|
The following conclusion was obtained by making the tensile test, the interpretation of the finite element method, and the 90 degree bending fatigue test in order to study the stress interpretation according to the wire bending angles when manufacturing orthodontic appliances with 0.7/0.8/0.9mm Cr-Ni alloyed stainless steel round wires(spring hard) manufactured by JINSUNG CORP, DENTAURUM and FORESTADENT inthe domestic market. l. As for tensile strength, they didn’t show any big difference. JINSUNG CORP 1,808 MPa DENTAURUM 1,824 MPa FORESTADENT 1,847 MPa 2. The biggest stress occurred at the juncture of the wire and the bending cylinder in the interpretation of 90 degree bending stress. 3. The biggest stress according to edge bending angles when R_(fix) was 0.2mm, increased by 30％, compared with the Rr_(fix) of 4.0mm. The biggest stress of Rr_(fix) of 0.5mm is 1,417 MPa, close to the yield strength of the test specimen(1,412 MPa). and has a bigger probability of fracture. 4. The shorter the wire diameter became in the 90 degree bending fatigue test, the weaker the resistance against fracture became. 5. The shorter the edge bending angle became in the order of 2.Omm,1.5mm and 1.0mm in the 90 degree bending fatigue test, the weaker the resistance against fracture became.
|