Your SlideShare is downloading. ×
The Importance of Access to Validated Data
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

The Importance of Access to Validated Data

985

Published on

Published in: Technology, Business
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
985
On Slideshare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
0
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Chris Middleton Engineering Librarian, University of Nottingham c.middleton@nottingham.ac.uk, 0115 8467463 The Importance of Access to Validated Data
  • 2. The context
    • Supporting engineering research
        • Standard texts
        • Research articles
        • Technical information
    • Also
    • Supporting engineering design
        • Student projects
        • Academic consultancy
        • Industrial R & D
  • 3. Sources of design data
    • Based on standard components
        • Supplier’s catalogues
    • From first principles
        • Standards from legislative bodies
          • British Standards, ASTM, IEC
        • Reference works
          • handbooks, data books
    • Using validated data…..
    W=S t (0.55d 2 - 0.25d) W=working strength S t = allowable working stress d=nominal outside diameter
  • 4. Validated data
    • What?
    • Proven data derived by empirical means
    • Why?
    • Informs complex situations not easily analysed theoretically
    • Reliable quality
    • Defence against negligence
    • Where?
    • ESDU - Engineering Science Data Units
  • 5. ESDU - www.esdu.com
    • View abstracts at: AERADE (http://aerade.cranfield.ac.uk/esdu_index.html)
            • TechXtra ( http://www.techextra.ac.uk/esdu/index.php)
    • Validated engineering design data, methods, equations and software based on 66 years' experience
    • Choose from 23 series covering aerospace, chemical, process, structural and mechanical engineering topics.
    • Performance
    • Physical Data, Chemical Engineering
    • Physical Data, Mechanical Engineering
    • Process Engineering Technology
    • Sound Propagation
    • Stress and Strength
    • Structures
    • Transonic Aerodynamics
    • Tribology
    • Vibration and Acoustic Fatigue
    • Wind Engineering
    • Aerodynamics
    • Aircraft Noise
    • Composites
    • Construction Engineering
    • Dynamics
    • Engineering Structures
    • Fatigue – Endurance Data
    • Fatigue – Fracture Mechanics
    • Fluid Mechanics – Internal Flow
    • Fluid Mechanics, Internal Flow (Aerospace) Heat Transfer
    • Mechanisms
  • 6. Example
    • Design a tension bolt to support a known load (F)
    • Factors to consider:
      • Strength of bolt material
      • Bolt diameter and thread design
      • Tightening torque
      • Pre-load (P)
    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. 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. British Standards
    • British Standards Institution, 1964. BS. 3580: 1964. Guide to design considerations on the strength of screw threads.
      • Gives formulae and details the relationships between material strength and features of bolt design and manufacture
      • Lists variables such as lubrication used, types of washers, coarse or fine threads
      • States “it is recommended that torque-tension relations be established experimentally for the conditions of the particular application.”
    • British Standards Institution, 2005. BS EN 14399-2:2005. High-strength structural bolting assemblies for preloading. Suitability test for preloading.
      • 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.
  • 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
    • But practical variations are listed: applied torque, thread design, friction forces between touching surfaces.
    • So safety margins and tests are required.
    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. ESDU 86014: Applying, measuring and maintaining pretension in steel bolts
    • Abstract:
    • 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.
  • 11.
    • All elements and variable subjected to test and analysis
    • Detailed graphs produced leading to design guidelines with indications of accuracy
  • 12. Summary
    • Designers need good quality data to ensure safety.
    • They need to:
      • Either
          • use theoretical methods to design a product
          • design test methods to prove the capabilities of the product
          • conduct tests to prove that critical elements meet all the required standards
      • Or
          • use validated data proved by extensive evaluation and accepted as reliable

×