Virtual Strain Sensing in a Type IV COPV Burst Test

<jats:p>This study evaluates data-driven virtual strain sensing in the cylindrical region of a Type IV composite overwrapped pressure vessel (COPV) using the open synchronized record of one vessel and one hydraulic burst test. The analysis is intentionally framed as a single-test comparative case study rather than a general reference standard. Twelve cylinder channels, representing six positions with axial and hoop gauges, were examined through position-holdout reconstruction within the same burst record, pressure-conditioned reconstruction without explicit time, and a within-record high-pressure stress test above 125 bar. Direction-wise same-time, pressure-bin, and isotonic baselines were compared with linear regression, ridge regression, random forest, and multilayer perceptron (MLP) models. The 115,308 long-format rows originate from one synchronized experiment and were therefore treated as correlated observations, not independent experimental replications. Within the cylinder subset, the same-time mean achieved R²=0.9915, while the MLP without coordinates achieved R²=0.9906±0.0002. When explicit time was removed, the pressure-bin baseline remained stronger than the time-free MLP. In the high-pressure stress test, all models deteriorated and the time-free MLP fell to R²=-1.8043. A supplementary dome analysis also showed substantially poorer reconstruction for hoop gauges. These findings indicate that replacement of a missing cylinder gauge is feasible within an already instrumented burst test, but they do not establish cross-vessel or cross-test generalization. Practical deployment will require repeated tests, multiple vessels, mechanics-aware models, and calibrated uncertainty estimates.</jats:p>