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Designing A Creep Tests Machine Engineering Essay

Designing A Creep Tests Machine Engineering Essay

Designing A Creep Testing Machine Engineering Essay

A Creep Testing Machine is one that accurately steps the creep of a materials under continuous load and at elevated temps until final rupture. Quite simply, it demonstrates the result of Temperature on Creep. Creep is normally defined as the time dependant deformation of a materials under continuous load at regular elevated heat range. The resulting 1000 word essay example strain is definitely a function of applied stress, temperature and time. Creep is increasingly crucial in industry in many different applications which range from turbine rotors, high pressure steam tubes, suspended wires, tightened bolts where materials are put through extremely high temperatures and stresses which may lead them to change size, shape and bring about rupture.

So the main aim of a creep test out is to measure what sort of given material will perform under constant loads and elevated temperatures to ensure they are ready for use in market under such circumstances. In a creep test, a tensile specimen is usually subjected to a constant load in the furnace set to a specified temp maintained at a frequent high temperature. The material will proceed through 3 phases of creep; primary, secondary (steady talk about, lengthiest level) and tertiary until it ruptures. The evaluation may run on for days until eventually the specimen fails and the creep properties are recorded.

http://spaceflight.esa.int/impress/text/education/Photos/MechanicalProperties/image075.png

Applications in industry

Creep testing is more and more important in large regions of industry. There are three types of temperature industry applications.

Displacement limited applications: where specific dimensions should be maintained, types of which will be in turbine rotors/aircraft turbine blades.

Rupture limited applications: where fracture must be avoided, such as for example in steam tubes.

Stress-leisure limited applications: where first tension relaxes with time such as in suspended cables and tightened bolts.

Aims and Objectives:

To fully design a Creep Testing Machine within a difficult budget in the given time frame – by the end of the semester in week 13.

The cause of the project is to supply AUT Engineering School with its first working Creep Machine. It’ll provide an chance for materials to be examined for Creep under incredibly high temperatures for exploration or educational purposes following the project is completed. The high temperatures permits testing stronger more complex materials such as alloys with higher melting points.

A fully detailed, clear and FEA tested 3D CAD drawing will become produced, effectively demonstrating the entire final design of the Creep Tests Machine in all of its sizes and absolute properties.

Deliverables:

The equipment will be designed to be cheap, practical, robust, reliable, simple to use, relatively lightweight, safe (to touch), resilient and professional looking.

The job meets the educational requirements of my qualification as it will require a great deal of knowledge I have obtained from papers such as for example: material science, making technology, CAD/solidworks engineering design, quantitative methods, thermodynamics, sturdy mechanics and temperature transfer papers.

Potential Market organisations involved:

Steel suppliers

high temperature material suppliers

high temp measuring/control device distributers

electronic and electric control distributers

insulation material suppliers

Resources (likely required):

Solidworks/CAD design applications, matlab/computer programming courses, Microsoft excel, electrical/digital equipment.

Workshop devices: milling, lathe, drilling, soldering, welding machines and extra.

Project Plan

Plan/chart will be at the mercy of refinement through the entire duration of the project.

Project Information

This project is supposed to be carried on through before end of the 4th year industrial project. From now until the end of the semester we will be designing the Creep Evaluating Equipment completely, putting the patterns through numerous assessments and immense scrutiny until it is certain that the design will end up being achievable and the task a complete success.

Our supervisor, Tim, informed us with the estimated cover this task of around $5,000NZ. That is a difficult budget and we are not to surpass it under any instances. Therefore a significant goal of this project is to stay under funds (by a respectable sized margin if possible) and design a comparatively cheap Creep Testing Machine that can be shipped realistically for the 4th year industrial project (where the machine ought to be produced).

The Creep machine includes several main elements that match three categories; High temperature, mechanics and control. The parts are as follows: Frame, Furnace, Control, Consumer electronics + Data acquisition, Strain measurement device (extra), Emergency shut off, Temperature measurement device, Hold system, Timer, On/Off move and Loading mechanism.

The furnace ought to be designed to reach exceedingly high temperature ranges of up to 800C so that it could be suited to creep testing on a wide variety of specimen materials (huge T alloys etc) for exploration and educational purposes what does a 500 word essay look like at the AUT Engineering department.

During our initial group meeting after the first formal ending up in our supervisor, we (the project team) assigned some components to each of us to handle detailed analysis and gather our results before the next ending up in Tim. The larger, more complex components namely the furnace and loading system had been both shared between me and Ramez, Steven and John-Paul respectively. The full details are illustrated in my own logbook.

Literature review

So the elements assigned to me for exploration were the Furnace, stress measuring unit and the framework. I started out dissecting the furnace into its individual components and features. A standard muffle furnace contains insulation, your body, heating element, heat range measurement/controller and door with locking mechanism, compartments for other parts (load train, measuring apparatus), mounting system and air vents.

After I finished some general research I developed an excellent and original idea of what our Creep tests machine will consist of:

Furnace insulation will also contain two different materials specifically refractory firebrick and refractory ceramic fibre blanket or solely simply ceramic fibre blanket/wool. They are highly heat resistance products (one which has especially low thermal conductivity benefit – k).

