It is necessary to determine the stresses in screw fastening due to both static and dynamic loading in order to determine their dimensions based on the strength of material being used. In order to design bolts for static loading both initial tightening and external loadings need be known.
Initial tightening load
When a nut is tightened over a screw following stresses are induced:
(a) Tensile stresses due to stretching of the bolt
(b) Torsional shear stress due to frictional resistance at the threads.
(c) Shear stress across threads
(d) Compressive or crushing stress on the threads
(e) Bending stress if the surfaces under the bolt head or nut are not perfectly normal to the bolt axis.
(a) Tensile stress
Bolts are usually designed on the basis of direct tensile stress with a large factor of safety. The initial tension in the bolt is estimated by an empirical relation P1 =284 d kN, where the nominal bolt diameterd is given in mm. The relation is used for steam tight joints. If such leakproofing is not required half of the above estimated load may be used (142 d kN).
23 April 2017
NPTEL Material on Design of Bolted Joints
http://www.nptel.ac.in/courses/112105125/pdf/Module-4_lesson-4.pdf
30 March 2012
Design of Fasteners and Power Screws
http://www.nd.edu/~manufact/FME%20pdf_files/FME_Ch16.pdf
Design of Threaded Fasteners
http://physicsarchives.com/index.php/courses/619
Bolted Joint Design
http://www.fastenal.com/content/feds/pdf/Article%20-%20Bolted%20Joint%20Design.pdf
15 page pdf file
Anchor Bolt – Fulfilling All Your Concrete Attachment Needs
Screw Thread Design - pdf file
Making a Deck - Picking out the Appropriate Nails, Screws, or Fixtures
Quick access fasteners catalogue
http://www.southco.com/product/default.aspx?hid=7337
Quick access fasteners catalogue
http://www.southco.com/product/default.aspx?hid=7337
Design of Machine Elements - Knol Book - Now in Blog post
Updated 23 April 2017, 30 March 2012
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