Predicting the Failure of Aluminum Exposed to Simulated Fire and Mechanical Loading Using Finite Element Modeling
Arthur, Katherine Marie
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The interest in the use of aluminum as a structural material in marine applications has increased greatly in recent years. This increase is primarily due to the low weight of aluminum compared to other structural materials as well as its ability to resist corrosion. However, a critical issue in the use of any structural material for naval applications is its response to fire. Past experience has shown that finite element programs can produce accurate predictions of failure of structural components. Parameter studies conducted within finite element programs are often easier to implement than corresponding studies conducted experimentally. In this work, the compression-controlled failures of aluminum plates subjected to an applied mechanical load and an applied heat flux (to simulate fire) were predicted through the use of finite element analysis. Numerous studies were completed on these finite element models. Thicknesses of the plates were varied as well as the applied heat flux and the applied compressive stresses. The effect of surface emissivity along with the effect of insulation on the exposed surface of the plate was also studied. The influence of the initial imperfection of the plates was also studied. Not only were the physical conditions of the model varied but the element type of both the solid and shell models as well as the mesh density were also varied. Two different creep laws were used to curve fit raw creep data to understand the effects of creep in the buckling failure of the aluminum plates. These predictions were compared with experiments (from a previous study) conducted on aluminum plates of approximately 800mm in length, 200mm in width, 6-9mm in thickness and clamped at both ends to create fixed boundary conditions. A hydraulic system and a heater were used to apply the compressive load and the heat flux respectively. Comparisons between predicted and experimental results reveal that finite element analysis can accurately predict the compression-controlled failure of aluminum plates subjected to simulated fire. However, under certain combinations of the applied heat flux and compressive stress, the mesh density as well as the choice of element may have a significant impact on the results. Also, it is undetermined which creep curve-fitting model produces the most accurate results due to the influence of other parameters such as the initial imperfection.
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