Tesi sul tema "Blast effect"
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1
Singh, Ajit 1951. "Photographic evaluation of blast fragmentation". Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63380.
Testo completo
2
Tsuga, Toshihiro. "Multi-objective optimization of blast simulation using surrogate model". Fairfax, VA : George Mason University, 2007. http://hdl.handle.net/1920/2916.
Testo completoAbstract (sommario):
Thesis (M.S.)--George Mason University, 2007.Title from PDF t.p. (viewed Jan. 22, 2008). Thesis director: Rainald Löhner. Submitted in partial fulfillment of the requirements for the degree of Master of Science in Computational Sciences and Informatics. Vita: p. 49 Includes bibliographical references (p. 44-48). Also available in print.
3
Matthews, Debra Sue. "Blast effects on prestressed concrete bridges". Online access for everyone, 2008. http://www.dissertations.wsu.edu/Thesis/Summer2008/D_Matthews_072908.pdf.
Testo completo
4
McClendon, Mark Andrew. "Blast resistant design for roof systems". Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/7974.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 1, 2008) Includes bibliographical references.
5
Kennedy, John Anthony. "Analytical and experimental evaluation of steel sheets for blast retrofit design". Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/5849.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (January 24, 2007) Includes bibliographical references.
6
Pingle, Shivnandan Mohan. "Metallic sandwich structures for mitigating sand blast loading". Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609669.
Testo completo
7
Adderley, Geoffrey. "The effect of tunnel blast design on vibration". Thesis, University of Essex, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506087.
Testo completo
8
Cimo, Renee. "Analytical modeling to predict bridge performance under blast loading". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 199 p, 2007. http://proquest.umi.com/pqdweb?did=1338919161&sid=3&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Testo completo
9
Tekalur, Srinivasan Arjun. "Faliure of marine composite materials due to blast loading /". View online ; access limited to URI, 2007. http://0-digitalcommons.uri.edu.helin.uri.edu/dissertations/AAI3284829.
Testo completo
10
Fox, Matthew J. "Numerical modeling of air blast effects on hybrid structures". Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2630.
Testo completoAbstract (sommario):
Thesis (M.S.)--West Virginia University, 2002.Title from document title page. Document formatted into pages; contains x, 114 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 42-45).
11
Hall, Julie. "Evaluation of blast fragmentation models for mine to mill applications /". [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19159.pdf.
Testo completo
12
Fitzmaurice, Silas James. "Blast retrofit design of CMU walls using polymer sheets". Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4569.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 17, 2009) Includes bibliographical references.
13
Mason, Michael Regis 1962. "Investigation into "bud blast" in the Easter lily (Lilium longiflorum Thunb)". Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277210.
Testo completoAbstract (sommario):
Ethylene and carbohydrate deprivation were investigated as possible causes of bud abortion in Lilium longiflorum Thunb. Silver thiosulfate (STS) was investigated as an inhibitor of ethylene-induced abortion. Fourteen days of 92.5% irradiance reduction increased bud abortion when plants were exposed to 2.07 mM ethephon. Percent bud abortion was 39% and 60% for plants grown in full irradiance and reduced irradiance, respectively. Ethephon resulted in 54% abortion, regardless of irradiance at 4.15 mM. A 70% irradiance reduction for 14 days did not increase bud abortion when plants were treated with ethephon. STS was applied to plants at visible bud +2 weeks followed by ethephon application 2 days later. Bud abortion was reduced from 69 to 13% with 2 mM STS; the STS x ethephon interaction was significant. STS inhibited ethephon-induced bud abortion when applied at visible bud, 4 weeks prior to ethephon application; However, STS application at flower bud initiation did not prevent/reduce ethephon-induced bud abortion.
14
Tahmilci, Fatih. "Analysis Of Blast Loading Effect On Regular Steel Building Structures". Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12609052/index.pdf.
Testo completoAbstract (sommario):
Concern about effect of explosives effect on engineering structures evolved after the damage of Second World War. Beginning from 90&rsquos with the event of bombing Alfred P. Murrah Federal building located in Oklahoma City this concern deepened and with the attack to World Trade Center twin towers on September 11, 2001 it is peaked. Recent design codes mainly focus on earthquake resistant design and strengthening of the structures. These code design methodologies may sometimes satisfy current blast resistant design philosophy, but in general code compliant designs may not provide recognizable resistance to blast effect. Therefore designer should carry out earthquake resistant design with the blast resistant design knowledge in mind in order to be able to select the most suitable framing scheme that provide both earthquake and blast resistance. This is only possible if designer deeply understands and interprets the blast phenomenon. In this study, it is intended to introduce blast phenomenon, basic terminology, past studies, blast loading on structures, blast structure interaction, analysis methodologies for blast effect and analysis for blast induced progressive and disproportionate collapse. Final focus is made on a case study that is carried out to determine whether a regular steel structures already designed according to Turkish Earthquake Code 2007 requirements satisfy blast, thus progressive collapse resistance requirements or not.
15
Jobe, Jeffrey M. "Blast resistant forced entrty [sic] steel stud wall design". Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/5850.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (January 23, 2007) Includes bibliographical references.
16
Schubak, Robert Brian. "Nonlinear rigid-plastic analysis of stiffened plates under blast loads". Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/31482.
Testo completoAbstract (sommario):
The large ductile deformation response of stiffened plates subjected to blast loads is investigated and simplified methods of analysis of such response are developed. Simplification
is derived from modelling stiffened plates as singly symmetric beams or as grillages thereof. These beams are further assumed to behave in a rigid, perfectly plastic manner and to have piecewise linear bending moment-axial force capacity interaction relations, otherwise known as yield curves.
A blast loaded, one-way stiffened plate is modelled as a singly symmetric beam comprised
of one stiffener and its tributary plating, and subjected to a uniformly distributed line load. For a stiffened plate having edges fully restrained against rotations and translations,
both transverse and in-plane, use of the piecewise linear yield curve divides the response of the beam model into two distinct phases: an initial small displacement phase wherein the beam responds as a plastic hinge mechanism, and a final large displacement phase wherein the beam responds as a plastic string. If the line load is restricted to be a blast-type pulse, such response is governed by linear differential equations and so may be solved in closed form. Examples of a one-way stiffened plate subjected to various blast-type pulses demonstrate good agreement between the present rigid-plastic formulation and elastic-plastic beam finite element and finite strip solutions.
The response of a one-way stiffened plate is alternatively analysed by approximating it as a sequence of instantaneous mode responses. An instantaneous mode is analogous to a normal mode of linear vibration, but because of system nonlinearity exists for only the instant and deformed configuration considered. The instantaneous mode shapes are
determined by an extremum principle which maximizes the rate of change of the stiffened plate's kinetic energy. This approximate rigid-plastic response is not solved in closed form but rather by a semi-analytical time-stepping algorithm. Instantaneous mode solutions compare very well with the closed-form results.
