Sürdürülebilir Kalkınma Amaçları
Yazarlar
Yayınlar
- MakaleAçık Erişim2014Scopus SJRQ3Free vibration analysis of a laminated composite beam with various boundary conditions
Balci, Murat; Nalbant, Mustafa Oǧuz; Kara, Ercan; Gündoǧdu, Ömer
This study presents a free vibration analysis of a laminated composite beam, based on the Euler-Bernoulli beam theory. A numerical model of the laminated composite beam was obtained for various boundary conditions based on different length-to-thickness ratios for a number of layers, using the finite element method. A planar beam bending element with two nodes, each having two degrees of freedom, was chosen according to Euler-Bernoulli beam theory. The natural frequencies of the laminated composite beam were obtained for each case, and presented in such a way as to display the effect of these changes on the natural frequencies. Eight natural frequencies of clamped-free, clamped-clamped (CC) and simple-simple (SS) composite beams were first obtained for different length-to-thickness ratios (Lx /h), numbers of layers, layer angles and for their different positions. It can be seen that natural frequencies decrease for all modes with increasing length-to-thickness ratio in all cases.
AtıfScopus19WoS11OpenAlex15
İncele - MakaleAçık Erişim2013Scopus SJRQ2Energetic and exergetic comparison of air to air and air to water heat pumps according to evaporator conditions
Çomakli, Kemal; Çakir, Uǧur; Şahin, Erol; Kuş, Ayşegül Çokgez
This paper presents an experimental energetic and exergetic comparison for a heat pump system that can be run in different modes as air to air and air to water. Components of the heat pump do not change when the running mode changes, except for the condenser. This means that some external and internal effects (like compressor type, pipe lines) that can affect the system performance will be the same for each running mode. The comparison which was made in this study demonstrates which system leads to an efficient conversion and supply of energy and exergy. In the analysis, four balance (mass, energy, entropy and exergy) equations are applied to the system for the two modes. Exergy and energy efficiency values for both systems are given, while exergy destructions in each of the systems are determined and presented. It is seen that the heat pump unit which has the highest COP value is the air to air type (3.45-3.8); second is the air to water type (3.35-3.41). The exergy efficiency of the air to air heat pump (29-32%) is higher than the exergy efficiency of the air to water type heat pump (24.1-25). Ranking of the exergy destruction rates of the two heat pump types from high to low is as follows: air to air and air to water.
AtıfScopus5OpenAlex5İncele - DergiInternational Journal of Automotive and Mechanical Engineering