Theoretical and Experimental Analysis of the Metal-Based Ignition Propensity Test Thermodynamics

Abstract

This research analysed in detail the performance of the newalternative ignition propensity test prescribed in thestandard ASTM E2187-16, which is based on the utilizationof a substrate comprising a thin steel plate along with onefilter paper. The analysis was performed both experimentally, by means of infrared temperature measurements,and theoretically by using a comprehensive finite elementmodel that was able to predict the temperature of the substrate with errors of only 7.3% and 15.7% in space andtime, respectively. While the new alternative test was ableto reduce the variability of the heat absorbance from 33%to only 4% with respect to the conventional tests, it showedseveral downsides that critically reduce its reliability. Theheat absorbance of the alternative test did not correctlyemulate the conventional procedure as it absorbed as muchheat as twice. The gravity effect on the plate increased theair gap thickness more than twice, thereby decreasingpotentially the heat absorbance by 13%. In addition, amechanical analysis showed that compressive stresses dueto high temperature gradients could cause irreversiblebuckling, creep and yielding of the plate. Experimentsshowed that in fact the concavity of the plate was prone toincrease after testing. Assuming the maximum concavityallowed by the standards, the heat absorbance was halvedin respect to a perfectly flat plate. In view of these results,the utilization of the conventional test method still appearsclearly more appropriate than the alternative one. [Beitr.Tabakforsch. Int. 28 (2018) 52–64]