Ablation sensor

Sensor device with switches for measuring surface recession of charring and noncharring ablator

Graphite and ablative material response to CO2 laser, carbon-arc, and xenon-arc radiation

The behavior was investigated of graphite and several charring ablators in a variety of high-radiative heat-flux environments. A commercial-grade graphite and nine state-of-the-art charring ablators were subjected to various radiative environments produced by a CO2 laser and a carbon arc. Graphite was also tested in xenon-arc radiation. Heat-flux levels ranged from 10 to 47 MW/sq m. Tests were conducted in air, nitrogen, helium, and a CO2-N2 mixture which simulated the Venus atmosphere. The experimental results were compared with theoretical results obtained with a one-dimensional charring-ablator analysis and a two-dimensional subliming-ablator analysis. Neither the graphite nor the charring ablators showed significant differences in appearance or microstructure after testing in the different radiative environments. The performance of phenolic nylon and graphite was predicted satisfactorily with existing analyses and published material property data. Good agreement between experimental and analytical results was obtained by using sublimation parameters from a chemical nonequilibrium analysis of graphite sublimation. Some charring ablators performed reasonably well and could withstand radiative fluxes of the level encountered in certain planetary entries. Other materials showed excessive surface recession and/or large amounts of cracking and spalling, and appear to be unsuitable for severe radiative environments

Thermoanalysis of ablation materials

Thermal analysis on pyrolysis of charring ablator material

Solution of the Frozen Flow Momentum Equation Status Report

Momentum equation solved for frozen flow in char zone of charring ablato

Analytical determination of the effect of thermal property variations on the performance of a charring ablator

Effects of thermal-property variations on performance of charring ablato

Experimental verification of the non-equilibrium model for predicting behavior in the char zone of a charring ablator Status report

Experimental simulation to establish accuracy of nonequilibrium flow model with system simulating charring during ablatio

Fire retardant foams developed to suppress fuel fires

Heat insulating polyurethane foam retards and suppresses fuel fires. Uniformly dispersed in the foam is a halogenated polymer capable of splitting off hydrogen halide upon heating and charring of the polyurethane

Fire analysis of timber composite beams with interlayer slip

The purpose of this paper is to model the behaviour of timber composite beams with interlayer slip, when simultaneously exposed to static loading and fire. A transient moisture-thermal state of a timber beam is analysed by the Luikov equations, and mechanical behaviour of timber composite beam is modelled by Reissner's kinematic equations. The model can handle layers of different materials. Material properties are functions of temperature. The thermal model is validated against the experimental data presented in the literature. Generally, the model provides excellent agreement with the experimental data. It is shown that the material properties of timber play an important role in the fire resistance analysis of timber structures when exposed to fire

Determination of charring rates of laminated veneer lumber made from selected Malaysian tropical timber exposed under standard fire exposure / Zulhazmee Bakri

EN 1995-1-2 (EC5) has been widely used for designing timber structures and the charring rate is used for protection against fire. The charring rate is an essential factor in the fire design of exposed structural timbers because it determines how rapidly the size of the original section decreases to a critical level. In EC5, the one-dimensional charring rate of LVL for density > 480kg/m3 is 0.65 mm/min and for two-dimensional or notional charring is 0.70mm/min. Unlike the EC5, the charring rate values published in the Malaysian standard are only for solid timber and based on their strength grade (SG). The charring rate value for Laminated Veneer Lumber (LVL) is not available. Therefore, thesis reports the study on the charring rate performance of LVL from selected Malaysian tropical timber and to develop predicted charring rate model. The two (2) main parameters investigated are one-dimensional, fio and two-dimensional or notional charring rate, fin. The LVL used were manufactured from Malaysian tropical timber namely Kedondong, Eucalyptus, Mengkulang, Rubber wood and Kasai. The fire tests were conducted in accordance with BS476: Part 22 and the determination of the charring rate was based on prEN 13381-7:2014. A series of tests were conducted by varying the width of LVL (50mm and 100mm width), exposure time (30 and 45 minutes), types of fire exposure (one-dimensional and two-dimensional) and timber densities (440kg/m3-740kg/m3). The charring rates were developed from direct and indirect measurements. The results show that the charring rate of these species ranged between 0.39 mm/min - 1.05mm/min. The test results also show that the density of timber have significantly affects the charring rate values as well as the scale effect. It is shown that for timber density less than 480kg/m3 and width < 50mm were not suitable for strucural element. The values of zero strength layer in this study shows good agreement compared with the proposed values in EC5. Three (3) predicted models were developed from statistical software from each species and were tested to obtain the suitable predicted model for fio and fin. The established models were validated by the lab experimental values. The predicted model for one-dimensional shows good agreement with measured but was quite conservative compared with EC5 model. However, for notional charring rate shows good agreement between measured and predicted charring rates models. The models of charring rates were also established to predict the effect of density, time, thickness of specimen, moisture content, temperature and specimens' size established using Buckingham PI theorem. It is quite apparent that good agreement is obtained between measured and predicted charring rates models

Reliability analysis of a glulam beam

The present case study is an example of the use of reliability analysis to asses the failure probability of a tapered glulam beam. This beam is part of a true structure built for a super market in the town of Kokemaki in Finland. The reliability analysis is carried out using the snow load statistics available from the site and on material strength information available from previous experiments. The Eurocode 5 and the Finnish building code are used as the deterministic methods to which the probabilistic method is compared to. The calculations show that the effect of the strength variation is not significant, when the coefficient of variation of the strength is around 15% as usually assumed for glulam. The probability of failure resulting from a deterministic design based on Eurocode 5 is low compared to the target values and lower sections are possible if applying a probabilistic design method. In fire design, if a 60 min resistance is required, this is not the case according to Eurocode 5 design procedures, a higher section would be required. However, a probabilistic based fire analysis results in bounds for the yearly probability of failure which are comparable to the target value and to the values obtained from the normal probabilistic based design. (C) 2006 Elsevier Ltd. All rights reserved