FACTORS CONTROLLING THE STRENGTH OF COMPOSITE BODIES (INTERPHASE FRACTURING OF COMPOSITE BODIES).
Abstract
Additional smooth tensile tests on solid epoxy show considerable scatter in fracture properties (tensile strength and elongation), but less in modulus and yield strength. The latter two properties decrease approximately 20% when the hardener content is increased from stoichiometric to 20 PHR, but are not affected by other composition changes. The higher post cure temperature gave lower values for these two than the lower temperature. Fracture toughness, G sub Ic, measurements also have been extended to solid epoxy. The increase in toughness with increasing hardener content for aluminum-bonded epoxy was also found in the bulk epoxy. For the latter, however, there was also an increase in general height of the curve and a broader scatter band. Cracking rate and its influence on toughness is being evaluated for homogeneous epoxy and continued on bonded specimens. When the cracking rate exceeds the equivalent cross-head speed, i.e. when the crack jumps, its velocity in bulk epoxies is an order of magnitude higher than that observed of bonds. As with the bonded specimens, little effect of cracking rate on G sub Ic was noted. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 17, 1964
- Accession Number
- AD0457147
Entities
People
- E. J. Ripling
- S. Mostovoy
Organizations
- Materials Research Laboratory