Contact problems for cracks under impact loading

Peer reviewedPublisher PD

Boundary integral equations in the frequency domain for interface linear cracks under impact loading

Peer reviewedPostprin

Contact Problems for Interface Cracks Under Harmonic Shear Loading

Publisher PD

Effects of Crack Closure and Friction for Linear Crack under Normal Impact

Peer reviewedPostprin

Evaluation of reaction kinetics and material properties of cementitious ceramic materials using ultrasonic velocity and attenuation measurements

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Ultrasonic velocity and attenuation measurements have been used to characterise a range of phosphate bonded, alumina filled, magnesia ceramics and other ceramic materials... Measurements were made over a range of frequency from 50kHz - 1 OM Hz, using a variety of commercial probes and equipment, and a variety of techniques. An ultrasonic double-probe method was used to monitor the setting process of the cementitious ceramics using commercial 2.25MHz and 2MHz transducers, for compressional and shear wave modes, respectively, in samples with alumina content in the range of 0 - 60 wt 0/0. The elastic properties of the material were determined from ultrasonic velocity measurements and were found to be dependent upon the filler volume fraction. The measured elastic moduli were found to Increase as porosity decreased, and this effect might possibly be used to estimate porosity. The composition dependence of the elastic moduli is compared with the Hashin and Shtrikman theoretical bounds for the elastic moduli of two-phase materials. All data lie between these bounds, suggesting that the alumina particles were well dispersed and well bonded to the matrix. However, the fact that the data are slightly above the lower bound suggested that the particles are not spherical, and this, together with other evidence obtained from an analysis of reaction rates, indicates the predominence of plate-like gram structures.Science and Engineering Research Council, Central Research Labroratories, and BA Chemicals Ltd