This preview shows pages 1–8. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: Chapter 8 Stress and Strain Objective z To introduce the concepts of normal and shear stresses, and to use them in the analysis and design f members subject to axial load and direct shear of members subject to axial load and direct shear z To define normal and shear strain, and show how they can be determined for various types of roblems problems Chapter 8 Stress and Strain Chapter 8 Stress and Strain 82 Introduction z Mechanics of materials is a branch of mechanics that studies the relationship between external loads applied to a deformable body and the intensity of internal forces (stresses) acting within the body. z It involves computing the deformation of the body, and it provides a study of the stability of the body when the body is subjected to external forces. 83 Chapter 8 Stress and Strain Chapter 8 Stress and Strain Structural Design Design Process: z Determine the forces acting both on and within its various members by using the principles of statics z Select the type of material alculate the size of the member by satisfying the allowable stresses z Calculate the size of the member by satisfying the allowable stresses z Check the deflection and stability of the member any formulas and rules for design as defined in engineering codes and sed Many formulas and rules for design, as defined in engineering codes and used in practice, are based on the fundamentals of mechanics of materials. 84 Chapter 8 Stress and Strain Chapter 8 Stress and Strain Properties of Materials Assumptions on properties of materials: z Continuous → consists of continuum or uniform distribution of matter having no voids z Cohesive → all portions are connected together, rather having breaks, p g , g , cracks or separations z Homogeneous → has the same physical and mechanical properties throughout its volume z Isotropic → has the same properties in all directions, i.e. steel nisotropic → has different properties in different directions i e timber z Anisotropic → has different properties in different directions, i.e. timber 85 Chapter 8 Stress and Strain Chapter 8 Stress and Strain Stresses Normal Stress, σ The intensity of force, or force per unit ti l t Δ A area, acting normal to Δ A Pull → tension, Push → compression Shear Stress, τ The intensity of force, or force per unit area acting tangent to Δ A. The first subscript specifies the orientation of the area, and the second subscript refers to the direction of the shear stress eneral States of Stress General States of Stress This state of stress is characterized by three components acting on each face of the element 86 Chapter 8 Stress and Strain Chapter 8 Stress and Strain Average Normal Stress in an Axially Loaded Bar The resultant of the internal forces for an axially loaded member is normal to a ti t di l t th b section cut perpendicular to the member axis. The force intensity on that section is defined as the normal stress, σ , and the average normal stress is: For design, it is important to find...
View
Full
Document
This note was uploaded on 09/09/2009 for the course CEE CV2101 taught by Professor Soh during the Spring '09 term at Nanyang Technological University.
 Spring '09
 SOH

Click to edit the document details