Straight-sided tensile specimen

The EDT specimen shown in Fig 3.34(a) has been used to characterize the interlaminar failure of the composite in opening mode I (Whitney and Knight, 1985). The straight-sided tensile specimen has starter cracks placed along the free edges at the laminate mid-plane (Fig 3.34(a)). Due to the low interlaminar shear... 

Mechanical Property Testing. Mechanical tests were performed on both unirradiated and irradiated materials at -157°C, 24°C, and 121°C. Specimens were kept dry prior to testing in an environmental chamber mounted in a tensile testing machine. Tensile test specimens of [0]4, [10]4, [45]4, and [90]4 laminates were cut from 4-ply composite panels. All specimens were straight-sided coupons. For tension and shear tests the length/width aspect ratio was 8. For the compression tests the aspect ratio was 0.25 and the unsupported length was 0.64 cm. The [0]4 laminates were used to measure the ultimate tension and compression strength, Xit the axial... 

ASTM D 5083, Test Methods for Tensile Properties of Reinforced Thermosetting Plastics Using Straight-Sided Specimens ... 

Fig. 11.33 displays at the left-hand side the correlation integral (Eq. 11.2 in Subsection 11.4.1) versus the distance (bold line) of Cluster No. 1. In this diagram, the fiactal dimensions D (Eq. 11.3) of 1, 2, and 3 are indicated by the thin straight lines (from left to right). The slope of 2 which proves true up to an interevent distance of about 2 cm represents a planar structure and is an evidence for critical AE activity. Indeed, the ultimate failure was a sudden tensile fiacture of the specimen exactly at the position where cluster No. 1 occurred. Interestingly, in the time interval of approximately 4 hours between the occurrence of the cluster and the ultimate failure of the specimen no further AE events were emitted from the cluster region. 

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