tempering temperature. Nanobainite steel has a high charpy impact energy of 170 J which decreases linearly with increasing tempering temperature. Fatigue strength of nanobainite steel is higher than tempered martensite, its decreases with increasing tempering temperature.

Effects of Lamination Layers on the Mechanical Properties for Above Knee Prosthetic Socket

J. S. Chiad; S. S. Hasan; M. J. jweeg

Engineering and Technology Journal, 2009, Volume 27, Issue 4, Pages 759-775

In order to initiate a database on materials properties of typical lamination
used in above knee prosthetic limb socket fourteen group of different lamination
materials layers are manufactured using perlon and fiber glass and acrylic resin
.The effect of increasing and decreasing of perlon and fiber glass layers on
mechanical and physical properties are examined subjected the eighty two
manufacturing sample of the different fourteen group of lamination to tensile and
flexural test .
Results show that the lamination which was layup from three layers of perlon plus
two layers of fiber glass plus three layers of perlon gives the optimum mechanical
properties . Comparing this lamination with the standard lamination used in
Baghdad center of five layers of perlon plus two layers of fiber glass plus five
layers of perlon it can be seen that ,in spite of the big reduction in perlon layers
form ten to six layers the yield stress increased with 14.75% while ultimate
strength remains at the same value and bending stress decreased with 1.3% only . It
is recommend to use this type of lamination for the layup the above knee socket
because it meets the requirement of good socket design for acceptable mechanical
properties and its minimizing the cost of socket lamination to suitable cost value.
Also it was found that increasing the fiber glass layers from zero to two layers
with fixing perlon layers leaded to increased in( E y ult s ,s , , flex flex s ,E ) with
(40%,30.4%,110.5% 36.4%and 20.4%) respectively. At the same time the results
show that the lamination group of sandwich lay up during which the layers of
perlon distributed equally (homogeneously) on each side of the central fiber glass
layers improved the mechanical properties set ( E y ult s ,s , , flex flex s ,E ) with ((21-
59)%,(12.4-66.4)%,(46.6-150)%,(5.2-60.2)%,(27.5-44.8)%) respectively compared
with the others group of unequally distributed lamination .

Predicting Mechanical Properties of High Performance Concrete by Using Non-destructive Tests

Sura F. Al-Khafaji; Waleed A. Al-Qaisi; Shakir A. Al-Mishhadani

Engineering and Technology Journal, 2009, Volume 27, Issue 3, Pages 425-444

In this study, high performance concrete mixes were produced by using high
range water reducing agent and also by using 10% silica fume or 10% high
reactivity metakaolin as a partial replacement by weight of cement. Three cement
contents (350, 450, and 550) kg/m3 were used through this study. A total of 330
(100 mm) cubes, 132 (100×200 mm) cylinders, 132 (100×100×400 mm) prisms,
and 66 (150×300 mm) cylinders were casted and cured to the required age of test .
All specimens were cured in tap water except 165 cubes, which were submerged in
Cl ˉ + SO4ˉ ˉ solution at concentration identical to those present in severe
aggressive environment to study the effect of this solution on the compressive
strength of high performance concrete mixes. Compressive strength, splitting
tensile strength, modulus of rupture, static modulus, rebound number, ultrasonic
pulse velocity, dynamic modulus, initial surface absorption, density ,and total
absorption tests were investigated for all mixes at 7, 28, 90, and 120 days age.
Results of the destructive tests (compressive tensile strength, strength, splitting
modulus of rupture, and static modulus) and non–destructive tests (hammer,
ultrasonic pulse velocity, and dynamic modulus) are statistically analyzed by using
SPSS Ver.15 software to study the possibility of predicting the mechanical
properties of high performance concrete by using non–destructive tests. Simple and
multiple linear regression analysis of the obtained results leads to the proposed
statistical models for evaluating the compressive strength, splitting tensile
strength, modulus of rupture, and static modulus by using one or two or three of
the above mentioned non–destructive tests. Analysis of variance (ANOVA)
and t–test was also used to investigate the adequacy of the statistical models.