Cone Crack Development during Ball on the Three Balls Test

摘要

A standardized uniaxial four respective three point bend loading of beams is used forrnstrength evaluation at present time. However, in many applications are ceramics components loadedrnin biaxial mode. Therefore appropriate results from biaxial tests are required. A number of testingrnprocedures for biaxial strength testing of plates exists; the ring on ring test is being the mostrncommon and standardized. The disadvantage of ring on ring test setup is significant sensitivity onrnsmall deviation from ideal plan parallel surfaces of test-piece.rnProposed ball on three balls test takes advantage of biaxial loading and very simple experimentalrnsetup allowing usage of various test-piece geometries. The loading configuration is insensitive tornsmall inaccuracies of disk shape. The only relevant parameter playing significant role is thernthickness of test-piece. The three supporting and one loading balls eliminate disadvantage of ring ofrnring test mentioned above. From the experiences of numerical analyses as well as experimentalrnresults is still unclear influence of contact stresses between test-piece and loading ball on resultingrnstress field respectively the influence of cone crack developed due to such stresses. The main aim ofrnthis paper is to describe possibility of cone crack development due to contact stresses.