İleri Malzeme Mekaniği Giriş ve Gözden Geçirme Dleri Malzeme Mekaniği Dr. Nusret MEYD ANLIK Ders Ders 1 1 Dleri Malzeme Mekaniği MK 645 Dr. Nusret MEYDANLIK nm-2011 - - G G DD R R DD Ş Ş - - Kaynak: Kaynak: -Mechanical Behavior of Materials Course Notes, Dr. Mark L. Weaver -Mechanical Metallurgy, G.E. Dieter Bölüm 1 Dleri Malzeme Mekaniği Dr. Nusret MEYDANLIK 2 Ders notları, sunulan slaytlar ve ödevler, derste kullanılan slaytları aşağıdaki adreste bulabilirsiniz. http:// http://nusretmeydanlik nusretmeydanlik. .trakya trakya.edu.tr/dersler. .edu.tr/dersler.htm htm Advanced Mechanics of Materials, ARTHUR P. BORESI & RICHARD J. SCHMIDT Mechanical Metallurgy, G.E. Dieter Web de konu ile ilgili siteler Email: nusretm nusretm@gmail.com @gmail.com Course MaterialsBölüm 1 Dleri Malzeme Mekaniği Dr. Nusret MEYDANLIK 3 Bu derste neler öğrenmeyi umuyorsunuz ? Giriş . . . . Bölüm 1 Dleri Malzeme Mekaniği Dr. Nusret MEYDANLIK 4 Course Information Course Information • Malzemelerin değişik yüklere karşı tepkisini mekanik davranış belirler. • What is mechanical behavior? We shall address this subject from both perspectives. WHY?Bölüm 1 Dleri Malzeme Mekaniği Dr. Nusret MEYDANLIK 5 Bölüm 1 Dleri Malzeme Mekaniği Dr. Nusret MEYDANLIK 6 Engineer Engineer’ ’s s Approach Approach to to Mechanical Mechanical Behavior Behavior • Solid mechanics approach (1) – Use of principles of elasticity and plasticity to predict material response. (statics, dynamics, and strength of materials, etc.). – Applied with great frequency in design. Still very useful and easy! (Finite element analysis/modeling) – This This approach approach neglects neglects the the microstructure microstructure of a of a material material. . This This approach approach treats treats a a material material as a as a “ “black black box box” ” wherein wherein properties properties never never change change. . – The advantages are that relatively few constants are needed to predict mechanical behavior. – Approach requires some assumptions.Bölüm 1 Dleri Malzeme Mekaniği Dr. Nusret MEYDANLIK 7 General General assumptions assumptions – The member is in static equilibrium •?F i =0; ?M i =0 (external forces = internal resisting forces) – The body is continuous • It contains no voids, holes, or spaces. >ALL materials contain flaws on some level. – The body is homogeneous • It has properties that are identical at any point >ALL materials and structures contain local inhomogeneities. – The body is isotropic • Properties don’t vary with direction or orientation. >Crystalline anisotropic materials are inherently anisotropic. Allows Allows for for “ “simple simple” ” mathematical mathematical treatment treatment in in design design Bölüm 1 Dleri Malzeme Mekaniği Dr. Nusret MEYDANLIK 8 Solid Solid mechanics mechanics approach approach a devam a devam – Problem: Problem: general theories break down when the atomic nature of materials is introduced. – – Examples Examples: : • Creep (a form of high temperature deformation). - microstructure changes with time. • Stress concentrations at crack tips. - Local stress may be higher than global stress. • Ductile-to-brittle transition temperature (DBTT) in steels. - Fundamental changes in the material behavior cause a brittle solid to function like a “plastic” material. • Etc.Bölüm 1 Dleri Malzeme Mekaniği Dr. Nusret MEYDANLIK 9 Solid Solid mechanics mechanics approach approach a devam a devam – In spite of the deficiencies, solid solid mechanics mechanics ( (strength strength of of materials materials or or mechanics mechanics of of materials materials) ) approaches approaches are still used in engineering design. – However However, to effectively effectively design design or properly properly select select a a material material for long term application, the structure of the material must be considered at some level. Macrostructure (x1) Microstructure (x10 6 ) Nanostructure (x10 9 ) Bölüm 1 Dleri Malzeme Mekaniği Dr. Nusret MEYDANLIK 10 Mekanik Mekanik ö özellikler zelliklerBölüm 1 Dleri Malzeme Mekaniği Dr. Nusret MEYDANLIK 11 Giriş ve gözden geçirme Gerilme genleme teorileri Dengenin diferansiyel denklemi Dnelastik malzeme davranışı Hasar teorileri Kalın cıdarlı silindirler Enerji yöntemleri . . . . . . Dersin i Dersin iç çeri eriğ ği i Bölüm 1 Dleri Malzeme Mekaniği Dr. Nusret MEYDANLIK 12 B B B B B B B B DD D DDD D D T T T T T T T T T T T T T T T T DD D DDD D D Haftaya g Haftaya g Haftaya g Haftaya g Haftaya g Haftaya g Haftaya g Haftaya g ö ö ö ö ö ö ö ö r r r r r r r r ü ü ü ü ü ü ü ü ş ş ş ş ş ş ş ş mek mek mek mek mek mek mek mek ü ü ü ü ü ü ü ü zere zere zere zere zere zere zere zere … … … … … … … … . . . . . . . .