Young's modulus surface and Poisson's ratio curve for tetragonal crystals

This paper gives the general expressions for the compliance s'_ijkl, Young's modulus E(hkl) and Poisson's ratio \upsilon (hkl, \theta) along arbitrary loading direction hkl for tetragonal crystals. The representation surface for which the length of the radius vector in the hkl direction equals E(hkl) and representation curve for which the length of the radius vector with angle \theta deviated from the reference directions 00\overline1, 100, 00\overline1, 10\overline1 and 11\overline2 equals \upsilon (100, \theta), \upsilon (001, \theta), \upsilon (110, \theta), \upsilon (101, \theta) and \upsilon (111, \theta) respectively, are constructed for nine tetragonal crystals (ammonium dihydrogen arsenate, ammonium dihydrogen phosphate, barium titanate, indium, nickel sulfate, potassium dihydrogen arsenate, potassium dihydrogen phosphate, tin and zircon). The characteristics of them are analysed in detail.