Sandwich Panel Cores for Blast Applications: Materials and Graded Density

Sandwich composites are of interest in marine applications due to their high strength-to-weight ratio and tailorable mechanical properties, but their resistance to air blast loading is not well understood. Full-scale 100 kg TNT equivalent air blast testing at a 15 m stand-off distance was performed on glass-fibre reinforced polymer (GFRP) sandwich panels with polyvinyl chloride (PVC); polymethacrylimid (PMI); and styrene acrylonitrile (SAN) foam cores, all possessing the same thickness and density. Further testing was performed to assess the blast resistance of a sandwich panel containing a stepwise graded density SAN foam core, increasing in density away from the blast facing side. Finally a sandwich panel containing compliant polypropylene (PP) fibres within the GFRP front face-sheet, was subjected to blast loading with the intention of preventing front face-sheet cracking during blast. Measurements of the sandwich panel responses were made using high-speed digital image correlation (DIC), and post-blast damage was assessed by sectioning the sandwich panels and mapping the damage observed. It was concluded that all cores are effective in improving blast tolerance and that the SAN core was the most blast tolerant out of the three foam polymer types, with the DIC results showing a lower deflection measured during blast, and post-blast visual inspections showing less damage suffered. By grading the density of the core it was found that through thickness crack propagation was mitigated, as well as damage in the higher density foam layers, thus resulting in a smoother back face-sheet deflection profile. By incorporating compliant PP fibres into the front face-sheet, cracking was prevented in the GFRP, despite damage being present in the core and the interfaces between the core and face-sheets

Preschool educational institution webpage

Pirmsskolas izglītības iestādes (PII) tīmekļa vietne ir tīmekļa vietne, kura paredz audzēkņu pievienošanu iestādes grupām, lietotāju saziņu un citu procesu funckionalitāti, ko var izlasīt sīkāk programmatūras prasību specifikācijā. Šī darba mērķis ir izstrādāt tīmekļa vietni pēc norādītās specifikācijas, papildināt esošās zināšanas, strādājot ar Laravel atvērtā koda PHP tīmekļa ietvaru, nostiprināt esošās ar phpMyAdmin tīmekļa pielikuma rīku un MySQL datubāziPreschool educational institution (PEI) webpage is a webpage, which provides student enrollment, user communication and other process functionalities, which can be read more in detail in the specification of software requirements. The aim of this work is to develop a webpage in accordance with the specification, to reinforce knowledge by wokring with Laravel in open source PHP framework, strengthen existing knowledge with phpMyAdmin web attachment tool and MySQL databas