Fire brick; will be the first type of insulation and the key barrier to heat reduction from the furnace chamber with a k worth of ~ 0.21 (@800C).

Ceramic fibre; will be the surrounding/main coating of insulation and you will be set around the fire brick and on the internal door surface. It has a k value of ~ 0.22 (@800C). There are many types of ideal fibre and one will be chosen based on its cost and thermal properties.

The factor that firebrick is being considered as a level of insulation is as a result of the ease of fitting it with heating elements. Nonetheless they are more heavy and considerably heavier than ceramic blankets.

The insulation selections will be theoretically analyzed for suitability using normal thermal resistance equations:

Qtransfer = ∆T/Rth

Rth = (1/hiA)+(L/kA)+ (1/hoA)

Where; L is the minimum thickness of insulation, k is certainly its thermal conductivity, h is the convection heating transfer coefficient and Rth is the total heat resistance.

Choice and set of possible heating components + why chosen. Take into accnt set up hting time

The minimum insulation thickness required is available as follows;

Properties:

Power in: 1.6kW heating element

∆T = TMAX – TAMB

Insulation, Ceramic fibre: k = 0.22W/m2K

hi = 10W/mK, ho = 40W/mK

Rth = (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 = 21.87mm

L

Specimen

HC

H

WC

WW

Body

Chamber

Initial Dimensions:

Specimen ASTM:

Round dog bone: Length, L = 127mm

Flat dog bone: Duration, L = 101mm

Gripping mechanism: Duration, L ~ 40mm

Only round pet bone specimens will tested – ASTM creep/fatigue specimens. Full dimensions below: ((+ gripping system size))

The bottom pull rod will be fixed in place but the top draw rod will be adjustable such that the specimen could be placed into the gripping mechanisms. As a result this will be considered when estimating the height of the furnace and its chamber. Preferably, the chamber ought to be small in size such that it really is heated up quicker and consume less energy thereby increasing the efficiency of the furnace.

Therefore,

Chamber width, WC = 150mm

Chamber Length, LC = 150mm

Chamber Height, HC = 350mm

As the minimum amount insulation thickness ranges from 21 to27mm (depending on heating element’s power rating) therefore, it’ll be necessary to have got two layers of 25mm thick insulation around the chamber. So the outer body measurements will be about:

Width, W = 250mm

Length, L = 200mm

Height, H = 450mm

The main body will almost certainly be made from mild steel because of its relatively low priced and robust, tough dynamics. The heating element will have to be either kanthal A1 or Nichrome most probably in wire form to ensure that it might be easily routed into specially manufactured grooves in the firebrick. With temperatures ranges up to 1800C and relatively low priced kanthal A1 may be more suitable in this instance. Enough time for the furnace to attain its required temperature will also be considered 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 well balanced working heat and the thickness of insulation required to just work at such energy inputs. Also set up heating element could be fitted into the insulation material is a factor.

Temperature measurement and control device will most probably be considered a standard temperature thermocouple. There are many different types, shapes and sizes but most are relatively cheap and inexpensive regarding the project finances. The thermocouple gives the give the browsing and control the temp in the chamber (keeping it at a continuous working temp) by hitting the relay on and off when necessary.

The furnace body will have to be made from a hard, tough and relatively solid material. Because of this , I feel that mild steel sheets should be purchased and created to the desired shape. Processes such as for example bending and cutting could be undertaken at the mechanical engineering workshop at AUT.

Mild steel plates/sheets prices per quantity + list of possible materials, choose the most suitable.

An idea that I have deemed suited to the furnace is that a simple solid, robust metal filing cabinet could be converted into a furnace body. Straight forward tools and workshop means available at AUT can be utilised to machine the necessary features to create it work as a muffle furnace. This may potentially save a lot of investment that could be used in other areas where it really is needed more (concerning the project).

The strain measuring product will have to be one that works successfully under the high temperatures experienced with muffle furnaces. I have narrowed it right down to either a high temperature extensometer or an LVDT. The best option device is the temperature extensometer as they are specifically suitable for such elevated temperatures and present an extremely accurate strain/displacement measurement beyond ASTM standards. They can even be attached easily to regular creep testing furnaces. On the other hand, a strain measuring system can be an optional extra as the specimen displacement could be accurately measured following the specimen ruptures and straightforward calculations can be used to determine the strain experienced. A stress measuring device would be for convenience purposes simply.

List of stress measuring devices, filtration system to high temp use devices, then the only suitable model + rates and deem if in fact suitable. Speak with Wassim. Extensometer or LVDT.

Resources

Introduction to Engineering Style, Andrew Samuel and John Weir

Manufacturing Engineering and Technology, Serope Kalpakjian

Heat and Mass Transfer a sensible approach, Yunus A Cengel

Thermodynamics an Engineering way, Cengel and Boles

Materials Research and Engineering an Intro, William D Callister Jr

http://www.atspa.com/3110_r2.pdf

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392005000400008

http://www.mts.com/ucm/groups/public/documents/library/dev_003704.pdf

http://www.zwick.de/en/products/static-materials-testing-machines/creep-test-machines.html

http://www.epsilontech.com/3448.htm

http://www.ariindustries.com/thermocouples/high_temperature_thermocouples.php3

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