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    Estimation of California bearing ratio by using soft computing systems
    (PERGAMON-ELSEVIER SCIENCE LTD, 2011) Yildirim, B.; Gunaydin, O.
    This study presents the application of different methods (simple-multiple analysis and artificial neural networks) for the estimation of the California bearing ratio (CBR) from sieve analysis, Atterberg limits, maximum dry unit weight and optimum moisture content of the soils. The resistance of granular soils, which are in the superstructure foundation and subgrade layers are usually tested by CBR (California bearing ratio), which is an old and still extensively used experiment. The data were collected from the public highways of Turkey's different regions. Regression analysis and artificial neural network estimation indicated strong correlations (R-2 = 0.80-0.95) between the sieve analysis, Atterberg limits, maximum dry unit weight (MOD) and optimum moisture content (OMC). It has been shown that the correlation equations obtained as a result of regression analyses are in satisfactory agreement with the test results. It is recommended that the proposed correlations will be useful for a preliminary design of a project where there is a financial limitation and limited time. (c) 2010 Elsevier Ltd. All rights reserved.
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    Investigation of Static and Fatigue Characteristics of Thermoplastic CF-UD/PEKK Material for Rotorcraft Lug Parts
    (Springer, 2024) Cakici, U. G.; Ece, R. E.; Toros, S.; Apatay, T.; Yildirim, B.
    In rotary wing aircraft, composite lug structures are perforated structures that connect the rotor and blades. They play a significant structural role in rotary wing aircraft. In this study the effect of lay-up parameters on mechanical strength of a thick composite part that represents a blade root. This part is autoclave manufactured polyetherketoneketone matrix carbon fiber reinforced (CF/PEKK) composites, which have recently been researched for usage in defense and aerospace is investigated. The chosen material carbon-fiber-reinforced polyetherketoneketone composites (CF-PEKK) have an excellent mechanical, physical, thermal performance. Aerospace sector has a special interest on this material due to material's low density and versatility. In this study, static and fatigue performance of rotorcraft lug part were investigated by applying non-destructive-test (NDT) methods and the mechanical strength values were discussed according to the experimental results. It has been observed that the component parts with -/+ 45 degrees layup has the highest mechanical strength. As a result of the static and fatigue tests, it is seen that satisfactorily performance in the view of the both static and dynamic loading states.