The instantaneous mode analysis is extended to the case of two-way stiffened plates, which are modelled by grillages of singly symmetric beams. For two examples of blast loaded two-way stiffened plates, instantaneous mode solutions are compared to results from super finite element analyses. In one of these examples the comparison between analyses is extremely good; in the other, although the magnitudes of displacement response
differ between the analyses, the predicted durations and mechanisms of response are in agreement.
Incomplete fixity of a stiffened plate's edges is accounted for in the beam and grillage models by way of rigid-plastic links connecting the beams to their rigid supports. Like the beams, these links are assumed to have piecewise linear yield curves, but with reduced bending moment and axial force capacities. The instantaneous mode solution is modified accordingly, and its results again compare well with those of beam finite element analyses.
Modifications to the closed-form and instantaneous mode solutions to account for strain rate sensitivity of the panel material are presented. In the closed-form solution, such modification takes the form of an effective dynamic yield stress to be used throughout the rigid-plastic analysis. In the time-stepping instantaneous mode solution, a dynamic yield stress is calculated at each time step and used within that time step only. With these modifications in place, the responses of rate-sensitive one-way stiffened plates predicted by the present analyses once again compare well with finite element and finite strip solutions.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
17
Doran, Catherine Margaret. "Effect of resuscitation strategies on coagulation following haemorrhage and blast exposure". Thesis, University of Newcastle upon Tyne, 2013. http://hdl.handle.net/10443/1868.
Testo completoAbstract (sommario):
Approximately one-third of trauma patients are coagulopathic on arrival to the emergency department. Acute traumatic coagulopathy and systemic inflammatory responses are serious secondary consequences of severe trauma and are linked to increased morbidity and mortality. Early tissue hypoxia is a major component in the aetiology of both complications. New resuscitation strategies are aimed at improving tissue oxygenation in the pre-hospital phase, and may attenuate coagulopathy and inflammatory sequelae. This is of particular importance in military personnel who suffer complex injuries, often from blast exposure, and may have extended evacuation times. This thesis evaluates the effect of a novel hybrid (NH) resuscitation strategy on coagulation and inflammation. Terminally anaesthetised pigs were randomised to one of two injury strands of haemorrhage +/- blast injury; initially resuscitated with 0.9% Saline to a hypotensive systolic blood pressure of 80mmHg for one hour. This was followed by either a return to a normotensive pressure (110mmHg) (NH) or a continuation at the hypotensive level. Over both injury strands NH significantly reduced Prothrombin Time, PT (mean proportion of baseline: 1.40±0.05 vs. 1.80±0.09; p=0.001) and interleukin-6 (IL6) levels (mean 1106±153 vs. 429±79 pg/ml; p=0.001) compared to the hypotensive groups. PT was positively correlated with IL6 (p=0.002) and base deficit (p=0.0004). These findings indicate that improving tissue oxygenation reduces the coagulation derangement and the pro-inflammatory response. No difference in coagulopathy was found between injury strands although blast did cause greater inflammation. Early identification of coagulopathic casualties is essential and a separate feasibility field study was preformed to assess the use of thromboelastometry in a deployed military hospital, evaluating the degree of coagulopathy in battlefield casualties and to monitor the coagulation status during the resuscitation process. In conclusion, NH attenuated the acute traumatic coagulopathy and inflammatory responses and therefore should be considered when an extended casualty evacuation is enforced.
18
Suthar, Kunal. "Effect of dead, live and blast loads on a suspension bridge". College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7181.
Testo completoAbstract (sommario):
Thesis (M.S.) -- University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Civil and Environmental Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
19
Gamber, Nathan K. "Shallow foundation systems response to blast loading". Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1176319209.
Testo completo
20
Weyer, Matthew. "An experimental and theoretical study on the effect of strain rate on ductile damage". Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20767.
Testo completoAbstract (sommario):
Simulation of fracture in ductile materials is a challenging problem, since it typically occurs at length scales that are orders of magnitude smaller than that of the structures in which the fracture is occurring and, hence, difficult to resolve . One approach is to avoid modelling the micro-mechanics of ductile fracture by describing the macroscopic effects of fracture using damage parameters. Damage in metals can be defined as a measure of discontinuous deformation of a body. Many numerical models include some measure of damage to predict when a material will fracture under certain conditions, however there is little consensus as to what measures and parameters will accurately predict the onset of fracture. Most notably, the effect of strain rate at the point of fracture is significant and must be taken into account. The literature indicates that in the quasistatic regime where inertial effects are negligible, an increase in strain rate increases the strain at fracture. However, the research conducted in this dissertation suggests the opposite is true. The aim of this research is to conduct further high strain rate ductile damage experiments so as to extend the available data set, and develop a pragmatic damage model to relate the plastic strain at fracture to material parameters such as triaxiality, lode angle and strain rate in a specimen, which is verified using experiments performed under various loading conditions and strain rates.
21
Kitchenka, Julie A. "Feasibility and design of blast mitigation systems for naval applications using water mist fire suppression systems". Thesis, Monterey California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1473.
Testo completoAbstract (sommario):
CIVINSThe recent trend of using fine water mist systems to replace the legacy HALON-1301 fire suppression systems warrants further study into other applications of the water mist systems. Preliminary research and investigation indicates that fine mists (20-25 micro droplet size) may reduce peak overpressures of a shock wave traveling through a space. Such pressure reductions could be used to mitigate the destructive effects of a shock wave (initiated by an explosive device) traveling through a structure. Currently these blast mitigation effects have only been demonstrated in small-scale shock tube tests and computer simulations. Uncertainty exists as to the scalability of such a system. The intention of this research is to investigate the applicability of such a blast mitigation system for shipboard use. Study into the degree of mitigation necessary to make a system practical for shipboard installation was conducted. In addition, a theoretical study of the mechanisms of blast mitigation using water mists was completed.
CIVINS
22
Schneider, Nathan A. "Prediction of surface ship response to severe underwater explosions using a virtual underwater shock environment". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FSchneider.pdf.
Testo completoAbstract (sommario):
Thesis (Mechanical Engineer and M.S. in Mechanical Engineering)--Naval Postgraduate School, June 2003.Thesis advisor(s): Young S. Shin. Includes bibliographical references (p. 161-162). Also available online.
23
Topbas, Selim. "Effect Of Trass, Granulated Blast Furnace Slag And Fly Ash On Delayed Ettringite Formation". Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612494/index.pdf.
Testo completoAbstract (sommario):
Properly proportioned, placed and cured concrete can be durable under most conditions. However, deterioration of concrete does occur under certain environments. One of the problems that affect the durability of hardened concrete is delayed ettringite formation (DEF) which is an important problem encountered in precast concrete industry where high temperature curing is applied. Although there had been many researches on DEF, there are still many uncertainties about its chemistry and mechanism.
