Cockpit structure analysis
Our customer, Delastek Inc., a manufacturer and integrator of aeronautical composite components, teamed up with Creaform in order to perform the structural validation and finite element modelling of its designs that were used on a completely new aircraft: the Cseries by Bombardier. Finite element models, with various levels of detail were built on Femap and computed with NEi Nastran. This increased the efficiency of the macroscopic design of the cockpit components as well as allowed the resolution of specific issues throughout the process.
In addition to modal and linear quasi-static analysis, non-linear transient simulations with non-linear ply-failure evaluations on detailed composite structures models were required to address potential strength issues. Furthermore, vibration analyses made it possible to identify potential issues raised by components’ natural frequencies and coupling. Finite element modelling made it possible to certify the robustness of designs with a precise and complete stress evaluation for in-use and abuse-load cases pointed out by Bombardier.
The project involved many structural engineers over a long period. Methodology and techniques were standardized by Creaform to ensure efficiency during the entire iterative design process. With an impressive loading to structural weight ratio of 44:1 (lbf:lbs), the weight optimization process was a challenging task. To overcome this, new composite materials and new manufacturing process were implemented. While cutting down the structural mass, no compromise was made on the stiffness, dynamic behavior and robustness. Dynamic analyses on composite layered materials aren’t simple and easy as they can be on metallic parts. Composite layered results were obtained and used to compute less conservative margins of safety than the typical process used by competitors.
- Preliminary analysis and structural recommendations prior to design
- Dynamics and vibration training and recommendations
- Structural substantiation methodology and techniques elaboration
- Geometry preparation using CAD software
- Finite element modeling using strict standards
- Static linear and non-linear analysis for flight loading and abuse loading (FAA FAR Part 25)
- Modal, dynamic (Sine) and life analysis for windmilling requirement (engine imbalance, FAA-AC 25-24)
- Weight optimization
- Margins of safety calculations for metallic, composites and interface joints (rivets, bonding, fasteners, fittings)
- Tests plans and procedures preparation for material qualifications and interface joints allowable
- Results presentation to the end customer and production of all methodology and substantiation reports
Tools and Methods Used
Based on the client’s needs, Creaform used the following tools and methods:
- Nei Nastran
- Static, modal, sine, non-linear progressive ply failure