Relaxation Of Compressive Residual Stress Research Articles

611 プラズマイオン注入・成膜法による厚膜 DLC の作製

The relaxation of compressive residual stress in a diamond-like carbon (DLC) film was achieved by a hybrid process of plasma-based ion implantation and deposition (PBIID), and made it possible to prepare tick DLC film. The compressive residual stress in the DLC film prepared using acetylene gas was decreased with an increase in the negative pulse voltage for ion implantation from 0.46 GPa at no pulsed voltage to 0.16 GPa at the pulsed voltage of -20 kV. The DLC film had about 0.22 GPa that was little dependent on the RF pulse width.

Investigation of residual stress relaxation under cyclic load

Compressive residual stresses induced by mechanical surface treatment such as shot peening, autofretage, hole expansion, laser shock peening, and low-plasticity burnishing can be highly beneficial to fatigue resistance. Cyclic relaxation of compressive residual stress, however, reduces the benefit. An analytical model is proposed for estimation of residual stress relaxation. Parameters considered by the model include the magnitude and distribution of the residual stress, the degree of cold working required, the applied alternating and mean stresses, and the number of applied loading cycles. An elasto–plastic finite element model was used to demonstrate the model.