Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Modulus of elasticity

Study the Mechanical and Physical Properties of Polyester Composite Reinforced by Multi Layers

Fadhil Abbas Hashim; Mohammed Sellab Hamza; Reham Raad Abdulla

Engineering and Technology Journal, 2016, Volume 34, Issue 9, Pages 1834-1843

In this research, a laminate composite has been prepared, using unsaturated polyester resin (UP) as a matrix reinforced with Kevlar fibers in different number of layers, glass fibers were added to the optimum product, by replacing one of the layers of Kevlar Fibers with a layer of Glass Fibers. Hand Lay-up method was used to prepare the test samples. To evaluate the composite material properties, tensile, hardness, impact, optical microscope tests were done.
The results of composite made of polyester reinforced with Kevlar Fibers show that the mechanical properties (Tensile strength, Modulus of elasticity, Hardness, Impact strength) increase with increasing the number of reinforced layers.
The best experimental values ofthe mechanical properties (Tensile strength, Modulus of elasticity, Hardness, Impact strength) were (190 MPa, 1.72 GPa, 79.25, and 68.75KJ/m2) respectively, for composite with three layers of Kevlar Fibers and then followed by composite with the sequence of layers (kevlar-glass-kevlar) and its mechanical properties (Tensile strength, Modulus of elasticity, Hardness, Impact strength) were (175.5 MPa, 1.69 GPa, 80, and 59.1 KJ/m2) respectively, Optical microscope shows welldistribution ofreinforcedlayers in composite.

Tensile Properties Distribution of Coir Natural Fiber Using Weibull Statistics

Ahmed Mudhafar Hashim; Jawad Kadhim Oleiwi

Engineering and Technology Journal, 2016, Volume 34, Issue 6, Pages 1080-1087

In current time, most of the composites based on polymer resins reinforced with natural fibers than synthetic fibers for environmentally friendly consideration. This work investigate the study of tensile properties distribution of coir natural fiber by using Weibull statistics to quantify the degree of variability in fiber strength. Single-fiber tensile and microscopy tests were performed to determination the tensile properties (tensile strength and modulus of elasticity) and fiber crosssectional
area respectively. The experimental results showed that the coir natural fiber have a good tensile strength and modulus of elasticity of 89.91–237.46 MPa and 2.55-8.78 GPa respectively. The Weibull distribution indicates that the coir natural fiber have a high degree of linearity of R2 = 0.942. The Weibull modulus for corn fibers was β = 3.650 , gives a good variability in tensile strength.

Impact Resistance of Lightweight Chopped Worn-Out Tires Concrete

Zaid M. K. Al-Azzawi; Dhafir T. F. Al-Khameesi

Engineering and Technology Journal, 2010, Volume 28, Issue 16, Pages 5200-5212

This study summarizes results of an experimental investigation of the
impact resistance of 12 lightweight concrete slabs made from incorporating chopped worn-out tires (Ch.W.T.) into the mixes as a partial replacement of the sand in mortar mixes, and as partial replacement for both sand and gravel for concrete mixes; volumetrically.
The main variables were; the partial replacement ratio (PRR) and the shape of the falling mass (striker). Data were obtained pertaining to compressive strength, static and dynamic modulus of elasticity, and modulus of rupture. In addition, the crack pattern under impact loading was studied to provide insight into the internal behavior and failure mechanism of lightweight Ch.W.T. concrete slabs. Results of this work indicate that incorporating Ch.W.T. into mortar and concrete mixes succeeded in reducing its unit weight from 17.9% to 26.2% according to type of mix and partial replacement ratio. In contrast, the ultimate
impact resistance, expressed in the number of blows required for complete separation of the specimen, increased from 91% to 186% for mortar mixes depending on the partial replacement ratio and the type of falling mass; and did not decreased significantly for concrete mixes.

Effect of Coarse Aggregate Characteristics on Drying Shrinkage of Concrete

Tareq Salih Al-Attar

Engineering and Technology Journal, 2008, Volume 26, Issue 2, Pages 146-153

Concrete is a composite material, consisting, mainly, of three phases: coarse
aggregate, cement mortar, and the interface zone between them. The characteristics
of the interface zone largely govern the bond between cement paste or mortar and
aggregate. The restraining effect of aggregate to drying shrinkage strain depends
much on the bond between aggregate and cement paste.
In this paper, it is aimed to investigate the effect of coarse aggregate
characteristics, that affect bond strength, such as; type, shape, surface texture, and
moisture content, on drying shrinkage. Four types of coarse aggregate were used.
Three of them were normal-weight, while the fourth was a light-weight one. Each
type of coarse aggregate was used in two moisture conditions, dry and saturated.
The testing program extended to 150-days age and comprised; length change,
modulus of elasticity, compressive and splitting tensile strength of concrete.
It is concluded that using saturated coarse aggregate always yields higher
shrinkage strain than dry aggregate. The percentage increase seems to be affected
by the aggregate water absorption. At early ages, After 28 days, there is large
differences in relative shrinkage for different mixes. Later than 28 days, the
variation in ratios settled to approximately fixed values