Accession Number : AD0713063

Title :   FRACTURE TOUGHNESS OF FILAMENT-WOUND COMPOSITES. PART I. EFFECT OF MATERIAL VARIABLES.

Descriptive Note : Final rept.,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON D C

Personal Author(s) : Sanford,Robert J. ; Stonesifer,Fred R.

Report Date : 29 JUL 1970

Pagination or Media Count : 23

Abstract : The application of the theory of linear fracture mehcanics to quasi-brittle, glass- reinforced-plastic composites is an important first step in understanding the basic mechanisms of failure of these materials. In this study, a simple test technique sensitive to small changes in the material based on fracture mechanics concepts. Six different resin-glass combinations were tested. The results of these tests indicate that (a) there is no difference in the fracture strenght of composites made with either E-glass or S- glass, (b) composites with 5-mil-diam fibers have a lower resistance to crack propagation than those with conventional 0.4 mil-diam fibers, and (c) a filament-wound composite has a much lower fracture toughness in the Bstaged state than in the fully cured state. In water immersion was investigated. These tests demonstrate that with the exception of the composite made with the large-diameter (5-mil) fibers there is no sysematic decline in fracture strength due to water immersion for periods up to 6 months. (Author, modified) FOR PERIODS UP TO 6 MONTHS. (Author, modified-PL)

Descriptors :   (*COMPOSITE MATERIALS, FILAMENT WOUND CONSTRUCTION), FRACTURE(MECHANICS), REINFORCED PLASTICS, GLASS TEXTILES, PRESSURE VESSELS, STRUCTURAL PROPERTIES, TEST METHODS

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE