Diana Długosz
Materials Test Engineer · Materials & Process Engineering
Warsaw, Poland
Materials Test Engineer responsible for planning and executing mechanical characterization test campaigns for aerospace alloys and AM materials. Operates high-temperature fatigue and creep rigs, manages test programs from specimen specification through data reduction and design allowables generation. Strong background in statistical analysis and MMPDS data reduction procedures.
Expertise
- LCF and HCF test planning and execution
- creep and stress rupture testing
- tensile and fracture toughness testing
- statistical fatigue data reduction (MMPDS)
- test equipment calibration and metrology
Technologies
Work History
2025-01
Automated test data reduction pipeline — built Python pipeline to extract raw force/displacement/temperature data from Instron and MTS test systems, compute derived quantities (stress, strain, modulus), and output to a structured database.
Challenge: Instron raw data files use a proprietary CSV format with variable header rows depending on test type and software version. Built a robust header parser that handles version differences, but two test types (compression, biaxial) had undocumented format differences discovered only in production.
Learned: Test machine data parsers must be tested against files from every test type and software version in use. Maintaining a reference file library covering all format variations, and running parser tests against it, prevents format corner cases from corrupting the production database.
2024-05
Creep test campaign for nickel superalloy turbine disk alloy — 36 specimens at 3 stress levels and 2 temperatures (700°C, 760°C). Generated Larson-Miller parameter curve for creep life prediction.
Challenge: Creep test times at low stress levels exceeded 3,000 hours — 6 tests were still running at the program design review deadline. Developed an extrapolation procedure using the available <3,000h data with confidence interval quantification to support the preliminary design review.
Learned: Creep data extrapolation for design allowables must include quantified uncertainty. A Larson-Miller fit to incomplete data with explicit confidence bounds is acceptable at PDR — but the bounds must be conservative and the test program must continue to confirm the extrapolation before CDR.
2023-10
HCF test campaign for compressor blade Ti-6Al-4V — 120 specimens at R = -1 and R = 0.1 ratio, 3 temperatures. Generated S-N curve data for fatigue limit and Goodman diagram construction.
Challenge: Specimen run-out definition at 10^7 cycles was insufficient for titanium — several specimens that run-out at 10^7 showed failures on re-test at 10^8 cycles, indicating a true HCF limit had not been reached. Extended run-out to 3×10^7 cycles for all remaining specimens.
Learned: Titanium alloys do not have a clear fatigue endurance limit at 10^7 cycles. HCF run-out criteria for titanium must account for the gradual reduction in strength beyond 10^7 — use run-out criteria of at least 10^8 or apply a fatigue strength reduction factor for the unknown region beyond 10^7.
2023-03
LCF test campaign for HPT disk IN718 alloy — 80 specimens at 3 temperatures (450°C, 550°C, 650°C) and 4 strain ranges. Executed constant strain amplitude tests with push-pull loading on Instron 8802 with induction heating.
Challenge: Induction heating temperature uniformity was insufficient for the 30mm gauge length specimens at 650°C — thermocouple at specimen center and end showed 18°C gradient. Required custom coil re-winding to improve field uniformity. Tests were repeated for 12 specimens that ran with the non-uniform heating setup.
Learned: Induction heating temperature uniformity must be validated with multiple thermocouple positions before running specimens. A center-only temperature measurement is insufficient — design the coil geometry to achieve <5°C gradient across the gauge length before committing to the test campaign.