What are the different types of Screw Heads? It is chemically unstable and susceptible to corrosion in marine environments. The fatigue failure usually takes place suddenly (without warning) and is catastrophic. Effect of nearby assemblies such as weldments and shrink fits on stress conditions. The indenter first overcomes the resistance of the material to elastic deformation and then a small amount of plastic deformation. A work is done on an object when the force acts on it in the direction of motion or has component in the direction of motion. There are quite a few variations of this type. Fundamentals of Engineering (FE) Exam Why take the FE Exam? A component list called as part list is prepared and put on one side of the drawing. They are mainly classified into. Figure 7.29 shows a symbol of a diode. Two gears working together are called a gear train. A refrigerator is essentially an insulated box with a heat pump system connected to it. Some names you may already be familiar with. However, these energy transformations are constrained by a fundamental principle, the Conservation of Energy principle, which is “Energy can neither be created nor destroyed”. 11 CAM The wax pattern itself can be made using a stereo lithography (or similar) model, which has been fabricated using a computer solid model master. The process can be industrial, infrastructure or facility based as described below: A SCADA system includes input/output signal hardware, controllers, HMI, networks, communication, database and software. Through a mechanical arrangement, the force to be sensed is used in deforming a strain gauge. Because the sliding core does not touch the inside of the tube, it can move without friction, making the LVDT a highly reliable device. Even though it is weak and soft in its pure form, its alloys are hard and rigid. Chains (Figure 4.31) generally have a long life if used under proper conditions. It even scores over riveted joints. Ductility can be defined as how easily a material can be drawn into thin wires or rolled into thin sheets. Heat engines typically run on a specific thermodynamic cycle. The limiting dimensions for manufacturing a part based on the tolerance specified by the designer is called the limit. The problem with these formulas still remains that these contain a dependence on ks. Deep groove, angular contact, cylindrical rollers. It is drawn as a thick dark line at the extremes and thin long line followed by two short lines in a chain. Hence the induced magnetic field gets attracted (because of the opposite polarity) and tries to be aligned with the main rotating magnetic field. They are available on main frame as well as on PC. As the load increases, the specimen will start yielding. The limits for the tolerance are specified by the designer on the drawing from the considerations of forming a desired fit between two parts. These types of switches are very commonly used as safety devices, for example to control the displacement of machinery parts. Different methods are used to express this error depending on the method used to determine the straight line relationship against which error will be measured. The metal surfaces develop anodic and cathodic characteristics because of structural and chemical inhomogeneities exising in the metals. Since fluctuations are temporal phenomena, there is some relationship between the timescale for the fluctuation and the minimum detectable amplitude. The four steps of the cycle are: The PV (pressure-volume) and Ts (temperature-entropy) diagrams are shown in Figure 10.11. The compressor is composed of several rows of airfoil cascades. The final gear on the train to which the force is first applied is called the driven gear. This section is very useful and elegant way of showing the interior portion of a symmetrical object. Heat exchangers are devices built for efficient heat transfer from one fluid to another and are widely used in engineering processes. The main components of a centrifugal pump are as follows: After motors, centrifugal pumps are arguably the most common machine, and they are a significant user of energy. When the heat waves hit the cooler thing, they make the molecules of the cooler object speed up. P = external tensile load The bottom line is that scheduling the rebuild of a machine which follows the pattern of the traditional bathtub curve actually increases the overall probability of a failure! When work is done by a thermodynamic system, it is usually a gas that is doing the work. The contacts may be normally open, closing when a magnetic field is present, or normally closed and opening when a magnetic field is applied. Nonlinearity (sometimes called Linearity). For this purpose it uses laws of physics and applies them to analyze their performance. Mechanical Engineering: Fundamentals - Kindle edition by Devendra Vashist. In a reaction turbine the nozzles that discharge the working fluid are attached to the rotor. The load on the bearing can be a radial or axial (thrust) load. Pump shaft power (Ps) is the actual horsepower delivered to the pump shaft, and can be calculated as follows: Pump efficiency = Hydraulic power / Pump shaft power. This chapter will cover various manufacturing process used in mechanical engineering. This chapter describes the engineering behind fluid pumps, turbines and other machines and their operations. Loss of energy is proportional to first power of velocity and first power of viscosity. They serve as a common language, defining quality and establishing safety criteria. There are two systems of dimensioning and each industry has its own preference. Convection happens when a substance that can flow, like water or air is heated in the presence of gravity. Tempering treatment consists of re-heating the steel after