In this study, the effects of partial cement replacement by different mineral admixtures (trass, blast furnace slag and fly ash), SO3/Al2O3 molar ratio and specific surface area of cement on DEF were investigated. For this purpose, 9 groups of control cements were prepared with 3 different specific surface areas and 3 different SO3/Al2O3 molar ratios. Different amounts of mineral admixtures were blended with the control cements. High temperature curing was applied to the cement pastes and the expansions of these pastes were measured periodically for 240 days.
v
The experimental results obtained were interpreted for a comparative analysis of the effects of the afore-mentioned parameters.
24
Nagy, N. M. A. "Dynamic soil structure interaction of buried concrete structures under the effect of blast loads". Thesis, University of Bradford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534654.
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25
Brown, Christian R. (Christian Randall). "Effect of hull-to-bulkhead flexible connection on blast resistance of double hulled ships". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/33434.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (p. 65).
The use of double hull construction is commonplace within the shipping industry though it is largely unexploited within naval vessels. The Impact and Crashworthiness Lab at MIT has proposed the use of adaptive sandwich structures to improve the blast resistance of naval hulls. This project will address two main areas of investigation through the use of simplified analytical models: the integration of hardening and softening plastic core responses in the crushing of a rigidly supported sandwich panel; and the deformation analysis of a sandwich panel supported by non-rigid connections. The analytical solutions were utilized to perform a series of parametric studies to evaluate both the useable range of the models as well as to investigate the general behavior of a sandwich panel under a uniform load when supported by crushable connections. This initial investigation provides the simplified tools to begin and to validate a more detailed, numerical analysis.
by Christian R. Brown.
S.M.
26
Raymond, Ian K. Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "Tools for the formation of optimised X-80 steel blast tolerant transverse bulkheads". Awarded by:University of New South Wales. School of Mechanical and Manufacturing Engineering, 2001. http://handle.unsw.edu.au/1959.4/20467.
Testo completoAbstract (sommario):
The Australian Maritime Engineering Cooperative Research Centre, and its partner organisation initiated this research effort. In particular, BHP and the Defence Science and Technology Organisation held the principal interest, as this research effort was a part of the investigation into the utilisation of X-80 steel in naval platforms. After some initial considerations, this research effort focussed on the development of X-80 steel blast tolerant transverse bulkheads. Unfortunately, due to the Australian Maritime Engineering Cooperative Research Centre not being re-funded after June 2000 and other project factors, the planned blast tests were not conducted, hence this research effort focussed on the tools needed for the formation of optimised blast tolerant transverse bulkheads rather than on the development of a single structural arrangement. Design criteria were formed from the worst case operational requirements for a transverse bulkhead, which would experience a 150 kg equivalent blast load at 8 m from the source. Since the development of any optimised blast tolerant structure had to be carried out using finite element analysis, material constants for X-80 steel under high strain rates were obtained. These material constants were implemented in the finite element analysis and the appropriate solid element size was evolved. The behaviour and effects of stress waves and high strain rates were considered and the literature reviewed, in particular consideration was given to joint structures and weld areas effects on the entire structural response to a blast load. Furthermore, to support the design criteria, rupture prediction and determination methodologies have been investigated and recommendations developed about their relevance. Since the response of transverse bulkheads is significantly affected by their joint and stiffener arrangements, separate investigations of these structures were undertaken. The outcomes of these investigations led to improvements in the blast tolerance behaviour of joints and stiffeners, which also improved the overall response of the transverse bulkhead to air blast loads. Finally, an optimisation procedure was developed that met all the design criteria and its relevant requirements. This optimisation procedure was implemented with the available data, to show the potential to develop optimised X-80 steel blast tolerant transverse bulkheads. Due to the constraints mentioned above the optimisation procedure was restricted, but did show progression towards more effective blast tolerant transverse bulkhead designs. Factors, such as double skin bulkheads, maximising plate separation, and the use of higher yield steel all showed to be beneficial in the development of optimal X-80 steel blast tolerant transverse bulkheads, when compared to the ANZACclass D-36 steel transverse bulkheads.
27
Tang, Edmond Kai Cheong. "Numerical simulation of a long span bridge response to blast loading". University of Western Australia. School of Civil and Resource Engineering, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0070.
Testo completoAbstract (sommario):
[Truncated abstract] As a consequence of the increase in terrorist incidents, many comprehensive researches, both experimental and numerical modelling of structure and blast interaction, have been conducted to examine the behaviour of civilian structures under dynamic explosion and its impact. Nevertheless most of the works in literature are limited to response of simple structures such as masonry walls, reinforced concrete beams, columns and slabs. Although these studies can provide researchers and structural engineers a good fundamental knowledge regarding blast load effect, it is more likely for blast load to act upon entire structures in actual explosion events. The interaction between blast load and structures, as well as the interaction among structural members may well affect the structural response and damage. Therefore it is necessary to analyse more realistic reinforced concrete structures in order to gain an extensive knowledge on the possible structural response under blast load effect. Among all the civilian structures, bridges are considered to be the most vulnerable to terrorist threat and hence detailed investigation in the dynamic response of these structures is essential. This thesis focuses on the study of the response of a modern cable-stayed bridge under blast loadings. ... Firstly, analysis is conducted to examine the failure of four main components namely pier, tower, concrete back span and steel composite main span under close proximity dynamic impact of a 1000 kg TNT equivalent blast load. Secondly, based on such results, the remainder of the bridge structure is then tested by utilizing the loading condition specified in the US Department of Defence (DoD) guideline with the aim to investigate the possibility of bridge collapse after the damage of these components. It is found that failure of the vertical load bearing elements (i.e. pier and tower) will lead to catastrophic collapse of the bridge. Assuming that terrorist threat cannot be avoided, hence protective measures must be implemented into the bridge structure to reduce the damage induced by explosive blast impact and to prevent bridge from collapse. As such, a safe standoff distance is determined for both the pier and tower under the blast impact of 10000 kg TNT equivalent. This information would allow the bridge designer to identify the critical location for placing blast barriers for protection purpose. For the case of bridge deck explosion, carbon fibre reinforced polymer (CFRP) is employed to examine in respect of its effectiveness in strengthening the concrete structure against blast load. In this research, appropriate contact is employed for the numerical model to account for the epoxy resin layer between the CFRP and concrete. In addition, to ensure that the CFRP can perform to its full capacity, anchors are also considered in the numerical study to minimize the chance of debonding due to the weakening of the epoxy. The results reveal that although severe damage can still be seen for locations in close proximity to the explosive charge, the use of CFRP did reduce the dynamic response of the bridge deck as compared to the unprotected case scenario. Further investigation is also carried out to examine the change in damaged zone and global response through variation in CFRP thickness.
