Abstract / Description of output
The mathematical modeling of combustion in structural laminates is a complex task requiring consideration of the heat transfer, chemistry and kinetics of polymer decomposition and combustion. It also requires adequate characterization of the mass transport of volatiles through melts and chars as well as the effect of temperature and resin mass loss on thermal expansion, ply delamination and retention of the mechanical properties of the composite immediately before, during and after combustion. A variety of workers have tackled this challenge in numerous works, and while there are many established macroscopic models of 'fire-in-a-room' scenarios, these tend to concentrate on large-scale engineering and safety situations rather than processes and mechanisms occurring at the microscopic scale within resins and residual chars during combustion. This chapter discusses the motivation for computer-modeling of structural composite behavior in fire at the microscopic level of resin and fiber chemistry. The current capabilities of composite fire models and the extent of their deployment in composite design with respect to fire resistance are discussed. Lastly, the remaining deficiencies in the predictive capability of these models with respect to actual composite behavior under fire load are identified. There are a number of improvements required for a fully representative model for combustion of structural composites and its effect on residual mechanical strength which require developments in the following areas; a) a more accurate determination of ignition temperature under a known fire load, b) a full, quantitative profile of the volatiles released during combustion enabling the calculation of more accurate heat of combustion, and c) better determinations of surface radiative emissivity and convective heat transfer coefficient. Thermo-mechanical models are hybrids of heat transfer and finite element models of residual strength. Through-thickness temperature profiles and resin mass-loss data from the thermal components of these models have been used respectively to predict residual modulus and increase in pressure due to accumulated volatiles within the burning composite material. It remains for such models to a) adequately represent mixed modes of mechanical failure b) accurately model ply layer delamination, and c) correctly model the directionality of thermally-induced strains as a function of ply orientation. The increasing amount of published work in this area indicates that a hybrid thermo-mechanical composite failure model may soon be achieved at the microscopic level of resin chemistry. The achievement of such a model is expected to enhance the ability of polymer chemists to formulate improved resins, as well as the capacity of engineers to design improved fire-resistant structures.
|Title of host publication||Modeling and Simulation in Fibrous Materials|
|Subtitle of host publication||Techniques and Applications|
|Publisher||Nova Science Publishers Inc|
|Number of pages||30|
|Publication status||Published - 1 Mar 2012|