Towards an Understanding of the Effect of Adding a Foam Core on the Blast Performance of Glass Fibre Reinforced Epoxy Laminate Panels

Abstract

This paper presents insights into the blast response of sandwich panels with lightweight foam cores and asymmetric (different thicknesses) glass fibre epoxy face sheets. Viscously damped elastic vibrations were observed in the laminates (no core), while the transient response of the sandwich panels was more complex, especially after the peak displacement was observed. The post-peak residual oscillations in the sandwich panels were larger and did not decay as significantly with time when compared to the equivalent mass laminate panel test. Delamination was the predominant mode of failure on the thinner facesheet side of the sandwich panel, whereas cracking and matrix failure were more prominent on the thicker side (which was exposed to the blast). The type of constituent materials used and testing conditions, including the clamping method, influenced the resulting failure modes observed. A probable sequence of damage in the sandwich panels was proposed, based on the transient displacement measurements, a post-test failure analysis, and consideration of the stress wave propagation through the multilayered, multimaterial structure. This work demonstrates the need for detailed understanding of the transient behaviour of multilayered structures with significant elastic energy capacity and a wide range of possible damage mechanisms. The work should prove valuable to structural engineers and designers considering the deployment of foam-core sandwich panels or fibre reinforced polymer laminates in applications when air-blast loading may pose a credible threat.

Blast Effects on Hyperloop’s Cylindrical Thin-Shell Structures

“…The threats to critical infrastructures such as hyperloop systems exist in the transportation industry [38][39][40][41]. In many countries, such a risk is deemed to be very to extremely high [42][43][44].…”

Using optical diagnostics for near field blast testing

“…The ability to transform a spatially varying load into an equivalent single-number equivalent has strong implications for developing future quick-running predictive methods, as well as allowing for implementation into simplified analysis tools such as the single-degree-of-freedom method. In recent work (Gabriel et al, 2021), we measured the transient mid-point displacement blast response of near-equivalent mass glass FRP composite laminate panels with sandwich panels comprising glass FRP skins with a polymeric foam core. The loading was generated by detonating small charges of PE4 explosive down a "blast tube" to produce a spatially nearuniform loading across the front surface of the fully clamped composite test panels.…”

“…The transient measurements aided in the development of a proposed sequence of damage within the sandwich panels (Gabriel et al, 2021). These observations would not have been possible without the use of high-speed stereo-imaging and DIC.…”