STATISTICAL STUDY OF ENVIRONMENTAL DEGRADATION IN RESIN TRANSFER MOLDED STRUCTURAL COMPOSITES

This paper describes experiments on the environmental degradation of r esin transfer moulded composites such as those sometimes used in the w astewater treatment industry. The rate of degradation of immersed spec imens, and the possibility of accelerating the testing process, were i nvestigated by varying a number of environmental and manufacturing fac tors. Statistical (Taguchi) methods were used for design of the factor ial experiments and analysis of the results. A two-level screening exp eriment was used to determine the factors with significant effects. Th ese were measured as loss of flexural (pinching) stiffness and creep-r elated ovalling deformation of the tubular specimens. A three-level ex periment was then used to quantify and predict the relationship betwee n the degradation and creep effects and three of the most crucial fact ors (time, temperature and strain). Predicted effects agreed well with results of independent verification experiments at elevated temperatu res, but stiffness at lower temperatures was incorrectly predicted to rise with time, owing to non-linear interactions not modelled within t he analysis. (C) 1998 Elsevier Science Ltd. All rights reserved.