Felicja Frankowska
Composites Engineer · Materials & Process Engineering
Warsaw, Poland
Composites Engineer specializing in CFRP structural design and analysis for aircraft nacelle and fan cowl components. Leads laminate design, fiber path optimization, and damage tolerance assessment for primary composite structures. Works closely with manufacturing engineering on fiber placement process constraints and with structural analysis team for FEM model hand-off.
Expertise
- CFRP laminate design and analysis
- composite nacelle panel structural analysis
- failure mode prediction (Tsai-Wu, Hashin)
- repair design for composite structures
- autoclave process and quality control
Technologies
Work History
2025-02
Automated laminate design tool — built Python tool integrating CATIA Composites Python API with Nastran FEM to automate the ply sizing iteration loop. Reduced laminate optimization cycle time from 3 days to 6 hours.
Challenge: CATIA Composites Python API has limited documentation for the ply definition and orientation objects. Reverse-engineering the API behavior from VBA macro recordings took 4 days — but the resulting Python layer was reusable across all composite panel projects.
Learned: Investing in a well-documented Python wrapper for CATIA Composites API pays back across multiple projects. The initial investment in reverse-engineering and wrapping the API was 4 days, but each subsequent composite project saved 2-3 days of manual ply definition work.
2024-05
Repair design for composite fan cowl hail impact damage — designed a bolted external patch repair for a 150mm x 80mm delamination zone. Provided repair engineering order (REO) with step-by-step procedure and structural substantiation.
Challenge: Bolted patch repair analysis must account for fastener shear-out in the damaged parent laminate — the delaminated region has reduced bearing strength. Conservative modeling of the delaminated zone bearing strength required test data from delaminated laminate specimens, which were not available. Commissioned 8 specimens for expedited testing.
Learned: Composite repair structural substantiation often requires test data that is not in existing databases. Plan for expedited specimen testing at the start of repair design development — trying to justify a repair analysis with generic literature bearing strength data is routinely rejected by DER.
2023-11
Barely visible impact damage (BVID) tolerance assessment — performed CAI (Compression After Impact) strength prediction for nacelle fan cowl panels. Tested 15 CFRP specimens to correlate with the Nastran analysis methodology.
Challenge: CAI strength scatter was 25% between specimens with nominally identical impact energy and panel geometry — driven by fiber damage variability at the impact site. Conservative design allowables required padding the mean CAI strength down by 2 sigma, consuming most of the structural margin.
Learned: CAI strength allowables for composite panels require large specimen populations to characterize scatter adequately. Using mean strength minus one sigma is a common but sometimes non-conservative simplification — for primary structure, use B-basis (90% probability, 95% confidence) allowables derived from 30+ specimens.
2023-04
CFRP nacelle inner fixed structure (IFS) laminate redesign — optimized ply angles and thicknesses for acoustic liner mounting loads and pressure differential. Targeted 12% weight reduction vs. aluminum baseline.
Challenge: Acoustic liner attachment points required local pad-up laminates that created out-of-plane stress concentrations. Hashin failure criterion implementation in NASTRAN (user DMAP) showed failure in the pad-up taper region at limit load — required 3 iterations of taper profile optimization.
Learned: Pad-up laminate tapers in composite structures are a common stress concentration source. Design the taper angle conservatively (≤1:20 ply drop rate) from the start — steep tapers invariably show failure in the first analysis iteration and require costly redesign cycles.