Analysis of Distortion and Deformation Revised by Roch J. Shipley and David A Moore, Packer Engineering and William Dobson, Binary Engineering Associates. Inc Introduction THIS HANDBOOK is organized according to four general categories of failure: fracture, corrosion, wear, and the subject of this article, distortion. One reason metals are so widely used as engineering materials is that they have high strength but also generally have the capability to respond to load(stress) by deforming. In fact, much of metallurgical engineering is concerned with balancing strength and ductility. Thus, distortion often is observed in analysis of other types of failures, and consideration of the distortion can be an important part of the analysis. Energy is absorbed during deformation, and in some situations, the amount of energy absorbed may also be an important factor. Furthermore, it should be noted that not all distortion necessarily constitutes This article first considers true distortion failures that is situations in which distortion occurs when it should not have occurred and in which the distortion is associated with a functional failure. Then, a more general consideration of distortion in failure analysis is introduced. As used here, distortion will refer to a condition in which the shape of a component has changed without loss of material. Deformation will refer to the process that results in the distortion Distortion failure occurs when a structure or component is deformed so that it can no longer support the load was intended to carry, is incapable of performing its intended function, or interferes with the operation of another component. Distortion failures can be plastic or elastic and may or may not be accompanied by fracture. There are two main types of distortion: size distortion, which refers to a change in volume(growth or shrinkage), and shape distortion(bending or warping), which refers to a change in geometric form. Most of the examples in this article deal with metals, but the concepts also apply to nonmetals. Materials as diverse metals, polymers, and wood are all susceptible to distortion, although the mechanisms may differ somewhat among the different classes of material Distortion failures are ordinarily considered to be self-evident, for example, damage of a car body in a collision or bending of a nail being driven into hard wood. However, the failure analyst is often faced with more subtle situations. For example, the immediate cause of distortion(bending) of an automobile-engine valve stem is contact of the valve head with the piston, but the failure analyst must go beyond this immediate cause in order to recommend proper corrective measures. The valve may have stuck open because of faulty lubrication; the valve spring may have broken because corrosion had weakened it. The spring may have had insufficient strength and taken a set, allowing the valve to drop into the path of the piston, or the engine may have been raced beyond its revolutions per minute limit many times, causing coil clash and subsequent fatigue fracture of the spring. Without careful consideration of all the evidence, the failure analyst may overlook the true cause of a distortion failure. Several common aspects of failure by distortion are discussed in this article, and suitable examples of distortion failures are presented for illustration Analysis of Distortion and Deformation Revised by Roch ]. Shipley and David A. Moore, Packer Engineering and william Dobson, Binary Engineering Associates, Inc. Overloading Every structure has a load limit beyond which it is considered unsafe or unreliable. Applied loads that exceed this limit are known as overloads and sometimes result(depending on the factor of safety used in design)in distortion or fracture of Thefileisdownloadedfromwww.bzfxw.comAnalysis of Distortion and Deformation Revised by Roch J. Shipley and David A. Moore, Packer Engineering and William Dobson, Binary Engineering Associates, Inc. Introduction THIS HANDBOOK is organized according to four general categories of failure: fracture, corrosion, wear, and the subject of this article, distortion. One reason metals are so widely used as engineering materials is that they have high strength but also generally have the capability to respond to load (stress) by deforming. In fact, much of metallurgical engineering is concerned with balancing strength and ductility. Thus, distortion often is observed in analysis of other types of failures, and consideration of the distortion can be an important part of the analysis. Energy is absorbed during deformation, and in some situations, the amount of energy absorbed may also be an important factor. Furthermore, it should be noted that not all distortion necessarily constitutes a “failure.” This article first considers true distortion failures, that is, situations in which distortion occurs when it should not have occurred and in which the distortion is associated with a functional failure. Then, a more general consideration of distortion in failure analysis is introduced. As used here, distortion will refer to a condition in which the shape of a component has changed without loss of material. Deformation will refer to the process that results in the distortion. Distortion failure occurs when a structure or component is deformed so that it can no longer support the load it was intended to carry, is incapable of performing its intended function, or interferes with the operation of another component. Distortion failures can be plastic or elastic and may or may not be accompanied by fracture. There are two main types of distortion: size distortion, which refers to a change in volume (growth or shrinkage), and shape distortion (bending or warping), which refers to a change in geometric form. Most of the examples in this article deal with metals, but the concepts also apply to nonmetals. Materials as diverse as metals, polymers, and wood are all susceptible to distortion, although the mechanisms may differ somewhat among the different classes of material. Distortion failures are ordinarily considered to be self-evident, for example, damage of a car body in a collision or bending of a nail being driven into hard wood. However, the failure analyst is often faced with more subtle situations. For example, the immediate cause of distortion (bending) of an automobile-engine valve stem is contact of the valve head with the piston, but the failure analyst must go beyond this immediate cause in order to recommend proper corrective measures. The valve may have stuck open because of faulty lubrication; the valve spring may have broken because corrosion had weakened it. The spring may have had insufficient strength and taken a set, allowing the valve to drop into the path of the piston, or the engine may have been raced beyond its revolutions per minute limit many times, causing coil clash and subsequent fatigue fracture of the spring. Without careful consideration of all the evidence, the failure analyst may overlook the true cause of a distortion failure. Several common aspects of failure by distortion are discussed in this article, and suitable examples of distortion failures are presented for illustration. Analysis of Distortion and Deformation Revised by Roch J. Shipley and David A. Moore, Packer Engineering and William Dobson, Binary Engineering Associates, Inc. Overloading Every structure has a load limit beyond which it is considered unsafe or unreliable. Applied loads that exceed this limit are known as overloads and sometimes result (depending on the factor of safety used in design) in distortion or fracture of The file is downloaded from www.bzfxw.com