Effect of statistical scatter in the elastic properties on the predictability of first ply failure of a polymer composite pressure vessel
Statistical variations in the elastic properties of composites are unavoidable. This work is concerned with the assessment of the probabilistic first ply failure of pressure vessel in response to the variations of elastic properties of T700 Carbon/Epoxy composite. Composite properties and failure data have been selected from published literature. Initially, deterministic failure pressure values are computed using Finite Element Analysis (FEA) software Ansys for all the elastic input properties considered. Variations or the uncertainties with respect to elastic properties are quantified by using Statistical software Minitab. Then, the PDS platform in FEA software Ansys has been utilized to perform probabilistic failure analysis. The statistical results in terms of the mean and standard deviation of first ply failure pressure are computed. It is expected to have the first ply failure within this limit when anyone set of properties defined by statistical input parameters is used. The probabilistic first ply failure pressure range determined at 99.997% confidence level is of good use in the design for critical applications. The adopted analysis also helps to assess the factor of safety in the case of anticipated variations in properties.