Designing A Creep Testing Machine Engineering Essay

Designing A Creep Testing Machine engine room EssayA Creep Testing Machine is angiotensin converting enzyme that accurately measures the creep of a actual under constant load and at elevated temperatures until final rupture. Basically, it demonstrates the effect of Temperature on Creep. Creep is defined as the time dependant deformation of a material under constant load at constant elevated temperature. The resulting strive is a function of utilize stress, temperature and time. Creep is increasingly burning(prenominal) in industry in many different applications ranging from turbine rotors, extravagantly pressure steam tubes, suspended cables, tightened bolts where materials argon subjected to extremely high temperatures and stresses which whitethorn cause them to change size, shape and lead to rupture.So the main objective of a creep test is to measure how a given material pull up stakesing perform under constant loads and elevated temperatures to make sure they be ready for use in industry under much(prenominal) conditions. In a creep test, a tensile exemplar is subjected to a constant load inside a furnace set to a specified temperature retained at a constant high temperature. The material will go through 3 phases of creep primary, secondary (steady state, lengthiest stage) and tertiary until it ruptures. The test may accord on for days until eventually the specimen fails and the creep properties are recorded.http//spaceflight.esa.int/impress/text/education/Images/MechanicalProperties/image075.pngApplications in industryCreep testing is increasingly important in large areas of industry. There are three types of high temperature industry applications.Displacement limited applications where precise dimensions must be maintained, examples of which are in turbine rotors/aircraft turbine blades. crush limited applications where fracture must be avoided, such as in steam tubes.Stress-relaxation limited applications where initial tension relaxes with time such as in suspended cables and tightened bolts.Aims and ObjectivesTo fully see a Creep Testing Machine within a hard budget in the given time skeletal system by the end of the semester in week 13.The reason behind the project is to permit AUT Engineering School with its starting run lowing Creep Machine. It will provide an opportunity for materials to be tested for Creep under extremely high temperatures for question or educational purposes after the project is completed. The very high temperatures will allow for testing stronger more complex materials such as alloys with higher melting points.A fully detailed, clear and FEA tested 3D CAD draw will be produced, effectively demonstrating the complete final design of the Creep Testing Machine in all of its dimensions and absolute properties.DeliverablesThe railroad car will be designed to be cheap, practical, robust, reliable, easy to use, relatively lightweight, safe (to the touch), long lasting and professional look ing.The project meets the academic requirements of my qualification as it will require a great deal of knowledge I study obtained from papers such as material science, manufacturing technology, CAD/solidworks engineering design, quantitative techniques, thermodynamics, solid mechanics and disturb transfer papers.Potential Industry organisations involvedSteel suppliershigh temperature material suppliershigh temperature measuring/control thingamabob distri hardlyerselectronic and electrical control distributers detachment material suppliersResources (likely required)Solidworks/CAD design programs, matlab/computer programming programs, Microsoft excel, electrical/electronic equipment.Workshop machines milling, lathe, drilling, soldering, welding machines and more.Project PlanPlan/chart will be subject to refinement throughout the duration of the project.Project InformationThis project is supposed to be carried on through until the end of the 4th year industrial project. From now unt il the end of the semester we will be designing the Creep Testing Machine completely, putting the designs through numerous tests and immense scrutiny until it is certain that the design will be achievable and the project a total success.Our supervisor, Tim, informed us with the estimated budget for this project of around $5,000NZ. This is a hard budget and we are not to exceed it under any circumstances. Therefore an important goal of this project is to stay under budget (by a decent sized allowance account if possible) and design a relatively cheap Creep Testing Machine that washstand be delivered rea be givenically for the 4th year industrial project (where the machine should be produced).The Creep machine constitutes of several main comp integritynts that fit into three categories Heat, mechanics and control. The components are as follows Frame, Furnace, Control, Electronics + Data acquisition, Strain measurement device (extra), hint shut off, Temperature measurement device, Grip system, Timer, On/Off switch and Loading mechanism.The furnace should be designed to reach exceedingly high temperatures of up to 800C so that it may be suitable for creep testing on a wide range of specimen materials (high T alloys etc) for enquiry and educational purposes at the AUT Engineering department.During our first group meeting after the first formal meeting with our supervisor, we (the project team) assigned several components to each of us to carry out detailed research and gather our findings before the next meeting with Tim. The larger, more complex components namely the furnace and loading mechanism were both shared between me and Ramez, Steven and John-Paul respectively. The full details are illustrated in my logbook.Literature reviewSo the components assigned to me for research were the Furnace, strain measuring device and the frame. I began dissecting the furnace into its individual components and features. A step muffle furnace consists of breakup, the body , heating system cistron, temperature measurement/controller and door with locking mechanism, compartments for other components (load train, measuring apparatus), mounting kit and air vents.After I completed some general research I developed a good and original idea of what our Creep testing machine will consist ofFurnace insulation