28
Gill, Trilochan Singh Materials Science & Engineering Faculty of Science UNSW. "Effect of PCI blending on combustion characteristics for iron-making". Publisher:University of New South Wales. Materials Science & Engineering, 2009. http://handle.unsw.edu.au/1959.4/43425.
Testo completoAbstract (sommario):
The PCI technology is well established for reducing the consumption of economic and environmentally expensive coke in blast furnace iron-making. Often, coal blends show unexpected combustion performance which cannot be explained on the basis of individual coal properties particularly coal rank and volatile matter. Several coals were combusted in this study under controlled conditions in a drop tube furnace. Fixed bed reactor, XRD, SEM and BET analyses were used to understand the mechanism of combustion of coal blends. Burnout of the coal blends did not change linearly with volatile matter of blends. The study demonstrated that combustion behaviour of coal blends was influenced by several properties of individual coals and cannot be estimated by using any single coal parameter. Carbon structure of coal as well as the interaction of volatile matter of individual coals was found to have a strong influence on the burnout of coal blends. Pet-cokes were generally found to burn with a greater difficulty. Carbon structure of pet-cokes was found to have a significant effect on the burnout such that coal blends with highly ordered pet-coke indicated lower burnout. The study shows that up to 10% of pet coke did not change the burnout of PCI blends significantly. As far as combustion is concerned, the drop tube furnace test provides a reasonable distinction of the effect of coal properties for PCI application.
29
ABU-NABAH, BASSAM ABDEL-JABER. "SWIRL ORIENTATION EFFECT ON THE INSTABILITY AND THE BREAKUP OF ANNULAR LIQUID SHEETS". University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1060978117.
Testo completo
30
Kriek, Shaun. "The effect of venting configuration on the blast response of an aircraft unit load device". Master's thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/31377.
Testo completoAbstract (sommario):
The inclusion of venting areas in aircraft unit load devices (ULDs) as a potential blast mitigation technique is investigated in this work. Damage to the ULD, such as large deflections or container rupture, from an internal explosion threatens to tear the aircraft skin and cause fuselage decompression. The loading within a luggage container was expected to be reduced when the explosive products were vented into the adjacent ULDs. Although previous work has investigated the effect of venting on ULD blast loading, this has only considered a single venting side and not multiple venting configurations. To determine if a multiple-venting system would be beneficial in ULDs, experimental blast testing was performed by subjecting a 1:6 scaled ULD box to representative blast loads with different venting configurations. The blast response of the side of the ULD which would be positioned closest to the fuselage was measured. Numerical simulations were established to provide insight into the blast loading effects not measured experimentally. The loading within the ULD box, in terms of the number and magnitude of blast wave reflections, and internal pressure build-up, was reduced when introducing venting areas. Final deformations were reduced by 11% and 22% when using a single- and double-venting configuration, respectively. Further deformation reduction was expected if more venting area was made available: unconfined blasts tests (demonstrating complete absence of ULD confinement) reduced deformations by 44%. The fully-confined (no venting) blast test resulted in rupture failure when blasted with a 20 g explosive, whereas the vented tests exhibited no tearing when blasted with higher charge masses. The double-venting configuration demonstrated better blast mitigation than the single-venting configuration. However, since both reduced the deformations and rupture probability of the container, the implementation of a multiple-venting system within aircraft ULDs would improve the survivability of the ULD container during a blast event.
31
Woertz, Jeffrey C. "Quasi-static tearing tests of metal plating /". Springfield, Va. : Available from National Technical Information Service, 2002. http://handle.dtic.mil/100.2/ADA410822.
Testo completo
32
De, Carufel Sarah. "Effect of High-Performance Steel Materials on the Blast Behaviour of Ultra-High Performance Concrete Columns". Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35380.
Testo completoAbstract (sommario):
Previous events have demonstrated the vulnerability of reinforced concrete infrastructure to blast loading. In buildings, ground-story columns are key structural components, and their failure can lead to extensive damages which can cause progressive collapse. To prevent such disasters, the steel reinforcement in such columns must be properly detailed to ensure sufficient strength and ductility. The use of modern concrete materials such ultra-high performance concrete (UHPC) is one potential solution to improve the blast performance of columns. UHPC shows high compressive strength, high tensile resistance and superior toughness, properties which make it ideal for use in the blast-resistant design of columns. The combined use of UHPC and high-performance steels can potentially be used to further enhance the blast resistance of columns. This thesis presents an experimental and analytical study which investigated the use of high-performance materials to increase the blast capacity and ductility of reinforced concrete columns. As part of the experimental study, a total of seventeen columns were tested under simulated blast loading using the University of Ottawa Shock-Tube. Parameters investigated included the effect of concrete type (NSC and UHPC), steel reinforcement type (normal-strength, high-strength or highly ductile), longitudinal reinforcement ratio, seismic detailing and fiber properties. The test program included two control specimens built with normal-strength concrete, five specimens built with UHPC in combination with high-strength steel, and ten columns built with highly ductile stainless steel reinforcement. Each column was subjected to a series of increasing blast pressures until failure. The performance of the columns is investigated by comparing the displacements, impulse capacity and secondary fragmentation resistance of the columns. The results show that using high-performance steels increases the blast performance of UHPC columns. The use of sufficient amounts of high-strength steel in combination with UHPC led to important increases in column blast capacity. The use of ductile stainless steel reinforcement allowed for important enhancements in column ductility, with an ability to prevent rupture of tension steel reinforcement. The study also shows that increasing the longitudinal reinforcement ratio is an effective means of increasing the blast resistance of UHPC columns
The thesis also presents an extensive analytical study which aimed at predicting the response of the test columns using dynamic inelastic, single-degree-of-freedom (SDOF) analysis. A sensitivity analysis was also performed to examine the effect of various modelling parameters on the analytical predictions. Overall, it was shown that SDOF analysis could be used to predict the blast response of UHPC columns with reasonable accuracy. To further corroborate the results from the experimental study, the thesis also presents an analytical parametric study examining the blast performance of larger-scale columns. The results further demonstrate the benefits of using UHPC and high-performance steel reinforcement in columns subjected to blast loading.
33
Cote, Dominic. "Effect of Realistic Boundary Conditions on the Behaviour of Cross-Laminated Timber Elements Subjected to Simulated Blast Loads". Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36993.
Testo completoAbstract (sommario):
Cross-laminated timber (CLT) is an emerging engineered wood product in North America. Past research effort to establish the behaviour of CLT under extreme loading conditions has focussed CLT slabs with idealized simply-supported boundary conditions. Connections between the wall and the floor systems above and below are critical to fully describing the overall behaviour of CLT structures when subjected to blast loads. The current study investigates the effects of “realistic” boundary conditions on the behaviour of cross-laminated timber walls when subjected to simulated out-of-plane blast loads.
