Bolted connections for every application

Calculations for bolted connections:

  • Comparison and evaluation of tightening
  • Local fatigue calculations for threads and bolt head
  • Damage analysis and cracking and fracture models
  • Tensile tests on bolts and threaded components
  • (Higher frequency) vibration tests on bolt fittings
Picture: Screws from M16 to M64
Bolt connection

Calculation of nonskid prestressed connections

Non-slip prestressed screw connections (designation GV) are used, for example, for lattice towers for wind energy plants. The professional design of the friction surfaces is of decisive importance in order to be able to guarantee the desired limit sliding force. 

The stress of the connection results from the internal forces of the components to be connected. In the example below, a double-shear GV connection with a pretensioned screw was selected. Between the plates and the washers there are additional contact elements to allow sliding or friction effects. 

 Essentially, the following calculation steps were necessary: 

  • Model geometry of the double shear GM connection
  • Specify constitutive equations and boundary conditions
  • Apply biasing force with Pretension elements
  • Define contact algorithm with corresponding coefficients of friction 
  • Load schedule (eg, tensile stress at the edge of the sheets)
  • StrukturanalysePostprocessing
FE-model for GM connection
Contact pressure
Contact status
Friction tension

Damage analysis with fracture mechanics methods

SKI Ingenieurgesellschaft has fracture mechanics methods and local fatigue concepts at its disposal to evaluate the service life of bolts under static and dynamic loads. For further details contact us .
Oscillation tests for different types of loading

It can be realized oscillation tests on screws with the following load types:

  • Tension
  • Bending
  • Tension + Bending
  • Torsion

The test frequencies are, depending on Bolts and strain size between 20 and 200Hz.  

 
Bruchbild im Gewinde einer Schraube
Fracture pattern in the thread of a bolt
Resonance test frame for tension
Resonance test frame for tension + bending
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