will either consist of two different materials namely refractory firebrick and refractory ceramic fibre blanket or solely just ceramic fibre blanket/wool. These are highly heat resistance materials (one that has especially low thermal conductivity value k).Fire brick would be the first line of insulation and the main barrier to heat loss from the furnace chamber with a k value of 0.21 (800C).Ceramic fibre would be the surrounding/main layer of insulation and will be put around the fire brick and on the inner door surface. It has a k value of 0.22 (800C). There are several types of suitable fibre and one will be chosen based on its cost and thermal properties.The reason that firebrick is being considered as a layer of insulation is because of the ease of capable it with heating elements. However they are more bulky and considerably heavier than ceramic blankets.The insulation choices will be theoretically tested for suitability using standard thermal resistance equationsQtransfer = T/RthRth = (1/hiA)+(L/kA)+ (1/hoA)Where L is the minimum thickness of insulation, k is its thermal conductivity, h is the convection heat transfer coefficient and Rth is the total heat resistance.Choice and list of possible heating elements + why chosen. Take into accnt start up hting timeThe minimum insulation thickness required is found as followsPropertiesPower in 1.6kW heating elementT = TMAX TAMBInsulation, Ceramic fibre k = 0.22W/m2Khi = 10W/mK, ho = 40W/mKRth = (1/hiA)+(L/kA)+ (1/hoA)Rth = (1/10*0.35*0.15)+(L/0.22*0.35*0.15)+ (1/40*0.35*0.15)L = 21.87mmLSpecimenHCHWCWW personateChamberInitial DimensionsSpecimen ASTMRound dog bone Length, L = 127mmFlat dog bone Length, L = 101mmGripping mechanism Length, L 40mm unaccompanied round dog bone specimens will tested ASTM creep/fatigue specimens. Full dimensions below ((+ gripping mechanism size))The bottom pull rod will be fixed in place but the top pull rod will be adjustable such that the specimen freighter be placed into the gripping mechanisms. Therefore this will be considered when estimating the height of the furnace and its chamber. Preferably, the chamber should be small in size such that it can be heated up up quicker and use up less energy thereby increasing the efficiency of the furnace.Therefore,Chamber width, WC = 150mmChamber Length, LC = 150mmChamber Height, HC = 350mmAs the minimum insulation thickness ranges from 21 to27mm (depending on the heating elements power rating) therefore, it will be necessary to have two layers of 25mm thick insulation around the chamber. So the outer(a) body dimensions will be aboutWidth, W = 250mmLength, L = 200mmHeight, H = 450mmThe main body will almost certainly be made from cushy steel due to its relatively low cost and robust, tough nature. The heating element will have to be either kanthal A1 or Nichrome most in all likelihood in wire form so that it may be easily routed into specially made grooves in the firebrick. With temperature ranges up to 1800C and relatively low cost kanthal A1 may be more suitable in this case. The time for the furnace to reach its required temperature will also be taken into account and the choice of heating element (power rating, shape and material) will be based on the time it takes to heat the chamber to a stable working temperature and the thickness of insulation required to work at such energy inputs. Also whether or not the heating element can be fitted into the insulation material will be a factor.Temperature measurement and control device will most probably be a standard high temperature thermocouple. There are many different types, shapes and sizes but most ar e relatively cheap and affordable regarding the project budget. The thermocouple will give the give the reading and control the temperature in the chamber (keeping it at a constant working temperature) by clicking the relay on and off when necessary.The furnace body will have to be made from a hard, tough and relatively thick material. This is why I think that mild steel sheets should be purchased and formed to the desired shape. Processes such as bending and cutting can be undertaken at the mechanical engineering workshop at AUT.Mild steel plates/sheets prices per quantity + list of possible materials, choose most suitable.An idea that I have deemed suitable for the furnace is that a simple solid, robust steel filing cabinet could be converted into a furnace body. Simple tools and workshop resources available at AUT can be used to machine the necessary features to make it work as a muffle furnace. This could potentially save a great deal of enthronization that could be used in oth er areas where it is needed more (concerning the project).The strain measuring device will have to be one that works expeditiously under the high temperatures experienced with muffle furnaces. I have narrowed it down to either a high temperature extensometer or an LVDT. The most suitable device is the high temperature extensometer as they are specifically suited to such elevated temperatures and give an extremely accurate strain/displacement measurement beyond ASTM standards. They can also be attached easily to standard creep testing furnaces. However, a strain measuring device is an optional extra as the specimen displacement can be accurately measured after the specimen ruptures and simple calculations can be used to determine the strain experienced. A strain measuring device would be for convenience purposes only.List of strain measuring devices, filter to high temp use devices, then the only suitable sit around + prices and deem if actually suitable. Speak with Wassim. Extensom eter or LVDT.ResourcesIntroduction to Engineering Design, Andrew Samuel and John WeirManufacturing Engineering and Technology, Serope KalpakjianHeat and Mass Transfer a practical approach, Yunus A CengelThermodynamics an Engineering approach, Cengel and BolesMaterials Science and Engineering an Introduction, William D Callister Jrhttp//www.atspa.com/3110_r2.pdfhttp//www.scielo.br/scielo.php?script=sci_arttextpid=S1516-14392005000400008http//www.mts.com/ucm/groups/public/documents/library/dev_003704.pdfhttp//www.zwick.de/en/products/static-materials-testing-machines/creep-test-machines.htmlhttp//www.epsilontech.com/3448.htmhttp//www.ariindustries.com/thermocouples/high_temperature_thermocouples.php3