PSI - Issue 77

Niels Grigat et al. / Procedia Structural Integrity 77 (2026) 365–375 Niels Grigat / Structural Integrity Procedia 00 (2026) 000 – 000

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The results obtained from these material tests form the quantitative basis for the simulation models presented in the following section. The present study systematically compares three fibre systems within identical epoxy matrix conditions, thereby enabling a detailed evaluation of the influence of fibre type on the mechanical integrity and hydrogen resistance of fibre-reinforced polymer (FRP) composites designed for pipeline applications. 3.3. Production of FRP Pipe Samples Subsequent to material characterisation, the fabrication of prototype FRP pipe sections is initiated for the purpose of validating the findings derived from preliminary tests under realistic conditions. The production process is meticulously engineered through the utilisation of state-of-the-art filament winding technology, which confers a high degree of precision in the modulation of fibre orientation, winding tension, and resin distribution. The process has been meticulously engineered to emulate scalable industrial manufacturing methodologies whilst upholding the level of laboratory-grade precision necessary for comparative analysis. The pipes are produced using towpreg systems, which have previously been characterised, and which are based on glass, carbon, and aramid fibres with epoxy resin matrices. Each fibre type is wound onto a mandrel with defined winding angles and layer sequences to achieve the required hoop and axial strength. The winding pattern generally combines ±54.7° helical and 90° hoop layers to balance internal pressure resistance with axial stiffness. The winding parameters – including fibre tension, resin viscosity, and winding speed – are meticulously regulated to ensure consistent laminate quality and reproducibility. Figure 3.1: Development steps of fibre-reinforce plastic pipelines for the transport of gaseous hydrogen Subsequent to winding, the composite structures undergo thermal curing in accordance with the temperature regime employed during material testing. Following the curing process, the mandrel is then removed, and the pipes are machined to the required dimensions for subsequent testing. The internal surfaces can be treated using Extreme High Speed Laser Application (EHLA) coating, which serves to enhance hydrogen diffusion resistance and surface durability. In order to verify the structural integrity of a given material, non-destructive testing (NDT) methods such as ultrasonic inspection are applied in order to detect potential voids or delaminations. Dimensional checks are conducted to ensure conformity with the designed geometries and wall thicknesses. The manufactured samples are employed as test specimens for mechanical validation under internal pressure, burst tests, and hydrogen permeation experiments, as outlined in the following chapter. The results from these prototype tests provide direct feedback for the refinement of both the material models and the winding process, thus completing the iterative development loop. [15, 16, 17] 4. Results & Discussion The subsequent section is devoted to the presentation and discussion of the results obtained from both experimental investigations and numerical simulations of the developed FRP hydrogen pipeline systems. These tests indicate first results as the studies are still ongoing. The evaluation is centred on two pivotal performance elements: the hydrogen diffusion behaviour of the material systems and the structural integrity of the pipeline under internal pressure loading. The experimental data from material-level tests will be combined with simulation results to provide a comprehensive