钻孔法中的残余应力场 Ⅰ.理论分析

Residual stress field in hole-drilling method-part I:Theoretical analysis

钻孔法测量残余应力时,由于切削力的作用,会在孔口附近产生加工硬化层。硬化层内材料的特性会发生明显变化,从而影响残余应力的释放。通过增大孔口附近区域材料的弹性模量的方式,将硬化层简化为一个异质圆环,利用弹性力学方法求得了无限大板在双向均布载荷作用下钻孔后的释放应力的解析解。应用有限元软件MSC/Patran&Nastran,对304不锈钢板在二向应力状态下的释放应力进行了数值计算,并与文中的解析解进行了比较。结果表明,将硬化层简化为异质圆环的分析模型是有效的,文中推导的解析解是正确的,钻孔法测量残余应力时考虑硬化层的影响会有助于提高测量精度。

During the residual stress measurement by using the hole-drilling method,a work-hardening layer near the hole will be formed due to the cutting force.As the material characteristics in the work-hardening layer will vary evidently,the layer surrounding the hole can affect the stress relieved after hole drilling.The work-hardening layer was simplified as a heterogeneous annulus by increasing the elastic modulus of the material near the hole,and the analytical solution of the release stresses after drilling in a infinite plate submitted to the biaxial uniform stresses was developed by using the method of elasticity.The release stresses in a 304 stainless steel plate under the biaxial stresses were numerically calculated by the FEM program MSC/Patran & Nastran and compared with the analytical solution.The results indicate that the simplified model is feasible and the analytical solution is valid.When the residual stresses are determined by using the hole-drilling method,it will be more accurate if the work-hardening layer is considered.