Material Selection Lab 7 PDF

Selecting the appropriate Materials Material selection and Testing Todays Objectives  Recap the machines present in Materials lab in any industry  Understand Material Selection Process and its key role in various industries  In-Class assignment to practice Material s...

Selecting the appropriate Materials Material selection and Testing Todays Objectives  Recap the machines present in Materials lab in any industry  Understand Material Selection Process and its key role in various industries  In-Class assignment to practice Material selection methodology Materials lab in industry Applications & Tests Materials lab in industry Why do we require a materials lab?  Investigate the strength of the material at hand  Test the modified design  Calculate the accuracy of machining processes  Safety measurements for vehicles  Checking the transparency or clarity of headlight lamps  Testing the thermal resistance of rocket nozzles  Understanding the effect of vibrations on airplane wings and bodies  Chemical interactions with plastic containers  Weather resistance of fitting and materials Type of tests needed  Tensile  Corrosion  Compression  Thermal investigation  Hardness  Friction  Bending  Magnetism  Crack strength  Electrical properties  Impact  Clarity and light properties  Creep  Accuracy and dimensional measurements  Microstructure investigation  Vibration and fatigue Material selection Reason and methodology What is Material Selection?  Material selection is the act of choosing the material best suited to achieve the requirements of a given application.  Material selection is a step in the process of designing any physical object. Why study Material Selection? Why study Material Selection? Why study Material Selection? Material selection Methodology in brief  The task, restated in two lines, is that of:  Identifying the desired attribute profile and then  Comparing it with those of real engineering materials to find the best match Material selection Methodology in detail  There are four main steps  Translation  Screening  Ranking  Supporting information and Local conditions Material selection Methodology in detail (example)  As a business owner you want to hire someone  The job is first analyzed and advertised, identifying essential skills and experience required of the candidate (translation).  Some of these are simple go/no go criteria like the requirement that the applicant ‘‘must have a valid driving license’’, or ‘‘a degree in computer science’’, eliminating anyone who does not (screening).  Others imply a criterion of excellence, such as ‘‘typing speed and accuracy are priorities’’, or ‘‘preference will be given to candidates with a substantial publication list’’, implying that applicants will be ranked by these criteria (ranking).  Finally references and interviews are sought for the top ranked candidates, building a file of supporting information — an opportunity to probe deeply into character and potential. Translation  How are the design requirements for a component (defining what it must do) translated into a prescription for a material? In-Class Assignment  Divided into 4 groups  Each group will have a specific application  The task is to perform a full material selection analysis on these applications  First part: Translation Screening  Screening, eliminates candidates that cannot do the job at all because one or more of their attributes lies outside the limits set by the constraints  As example, the requirement that ‘‘the component must function in boiling water’’, or that ‘‘the component must be transparent’’ imposes obvious limits on the attributes of maximum service temperature and optical transparency that successful candidates must meet.  We refer to these as attribute limits. Screening Ashby charts  Also called Material Property charts  Used to determine the materials needed to follow the translation  The X and Y axes are in terms of the desired properties (stiffness, conductivity, resistivity) In-Class Assignment  Now using the Ashby charts (material property charts) select the materials that best suit your objective and constraint Ranking  To order the candidate we need a criteria of excellence, or an optimization criteria  Usually maximizing or minimizing a property, may not be the most perfect solution, but the mix or the sweet point between them is.  The difference between screening and ranking is: Screening isolates candidates that are capable of doing the job; Ranking identifies those among them that can do the job best. In-Class Assignment  Ranking the screened materials according to the constraints given and the objective desired Supplementary information  Help us make the final decision  We can ask question about the top ranked material to investigate deeply about it:  What are its strengths and weaknesses?  Does it have a good reputation?  What, in a word, is its credit-rating? Local Conditions  It is like a slap back to reality  The questions that may block the usage of a certain material:  Is it actually present locally or with local vendors?  The presence of in-house expertise or equipment In-Class Assignment Supporting Info and Local Conditions  Carbon fiber (CFRP) is not imported in Egypt  Aluminum and its alloys are well established in the aerospace industry  Using steel in car chassis is an old trend, and is being replaced by Aluminum and fiber composites  Aluminum nitride (AlN) is readily manufactured and used in the heat sink industry.  Both Aluminum and Copper are used in high voltage cables, yet copper is more common. Quick recap