The Use of Doublers in Delamination Toughness Testing

摘要: In this paper, the data reduction equations for common delamination toughness tests are rederived use with specimens which have bonded doublers. The considered here double cantilever beam (DCB) mode I toughness; end notch flexure (3ENF) and 4 point ENF (4ENF) II mixed bending (MMB) test testing under combined loading. Because addition of doublers changes stiffness specimens, these may need to be corrected. Doublers were added solve a premature failure problem. Delamination is normally tested using an imbedded insert so that one specimen split into two arms. If too thin, or if material high, arm fail in before grows. When occurs, cannot determined. To delay growth doubler plates both top bottom surfaces specimen. A parameter, beta, describes how much changed ratio full thickness delaminated stiffnesses, was defined. required, minor when written terms beta parameter. plate technique demonstrated by measuring mixed-mode fracture carbon-carbon composite would otherwise failed occurred. several problems can encountered toughness.