The impact fracture created in the elastic-plastic response régime has been characterized in terms of its surface extension and penetration. A numerical dynamic analysis has been performed of a typical impact within this régime to indicate some of the principal characteristics of the contact behaviour and the stress field. The damage has then been analysed, by using simplified postulates based on key features of the impact dynamics and basic fracture mechanics concepts. This has enabled the primary material and target parameters affecting the impact fracture to be identified. Thereafter, some implications for strength degradation and erosion have been discussed.

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The damage threshold for brittle materials impacted by water drops has been studied by using a combination of analytic and numerical approaches to obtain solutions for the impact stress fields and dynamic stress intensity factors. It has been shown that expressions for the damage threshold, which consists of the activation of preexistent surface microcracks, can be derived from these solutions. The expressions identify three types of behavior, depending upon the adjacence of the preexistent cracks to the impact center, vis-a-vis their size, and describe the respective roles of the three important target parameters, the fracture toughness, the elastic wave velocity, and the preexistent flaw size. An absolute damage threshold has also been defined. The conditions at this threshold are demonstrated to be reasonably consistent with available threshold measurements.

The erosive damage of an infrared transparent material by a subsonic water drop impact has been numerically simulated. The important early-time pressure loading characteristics from a water drop impact are discussed, and the predicted target damage (in terms of fracture patterns) is presented for variations in material flaw size, material gain size, and impact velocity.

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