| Eccentric load |
The external load on a fastener or groups of fasteners is said to be eccentric if the resultant of that load does not pass through the centroid of the group of fasteners (eccentric shear load ) or does not coincide with the bolt axis (eccentric tensile load ). |
| Edge distance |
The distance from the edge of a bearing specimen to the center of the hole in the direction of applied force. |
| Edge distance ratio |
The ratio of the edge distance to the pin diameter in a bearing test. |
| Effective crack size (ae) |
The physical crack size augmented for the effects of cracking plastic deformation. Sometimes the effective crack size is calculated from a measured value of a physical crack size plus a calculated value of a plastic-zone adjustment. A preferred method for calculation of effective crack size compares compliance from the secant of a load-deflection trace with the elastic compliance from a calibration for the type of specimen. |
| Effective discharge area (Unit m2) |
A nominal area for flow through a pressure relief valve used to determine the valve’s flow capacity given the pressure difference across it, the fluid density and correction factors to allow for compressibility, the back pressure and the coefficient of discharge. |
| Effective length of a bolt |
The grip length plus some portion of the bolt (often one-half of the thickness of the nuts) which lies within the nut(s) plus some portion (often one-half the thickness) of the head. |
| Effective radius of nut, bolt head, or threads |
Distance between the geometric center of the part and the circle of points through which the resultant contact forces between mating parts passes. Must be determined by integration. |
| Effective yield strength |
An assumed value of uniaxial yield strength that represents the influence of plastic yielding on fracture test parameters. |
| Elastic calibration device |
A device for use in verifying the load readings of a testing machine consisting of an elastic member(s) to which loads may be applied, combined with a mechanism or device for indicating the magnitude (or a quantity proportional to the magnitude) of deformation under load. |
| Elastic constants |
The factors of proportionality that relate elastic displacement of a material to applied forces. |
| Elastic deformation |
A change in dimensions directly proportional to and in phase with an increase or decrease in applied force. |
| Elastic energy |
The amount of energy required to deform a material within its elastic range of behavior, neglecting small heat losses due to internal friction. The energy absorbed by a specimen per unit volume of material contained within the gage length being tested. It is determined by measuring the area under the stress-strain curve up to a specified elastic strain. See also modulus of resilience and strain energy. |
| Elastic interactions |
When a bolt is tightened it partially compresses the joint members ‘‘in its own neighborhood.’’ When nearby bolts are tightened later, they further compress the joint in this region. This allows the first bolt to relax a little (lose a little preload). Tightening bolts on the opposite side of the joint, however, might increase preload in some of the earlier bolts tightened on the near side. These shifts and changes in the elastic energy stored in individual bolts, during assembly, are called elastic interactions. |
| Elastic limit |
The maximum stress which a material is capable of sustaining without any permanent strain (deformation) remaining on complete release of the stress. |
| Elastic limit |
The maximum stress that a material is capable of sustaining without any permanent strain (deformation) remaining upon complete release of the stress. |
| Elastic recovery |
Amount the dimension of a stressed elastic material returns to its original (unstressed) dimension on release of an applied load. In hardness testing, the shortening of the original dimensions of the indentation upon release of the applied load. |
| Elastic resilience |
The amount of energy absorbed in stressing a material up to the elastic limit; or, the amount of energy that can be recovered when stress is released from the elastic limit. |
| Elastic strain energy |
The energy expended by the action of external forces in deforming a body elastically. Essentially, all the work performed during elastic deformation is stored as elastic energy, and this energy is recovered upon release of the applied force. |
| Elasticity |
The property of a material by virtue of which deformation caused by stress disappears on removal of the stress. A perfectly elastic body completely recovers its original shape and dimensions after release of stress. |
| Elbow |
1. A fitting that connects the ends of two pipes at an angle, 45°, 90°, and 180° being the most common. 2. The third joint on an articulated robot corresponding to the human elbow. |
| Electrode |
The two metallic bodies in a battery or Corrosion cell which give up electrons (the Anode) or which attract them (the Cathode). |
| Electrolyte |
The liquid with which the Electrodes of a battery or Corrosion cell are wetted. |
| Electroplating |
Deposition of one metal on to another using electrolysis. The metal to be plated forms the cathode in an electrolytic cell, and the metal to be deposited forms the anode. |
| Elongation |
A term used in mechanical testing to describe the amount of extension of a test piece when stressed. |
| Elongation measurement |
Bolt elongation is directly proportional to axial stress when the applied stress is within the elastic range of the material. If both ends of a bolt are accessible, a micrometer measurement of bolt length made before and after the application of tension will ensure the required axial stress is applied. |
| Embedment |
Localized plastic deformation in heavily loaded fasteners allows one part to sink into, or smooth the surface of, a softer or more heavily loaded second part. Nuts embed themselves in joint surfaces. Bolt threads embed themselves in nut threads, etc. |
| Embrittlement |
The loss of ductility or fracture toughness of materials, either during processing or in service. |
| Embrittlement |
The severe loss of ductility or toughness or both, of a material, usually a metal or alloy. Many forms of embrittlement can lead to brittle fracture. Many forms can occur during thermal treatment or elevated-temperature service (thermally induced embrittlement). Some of these forms of embrittlement, which affect steels, include blue brittleness, 885 °F (475 °C) embrittlement, quench-age embrittlement, sigma-phase embrittlement, strain-age embrittlement, temper embrittlement, tempered martensite embrittlement, and thermal embrittlement. In addition, steels and other metals and alloys can be embrittled by environmental conditions (environmentally assisted embrittlement). The forms of environmental embrittlement include acid embrittlement, caustic embrittlement, corrosion embrittlement, creep-rupture embrittlement, hydrogen embrittlement, liquid metal embrittlement, neutron embrittlement, solder embrittlement, solid metal embrittlement, and stress-corrosion cracking. |
