# Mechanics of Materials

 The flashcards below were created by user timothyowens on FreezingBlue Flashcards. Mechanics of Materials -1 - deals with the elastic behaviour of materials and the stability of members. - mechanics of materials concepts are used to determine the stress and deformation of axially loaded members, connections, tortuonal members, thin-walled pressure vessels, beams, eccentrically loaded members, and columns. Stress - is force per unit area - typical units of stress are lbf/in2 , Ksi, and MPa. - There are two primary types of stress: normal stress and shear stress. - With normal stress, o-, the force is normal to the surface are alpha? - With shear stress, T, the force is parallel to the surface are: o- = Pnormal to the area / A Tao = Pparallel to area / A Linear Strain, Epsilon - is a change of the length per unit of length - Linear strain mah be listed as having unites of in / in, mm / mm, percent or no units at all. Shear Strain, Tao - is an angular deformation resulting from shear stress. - shear strain may be presented in units of radians, percent or no units at all. Epsilon = delta / L Tao = deltaparallel to area / height = tan theta aprox = theta [ theta is in radians ] Hooke'a law - is a simple mathematical statement of the relationship between elastic stress and strains: stress is proportional to strain. - For normal stress, the constant of proportionality is the modulus of elasticity ( Youngs modulus ), E o- = E*epsilon Poison ratio, y is a constant that relates the lateral strain to the axial strain for axially loaded members. y= Epsionlateral / Epsilonaxial Theoretically, Poison's ratio could vary from zero to 0.5 but the typical values are 0.35 for aluminum and 0.3 for steel. Hookes Law - 2 - shear modulus - Hooke's law may also be applied to a plane element in pure shear/ - For such an element, the shear stress is linearly related to the shear, strain, Tao , by the shear modulus ( also known as the modulus of regidity ) G. Tao = Gtao Hooke's Law 3 Modulus of Elasticity / Shear modulus / Poison's Ratio - For an elastic isotropic material , the modulus of elasticity, shear modulus and Poinsons ratio are related by G= E/ 2(1+V) E = 2G(1+V) Material Properties materials |units (a)| steel|aluminnum |Cast Iron |WoodFir Modulus of | Mpsi |29.0...| 10.0 ....... | 14.5....... | 1.6 elasticity, E | GPa |200.0| 69.0.........| 100.0.......|11.0 modulus of | Mpsi| 11.5..| 3.8............| 6.0..........| 0.6 rigidity, G | GPa | 80....|26.0............| .41.4.......| 4.1 Authortimothyowens ID136487 Card SetMechanics of Materials DescriptionFE - Mechanics of Materials Updated2012-02-26T17:53:01Z Show Answers