- Numerical Simulation

- Conventional Calculations

- Fatigue & Damage Tolerance Analysis

- Testing

- Certification

- Programming

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Numerical Simulation

  • Creation and modification of FE models
  • Analysis and interpretation of the results
  • Linear, non-linear, buckling, dynamic 

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Stehlin Engineering adopted NX/NASTRAN as finite element code and FEMAP as pre- and postprocessor. A robust interface between CAD data and FEM data is provided via ASIS or PARASOLID engines. This permits to model and analyse very complex 3D parts and give feedback to the designers in electronic form if desired. 

Conventional Calculations

  • Strength
  • Stiffness
  • Stability
  • Connections
  • Metallic materials
  • Composite materials
  • Sandwich structures

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Stehlin Engineering performs detailed stress analyses of structures using established practices from the aerospace industry. The company has built up a strong knowledge in the design and analysis of composite, sandwich and classical reinforced skin-stringer structures with an in-depth expertise in the calculation of local effects, such as load introductions, connections, fittings, local instabilities, etc....

The company intensively uses data sheets and manuals such as the ESDU's (Engineering Sciences Data Unit), MIL Handbooks, ESA and NASA Handbooks, Bruhn, etc.

Fatigue & Damage Tolerance Analysis

  • Spectrum development
  • Stress concentration assessment
  • Beta solutions development
  • Dedicated in-house tool (pyNASSIF)
  • Residual strength (R-Curve)
  • Crack initiation calculations (CI)
  • Crack growth calculations (CG)
  • Analysis methods development


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Stehlin Engineering adopted AFGROW as crack initiation and crack growth code and FRANC2D as stress intensity computation tool.

In 2002, Stehlin Engineering developed an original method to perform fatigue analysis of bolted and riveted connections in a very efficient way using the Finite Element Method. Stehlin Engineering has been selected to write a paper on this subject for the ICAF 2003.

In 2012 Stehlin Engineering developed a tool, which aim is to compute the stress intensity factor (K) along a given crack path in function of the crack length in structures idealized by PLATE elements in FEM models based on the NASTRAN solver: pyNASSIF.

In 2014 Mr Thierry Stehlin was selected to hold a presentation at the ASIP conference in name of ruag. The presentation shows an application of the use of pyNASSIF to perform CG analysis in a spar of the outer wing of the Swiss F/A-18 aircraft (ASIP 2014).


  • Test specifications
  • Test plans
  • Predictions
  • Test survey
  • Results interpretation
  • Reporting

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  • Certification reporting
  • CVE activities for companies holding an EASA DO approval


  • Python
  • Visual Basic for Applications (VBA)


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