| End-quench hardenability test |
A laboratory procedure for determining the hardenability of a steel or other ferrous alloy. Hardenability is determined by heating a standard specimen above the upper critical temperature, placing the hot specimen in a fixture so that a stream of cold water impinges on one end, and, after cooling to room temperature is completed, measuring the hardness near the surface of the specimen at regularly spaced intervals along its length. The data are normally plotted as hardness versus distance from the quenched end. |
| Endurance |
The capacity of a material to withstand repeated application of stress. |
| Endurance limit |
The maximum stress below which a material can presumably endure an infinite number of stress cycles. The value of the maximum stress and the stress ratio also should be stated. |
| Endurance limit |
That completely reversing stress limit below which a bolt or joint member will have an essentially infinite life under cyclic fatigue loads. Note that the mean stress on the bolts here is zero. |
| Energy losses (Unit kJ) |
A commonly-used misnomer in view of the conservation-ofenergy principle, but used to mean energy converted into forms that are not used in a process, for example thermal energy from a heat engine dissipated to the surroundings, or produced by friction in a machine, or by surface drag. |
| Engine |
A machine that converts energy, including the chemical energy in a fuel and electrical energy, into mechanical energy, usually to produce power delivered through a rotating shaft or thrust. Examples include internal-combustion engines, gas and steam turbines, rocket engines, electric, hydraulic and pneumatic motors. |
| Engine emissions |
(exhaust emissions) The pollutants contained in the exhaust gases from an internal-combustion engine. |
| Engineering strain (e) |
A term sometimes used for average linear strain or conventional strain in order to differentiate it from true strain. In tension testing it is calculated by dividing the change in the gage length by the original gage length. |
| Engineering stress (s) |
A term sometimes used for conventional stress in order to differentiate it from true stress. In tension testing, it is calculated by dividing the breaking load applied to the specimen by the original crosssectional area of the specimen. |
| Equation, long form |
An equation which relates the torque applied to a bolt to the preload created in it, and involves fastener geometry and the coefficient of friction between mating surfaces. A theoretical equation based on rigid body mechanics and the assumption that the geometry of the fastener is perfectly described by blueprint dimensions. |
| Equation, short form |
An empirical equation which relates the torque applied to the bolt to the preload created in it, and which depends mainly on an experimentally derived factor called the Nut factor. |
| Equilibrium diagram |
A graphical representation of the temperature, pressure and composition limits of phase fields in an alloy system as they exist under conditions of complete equilibrium. In metal systems, pressure is usually considered constant. |
| Erosion |
Progressive loss of original material from a solid surface due to mechanical interaction between that surface and a fluid, a multicomponent fluid, or impinging liquid or solid particles. |
| Essential conditions |
Each type of failure to which bolted joints are subject is set up by three or four conditions. The conditions vary, depending on the mode of failure, but never number more than four. Eliminating any one of the essential conditions for a particular type of failure can prevent that type of failure. |
| Eutectic |
(1) An isothermal reversible reaction in which a liquid solution is converted into two or more intimately mixed solids on cooling, the number of solids formed being the same as the number of components in the system. (2) An alloy having the composition indicated by the eutectic point on an equilibrium diagram. (3) An alloy structure of intermixed solid constituents formed by a eutectic reaction. |
| Eutectic carbide |
Carbide formed during freezing as one of the mutually insoluble phases participating in the eutectic reaction of ferrous alloys. |
| Eutectic melting |
Melting of localized microscopic areas whose composition corresponds to that of the eutectic in the system. |
| Eutectoid |
(1) An isothermal reversible reaction in which a solid solution is converted into two or more intimately mixed solids on cooling, the number of solids formed being the same as the number of components in the system. (2) An alloy having the composition indicated by the eutectoid point on an equilibrium diagram. (3) An alloy structure of intermixed solid constituents formed by a eutectoid reaction. |
| Expansion bolt |
When a through bolt cannot be used for attaching a pipe hanger, bracket, or other part, to a wall or ceiling of brick or concrete, what are known as expansion bolts are often used. The body of an expansion bolt is divided and the arrangement is such that, when the head of the bolt is turned, the sections forming the body of the bolt are forced outward and against the wall of the hole which has been drilled into the brick, concrete, or stone, as the case may be. Bolts of this type are made in quite a variety of designs. The nominal size represents the diameter of the bolt proper and not the diameter of the casing or expansion member. |
| Extensometer |
An instrument for measuring changes in length over a given gage length caused by application or removal of a force. Commonly used in tension testing of metal specimens. |
| Extensometer |
Any instrument which measures the change in length of a part as the part is loaded. |
| External load |
Forces exerted on fastener and=or joint members by such external factors as weight, wind, inertia, vibration, temperature expansion, pressure, etc. Does not equal the Working load in the fastener. |
| Extra hard |
A temper of nonferrous alloys and some ferrous alloys characterized by tensile strength and hardness about one-third of the way from full hard to extra spring temper. |
| Extra spring |
A temper of nonferrous alloys and some ferrous alloys corresponding approximately to a coldworked state above full hard beyond which further cold work will not measurably increase the strength and hardness. |
| Eye bolt |
A bolt threaded at one end and bent to a loop at the other end. |
| Eyebolt (eyescrew) |
A bolt or screw with a closed loop in place of a head. |
