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Unformatted text preview:  www.07Met.tk  An Activity by Metallurgical & Materials Engineers  Email: arslanafzal321@gmail.com Simple Stresses Simple stresses are expressed as the ratio of the applied force divided by the resisting area or σ = Force / Area. It is the expression of force per unit area to structural members that are subjected to external forces and/or induced forces. Stress is the lead to accurately describe and predict the elastic deformation of a body. Simple stress can be classified as normal stress, shear stress, and bearing stress. Normal stressdevelops when a force is applied perpendicular to the crosssectional area of the material. If the force is going to pull the material, the stress is said to be tensile stressand compressive stressdevelops when the material is being compressed by two opposing forces. Shear stressis developed if the applied force is parallel to the resisting area. Example is the bolt that holds the tension rod in its anchor. Another condition of shearing is when we twist a bar along its longitudinal axis. This type of shearing is called torsion and covered in Chapter 3. Another type of simple stress is the bearing stress, it is the contact pressure between two bodies. Suspension bridges are good example of structures that carry these stresses. The weight of the vehicle is carried by the bridge deck and passes the force to the stringers (vertical cables), which in turn, supported by the main suspension cables. The suspension cables then transferred the force into bridge towers. www.07Met.tkNormal Stress Stress Stress is the expression of force applied to a unit area of surface. It is measured in psi (English unit) or in MPa (SI unit). Another unit of stress which is not commonly used is the dynes (cgs unit). Stress is the ratio of force over area. stress = force / areaSimple Stresses There are three types of simple stress namely; normal stress, shearing stress, and bearing stress. Normal Stress The resisting area is perpendicular to the applied force, thus normal. There are two types of normal stresses; tensile stress and compressive stress. Tensile stress applied to bar tends the bar to elongate while compressive stress tend to shorten the bar. where P is the applied normal load in Newton and A is the area in mm2. The maximum stress in tension or compression occurs over a section normal to the load. SOLVED PROBLEMS IN NORMAL STRESS Problem 104A hollow steel tube with an inside diameter of 100 mm must carry a tensile load of 400 kN. Determine the outside diameter of the tube if the stress is limited to 120 MN/m2. www.07Met.tkSolution 104Problem 105A homogeneous 800 kg bar AB is supported at either end by a cable as shown in Fig. P105. Calculate the smallest area of each cable if the stress is not to exceed 90 MPa in bronze and 120 MPa in steel....
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This note was uploaded on 02/26/2011 for the course ENGINEERIN 1 taught by Professor Cruz during the Spring '11 term at Xavier.
 Spring '11
 cruz
 Stress

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