For your navigation on our web site, you have to accept the use of cookies on your device. Those cookies are necessary for all features to operate properly. Find out more... Close and accept


Back > Software

Cetim Cobra : Bolted joint design

Cetim Cobra Software


The strength of the world leader for bolted joint design and failure analysis



 V6 version of Cetim’s Cobra software provides you with a French - English bilingual solution.




Bolted joints analysis, review, verification and dimensioning, with controlled torque pre-tightening, following VDI 2230 recommendation (and extensions to standards NF E 25030-1, NF E 25030-2):

  • Benefit from Cetim's expertise in bolted joint design and verification in the analysis of your assembly
  • Improve your understanding of complex assemblies with the best validated software on the market
  • Deliver reliable documentation with your validation report including design options
  • Reduce verification and design time of complex assemblies
  • Perform strength analysis beyond VDI 2230 recommendation




Cetim Cobra is used in the industry to address complex bolted and screwed joints with critical safety and security issues

  • Major companies of the transportation industry (automotive, rail, air, defense and space) use Cobra to analyse dynamic assemblies
  • Cobra is widely used across the industry (gas, petroleum, agriculture, construction) for the design and analysis of heavy duty assemblies




Cetim has a unique experience in bolted and screwed joints verification and failure analysis. From this experience, Cetim has developed design and analysis functions beyond those of VDI 2230

  • Improved computation of alternate stress for dynamic loading, accountable for 80% of failures in bolted joints
  • Unique computation of geometry and tolérances, thread tolérances and material properties dispersion, tightening tool and friction coefficient dispersion for static loading validation
  • Selection of appropriate torque level to support the design of complex bolted joints




  • Mechanical and/or thermal stresses
  • Fastener geometry (screw, stud, threaded rod, nut, washers...) and its mechanical properties. Threads ISO, UN, UNR
  • Clamped part geometry
  • Tightening conditions, method, friction coefficients, limitations etc...

The software can determine the optimum tightening conditions taking into account:

  • The dispersion of the tightening process (material + Tools + operators)
  • The friction coefficients (Under head or nut and in the thread)
  • The risk of surface embedding
  • The mechanical stress in the screw (tensile + torsion + bending)
  • The failure load of the threads
  • The presence of self-locking elements or prevailing torque (locknuts, tight fitting parts)

Once the calculation is performed, the software provides the following information:

  • Load factor
  • Dynamic stress range
  • Stress distribution in the assemby
  • Tightening method (torque, torque + angle, tensioning...)
  • Minimum thread engagement




Benefit from the experience of a world leader in bolted joint verification and failure analysis

  • 30 minutes design and verification time for a complex assembly --> Hand calculations or verification with other Tools usually take days
  • 100% focused on operational data and production --> takes into account installation error and data dispersion
  • 100% validated: continuous verification of data compliance / validation --> Cetim is the only software editor with laboratory testing facilities
  • 100% dedicated to the industry --> Cetim is the only software editor "managed" by the industry
  • 450 experts able to provide support sessions in addition to onsite training --> Cetim is the only editor with recognized field expertise




Specific data bases are provided:

  • Materials (Re, Rm, E, Thermal influence)
  • Screws, nuts, washers (diameter, length, property class, screw head size)
  • Standard holes (fine series, medium, large)
  • Standard torque




  • Resilience (or stiffness) of the fastener and the clamped parts
  • Dynamic stress (fatigue resistance)
  • Minimum tightening force to prevent opening and/or sliding
  • Maximum allowable preload
  • Minimum and maximum achieved preload
  • Minimum required properties of fastener, when quality class not defined
  • Elogation of the fastener after tightening
  • Maximum stresses in the elastic washers
  • Bearing pressure on contact surfaces (risk of embendding)
  • Minimum threaded length (risk of stripping)
  • Tightening settings determination (torque, angle, tension etc...)
    • tension in the screw
    • bearing pressure on the different contact surfaces
    • failure load of threads
    • required and/or a prevailing torque (on first tightening)



For more information, contact your sales representative: Anouar OKADI



Training to bolted joint dimensioning


Cetim offers various training sessions to better suit your needs:


Training session in your premises: Optimisation and dimensioning of bolted joints with COBRA V6 software

  •  duration: 4.5 days on site,
  •  personnel concerned: training for technical advisors and design office or process engineers,
  •  content:
    •  knowledge of standards,
    •  characteristics of a bolt,
    •  behaviour of bolted joint,
    •  presentation of Cobra V6 software,
    •  practical work with Cobra V6,
    •  study of a concrete case with Cobra V6.


Inter-company training: Dimensioning of bolted joints and use of the Cobra V6 software

  • duration: 3 days in Cetim’s premises,
  • personnel concerned: training for design office or process technicians and engineers,
  • content:
    •  static and dynamic characteristics of attachment parts,
    •  design of a bolted joint,
    •  determination of the tightening torque,
    •  presentation of Cobra V6 software,
    •  practical work with Cobra V6,
    •  loosening, off-centred forces,
    •  Cobra V6 database.


Inter-company training: Use of the V6 Cobra software

  • duration: 1 day in Cetim’s premises or on site,
  • personnel concerned: design office or process technicians and engineers involved in the calculation of bolted joints and the implementation of the tightening torque,
  • content:
    •  introduction to bolted joints,
    •  presentation of Cobra V6,
    •  practical work with Cobra V6,
    •  loosening, off-centred forces,
    •  Cobra V6 database.



Documentation - Contact


                          Click here :


- to download documentation


- if you are interested in distributing

   the Cetim's software


- or to contact us about our training course