Four aspects of service loading of ceramic lined cannons are considered,based upon recentwork with ceramics under cannon thermomechanical loads and upon experience with cannonsmade from more conventional materials.First,candidate ceramics are evaluated by comparingmodels of thermal compressive firing stress with their measured compressive strength at elevatedtemperatures.The strength of each of the ceramics exceeds typical near-bore firing stress,withSiAlON having more margin between high temperature strength and near-bore firing stress thanSiC and Si3N4. Second,an upper bound analysis is performed of the shear failure of a typicalceramic "island"created by thermal cracks and subjected to further compressive firing stress.The analysis shows that failure of cracked ceramic islands is possible.Third,a generic designconcept of a thin ceramic liner is considered,supported by a thicker,intermediate,shrink-fitted,steel liner,and further supported by a shrink-fitted steel or tension-wrapped carbon fiber/epoxyjacket.Radial and hoop fabrication and firing stresses are calculated and axial fabricationstresses are estimated for typical cannon steel and composite properties,showing radial crushingof composites to be a concern.Fourth,a fracture mechanics analysis is used to calculate thecannon firing pressure at which a thermal crack would grow to full depth of the ceramic liner.The low fracture toughness of SiC is a limitation.
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