Work

Strain rate-dependent crashworthiness of radially graded Al–PU hybrid foam-filled tubes under axial crushing

Year: 2026

Type: article

Abstract: Radially graded Al-PU hybrid foam-filled tubes are compact energy absorbers in which aluminum thin-walled tubes are filled with hybrid cores composed of aluminum foam (AF) and polyurethane foam (PF) arranged in controlled radial layouts. This study quantifies their strain rate (SR)-dependent crashworthiness under axial crushing, where SR refers to the initial nominal engineering strain rate, by isolating the coupled roles of radial stiffness placement and metallic confinement. Two hybrid core architectures were created by reversing the radial position of closed-cell AF and PF (OIG vs IOG), while enforcing equal cross-sectional area fractions to isolate architectural effects. Unconfined hybrid cores (URHFCs), tube-confined hybrids (CRHFCs), and an empty-tube baseline (UMET) were tested from quasi-static to impact over four initial nominal engineering SRs. URHFCs exhibit architecture-controlled collapse, shifting from shear-band-governed compaction (OIG) to contact-induced axial cracking and brittle fragmentation of the polymer shell (IOG). Confinement suppresses these localized mechanisms and promotes concertina-type progressive folding, producing a more regular load-stroke response. Increasing initial nominal SR increases load capacity and alters collapse stability and densification behavior, captured by indicators spanning pre-collapse stiffness, peak/mean crushing forces, densification strain/slope, and plateau variability. Energy analysis confirms strong initial nominal SR amplification of absorbed work and shows a persistent CRHFC capacity advantage over UMET. Peak load demand in CRHFCs remains higher than UMET, consistent with tube-core interaction strengthening. Although core mass reduces SEA relative to UMET, CRHFCs retain higher load efficiency and the best multi-metric balance overall. Performance maps and direction-consistent radar synthesis indicate that CRHFCs provide the most favorable multi-metric compromise within the investigated dataset, with OIG favoring energy-absorption capacity and IOG favoring collapse stability.

Source: Construction and Building Materials

DOI: 10.1016/j.conbuildmat.2026.147590

Authors: Andreea-Iustina Rusu, Nima Movahedi, Emanoil Linul

Institutions: Politehnica University of Timisoara, University of Newcastle Australia

Language: English

Topic: Cellular and Composite Structures

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,540

Funders: Corporation for National and Community Service, Ministerul Cercetării, Inovării şi Digitalizării, Unitatea Executiva pentru Finantarea Invatamantului Superior, a Cercetarii, Dezvoltarii si Inovarii