The Importance of Access to Validated Data

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The Importance of Access to Validated Data

  1. 1. Chris Middleton Engineering Librarian, University of Nottingham c.middleton@nottingham.ac.uk, 0115 8467463 The Importance of Access to Validated Data
  2. 2. The context <ul><li>Supporting engineering research </li></ul><ul><ul><ul><li>Standard texts </li></ul></ul></ul><ul><ul><ul><li>Research articles </li></ul></ul></ul><ul><ul><ul><li>Technical information </li></ul></ul></ul><ul><li>Also </li></ul><ul><li>Supporting engineering design </li></ul><ul><ul><ul><li>Student projects </li></ul></ul></ul><ul><ul><ul><li>Academic consultancy </li></ul></ul></ul><ul><ul><ul><li>Industrial R & D </li></ul></ul></ul>
  3. 3. Sources of design data <ul><li>Based on standard components </li></ul><ul><ul><ul><li>Supplier’s catalogues </li></ul></ul></ul><ul><li>From first principles </li></ul><ul><ul><ul><li>Standards from legislative bodies </li></ul></ul></ul><ul><ul><ul><ul><li>British Standards, ASTM, IEC </li></ul></ul></ul></ul><ul><ul><ul><li>Reference works </li></ul></ul></ul><ul><ul><ul><ul><li>handbooks, data books </li></ul></ul></ul></ul><ul><li>Using validated data….. </li></ul>W=S t (0.55d 2 - 0.25d) W=working strength S t = allowable working stress d=nominal outside diameter
  4. 4. Validated data <ul><li>What? </li></ul><ul><li>Proven data derived by empirical means </li></ul><ul><li>Why? </li></ul><ul><li>Informs complex situations not easily analysed theoretically </li></ul><ul><li>Reliable quality </li></ul><ul><li>Defence against negligence </li></ul><ul><li>Where? </li></ul><ul><li>ESDU - Engineering Science Data Units </li></ul>
  5. 5. ESDU - www.esdu.com <ul><li>View abstracts at: AERADE (http://aerade.cranfield.ac.uk/esdu_index.html) </li></ul><ul><ul><ul><ul><ul><li>TechXtra ( http://www.techextra.ac.uk/esdu/index.php) </li></ul></ul></ul></ul></ul><ul><li>Validated engineering design data, methods, equations and software based on 66 years' experience </li></ul><ul><li>Choose from 23 series covering aerospace, chemical, process, structural and mechanical engineering topics. </li></ul><ul><li>Performance </li></ul><ul><li>Physical Data, Chemical Engineering </li></ul><ul><li>Physical Data, Mechanical Engineering </li></ul><ul><li>Process Engineering Technology </li></ul><ul><li>Sound Propagation </li></ul><ul><li>Stress and Strength </li></ul><ul><li>Structures </li></ul><ul><li>Transonic Aerodynamics </li></ul><ul><li>Tribology </li></ul><ul><li>Vibration and Acoustic Fatigue </li></ul><ul><li>Wind Engineering </li></ul><ul><li>Aerodynamics </li></ul><ul><li>Aircraft Noise </li></ul><ul><li>Composites </li></ul><ul><li>Construction Engineering </li></ul><ul><li>Dynamics </li></ul><ul><li>Engineering Structures </li></ul><ul><li>Fatigue – Endurance Data </li></ul><ul><li>Fatigue – Fracture Mechanics </li></ul><ul><li>Fluid Mechanics – Internal Flow </li></ul><ul><li>Fluid Mechanics, Internal Flow (Aerospace) Heat Transfer </li></ul><ul><li>Mechanisms </li></ul>
  6. 6. Example <ul><li>Design a tension bolt to support a known load (F) </li></ul><ul><li>Factors to consider: </li></ul><ul><ul><li>Strength of bolt material </li></ul></ul><ul><ul><li>Bolt diameter and thread design </li></ul></ul><ul><ul><li>Tightening torque </li></ul></ul><ul><ul><li>Pre-load (P) </li></ul></ul>Applying torque to increase the pre-load minimises the effect of the load forces and so increases fatigue life. Source: Parmley, R.O.,ed., 2000. Illustrated sourcebook of Mechanical Components. New York: McGraw-Hill. pp19 -12.
  7. 7. Standards relating to bolt design Standard grade specifications give the minimum mechanical properties for the bolt. Source: Oberg, E., et al., eds. Machinery's handbook 26th ed. New York : Industrial Press, 2000. pp. 1488
  8. 8. British Standards <ul><li>British Standards Institution, 1964. BS. 3580: 1964. Guide to design considerations on the strength of screw threads. </li></ul><ul><ul><li>Gives formulae and details the relationships between material strength and features of bolt design and manufacture </li></ul></ul><ul><ul><li>Lists variables such as lubrication used, types of washers, coarse or fine threads </li></ul></ul><ul><ul><li>States “it is recommended that torque-tension relations be established experimentally for the conditions of the particular application.” </li></ul></ul><ul><li>British Standards Institution, 2005. BS EN 14399-2:2005. High-strength structural bolting assemblies for preloading. Suitability test for preloading. </li></ul><ul><ul><li>The principle of the test is to tighten the assembly and to measure, during tightening, the following parameters: the bolt force; the relative rotation between the nut and the bolt; the torque, if required; the bolt elongation, if required. </li></ul></ul>
  9. 9. Cobb, B.J. Preloading of bolts. In: Parmley, R.O.,ed., 2000. Illustrated sourcebook of Mechanical Components. New York: McGraw-Hill. pp 19-12 to 19-16 <ul><li>But practical variations are listed: applied torque, thread design, friction forces between touching surfaces. </li></ul><ul><li>So safety margins and tests are required. </li></ul>Design curves are produced based on the stress-torque equation and the preload-torque equation: For a given bolt diameter read up to the desired load for the tightening torque and read down for the material strength requirement.
  10. 10. ESDU 86014: Applying, measuring and maintaining pretension in steel bolts <ul><li>Abstract: </li></ul><ul><li>ESDU 86014 discusses factors affecting the tension in a bolt, and indicates the methods by which a desired tension may be obtained, with a comparison of their relative accuracy and cost. Methods of measuring the bolt loads are also discussed. To determine the bolt pretension achieved by application of a known torque, the results of 1900 tests were analysed to yield curves for both lubricated and unlubricated threads of BSF(BA) and Unified or ISO metric forms . The test data related to nuts of mild and high strength steel seated on mild or high strength steel or aluminium alloy washers , and lubricants ranged from light oil to extreme pressure greases . No significant trend with material or lubricant could be isolated. Techniques for applying a known torque are considered, and their accuracy reviewed . Methods of locking the nut are described , together with their advantages and disadvantages, and include mechanical, frictional, adhesive or deformation techniques. </li></ul>
  11. 11. <ul><li>All elements and variable subjected to test and analysis </li></ul><ul><li>Detailed graphs produced leading to design guidelines with indications of accuracy </li></ul>
  12. 12. Summary <ul><li>Designers need good quality data to ensure safety. </li></ul><ul><li>They need to: </li></ul><ul><ul><li>Either </li></ul></ul><ul><ul><ul><ul><li>use theoretical methods to design a product </li></ul></ul></ul></ul><ul><ul><ul><ul><li>design test methods to prove the capabilities of the product </li></ul></ul></ul></ul><ul><ul><ul><ul><li>conduct tests to prove that critical elements meet all the required standards </li></ul></ul></ul></ul><ul><ul><li>Or </li></ul></ul><ul><ul><ul><ul><li>use validated data proved by extensive evaluation and accepted as reliable </li></ul></ul></ul></ul>

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