hardening to temperatures below the critical line, holding it there for considerable time (not less than 4 to 5 minutes for each millimeter of section) and then slow cooling. It will require the following steps: We know that predictive maintenance is based on condition of the equipment. Steel after quenching is hard and brittle, with large internal stresses. Lap joints Fatigue is a very important consideration for machines which are subjected to continuous cyclic loading such as springs, gear teeth, valves, turbine blades, aircraft, gas engines, bridges, etc. The woodruff key consists of a segment of a circular disc of uniform thickness. But for laminar flow it is possible to calculate a theoretical value for a given velocity, fluid and pipe dimension. The relationship between torque and force is: where It is possible to achieve very low speed synchronous rotation with a load that is directly coupled to the shaft. This in itself is sufficiently clear to indicate the type of welding. This type of threads are used for special purpose. The relative motion between the two parts is prevented by the use of keys placed in the key ways. D = Diameter of the pipe Use gradual changes in section and symmetry of design to reduce secondary flexure. Corrosion is a serious concern in chemical industries. A needle spear moving inside the nozzle controls the fluid flow through the nozzle and the same time provides a smooth flow. Find the speed of dynamo shaft, when A) there is no slip, and B) there is a slip of 2% at each drive. Establishing an effective predictive maintenance program that utilizes powerful and accurate technologies such as Ultrasound and Infrared, enables maximum profitability through the ability to see and hear areas of concern we never could before – with precise, timely results, granting an enormous advantage over standard predictive maintenance practices. Oil produced at the wells is piped or shipped for use as feedstock in petroleum refineries. The ball has a hole, or port, through its middle. Often this term is also used to indicate the sensitivity to inputs other than that being measured, i.e. This is very important if the drawings are stored in a software form. Confusion due to lack of communication is completely eliminated. The instruments are placed at the primary location where oil enters from sump or in the oil itself. When fluid flows in a pipe, it experiences some resistance to its motion, due to which its velocity and ultimately the head available is reduced. Fundamentals of Engineering Exam - Mechanical Engineering - Purdue University One has to appreciate that the study of an electrical machine can be interchangeably associated with either a motor or a generator. The three categories are parallel flow, counter flow and cross flow. The development of turbine meters giving accurate measurement over a wide range of flow rates for a large number of fluids, coupled with the advances made in the electronics industry in utilizing the turbine output for flow control and integration, are the reasons for universal acceptance of the turbine principle. This joint is not really advisable due to lower strength. The flux reacts with impurities. The basic concept is similar to the principle of squirting toothpaste from a tube. which can selected and used with a click of mouse to generate a drawing. These pumps operate with good efficiency in this region, but also can produce pressure pulsations. Sometimes there could be more than one material which will satisfy all the requirements of design, however the cost may be the consideration for choosing one amongst them. The flux reacts with impurities. Francis turbines have mixed flow runners, which are used for low heads and large quantities of flow. Plastic deformation gives warning of imminent fracture. It is the head measured across the pump inlet and outlet flanges. The maximum coefficient of such an air conditioner is Typical IC engines are classified as Spark and Compression ignition engines. Strain is plotted against time. A gear train is the arrangement of gears in a gear box to achieve the required speed reduction or higher speed and torque or power. The material breaks into pieces under impact or under a tensile load. The use of a variable rack was invented by Arthur E. Bishop, to improve vehicle response and steering “feel” on-centre, and was fitted to many new vehicles after he created a hot forging process to manufacture the racks, thus eliminating any subsequent need to machine the form of the gear teeth. With special tools, a shaper is able to cut external and internal keyways, spiral grooves, gear racks, dovetails and T-slots. The thread has rounded crests and roots (Figure 4.66). The PLC uses a digital output to open and close the inlet valve into the tank. We can conclude few points from this graph such as those listed below. There are three possible modes of failure of a material: fracture, fatigue and creep. Since there is an inverse relationship between the bandwidth and measurement time, it can be said that the noise decreases with the square root of the measurement time. Thus the total amount of energy available in the Universe is constant”. ♦ Measurement of the amount by which object moved. In a double acting cylinder, compression takes place at both the head end and crank end of the cylinder. The ratio of lateral strain to axial (longitudinal) strain is known as Poisson’s ratio, and is denoted by μ. The types of materials that can be cast are aluminum alloys, bronzes, tool steels, stainless steels and precious metals. This directly affects output and has financial impact. The contaminants can come in a great many forms; some are highly destructive to the oil, its additives, and machine surfaces. Oil goes through a non-return valve, pressure relief