The methodology followed in the current research consists of experimental and analytical components. The experimental component was conducted in the Blast Research Laboratory at the University of Ottawa, where shock waves were applied to the specimens. Configurations with seismic detailing were considered, in order to evaluate whether existing structures that have adequate capacities to resist high seismic loads would also be capable of resisting a blast load with reasonable damage. In addition, typical connections used in construction to resist gravity and lateral loads, as well as connections designed specifically to resist a given blast load were investigated.
The results indicate that the detailing of the connections appears to significantly affect the behaviour of the CLT slab. Typical detailing for platform construction where long screws connect the floor slab to the wall in end grain performed poorly and experienced brittle failure through splitting in the perpendicular to grain direction in the CLT. Bearing type connections generally behaved well and yielding in the fasteners and/or angles brackets meant that a significant portion of the energy was dissipated there reducing the energy imparted on the CLT slab significantly. Hence less displacement and thereby damage was observed in the slab. The study also concluded that using simplified tools such as single-degree-of-freedom (SDOF) models together with current available material models for CLT is not sufficient to adequately describe the behaviour and estimate the damage. More testing and development of models with higher fidelity are required in order to develop robust tools for the design of CLT element subjected to blast loading.
34
Chapman, Michael Wallace. "Insoluble oxide product formation and its effect on coke dissolution in liquid iron". School of Mechanical, Materials and Mechatronic Engineering - Faculty of Engineering, 2009. http://ro.uow.edu.au/theses/3039.
Testo completoAbstract (sommario):
A significant body of work exists around coke dissolution into liquid iron, however there are key aspects of this important reaction that are not well described. This study was focused on gaining the answers to the questions “How does the coke mineral matter behave during coke dissolution?” and “Can the effects of sulphur and oxide layer formation on the dissolution rate be separated and quantified?”. Issues that must be addressed if the understanding of the kinetics of this reaction is to be advanced and coke's use in the blast furnace further optimised.To this end, a detailed investigation was conducted examining the influence of coke mineral matter on coke (carbon) dissolution into liquid iron. This project was focused on the mineral matter layer that forms at the coke/iron interface and how the presence of this layer affects the kinetics of carbon dissolution from the coke into the liquid iron. A range of experimental techniques were used to identify and characterise the mineral layer as it formed at the coke/iron interface and to assess the layers influence on the carbon dissolution kinetics.Carbon dissolution experiments, utilising a carburiser cover technique, were carried out where carbon and sulphur transfer to an iron-carbon melt was measured over time at temperatures of 1450°C, 1500°C and 1550°C. This technique allowed fundamental data on the dissolution rate constant to be calculated, and the effects of temperature, melt sulphur and different carbonaceous materials to be explored.Development of the mineral layer at the coke/iron interface as a function of both time and temperature was studied utilising a quenched carbon dissolution technique that was developed during the project. This technique had the additional benefit of allowing the composition of the melt to be determined for a larger range of elements than the dissolution experiments. The quenched carbon dissolution experiments complemented the carbon dissolution experiments and allowed direct comparisons between the dissolution behaviour measured in the dissolution experiments and the composition and morphology of the mineral layer observed in the quenched samples.The dissolution studies were further complemented by sessile drop measurements of the wetting behaviour of iron on the mineral phases that were identified in the mineral layer present at the coke/iron interface, thermodynamic modelling utilising the MTDATA software package and a conceptual model of the interfacial mineral layer.A mineral layer was observed to have formed at the coke/iron interface during coke dissolution into liquid iron at experimental temperatures ranging from 1450°C to 1550°C. The mineral layer was solid at these temperatures and persistent at the interface. The amount of mineral matter present in the mineral layer was observed to be increasing with increased reaction time. The composition and structure of the mineral layer changed with both experimental time and temperature. The composition of the mineral layer was principally composed of oxides of aluminium and calcium, present as various calcium aluminates and calcium sulphides. Initially the mineral layer was a loose agglomeration of particles of which a majority were alumina particles. As the dissolution reaction proceeded, the loose agglomeration of particles was replaced by an open acicular layer that was predominantly the calcium aluminate CaO.6Al2O3 (CA6). As the dissolution reaction continued further, the calcium aluminates became increasingly richer in calcium oxide, with the predominate phase present in the mineral layer progressing through the calcium aluminates phases CA6 to CaO.2Al2O3 (CA2) and onto CaO.Al2O3 (CA). The apparent calcium enrichment of the mineral layer was observed to occur more rapidly as the experimental temperature increased. Accompanying the compositional changes in the mineral layer, the morphology of the mineral layer was also observed to change. The mineral layer was formed as an initial loose agglomeration of alumina particles, changing to an open acicular structure consisting of CA6/CA2 before being converted to a dense layer as the dissolution reaction proceeded and the composition of the mineral layer changed to CA and calcium sulphide (CaS) appeared at the interface.It was found that the formation of the calcium sulphide layer was preceded by the formation of the calcium aluminate layer. Only after the calcium aluminate layer had experienced progressive calcium enrichment and the CA and CA2 phases had formed did the CaS phase appear at the iron interface. Thermodynamic analysis of the experimental results confirmed that the formation of the calcium enriched calcium aluminates, CA2 and CA, were a necessary requirement to stabilise the calcium sulphide layer for the coke composition studied.The kinetics of carbon dissolution from the coke to the liquid iron were observed to be dependent on the structure of the interfacial mineral layer. This dependence was manifest as two stage behaviour in the first order mass transfer plots. The initial stage, characterised by rapid carbon dissolution, was observed while the mineral layer was developing or had the open acicular structure of the CA6/CA2 layer. The second stage was characterised by a significant reduction in the rate of carbon dissolution. The onset of the second stage was coincident with the change in the composition of the mineral layer from CA6/CA2 to CA2/CA and the associated densification of the mineral layer. In stating that the nature of the mineral layer affects the dissolution kinetics, a change in the reaction control mechanism is implied. This represents a change in the coke dissolution kinetics from simple mass transfer control to a mixed control regime where both mass transfer and the mineral (product) layer are active.In an attempt to overcome the problems associated with the heterogeneity of coke a coke analogue was developed. In the coke analogue the composition and dispersion of the carbonaceous and mineral matter (oxides) are controlled and the porosity is fixed. When single phase calcium aluminates were introduced into the coke analogues, calcium enrichment of the resulting calcium aluminate mineral layer was observed. The observed carbon dissolution kinetics were dependant on the structure of the interfacial calcium aluminate layer. Consistent with the coke dissolution studies, the calcium aluminate layer formed at the coke analogue iron interface during carbon dissolution was at least in part rate controlling the carbon dissolution reaction for the coke analogues studied.Utilising the sessile drop experimental technique the wettability with liquid ironcarbon-sulphur alloys of the predominate phases that were observed in the mineral layer were measured. It was observed that the contact angle decreased as the proportion of lime (CaO) in the calcium aluminate increased. Further it was observed that while the presence of sulphur in the melt increased the contact angle for the alumina and CA6 substrates, on the CA2 and CA substrates the contact angle was decreased. The improvement in the wetting of the CA2 and CA substrates with sulphur was attributed to the formation of CaS at the substrate/droplet interface.This study has produced new fundamental data on the growth and development of the mineral layer and the wettability of the predominate calcium aluminates observed in the mineral layer. These detailed studies have illuminated the changing nature of the layer in terms of both composition and morphology and found that the kinetics of carbon dissolution from the coke to the liquid iron were dependant on the structure of the interfacial mineral layer.
