The first goal is to get rid of waste and reduce environmental pollution, and the other goal is to investigate the effect of these fibres on properties (resistance of composite materials for bending and tensile testing) of polyester and use them in applications. Also, The moisture environment effect on the properties of composite materials was studied. It uses natural fibres, which are considered waste, namely eggshell and sawdust with polyester. Several samples were prepared with different weight percentages (30% and 40%), and their mechanical properties were studied and immersed in water for 15 days. And studying the effect of water on these properties. It was found that it is possible to use these fibres (waste) with polyester and benefit from them. It was found that when adding fibres to polyester, the tensile strength decreases, but the bending increases the strength. Finally, it was found that when the samples are immersed in water, the material weakens, and its mechanical properties decrease. It can be noticed that adding natural fibres by 40% and 30% improved the mechanical properties of polyester in the bending test, where the bending test increased with increased volume fraction of fibre. It can be noticed that adding natural fibres by 40% and 30% decreased the mechanical properties (tensile strength) of polyester in a tensile test. When the natural composite materials were treated with water for 15 days, water decreased the mechanical properties in bending and tensile test. One of the limitations of this research that was found through the work is that when increasing the weight ratios of the fibres added to polyester leads to the failure of polyester, so we recommend using lower weight ratios of fibre. One of the limitations of this research that was found through the work is that when increasing the weight ratios of the fibres added to polyester leads to the failure of polyester, so we recommend using lower weight ratios of fibre.
The current review covers numerical analysis using Matlab program for multi-layer composite materials. Which involves studies are related to the intersection with fibers, between layers and piezoelectric layer or patch. It has been reported that using Matlab program has a great flexibility in analysis due to its library which includes various numerical methods. In addition to the ability of programming and developing the finite element technology to calculate the stress and strain in each layer based on different deformation methods such as (FSDT and HSDT), to obtain mechanical properties. It has been claimed that there is a deviation in results between Matlab and Ansys for the same 20-layer composite material. Using Matlab in dynamic analysis in various methods such as Newmark, Rayleigh damping, Timoshenko, and Euler-Bernoulli exhibit good agreement with natural frequencies and mode shapes. Moreover, Matlab is useful for the real-time process of data acquisition to deliver a digital model of a composite material coated with a piezoelectric plate and is an ideal material for sensing, detecting, and controlling vibration inhibition.
This paper presents a theoretical and experimental study to investigate the effect of the bearing position on the vibration response of a centrifugal fanrotorbearing system. The theoretical analysis includes fluidstructure interaction (FSI) analysis. ANSYS Parametric Design Language (APDL) was used for this purpose. The interaction between the two fields typically takes place at the boundary of the model solution (the fluidstructure interface on the fan impeller), where the results of one field are passed to other field as a load. This load is already sensitive to dynamic pressure pulsation developed either as a part of normal fan operation or as a result of abnormal structure dynamic or aerodynamic un stabile conditions. The experimental work is done on a test rig designed and constructed at the workshop of Baghdad-South Steam Power Plant. A singlestage centrifugal fan impeller is driven by a motor through coupling and driving rotor. The rotor is supported by two journal bearings, where the axial position of one of them is controlled by means of sliding mechanism and control circuit. The test rig is equipped with multisensory system for measuring the essential experimental parameters. The results indicated distinguished bearing positions at which the response is so high. These positions must be taken into account to avoid the higher response of vibration. The values of the stiffness and damping coefficients are fluctuating along the span position due to the change in the value of the external loads on the bearings. Also, their behavior depends on the bearing oil pressure.
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