“…58,[116][117][118][119][120][121][122][123] However, it is still not clear how to design ceramics with these desirable properties (particularly the friction and the erosiveness), though progress is being made in understanding what governs the particle size when a brittle material is comminuted during impact 58,[124][125][126][127][128][129][130][131][132][133][134][135][136][137][138][139][140][141][142] and in measuring the shear strength and friction properties of comminuted ceramic under impact conditions. [143][144][145][146][147][148] There also exists a large body of knowledge about the properties of soils and sands relevant to piledriving, some of which may be relevant to ballistic impact, [149][150][151][152] and also their high strain rate, [153][154][155][156] shock [157][158]…”