Background

It is common practice to use various residual stress measurement methods to complement each other and fully define a through-thickness stress distribution. Incremental hole-drilling (IHD) and X-ray diffraction (XRD) are two of the most widely used techniques. Although IHD readily provides stress data to some depth, the method is susceptible to large stress uncertainties near the surface. XRD, in contrast, is most suited to finding near-surface stresses.

Objective

Constrain the residual stress distributions obtained through series expansion by using XRD measurements, thereby obtaining full depth stress measurements with reduced uncertainty near the surface.

Method

The proposed method enforces suitable relationships between the amplitude coefficients of the series expansion such that the resultant stress distributions match the XRD measurements. The method is demonstrated on an aluminium alloy 7075 specimen of 10 mm thickness that underwent laser shock peening treatment.

Results

Strong correlation in calculated residual stress distributions was found between the proposed method, standard series expansion and the regularized integral method. The proposed method has reduced stress uncertainty near the surface when compared to both standard series expansion and integral methods of IHD due to its incorporation of near-surface XRD data.

Conclusions

The proposed method allows XRD measurements to be rigorously incorporated into IHD results. The effect of XRD uncertainty on the overall IHD stress distribution is localised to the near-surface measurements.

中文翻译：

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一种利用级数展开法结合XRD和IHD残余应力测量的方法

背景

通常的做法是使用各种残余应力测量方法来相互补充，并完全定义厚度方向的应力分布。增量钻孔（IHD）和X射线衍射（XRD）是最广泛使用的两种技术。尽管IHD可以轻松提供一定深度的应力数据，但该方法易于在表面附近产生较大的应力不确定性。相反，XRD最适合查找近表面应力。

客观的

通过使用XRD测量来限制通过级数展开获得的残余应力分布，从而获得具有减小的表面不确定性的全深度应力测量。

方法

所提出的方法强制了级数展开的振幅系数之间的适当关系，以使所得的应力分布与XRD测量值匹配。该方法在厚度为10 mm的铝合金7075样品上进行了激光冲击喷丸处理。

结果

在建议的方法，标准级数展开和正则化积分方法之间发现了在计算的残余应力分布中的强相关性。与IHD的标准系列扩展法和积分法相比，该方法由于结合了近地表XRD数据而降低了地表附近的应力不确定性。

结论

所提出的方法允许将XRD测量严格地合并到IHD结果中。XRD不确定性对整体IHD应力分布的影响仅限于近地表测量。