Composite Materials Research Progress

160
Yuanxin Zhou, Hassan Mahfuz, Vijaya Rangari et al.
Figure 27. Relationship between composite’s tensile strength and interface strength.
Interface strength is a very important parameter affecting the strength of composite.
Based on the current numerical model, the effect of interface strength on the tensile failure
process of unidirectional composites has been studied. Figure 26 shows the tensile stress–
strain curves of composite with different interface strength (100, 50, 20 and 10MPa). The
relationship between the strength of composites and interface strength are shown in Figure 27.
From Figure 26 and 27, it can be observed that the tensile strength of the composites
increases with interface strength, and when the value of interface strength is over 50 MPa, the
tensile strength of composites tends to be a constant and not affected by interface strength.
Figure 28 shows the simulated micro damage patterns of the composites with weak interface
and strong interface. Comparing these patterns with the macro stress–strain curves, it is
evident that: when the interface strength gets weaker, the adjacent interfaces get easier to
break after the fibers break, the load transfer along the traverse direction gets more
ineffective, the reinforced function of fiber gets more insufficient, the damage area gets
larger, the damage pattern gets more disordered, the negative effect gets greater, thus the
composite’s strength gets lower; when the interface strength gets stronger, the fiber breakage
propagates throughout the composite along the straight line and the composites strength gets
higher.