โ Scribed by David E Lambert; C Allen Ross
No coin nor oath required. For personal study only.
An experimental procedure and accompanying theoretical analysis is presented to produce a wellcharacterized technique for quantifying dynamic fracture properties of quasi-brittle materials. An analytical and experimental investigation of mode I fracture of concrete was conducted under the dynamic loading of a split Hopkinson pressure bar. Fracture specimens in the form of notched-cavity splitting tension cylinders were subjected to stress wave loading that produced strain rates nearing 10/s. Fracture parameters were extracted by the application of the two-parameter fracture model, a nonlinear fracture model for quasi-brittle materials. Finite element analysis veri"ed the experimental con"guration and addressed inertial contributions within the dynamic environment. Ultra-high-speed digital photography was synchronized with the fracture process to provide additional validation and insight to the experimental technique. Results show that the e!ective fracture toughness and specimen strength both increase signi"cantly with loading rate. The numeric and photographic results validate the experimental technique as a new tool in determining rate dependent material properties.
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