Sub-Zero Transverse Impact Response of Filament-Wound Glass–Carbon/Epoxy Hybrid Tubes with Reciprocal Radial Stacking

The transverse impact response of filament-wound composite tubes depends on impact conditions and through-thickness construction. This exploratory study examines two four-block glass–carbon/epoxy configurations: 45G45C (inner-to-outer G45/C45/G75/C75, outer carbon) and 45C45G (C45/G45/C75/G75, outer glass). Instrumented drop-weight tests at nominal energies of 40, 60, and 80 J after conditioning at 20, 0, −20, −40, and −60 °C provided a complete 30-cell descriptive map. Across both configurations and all temperatures, increasing energy from 40 to 80 J raised the mean peak force from 7.50 to 10.41 kN and the mean maximum displacement from 8.84 to 13.38 mm. The ratio of instrument-reported absorbed energy to nominal incident energy increased from 0.949 to 0.985. No monotonic temperature ordering was observed. Condition-specific peak-force contrasts approached 20%, whereas the sole repeated condition gave a 5.02% pair difference. These observations identify conditions for replication but do not establish a reproducible energy–temperature–stacking interaction. Differences in mean wall thickness also prevent the isolation of a stacking-only effect. Quantitative curve descriptors and conditional thermal sensitivity calculations supplement the response map. Photographs describe surface appearance only. With one specimen in 29 cells and no direct temperature measurement at first contact, the comparisons remain specific to the tested specimens and as-manufactured configurations.