stress and strain FREE STUDY（应力和应变自由学习）.pdfVIP

MECHANICAL PRINCIPLES HNC/D PRELIMINARY LEVEL TUTORIAL 1 BASIC STUDIES OF STRESS AND STRAIN This tutorial is essential for anyone studying the group of tutorials on beams.  Essential pre-requisite knowledge for Edexcel HNC Mechanical Principles UNIT 4 outcome 2.  Essential pre-requisite knowledge for the Engineering Council Diploma exam D209 Mechanics of Solids.  Essential pre-requisite knowledge for the Engineering Council Certificate Exam C105 Mechanical and Structural engineering.  Covers part of the syllabus for the Engineering Council Certificate Exam C103 Engineering Science. You should judge your progress by completing the self assessment exercises. These may be sent for marking at a cost (see home page). On completion of this tutorial you should be able to do the following.  Define direct stress and strain.  Define shear stress and strain.  Define the modulus of elasticity and rigidity.  Solve basic problems involving stress, strain and modulus. It is assumed that the student is already familiar with the concepts of FORCE. © D.J.DUNN 1 1. DIRECT STRESS  When a force is applied to an elastic body, the body deforms. The way in which the body deforms depends upon the type of force applied to it. A compression force makes the body shorter. Figure 1 A tensile force makes the body longer. Figure 2 Tensile and compressive forces are called DIRECT FORCES. Stress is the force per unit area upon which it acts. Stress =  = Force/Area N/m2 or Pascals. The symbol  is called SIGMA 2 NOTE O