Fonksiyonel Derecelendirilmiş İç Dış Basınca Maruz Sabit Açısal Hızla Dönen Silindirik Ve Küresel Kaplarda Elastisite Denklemlerinin Analitik Çözümleri

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2015Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2015Bu çalışmada radyal doğrultuda basit kuvvet (simple power) fonksiyonu ile derecelendirilmiş, iç ve dış basınca maruz, kalın cidarlı sabit açısal hızla dönen silindirik ve küresel basınçlı kaplarda elastisite denklemleri analitik olarak çözülmüş; radyal ve teğetsel doğrultudaki gerilmeler ile radyal doğrultudaki yer değiştirme ifadeleri tasarımcılar, mühendisler, akademisyenler ve diğer kullanıcılar için en basit ve en kullanışlı formda sunulmuştur. İç ve dış basıncın eş zamanlı olarak dönen yapıya etkimesi durumu için elde edilen kapalı çözümler, üç farklı metal-seramik çifti için grafikler halinde sunulmuştur. Ayrıca iç ve dış basınç ile sabit açısal dönme hızının da etkileri ayrık olarak ta incelenmiştir.In this study, by using the simple power material grading rule, the elasticity equations of radially functionally graded pressurized thick-walled rotating cylindrical and spherical vessels are solved analytically. Afterwards, the closed-form solutions of both the radial and hoop stresses, and the radial displacements are presented to be the simplest and most convenient form for scientists, designers, engineers, and the others. Considering three different metal-ceramic pairs, the results of the closed-form solutions are presented graphically in the case that the internal and external pressures are applied simultaneously on the rotating structure. Apart from these unique effects of both the internal and external pressures and constant angular velocity are also investigated separately

Tek doğrultulu kompozit helisel bası yaylarının burkulma ve titreşim analizleri.

TEZ10204Tez (Doktora) -- Çukurova Üniversitesi, Adana, 2013.Kaynakça (s. 139-144) var.xxi, 154 s. : res., tablo ; 29 cm.Klasik makina elemanları olarak silindirik veya silindirik olmayan ön yüklü yaylar, sıklıkla dinamik yüklere maruz kalırlar. Bu nedenle bunların statik, dinamik ve burkulma davranışlarının anlaşılması önemlidir. Son otuz yılda helisel yaylar konusunda çok sayıda araştırma yapılmasına rağmen, problemin karmaşıklığından dolayı izotropik ön yüklü helisel yaylar konusunda literatürde çok az sayıda çalışma mevcuttur. Üstelik ön yüklü kompozit helisel yaylar konusunda literatürde hiçbir çalışma bulunmamaktadır. Bu tezde, pratikte kullanılan kompozit ön yüklü helisel yayların titreşim ve burkulma gibi iki önemli konusu ele alınmıştır. Literatürde mevcut ön yük etkisini de içeren hareket denklemleri kompozit helisel yaylar için genişletilmiştir. Birinci mertebe teorisine dayanan rijitlik matrisi yöntemi kullanılmıştır. Eleman rijitlik matrisi tamamlayıcı fonksiyonlar ve taşıma matrisi yöntemlerine dayanılarak kesin olarak elde edilmiştir. Sayısal sonuçlar literatürdeki ön yüklü izotropik helisel yay sonuçları ile doğrulanmıştır. Sonuç olarak, bu tip yayların burkulma/titreşim problemlerinin formülasyonunda ön yük nedeni ile oluşan deformasyon sonrası yayın geometrik özelliklerinin doğru bir şekilde hesaplanması gerekli olduğundan, ön yüke maruz büyük helis açılı helisel yayların eksenel doğrultudaki yer değiştirmesi birinci Castigliano teoremi yardımı ile analitik olarak çözülmüştür.As a standard member of machines, springs with pre-load either cylindrical or non-cylindrical shaped are frequently subjected to dynamic loads. Hence it is important to understand their static, dynamic, and buckling behaviours. Although many investigations of helical springs were performed in the last three decades, Few studies on the buckling and vibration behaviour of isotropic helical springs subjected to an axial load may be found in the available literature due to the complexity in the formulation of the problem. Besides this, there is no study about the analysis of composite helical springs subjected to an axial force. In this thesis, two important phenomena namely the buckling and vibrational analysis of the most commonly used composite helical compression springs subjected to an axial force are studied. The existing governing equations which consider the pre-axial load effect in the literature will be extended to composite helical springs. Stiffness method is used based on the first order shear deformation theory. The element stiffness matrix is obtained exactly based on the both the complementary functions and the transfer matrix methods. Numerical results are verified by the benchmark studies for isotropic helical springs subjected to an axial force. It is concluded that, since the true geometrical properties after deformation due to the axial static load are required in the formulation to understand the buckling/vibration behaviour of such pre-loaded springs, closed-form solutions for the vertical tip deflection of those helical springs having large pitch angles are derived using the Castigliano’s first theorem

Free vibration/buckling analyses of noncylindrical initially compressed helical composite springs

WOS: 000386159000004This article presents the use of the stiffness matrix method based on the first-order shear deformation theory to predict the fundamental natural frequencies and buckling loads of noncylindrical unidirectional composite helical springs subjected to initial static axial force and moment. This theoretical study about such springs with circular/rectangular cross-sections and large pitch angles is performed for the first time in the literature. The validity of the present results is verified by the benchmark studies related with initially compressed isotropic cylindrical springs

