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Exact thermomechanical analysis of functionally graded (FG) thick-walled spheres

100%

Yildirim V.

2018

tom Vol. 22, nr 4

1197--1221

The present study aims to provide a deeper understanding for the thermo-mechanical analysis of spheres made of non-homogeneous isotropic materials. To this end, Navier equations are solved analytically based on the spherically-symmetric plain-strain assumptions and closed-form formulas are proposed for the elastic fields in a simple-power-law graded spheres subjected to steady-state thermal and internal/external pressure loads. A comprehensive parametric study is then performed with both functionally-graded hypothetical and physical materials. Two benchmark examples are reconsidered with hypothetically chosen inhomogeneity indexes. Effects of inhomogeneity indexes are reviewed in these examples. Differently from the literature, thickness effects are also examined under separate and combined loads together with the thermo-mechanical behavioral differences in spheres and cylinders. Finally three physical metal-ceramic pairs are studied originally with appropriate inhomogeneity indexes which are deffned as the inner surface is full ceramic and the outer surface is full metal. Results are presented in graphical and tabular forms.

An integrated spatial method for minimizing environmental damage of transmission pipelines

38%

Yildirim V. , Yomralioglu T. , Nisanci R. , Colak E. H. , Bediroglu S. , Memisoglu T.

Polish Journal of Environmental Studies

2016

tom 25

nr 6

Pipelines are essential for transporting energy resources over long distances. Pipeline projects cause many environmental, economic, and social problems. The construction of large-scale infrastructures such as natural gas/oil pipelines involves extensive disturbance for regional ecosystems. Therefore, it is very important to ensure bad effects of transmission pipeline routes considering environmental sensitivities. In order to do this, we used a geographical information system with multi-criteria decision-making techniques to create an environmental care model. In this study, we applied the order preference by similarity to ideal solution technique to integrate environmental sensitivity into the planning of a natural gas transmission pipeline project. For this purpose, route optimization was carried out for the ongoing operation of an existing 84.33 km natural gas transmission line. An environmentally sensitive optimum route was determined according to environmental impact assessment criteria. The experimental studies confirmed that our road is superior to the current road when compared with the 13 spatial criteria used for analysis. Our road has only seven stream passes while the current road has 20, our road has no quality soil pass on the other side while the current road has a 661-m quality soil pass, and our road is more cost-efficient at 77.89 km as opposed to the current road’s 84.33 km. This paper declares that optimized and sophisticated GIS-multicriteria decision method tools/models solve natural gas transmission project routing problems in terms of environmental sensitivities and costefficiency.