常（恒）阈值监控因切削参数或条件的变化而常常导致误判。
Constant thresholds often cause monitoring failures due to changing cutting parameters or conditions .
建立了恒幅常应力和恒幅变应力情况下疲劳寿命可靠度的计算公式。
And set up calculating formulae on the fatigue life reliability under un varying stress amplitude and varying stress amplitude .
常恒