A method for the Computational Frequency Sweep Analysis of Nonlinear ODEs using GPU Acceleration

Computational sweep analysis of nonlinear ODEs (ordinary differential equations) is of importance in engineering system analysis and design. Sweep analyses usually demand intense computational power according to the number of points and the number of system parameters. This paper presents an efficient parallel algorithm for the sweep analysis of nonlinear ODEs based on graphical processing unit acceleration. The developed method preserves the jump phenomenon characteristics intrinsic to nonlinear ODEs and reduces the effects of irregular computational load. Experiments were realized using Duffing equation by sweeping frequency, amplitude, and equation coefficients. Directly, data parallel implementation and proposed implementations are compared to show the efficiency of the proposed method. Experimental results show that the new method provides significant reductions in the computational durations when compared to sequential implementation

Review of warm forming of aluminum-magnesium alloys

WOS: 000259786200001Aluminum-magnesium (Al-Mg) alloys (5000 series) are desirable for the automotive industry due to their excellent high-strength to weight ratio, corrosion resistance, and weldability. However, the formability and the surface quality of the final product of these alloys are not good if processing is performed at room temperature. Numerous studies have been conducted on these alloys to make their use possible as automotive body materials. Recent results show that the formability of these alloys is increased at temperature range from 200 to 300 degrees C and better surface quality of the final product has been achieved. The purpose of this paper is to review and discuss recent developments on warm forming of Al-Mg alloys. (C) 2008 Elsevier B.V. All rights reserved.Scientific and Technological Research Council of Turkey (TUBITAK) [106M058]This work is supported by The Scientific and Technological Research Council of Turkey (TUBITAK). Project Number: 106M058, Title: "Experimental and Theoretical investigations of The Effects of Temperature and Deformation Speed on Formability". TUBITAK support is profoundly acknowledged

Defects and Remedies in Stamping of Advanced High Strength Steels

In recent years, the use of advanced high strength steels (AHSS) in the automotive industry has increased due to their potential in reducing weight, leading to lower fuel consumption and carbon dioxide emissions. The AHSS structures would be the optimum choice for many applications; however, there are many defects to overcome in their stamping. In this present study, different types of defects and remedies of AHSS stampings are presented

New trend in aerospace industry: Al-Li based alloys

WOS: 000462490600020Al-Li (Aluminum-Lithium) alloys have become the focus of the aerospace industry due to their low density and high elasticity modulus, excellent corrosion resistance, high hardness, high fatigue crack growth resistance, and low fracture toughness. Alloys continue to be used in various structural parts of the aircrafts such as seat beams, floor beams and columns, wing beams, cradle frames, and research studies are intensively going on about its future use for other structural parts. As with all materials, there are various problems in these alloys. In this study, the use of Al-Li based alloys in the aerospace industry, the problems encountered, and the proposal of solutions have been examined

Fonksiyonel Derecelendirilmiş Malzemeden (Fgm) Yapılmış Silindir, Küre Ve Değişken Kalınlıklı Diskte Radyal Doğrultuda Sürekli Rejimde Fourıer Isı İletimi İçin Analitik İfadeler

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2015Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2015Bu çalışmada sürekli rejimde Fourier ısı iletimi teorisi kullanılarak, radyal doğrultuda basit kuvvet (simple power) fonksiyonuna uyacak şekilde fonksiyonel derecelendirilmiş kalın cidarlı silindirik ve küresel kaplar ile değişken kesitli disklerin ısıl analizleri, iç ve dış yüzeylerde tanımlı sabit sıcaklık sınır şartları (birinci tip sınır şartı/Dirichlet şartları) kullanılarak analitik olarak gerçekleştirilmiştir. Euler-Cauchy tipinde elde edilen diferansiyel denklemler çözülerek, söz konusu yapılarda radyal doğrultuda sıcaklık ve ısı akısı değişim fonksiyonları kapalı olarak sunulmuştur. Bu çalışmada elde edilen formüller doğrudan ilgili yapıların analitik ısıl gerilme analizlerinde kullanılabileceği gibi sayısal analizlerden elde edilen sonuçların doğruluğunun kontrol edilmesi amacıyla da kullanılabilecektir. Üç farklı FGM için gerçekleştirilen uygulamada, yoğunluk ve özgül ısının radyal doğrultudaki değişimlerinin hassas bir ısıl analiz için mutlaka göz önüne alınması gerektiği anlaşılmıştır.In this study, thermal analysis of radially functionally graded thick-walled cylindrical, spherical vessels, and variable cross-section discs is investigated analytically by steady-state one dimensional Fourier heat conduction theory with first kind (prescribed temperature/ Dirichlet conditions) boundary conditions at inner and outer surfaces. By solving differential equations in the form of Euler-Cauchy and by using the simple power material grading rule, the temperature and heat flux functions in the radial direction are presented in closed forms. Present formulas may be used directly for the analytic thermal stress analysis of such structures and for testing the results obtained by numerical analyses as benchmark formulas, as well. In three different FGM applications, it is revealed that the radial variation of both the density and specific heat should be account for an accurate thermal analysis