The design of an impulse meter to characterise vertical blast loads

Strydom, Kurt Ralph (2007-03)

Thesis (MScIng) -- University of Stellenbosch, 2007.

Thesis

ENGLISH ABSTRACT: This report covers the development of an impulse meter for the characterization of vertically applied blast loads in terms of total impulse transferred to a test structure. The Spring-Mass Impulse Meter (SMI) was developed for the Blast Impact and Survivability Research Unit (BISRU) based at the University of Cape Town (UCT). The SMI was developed specifically for the measurement of impulses due to the momentum transfer between blasts from soil buried charges and thin plates or small structures for landmine related research. Several impulse measurement methods and concepts were investigated and compared; the SMI was shown by qualitative comparisons to be the concept that is most likely to satisfy BISRU's needs. The resulting SMI structure was analysed using Finite Element Analysis to confirm its structural integrity and acceptable dynamic response. The system dynamics and impulse response were analysed and optimised using single degree of freedom spring-mass models. The SMI was manufactured, installed at UCT and also calibrated against a horizontal ballistic pendulum with a series of bulge tests. The calibration tests were done on plates with thicknesses ranging from 1.6 mm to 4 mm using PE4 plastic explosive as the impulse source. Tests results showed the SMI to be capable of measuring impulses between 10 N·s and 75 N·s with accuracy and repeatability similar to that of a ballistic pendulum.

AFRIKAANSE OPSOMMING: Hierdie verslag dek die ontwikkeling van 'n impulsmeter met die doel om vertikale plofbelastings te karakteriseer in terme van totale impuls oorgerdra aan 'n toetsstruktuur. Die Veer-massa Impuls meter, "Spring-Mass Impulse Meter" (SMI) is ontwikkel vir die "Blast Impact and Survivability Research Unit" (BISRU) wat by die Universiteit van Kaapstad gesetel is. SMI is spesifiek ontwikkel vir die meting van impuls as gevolg van die momentum oordrag tussen ontploffings vanaf grondbedekte plofladings en dun plate of kleiner strukture vir landmyn navorsing. 'n Aantal verskillende impuls meet-metodes en konsepte is ondersoek en vergelyk, die SMI is deur middel van kwalitatiewe vergelyking uitgewys as die konsep wat die grootste potensiaal het om aan BISRU se behoeftes te voorsien. Die gevolglike SMI struktuur is met Eindige Element Analises ondersoek om strukturele integriteit en aanvaarbare dinamiese respons te bevestig. Die stelsel dinamika en impuls respons is met behulp van een vryheidsgraad veer-massa modelle bestudeer en geoptimeer. Die SMI stelsel is vervaardig, by die Universiteit van Kaapstad geinstalleer en ook gekalibreer met betrekking tot 'n horisontale ballistiese pendulum tydens 'n reeks van plaat-duik toetse. Die kalibrasie en aanvaardingstoetse is op plate met diktes tussen 1.6 mm en 4 mm gedoen met PE4 springstof as impulsbron. Die toets resultate het getoon dat die SMI stelsel in staat was om impuls tussen 10 N·s en 75 N·s te meet met akkuraatheid wat vergelykbaar is met die van 'n horisontale ballistiese pendulum.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/50752
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