Design and testing of composite materials for use in ramjet inlet structures

Some aspects of the fracture of boron-aluminium composites

“…11 (inset), along with the S/N curve constructed from the results. The nearly flat curve obtained agrees well with previously reported data on B-Alcomposites [7,8], although the present results are at a slightly lower stress level and in addition there is no noticeable tendency for the heat-treated composites to give slightly inferior results.…”

“…The longitudinal tensile strength levels obtained in the samples suggest that a high proportion of the original fibre tensile strength is being utilised, confirming that the fabrication process has been 436 successful in avoiding significant fibre damage. The noticeable increase in tensile strength resulting from heat treatment confirms more extensive results reported by other workers [7,8]. This increase was also apparent in the longitudinal flexural tests, although it is perhaps unwise to compare the absolute flexural strength values directly with the tensile results because of the inevitable uncertainty in the stress distribution in a flexural test, particularly in a composite containing an inelastic component.…”

“…3. The UTS values are given in table I and appear in reasonable agreement with predictions based on "rule of mixtures" and also well within the spread of results reported in the literature [6][7][8].…”

“…The sheets were fabricated by laying up the fibres between foils of the matrix and consolidating by a diffusion bonding process. The matrix chosen was 6061 alloy (1~ Mg, 0.6~ Si, 0.25~ Cu, 0.25~ Cr, balance AI), which has the additional advantage of being amenable to heat treatment with a consequent improvement in both longitudinal and transverse composite strength [7][8][9].…”