Issue 48

O. A. Mocian et alii, Frattura ed Integrità Strutturale, 48 (2019) 230-241; DOI: 10.3221/IGF-ESIS.48.24 230 Low velocity failure and integrity assessment of foam core sandwich panels Oana Alexandra Mocian, Dan Mihai Constantinescu, Ş tefan Sorohan, Marin Sandu University POLITEHNICA of Bucharest, Department of Strength of Materials, 060042 Bucharest, Romania mocianoana@gmail.com , https://orcid.org/0000-0003-3093-7788 dan.constantinescu@upb.ro, https://orcid.org/0000-0001-5400-7804 stefan.sorohan@upb.ro, https://orcid.org/0000-0002-9400-5843 marin.sandu@upb.ro , https://orcid.org/0000-0002-9183-5104 A BSTRACT . Impact resistance and energy absorbing capability are of great interest in the design of composite sandwich structures. This paper experimentally studies damage, failure and energy absorption properties of foam core sandwich panels with aluminum and glass fiber reinforced plastic (GFRP) facesheets subjected to low velocity impact. Tests are performed using a drop weight impact tower at different impact velocities. The energy absorbing capabilities of aluminum and composite facesheet sandwich panels with PUR and PS foam core are evaluated by means of absorbed energy-time histories and by specific parameters as normalized absorbed energy, specific energy absorption, and crush force efficiency. Stiffer panels behave better at lower impact velocities, while more ductile ones do better if impact energy is increased. K EYWORDS . Low velocity impact; Sandwich panels; Skin and core damage; Energy absorption parameters. Citation: Mocian, O.A., Constantinescu, D.M., Sorohan, Şt., Sandu, M., Low velocity failure and integrity assessment of foam core sandwich panels, Frattura ed Integrità Strutturale, 48 (2019) 230-241. Received: 20.01.2019 Accepted: 15.02.2019 Published: 01.04.2019 Copyright: © 2019 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION ne of the main design drivers of modern engineering is weight reduction whilst still ensuring high level of operational safety. Lightweight design can protect human life, avoid financial losses and reduce vehicles emissions. Seeking suitable lightweight materials has led to the development of composite materials, plastics and alternative new materials and sandwich construction. The last, usually consists of two strong and stiff facesheets separated by a low- density core. Faces are generally made of metal alloys [1], fiber reinforced composites [2] or fiber metal laminates [3] and are responsible for carrying the transverse loads or bending moments. The core of sandwich structures comprises of honeycombs [4], corrugated materials [5], polymeric/metallic foams [6, 7], lattices [8] or balsa wood [9] and is responsible for absorbing the impact energy by local plastic deformation whilst still offering enough overall support to prevent high local bending strains in the facesheets. A comprehensive review of the current trends in the research and applications of sandwich structures is done by Birman and Kardomateas, [10]. During service life, sandwich structures may be subjected to O