35
Guest, A. R. "The dynamic breakage of Kimberlite in the near field /". [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18507.pdf.
Testo completo
36
Miles, Aaron R. "The effect of initial conditions on the nonlinear evolution of perturbed interfaces driven by strong blast waves". College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1374.
Testo completoAbstract (sommario):
Thesis (Ph. D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
37
Melançon, Christian. "Effect of High-Performance Concrete and Steel Materials on the Blast Performance of Reinforced Concrete One-Way Slabs". Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34102.
Testo completoAbstract (sommario):
The mitigation of blast hazards on critical reinforced concrete structures has become a major concern in regards to the safety of people and the integrity of buildings. Recent terrorist incidents and accidental explosions have demonstrated the need to study the effects of such threats on structures in order to develop effective methods of reducing the overall impact of blast loads. With the arrival of innovative materials such as steel fibre reinforced concrete (SFRC), ultra-high performance fibre reinforced concrete (UHPFRC) and high strength steel reinforcement, research is required in order to successfully adapt these new materials in blast-resistant structures. Hence, the objective of this thesis to conduct an experimental parametric study with the purpose of investigating the implementation of these innovative materials in reinforced concrete slabs and panels.
As part of the study, a total of fourteen one-way slab specimens with different combinations of concrete, steel fibres and steel reinforcement are tested under simulated blast loads using the University of Ottawa Shock-Tube Facility. The test program includes three slabs constructed with normal-strength concrete, five slabs constructed with SFRC and six slabs constructed with UHPFRC. Among these specimens, four are reinforced with high-performance steel reinforcement. The specimens are subjected to repeated blast loading with gradually increasing reflected pressure and reflected impulse until failure. The performance of the slabs is studied using various criteria such as failure load and mode, maximum and residual deflections, as well as tensile cracking, spalling and secondary fragmentation control.
The behaviour of all specimens is compared in different categories to determine the effects of concrete type, steel reinforcement type, steel fibre content and steel fibre type on blast performance.
As part of the analytical study the response of the slab specimens is predicted using dynamic inelastic single-degree-of-freedom (SDOF) analysis. The dynamic analysis is conducted by generating load-deformation resistance functions for the slabs incorporating dynamic material properties.
38
Ungerer, Delmarie. "Investigating the use of rubber to attenuate the effect of blast load applied to a surrogate lower leg". Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/5461.
Testo completoAbstract (sommario):
Includes abstract.Includes bibliographical references (leaves 191-197).
Landmines are the epitome of the perfect soldier: always ready, never tiring. Landmines also do not choose their victims - it may very well be an armed and protected soldier or an innocent civilian who activates the detonator. As such, land mines have reached epidemic proportions in the Third World, affecting both combatants and civilians, whether they are on foot or in a vehicle. When stepping on an anti-personnel land mine, traumatic amputation of the foot, lower leg or upper leg is generally expected. However, an anti-vehicle landmine detonating underneath a vehicle can have equally as detrimental results, as the occupants of the vehicle are bound to sustain serious injuries to the lower extremities. These injuries can vary from being less life threatening to being fatal in some extreme cases. Anthropomorphic test devices have been developed and refined over the years to represent the occupant exposed to simulated land mine detonation and then to retrieve valuable technical information from the test data. In the present investigation a simplified aluminium surrogate lower leg was designed, manufactured and subjected to axial blast testing. In addition, a rubber layer representing the sole of a standard army combat boot was placed below the foot model in a separate series of blast tests. The main factors investigated in this study were the effect of varying the amount and positioning of the explosives and the attenuation produced by including the rubber sole layer. The blast tests were conducted using a horizontal ballistic pendulum, with the foot model placed axially in the pendulum. The disc shaped explosives of different mass was placed in the centre of the detonation plate and axially in line with the heel respectively to draw a comparison between the respective stresses induced in the lower leg. As expected, the stress recorded by the strain gauges placed on the lower leg was significantly higher when the explosives were positioned in line with the heel than when placed in the centre of the detonation plate. The same series of blast tests were performed with the rubber sole being included in the test setup. Alternating the positioning of the explosives did not yield a significant difference in induced stress. Investigation of the blast attenuation provided by the rubber layer showed that the peak stress is mitigated by approximately 70%, which was much greater than expected. An elementary analytical solution was performed as a preliminary validation of the experimental test results. Furthermore, a finite element model of the aluminium surrogate foot and the rubber layer was created and a numerical simulation of each blast test was executed. Material data for the aluminium and rubber obtained via Split-Hopkinson Pressure Bar testing were employed to construct the material models used in the finite element model. The results from the numerical simulations compare well to the experimental test results for the blast loading conditions where the rubber layer was excluded from the test setup. In the case where the rubber layer was included in the testing, the trend and shape of the stress graphs obtained from the numerical simulation results agrees with the stress curves recorded during the actual blast tests. However, the peak stresses recorded during the experimental blast tests are found to be significantly higher than the peak stresses yielded by the numerical simulations.
39
Johnson, William J. "The Effect of Chemical Composition of Blast-Furnace Slag on Compressive Strength and Durability Properties of Mortar Specimens". Scholar Commons, 2017. https://scholarcommons.usf.edu/etd/7410.
Testo completoAbstract (sommario):
In an effort to make structures more sustainable and durable, supplementary cementitious materials are often used to replace cement. Ground granulated blast furnace slag, for instance, is an industrial by-product of iron refinement and is frequently used in concrete mixture design to not only reduce cost, but also increase later-age strength as well as durability. However, published literature indicates that slags with a high alumina content may have a detrimental effect when concrete is exposed to a sulfate environment. ASTM standard C989 does not suggest any information or guidelines regarding using slags with an alumina content between 11-18%. Therefore, the objective of this study was to fill in the gap of this standard by studying slags of variable alumina content as high as 16 percent.
This study presents data collected for compressive strengths of mortar cubes exposed to lime and 5 percent sodium sulfate solution at ages of 7, 28, 91, and 182 days from the date of mixing as well as expansion data for mortar bar specimens exposed to 5 percent sodium sulfate solution up to 120 days. Slag replacement levels used here were 0, 30, 50, and 70%. Mortar bar specimens showing deterioration were analyzed using x-ray diffraction coupled with Rietveld refinement to assess the mechanism of deterioration. Cubes were stored in lime and sulfate solutions abiding by ASTM C1012 in order to analyze the resistance to sulfate attack. Sulfate resistance was measured in terms of decalcification of the CSH gel as well as expansion.
