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Cetim Cobra : Bolted joint design
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.
INDUSTRIAL REQUIREMENTS
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
APPLICATION DOMAINS
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
UNIQUE FEATURES
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
SCOPE OF APPLICATIONS
- 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
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WHY SELECT COBRA
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
EXPERIENCE RETURN
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
COMPUTATION RESULTS
- 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)
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For more information, contact your sales representative: Anouar OKADI
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Training to bolted joint dimensioning
Cetim offers various training sessions to better suit your needs:
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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.