2001-- © L. R. Xu at Vanderbilt University and

A. J. Rosakis at California Institute of Technology

If you move your mouse (arrow) to the movie picture, you can watch a real movie. After one impact experiment, we can get 80 photos from the high-speed camera. I just stack 80 pictures altogether and show them again in a slow order. Notice that the real inter-frame time is around 2-8 ms. I used a very slow inter-frame time (0.33 s) in these movies thus your eyes can watch the clear failure process. Those fringes are proportional to the maximum in-plane shear stress according to dynamic photoelasticity. The moving fringe concentration is the dynamic crack tip.

Movie –1 Impact failure process at the center of a model composite laminate. Clear shear shock waves were observed in the Homalite layer because the interfacial crack (delamination) exceeded the shear wave speed of the Homalite material (a kind of brittle polymers). The measured interfacial crack speed was more than 1200 m/s.

Movie –2 The field of view was off the specimen center. Complicated interfacial crack and wave propagation were observed. The intra-layer crack kinked from the upper interface is a kind of mode-I cracks in terms of fracture nature.

Movie 3---Impact failure process at the edge of a model composite laminate recorded by the high-speed camera. First, the stress wave approached the edge, due to the stress singularity at the bi-material edge, interfacial cracks soon initiated and propagated towards the specimen center.

	Movie 4 and 5. Projectile penetration process inside a brittle Homalite layer to simulate the ceramics failure of the ceramics/steel armor

Movie –6. Stress wave propagation and impact failure process in a layered system constituted by a single polymer material (Homalite) with two strong interfacial bonds (the horizontal lines)

	Movie –7. Stress wave propagation and impact failure process in a layered system constituted by a single polymer material (Homalite) with one weak and ductile interface (the horizontal line)

Movie –8. Interaction of the intra-layer crack and the inter-layer crack (the dynamic equivalent of Cook-Gordon Mechanism). Mode-I cracks originated from the free edge due to stress wave reflection. Then, interfacial crack was induced before these branched mode-I crack reached the interface.

Field of view

Movie-9. Dynamic failure process of a two-layer specimen with an initial notch. The crack initiated from the notch induced an interfacial crack. Then, this interfacial crack reduced its speed and branched at the interface because of the coming stress wave.

Movie-10. Dynamic crack deflection at an interface in homogeneous materials. At first, the mode-I incident crack (like a small butterfly) approached the interface (the inclined thin line---interfacial angle 60 degrees). It deflected at the interface and formed a mixed-mode interfacial crack. This mixed-mode interfacial crack then kinked from the interface and branched into many mode-I cracks (similar to a beautiful dragonfly).

	Movie-11. Dynamic crack deflection at an interface in homogeneous materials. At first, the mode-I incident crack (like a small butterfly) approached the interface (the inclined thin line---interfacial angle 45 degrees). It deflected at the interface and formed a mixed-mode interfacial crack.