Abstract
Experimental and theoretical studies of edge effects in rectangular composite strips under tension are discussed. The objective of the study was to investigate the effect of various parameters, including reinforcement material, fiber orientation and the structure of the reinforcement, on the various quantities which are observed in the vicinity of free edges in multidirectionally reinforced laminates. Of particular interest was the confirmation of theoretical results related to differences in response of graphite- and boron-reinforced laminates. Experiments consisted of moiré measurements of surface-displacement patterns which were compared with theoretical predictions, and examination of failure levels. The experiments were carried out on AVCO 5505 boron and Whitaker 5206 MODMOR II graphite-reinforced angle-ply laminates in which both stacking sequence and fiber orientation were varied parametrically. Moiré techniques were developed which allowed observation of displacements on both the wide surface and along the narrow edge of 1 in.-wide × 16-ply-thick (.085 in.-.105 in.) laminates.
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Abbreviations
- A 11,A 16,A 66 :
-
compliance coefficients of fiber layers (lb−1 in.2)
- b :
-
half width of laminate (in.)
- h :
-
thickness of laminate (in.)
- G m :
-
matrix layer-shear modulus
- S Lc ,S Lt :
-
longitudinal uniaxial strength of fiber layers, compression and tension, respectively (lb-in.−2)
- S Tc ,S Tt :
-
transverse uniaxial strength of fiber layers, compression and tension, respectively (lb-in.−2)
- t m ,t f :
-
matrix-layer and fiber-layer thickness (in.)
- T TL ,T IL :
-
in-plane and interlaminar shear strengths (lb-in.−2)
- u :
-
axial displacement (in.)
- x,y,z :
-
cartesian coordinates with respect to geometric axes (in.)
- θ:
-
fiber orientation (deg)
- \( \in _x \) :
-
axial strain (dimensionless)
- \(\overline \in \) :
-
uniform axial strain (dimensionless)
- \(\sigma _x ,\sigma _y ,\sigma _z ,\tau _{yz} ,\tau _{xz} ,\tau _{xz} \) :
-
stresses in cartesian coordinates with respect to geometric axes of laminate (lb-in.−2)
References
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Oplinger, D.W., Parker, B.S. & Chiang, F.P. Edge-effect studies in fiber-reinforced laminates. Experimental Mechanics 14, 347–354 (1974). https://doi.org/10.1007/BF02323560
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DOI: https://doi.org/10.1007/BF02323560