The results suggest using high alumina slags at a low percentage adversely affects sulfate resistance since the acquired strength at 182 days fell below that of 28 day strength, which is often used in the industry as the parameter which constitutes whether a mixture is adequate. It was also seen that increasing alumina content of the slag resulted in increased expansion. X-ray diffraction analysis indicates that the mechanism of deterioration, of the control as well as the blended mortar, is due to secondary gypsum and secondary ettringite formation. Therefore, it is recommended that slags having a high alumina content should be further analyzed in laboratory tests to examine their performance especially if concrete will be subjected to a sulfate environment during its service life.
40
Lopez-Molina, America Maria. "The Effect of Steel Strapping Tensioning Technique and Fibre-Reinforced Polymer on the Performance of Cross-Laminated Timber Slabs Subjected to Blast Loads". Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38247.
Testo completoAbstract (sommario):
Engineered wood products (EWP) are becoming extremely popular and a viable material option for the construction of residential, commercial, and hybrid buildings. Cross-laminated timber (CLT) is among one of the many EWP available in North America, which can be utilized for many different applications such as: walls, floors, and roofs. Despite the available requirements in the Canadian blast design standard (CSA, 2012) with regard to the design of wood structures, there are currently no provisions on how to retrofit timber structures to improve their performance when subjected to blast loads. The current study is aimed at investigating the effect of different retrofitting alternatives in order to improve the overall behaviour of CLT when exposed to out-of-plane bending.
The experimental program examined the behaviour of seventeen reinforced CLT slabs. Testing was conducted at the University of Ottawa by means of a shock tube capable of simulating high strain rates similar to those experienced during a blast event. The current study was divided into two phases. The first consisted of CLT slabs retrofitted with steel straps where strap spacing, location, and order of installation was investigated. The second phase focused on the development of dynamic properties of CLT panels when reinforced with GFRP. Lay-up configuration and fabric orientation were among the parameters explored.
The results from the experimental program show that reinforcing the panels with steel straps had minimal effect on the ultimate strength, but significant levels of post peak resistance and ductility was achieved. The horizontal straps were able to restrict the failure to small regions and to promote flexural failure by preventing rolling shear failure. It also eliminated flying debris and enhanced the ultimate strength, stiffness as well as ductility. Applying GFRP layers enhanced the overall behaviour of the slab resulting in a significant increase in peak resistance, ductility, and stiffness when compared to the dynamic results of an unretrofitted panel. The post peak resistance was also greatly improved. In particular, applying stacked quadraxial lay-up configuration significantly improved the ductility and resulted in the greatest post peak resistance. The effect of steel straps on damaged and retrofitted was relatively minimal, and only partial recovery of the resistance and the stiffness was achieved. GFRP with full confinement yielded better performance compared to the unretrofitted and undamaged counterpart. More work is needed to quantify the benefits of using GFRP in these applications.
41
Kirca, Onder. "Temperature Effect On Calcium Aluminate Cement Based Composite Binders". Phd thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607454/index.pdf.
Testo completoAbstract (sommario):
In calcium aluminate cement (CAC) systems the hydration process is different than portland cement (PC) systems. The hydration products of CAC are subjected to conversion depending on temperature, moisture, water-cement ratio, cement content, etc. Consequently, strength of CAC system can be seriously reduced. However, presence of other inorganic binders or additives may alter the hydration process and improve various properties of CAC based composites.
The objective of this study is to investigate the temperature effect on the behaviour of CAC based composite binders. Throughout this research, several combinations of CAC-PC, CAC-gypsum, CAC-lime, CAC-ground granulated blast furnace slag (CAC-GGBFS) were studied. These CAC based composite binders were subjected to seven different curing regimes and their strength developments were investigated up to 210 days. In addition, the mechanism of strength development was examined by XRD analyses performed at 28 and 210 days. Finally, some empirical relationships between strength-time-curing temperatures were formulated.
Experimental results revealed that the increase in ambient temperature resulted in an increase in the rate of conversion, thereby causing drastic strength reduction, particularly in pure CAC mix. It has been observed that inclusion of small amount of PC, lime, and gypsum in CAC did not induce conversion-free CAC binary systems, rather they resulted in faster conversion by enabling rapid formation of stable C3AH6 instead of metastable, high strength inducing CAH10 and C2AH8. On the other hand, in CAC-GGBFS mixes, the formation of stable straetlingite (C2ASH8) instead of calcium aluminate hydrates hindered the conversion reactions. Therefore, CAC-GGBFS mixes, where GGBFS ratio was over 40%, did not exhibit strength loss due to conversion reactions that occurred in pure CAC systems.
42
Lindsey, Douglas E. "An investigation of blasting criteria for structural and ground vibrations". Ohio : Ohio University, 1989. http://www.ohiolink.edu/etd/view.cgi?ohiou1182441854.
Testo completo
43
Benedetti, Robert. "Mitigation of explosive blast effects on vehicle floorboard". College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8350.
Testo completoAbstract (sommario):
Thesis (M.S.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
44
Akin, Faith W., Owen D. Murnane, Sherri Smith e Kristal M. Riska. "Effects of Blast on Auditory & Vestibular Function". Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/1872.
Testo completoAbstract (sommario):
The purpose of this session is to examine the effects of blast on auditory and vestibular function. We will present results of auditory and vestibular function tests and neuroimaging results in a group of individuals with blast exposure and dizziness/imbalance and in an age-matched healthy control group.
45
Anthistle, Thomas. "Modelling the effects of blast loads in rail vehicles". Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/9345/.
Testo completoAbstract (sommario):
This thesis describes the development of modelling techniques to understand the effects of an Improvised Explosive Device on the passengers and structure of a rail vehicle. The work aims to establish if rail vehicle design could influence the distribution of passenger injuries within a rail vehicle. Finite element models were used to predict the detonation and propagation of the blast pressures, and the structural response of a rail vehicle. Models were developed to allow the prediction of human injury, using validated work from the open literature and from basic principles. After a detailed review of existing work on injury, chest injury from blast pressures and penetrating injuries from high speed projectiles were chosen as the injury modes to be included in the model. To provide data to validate numerical models, experimental blast testing in confined geometry was undertaken. Four configurations of a test cell were used to gain an understanding of the effect of vertical baffles on pressures and cumulative impulse. Excellent correlation was seen between test shots in each arrangement. Baffles were seen to increase the cumulative impulse seen at the wall opposite where they were fixed, although the number and spacing of them was seen to have no significant effect. Numerical modelling of the experimental test arrangements showed good correlation between the experimental pressure time history data and the numerical predictions. Secondary combustion was considered using an energy release function, after which cumulative impulse calculated from experimental data were was predicted by the numerical models. Risk prediction and finite element models were combined to model the effects of an IED blast in a representative rail vehicle. A number of key variables were studied, and it was identified that although rail vehicle design can affect the injury severity, passenger spatial density was the driver for determining the distribution of injuries.