valve (PRV) to the services. A prerequisite for hardening is sufficient carbon and alloy content. The supervisory control system is a system that is placed on top of a real-time control system to control a process that is external to the SCADA system (i.e. This is the simplest type of section in which the cutting plane cuts the object in two and half the object nearer to the observer is removed. In the end the piece may be brought back to original shape but it would have undergone considerable strain hardening. Slope of hatching lines should be changed by 90 degrees on adjacent parts in the assembly drawings. The reaction involves transfer of electrons from one surface to another. Torsional Shear Stress caused by Frictional resistance of the threads during its tightening. Choose proper surface finishes, but not overly severe (rivet holes, welds, openings, etc. The difference in the emfs generated by the two conductors is then given by: where E is the net emf generated and Sa and Sb are the Seebeck coefficients of conductors a and b. Free PDF Books - Engineering eBooks Free Download online Pdf Study Material for All MECHANICAL, ELECTRONICS, ELECTRICAL, CIVIL, AUTOMOBILE, CHEMICAL, COMPUTERS, MECHATRONIC, TELECOMMUNICATION with Most Polular Books Free. Heat treating is the operation of controlled heating and cooling of a metal in its solid state to change its physical and mechanical properties. X = difference in height between the extreme corners of the nut. Where Ni is the number of cycles for crack propagation and Np is number of cycles for crack propagation before failure. Who studied the laminar flow through a circular tube experimentally? The difference between the maximum and minimum size is known as tolerance. The hardening temperature is about 750-760°C for 0.5 % carbon steel and 790-800°C for alloy steel. i.e. In the unidirectional method, all dimension lines are placed horizontally as in aligned method but the dimensions are placed in the center of the dimension line drawn horizontal or vertical. Refrigerators and air conditioners are both examples of heat pumps operating only in the cooling mode. Two useful properties that are often increased by alloying are …. Certain conventions should be followed. Such pumps are found in virtually every industry, and in domestic service in developed countries for washing machines, dishwashers, swimming pools, and water supply. This is a very expensive activity which decreases the reliability of mechanical systems. Their use is voluntary. The relationship is linear on these scales and becomes non-linear if drawn on a normal uniform scale. A perfectly plastic material will not require any further increase of stress for further increase of strain, the material just keeps elongating without much increase of stress. Cast iron has poor malleability. The force and the displacement are given in the problem statement. Gasoline/Petrol engine, high-speed diesel engine), Diesel cycle (e.g. Some metals show a non-linear deformation still within elastic limit. The three views as mentioned above will be different for the same object if the selection of the three planes is different in each case. When it comes to corrosive applications such as landfill gas, the reciprocating compressor will provide the most flexibility, including multiple staging and ability to add or remove staging should conditions warrant. Full section view Download it once and read it on your Kindle device, PC, phones or tablets. Lack of confidence or uncertainty arise due to various factors, for example: In this section we will discuss some of the main mechanical components, We can divide the components into two categories transmission components and supporting components. The Kelvin scale is absolute, meaning 0° Kelvin is mathematically the lowest possible temperature in the universe. It is also known as a screw. Mechanical engineers are concerned with the principles of force, energy and motion. There are different methods of strengthening of metals such as: Pure metals are rarely used in any industrial or engineering applications because in their pure state they have poor physical and mechanical properties. Δt = Effective temperature difference This method produces shapes of high strength, good accuracy and surface finish at high production speeds and low die cost. The surface is generally perpendicular to the direction of applied stress. Se = endurance limit of mechanical element Heat cannot be transferred from a colder to a hotter body. It is true that random failures will crop up, but there are many steps you can take. Used to transmit power in one direction only. Details of indenter and formulae for calculation of hardness are given in Table 2.1. Must have a certain axial load to prevent sliding. The pressure of fluid on a surface will always act normal to the surface. 4. Elasticity is measured by elastic modulus that is called as Young’s modulus. At this load component have an infinite life. The ratio of lateral strain to axial (longitudinal) strain is known as Poisson’s ratio, and is denoted by μ . f appears on both sides in a square root term and so cannot be calculated easily. Angle of contact: the greater the angle the more axial load it can carry. A two-position valve has two squares; a three-position valve has three etc. Flexible couplings are used to compensate for minor amounts of misalignment and random movement between the two shafts. It has been shown that Newton’s laws of physics are only applicable in certain conditions. Cross flow, as illustrated in Figure 10.20, exists when one fluid flow perpendicular to the second fluid; that is, one fluid flows through tubes and the second fluid passes around the tubes at 90° angle. When a definite velocity ratio is required in a watch mechanism,……………….