Active control of passive safety in passenger motor vehicles : a feasibility study investigating dynamic denting of members using pyrotechnic devices

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dc.contributor.advisorNurick, Gerald Nen_ZA
dc.contributor.authorMarshall, N Sen_ZA
dc.date.accessioned2016-10-03T13:59:52Z
dc.date.available2016-10-03T13:59:52Z
dc.date.issued1995en_ZA
dc.description.abstractThis report describes a feasibility study investigating dynamic denting of members using pyrotechnic devices to engineer favourable energy absorption characteristics into thin walled tubes. A tube of sufficiently low slenderness ratio and wall thickness, when loaded axially to failure, will collapse in the progressive buckling mode. After the ultimate buckling load has been exceeded, and as the tube continues to compress, the load oscillates between loads considerably lower than the ultimate buckling load. The object of introducing an advantageous deformation is to decrease the ultimate buckling load to a magnitude comparable with the subsequent peak loads, but at the same time avoiding a change in the buckling mode which is not advantageous. Testing was limited to thin walled square mild steel tubes. The test procedure began with a process to determine the limitations imposed on the geometric imperfections that could be achieved by the use of explosive. It was found that all the explosively induced deformations were rounded, i.e. the dents were hemi-spherical in shape. It was also found that a smooth edged round hole could be created in the centre of the dent with the use of a round, flat explosive charge. Geometric imperfections that could be induced explosively in the specimens (as well as other deformation shapes, tested for comparative purposes) were mechanically formed in the specimens. The tubes were then quasi - statically crushed to determine the energy absorption characteristics induced by the deformations. When spherical dents were induced, the deformation affected the tube beyond the immediate spherical dent and hence the distance between the plastic hinges was increased and instabilities in the crushing process were introduced. Holes (without any visible denting) decreased the distance between the plastic hinges and thus also induced instabilities. In both cases the tubes tended to skew over to one side and in extreme cases Euler buckling ensued.en_ZA
dc.identifier.apacitationMarshall, N. S. (1995). <i>Active control of passive safety in passenger motor vehicles : a feasibility study investigating dynamic denting of members using pyrotechnic devices</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Mechanical Engineering. Retrieved from http://hdl.handle.net/11427/22084en_ZA
dc.identifier.chicagocitationMarshall, N S. <i>"Active control of passive safety in passenger motor vehicles : a feasibility study investigating dynamic denting of members using pyrotechnic devices."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Mechanical Engineering, 1995. http://hdl.handle.net/11427/22084en_ZA
dc.identifier.citationMarshall, N. 1995. Active control of passive safety in passenger motor vehicles : a feasibility study investigating dynamic denting of members using pyrotechnic devices. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Marshall, N S AB - This report describes a feasibility study investigating dynamic denting of members using pyrotechnic devices to engineer favourable energy absorption characteristics into thin walled tubes. A tube of sufficiently low slenderness ratio and wall thickness, when loaded axially to failure, will collapse in the progressive buckling mode. After the ultimate buckling load has been exceeded, and as the tube continues to compress, the load oscillates between loads considerably lower than the ultimate buckling load. The object of introducing an advantageous deformation is to decrease the ultimate buckling load to a magnitude comparable with the subsequent peak loads, but at the same time avoiding a change in the buckling mode which is not advantageous. Testing was limited to thin walled square mild steel tubes. The test procedure began with a process to determine the limitations imposed on the geometric imperfections that could be achieved by the use of explosive. It was found that all the explosively induced deformations were rounded, i.e. the dents were hemi-spherical in shape. It was also found that a smooth edged round hole could be created in the centre of the dent with the use of a round, flat explosive charge. Geometric imperfections that could be induced explosively in the specimens (as well as other deformation shapes, tested for comparative purposes) were mechanically formed in the specimens. The tubes were then quasi - statically crushed to determine the energy absorption characteristics induced by the deformations. When spherical dents were induced, the deformation affected the tube beyond the immediate spherical dent and hence the distance between the plastic hinges was increased and instabilities in the crushing process were introduced. Holes (without any visible denting) decreased the distance between the plastic hinges and thus also induced instabilities. In both cases the tubes tended to skew over to one side and in extreme cases Euler buckling ensued. DA - 1995 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1995 T1 - Active control of passive safety in passenger motor vehicles : a feasibility study investigating dynamic denting of members using pyrotechnic devices TI - Active control of passive safety in passenger motor vehicles : a feasibility study investigating dynamic denting of members using pyrotechnic devices UR - http://hdl.handle.net/11427/22084 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/22084
dc.identifier.vancouvercitationMarshall NS. Active control of passive safety in passenger motor vehicles : a feasibility study investigating dynamic denting of members using pyrotechnic devices. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Mechanical Engineering, 1995 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/22084en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Mechanical Engineeringen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherMechanical Engineeringen_ZA
dc.titleActive control of passive safety in passenger motor vehicles : a feasibility study investigating dynamic denting of members using pyrotechnic devicesen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMSc (Eng)en_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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