Splitting initiation and propagation in notched unidirectional graphite/epoxy composites under tension-tension cyclic loading

https://doi.org/10.1016/0263-8223(85)90002-9Get rights and content

Abstract

The initiation and propagation of splitting damage in notched unidirectional graphite/epoxy composites under tension-tension cyclic loading were investigated experimentally. One-hundred-and-twenty [0°]8 specimens, notched at the center with a 3·175, 6·350, or 9·525 mm hole or slit, were tested. Thirty specimens were loaded monotonically to failure to determine the static splitting stress. Ninety specimens were cycled at maximum loads corresponding to 80%, 70%, and 60% of their predicted static splitting stress. The stress ratio of the load cycle was maintained at a nominal value of Rσ = 0·1, while the frequency was changed with the stress amplitude to maintain the same loading rate. The results show that the static splitting stress is sensitive to both notch type and size and that the split length varies linearly with the natural logarithm of the number of accumulated load cycles. The intercept of this linear relation depends on the notch type, notch size, and stress level while its slope depends only on the notch size and stress level. Empirical functional forms are derived using multiple linear regression analyses of the test data.

References (7)

  • J.W. Mar

    Fracture, longevity, and damage tolerance of graphite/epoxy filamentary composite materials

  • J.W. Mar et al.

    Characterization of splitting process in graphite/epoxy composites

    Journal of Composite Materials

    (Oct. 1979)
  • R.E. Rowlands et al.

    Geometric and loading effects on strength of composite plates with cutouts

There are more references available in the full text version of this article.

Cited by (11)

  • A continuum damage model for composite laminates: Part IV- Experimental and numerical tests

    2021, Mechanics of Materials
    Citation Excerpt :

    The study of this type of notched specimens under fatigue loads has also become the subject of extensive experimental and numerical investigations. For example, the slot-shaped specimen representing severe damage inflicted by a service accident (Spearing and Beaumont, 1992; Spearing et al., 1992a, b), the DENT specimen (Hallett and Wisnom, 2005a, 2005b), or the OHT specimen to study the circular hole that is commonly cut into the laminates for fasteners, or to allow the pass of electrical and hydraulic lines (Aidi et al., 2015; Ambu et al., 2005; Aymerich and Found, 2000; Nixon-Pearson et al., 2013b; Nixon-Pearson and Hallett, 2015; Daken and Mar 1985; Hochard et al., 2013). This paper is organized as follows.

  • Effect of milled notches on the strength of open hole, filled holes, single and double lap shear CFRP tension coupons

    2020, Composite Structures
    Citation Excerpt :

    This effect has been identified from an experimental point of view by many authors [8–21] and demonstrated by a test-calculation dialogue using different, mostly discrete, modeling strategies [22–29]. This explains the interest in this type of fatigue damage, which, in some cases, would allow an increase in residual resistance [13–21]. In addition, it has been shown [27] that, depending on the position of the plies in the thickness, this type of damage is favored and consequently the static resistance can be improved by about 10%.

  • Residual modulus degradation model for woven fabric composite determined by impulse excitation technique

    2020, International Journal of Fatigue
    Citation Excerpt :

    The longitudinal cracks appeared at the very first cycles for all studied stress ratios, reaching approximately 15 mm in length within the first thousand cycles, and propagating until stabilization. The cracks occurred by matrix splitting, which has been described in the literature for unidirectional composites under tensile static tests, [27,31,32], tractive and compressive fatigue tests [33–35]. Fig. 8 shows the crack growth on both sides of the hole as a function of the number of cycles.

View all citing articles on Scopus
View full text