rcises-rciseswithworkedsolutions-ma-uoc-en.pdf

1、 M.F. Ashby 2010 1 Professor Mike Ashby Department of Engineering University of Cambridge This compilation of Exercises with worked solutions is a part of a set of teaching resources created by Mike Ashby to help introduce students to materials, processes and rational selection. The Teaching Resources website aims to support teaching of materials-related courses in Design, Engineering and Science. Resources come in various formats and are aimed primarily at undergraduate education. Some of them

2、are open access. M. F. Ashby, 2010 For reproduction guidance see back page Exercises With Worked Solutions CES EduPack Exercises with Worked Solutions M.F. Ashby 2010 2 Adapted from the Solution Manual to Materials selection in mechanical design, 4th edition, Prof. Mike Ashby Engineering Department, University of Cambridge, CB2 1PZ. Exercises with worked solutions Contents E1. Introduction to exercises E2. Material evolution in products E3. Devising concepts E4. Using material properties E5. Usi

3、ng material selection charts E6. Translation: constraints and objectives E7. Deriving and using material indices E8. Multiple constraints and objectives E9. Selecting material and shape E10. Hybrid materials E11. Selecting processes E12. Materials and the environment CES EduPack Exercises with Worked Solutions M.F. Ashby 2010 3 E1 Introduction to exercises These exercises are designed to develop facility in selecting materials, processes and shape, and in devising hybrid materials when no monoli

4、thic material completely meets the design requirements. Each exercise is accompanied by a worked solution. They are organized into the twelve sections listed on the first page. The early exercises are easy. Those that follow lead the reader through the use of material properties and simple solutions to mechanics problems, drawing on data and results contained in the CES EduPack and the booklet “Useful Approximate Solutions to Standard Problems” (UASSP which can be found as an open access resourc

5、e on the teaching resource website.) ; the use of material property charts; techniques for the translation of design requirement to identify constraints and objectives; the derivation of indices, screening and ranking, multi-objective optimization; coupled choice of material and shape; devising hybrids; and the choice of materials to meet environmental criteria. Three important points. 1. Selection problems are open-ended and, generally, under- specified; there is seldom a single, correct answer

6、. The proper answer is a sensible translation of the design requirements into material constraints and objectives, applied to give a short-list of potential candidates with commentary suggesting what supporting information would be needed to narrow the choice further. 2. The positioning of selection-lines on charts is a matter of judgement. The goal is to place the lines such that they leave an adequately large short list of candidates (aim for 4 or so), drawn, if possible, from more than one cl

7、ass of material. 3. A request for a selection based on one material index alone (such as /EM 2/1 =) is correctly answered by listing the subset of materials that maximize this index. But a request for a selection of materials for a component a wing spar, for instance (which is a light, stiff beam, for which the index is /EM 2/1 = ) requires more: some materials with high /E 2/1 such as silicon carbide, are unsuitable for obvious reasons. It is a poor answer that ignores common sense and experien

8、ce and fails to add further constraints to incorporate them. Students should be encouraged to discuss the implications of their selection and to suggest further selection stages. All the materials selection problems can be solved using the Standard databases in the CES EduPack software, which is particularly effective when multiple criteria and unusual indices are involved. This version of the solution manual has been written such that it can be completed without having to refer to the book Mate

9、rials Selection in Mechanical Design, 4th edition. The original solution manual for the book can be found on the Granta Design website. Hint: When using the CES EduPack, you can avoid manually calculating the average values of material properties (they tend to span a range) by going to Tools?Options?Numbers and checking the “Display data ranges as average values” checkbox. CES EduPack Exercises with Worked Solutions M.F. Ashby 2010 4 E2 Material evolution in products E2.1. Use Google to research the history and uses of one of the following materials ? Tin ? Glass ? Cement ? Titanium ? Carbon fiber Present the result as a short report of about 100 - 200 words (roughly half a page). Specimen answer: tin. Tin (symbol Sn), a silver-white metal, has a long history. It was traded in the civilisations of the Mediterranean as early as 1500 BC (the Old Testament of the Christian bible contains many references to

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