1·Finally the influence of pretension force to bolt fatigue life is studied and the method that extends the bolt life is proposed.
并研究了螺栓预紧力对螺栓疲劳寿命的影响，提出了延长螺栓寿命的方法。
2·The optimum design for pretensioned structures considering both the pretension force variables and the size variables was discussed.
探讨了以预张力和截面尺寸为设计变量的预张力结构优化设计问题。
3·The principle of the hydraulic pretension is analyzed, the calculation of bolt elongation and pretightening force is also given.
分析了液压拉伸预紧的工作原理，并给出了螺栓伸长量和预紧力的确定方法。