Figure 18. SEM fracture surface image of the 6.35-mm-thick I4 DCB specimen tested under con- Figure 18. SEM fracture surface image of the 6.35-mm-thick I4 DCB specimen tested under constant Figure 18. SEM fracture surface image of the 6.35-mm-thick I4 DCB specimen tested under con- stant amplitude fatigue. amplitude fatigue. stant amplitude fatigue.