46
Nyein, Michelle K. (Michelle Kyaw). "Computational modeling of primary blast effects on the human brain". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82474.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2013.This electronic version was submitted and approved by the author's academic department as part of an electronic thesis pilot project. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from department-submitted PDF version of thesis.
Includes bibliographical references (p. 155-167).
Since the beginning of the military conflicts in Iraq and Afghanistan, there have been over 250,000 diagnoses of traumatic brain injury (TBI) in the U.S. military, with the majority of incidents caused by improvised explosive devices (IEDs). Despite the urgent need to understand blast-induced TBI in order to devise strategies for protection and treatment, much remains unknown about the mechanism of injury, the effects of personal protective equipment (PPE) such as helmets, and injury metrics and thresholds. In order to help address these gaps, this thesis has four objectives: 1) to present a comprehensive computational framework for investigating the mechanical response of the human head to blasts that includes blast-structure interaction codes, a detailed, three-dimensional model of a human head generated from high-resolution medical imaging data, and an experimentally-validated constitutive model for brain tissue; 2) to validate the framework against a broad range of experiments, including free-field blast tests involving physical human head surrogates and laboratory-scale shock tube tests involving animals and human cadavers; 3) to use the computational framework to investigate the effect of PPE on the propagation of stress waves within the brain following blast events and evaluate their blast protection performance; and 4) to develop interspecies scaling laws for the blast response of the brain that would allow translation of injury metrics from animals to humans.
by Michelle K. Nyein.
Ph.D.
47
Maxa, Andrew J. "Mitigation of blast effects on existing structures in austere environments". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74467.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 52-53).
Military commanders in austere environments often face challenges in setting up headquarters buildings that offer protected areas for sensitive equipment. One solution to this problem is simply to build a structure that can be used for this purpose. This method can prove to be difficult in that it could either require large amounts of prefabricated concrete, heavy earthmoving equipment, or a significant effort in digging by hand. Clearly, all of these options are unsuitable for constructing a headquarters building that would be occupied for a short time or if the resources required were unavailable. Another solution to this problem is to simply occupy an existing structure. This method is extremely favorable with respect to resources required; with the major drawback being that at times existing structures may offer limited protection from hostile forces. Since the US Army often has overwhelming firepower when compared to contemporary threats, many times hostile forces will resort to suicide or remotely detonated explosive devices when attempting to destroy or damage structures of this type. In order to determine the feasibility of mitigating this threat, this paper will explore the effects of various explosive devices on model building types that may be found in austere environments, and explore the effects of possible reinforcement schemes in mitigating blast threats to these structures.
by Andrew J. Maxa.
S.M.
48
Akin, Faith W., Courtney D. Hall e Owen D. Murnane. "Noise and Blast-related Effects on Vestibular and Balance Function". Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etsu-works/2707.
Testo completo
49
Bur, Nicolas. "Etude des caractéristiques physico-chimiques de nouveaux bétons éco-respectueux pour leur résistance à l'environnement dans le cadre du développement durable". Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00804542.
Testo completoAbstract (sommario):
La compréhension des mécanismes à l'origine de la formation de la porosité et de ses propriétés dans les matériaux cimentaires est un enjeu majeur pour l'évaluation de leur durabilité. L'utilisation des laitiers de haut fourneau comme liant hydraulique modifie les phases formées, leur proportion et la microstructure des mortiers et bétons. Il reste un grand nombre de verrous scientifiques à lever concernant les paramètres modifiant les valeurs de porosité, le rayon des capillaires et, par conséquent, la perméabilité. Des échantillons de mortiers ont été réalisés avec différents mélanges de CEM I et de laitiers de haut-fourneau puis différentes cures ont été utilisées afin d'évaluer l'influence de la baisse de la température ou de l'hygrométrie sur la géométrie de leur porosité. Différentes techniques d'analyses de porosité et de perméabilité ont permis de mettre en évidence principalement une augmentation de la porosité totale et libre, des rayons des capillaires et de la perméabilité avec l'augmentation de la proportion de laitier et la diminution de l'hygrométrie. Des observations au microscope électronique à balayage à pression de vapeur d'eau contrôlée ont permis de montrer le lien entre l'ouverture des capillaires et l'hygrométrie. Ainsi les forces exercées par les pressions de disjonction et les pressions capillaires déforment les hydrates de manière à fermer les capillaires avec l'augmentation de l'hygrométrie. La mise au point d'une méthode originale de cartographie de la porosité à partir de données de conductivité thermique a permis de confirmer la présence d'une peau et de déterminer son étendue. Grâce à cette technique, il est possible d'évaluer la distribution des taux de porosité au travers des échantillons. De plus, une nouvelle approche d'analyse a permis de cartographier à partir du même modèle la distribution des proportions relatives de granulats.
50
Avachat, Siddharth. "Experimental and numerical analyses of dynamic deformation and failure in marine structures subjected to underwater impulsive loads". Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44904.
Testo completoAbstract (sommario):
The need to protect marine structures from the high-intensity impulsive loads created by underwater explosions has stimulated renewed interest in the mechanical response of sandwich structures. The objective of this combined numerical and experimental study is to analyze the dynamic response of composite sandwich structures and develop material-structure-property relations and design criteria for improving the blast-resistance of marine structures. Configurations analyzed include polymer foam core structures with planar geometries. A novel experimental facility to generate high-intensity underwater impulsive loads and carry out in-situ measurements of dynamic deformations in marine structures is developed. Experiments are supported by fully dynamic finite-element simulations which account for the effects of fluid-structure interaction, and the constitutive and damage response of E-glass/polyester composites and PVC foams.
Results indicate that the core-density has a significant influence on dynamic deformations and failure modes. Polymeric foams experience considerable rate-effects and exhibit extensive shear cracking and collapse under high-magnitude multi-axial underwater impulsive loads. In structures with identical masses, low-density foam cores consistently outperform high-density foam cores, undergoing lesser deflections and transmitting smaller impulses. Calculations reveal a significant difference between the response of air-backed and water-backed structures. Water-backed structures undergo much greater damage and consequently need to absorb a much larger amount of energy than air-backed structures. The impulses transmitted through water-backed structures have significant implications for structural design. The thickness of the facesheets is varied under the conditions of constant material properties and core dimensions. The results reveal an optimal thickness of the facesheets which maximizes energy absorption in the core and minimizes the overall deflection of the structure.