The prediction of the critical buckling conditions of shell structures is plagued by imperfection sensitivity. Non-destructive testing through point-load probing has been recently proposed to map the stability landscape of cylindrical shells. However, the counterpart procedure for spherical shells is still debatable. Here, we focus on the mechanical response of pressurized spherical shells containing a single dimple–like defect to a point probe. Combining experiments, finite element modeling, and existing results from classic shell theory, we characterize the nonlinear force-indentation response of imperfect shells at different pressurization levels. From these curves, we seek to identify the critical buckling pressure of the shell. In particular, the indentation angle is varied systematically to examine its effect on the probing efficacy. We find that the critical buckling point can be inferred non-destructively by tracking the maxima of the indentation force–displacement curves, if the probe is implemented sufficiently close to the defect. When probing further away from the defect, the test fails in predicting the onset of buckling since the deformation due to indentation remains localized in the vicinity of the probe. Using FEM simulations and shallow shell theory, we quantify the characteristic length associated with this localized deformation, both in the linear and nonlinear regimes. Our results demonstrate the limiting conditions of applicability for the usage of probing as a non-destructive technique to assess the stability of spherical shells.

壳结构临界屈曲条件的预测受到缺陷敏感性的困扰。最近有人提出通过点载荷探测进行无损检测来绘制圆柱壳的稳定性图。然而，球壳的对应程序仍然存在争议。在这里，我们专注于包含单个凹坑状缺陷的加压球壳对点探针的机械响应。结合实验、有限元建模和经典壳理论的现有结果，我们表征了不完美壳在不同加压水平下的非线性力-压痕响应。从这些曲线中，我们试图确定壳的临界屈曲压力。特别是，压痕角度被系统地改变以检查其对探测效率的影响。我们发现，如果探头足够靠近缺陷，则可以通过跟踪压痕力 - 位移曲线的最大值来非破坏性地推断出临界屈曲点。当探测远离缺陷时，该测试无法预测屈曲的开始，因为压痕引起的变形仍然局限在探针附近。使用有限元模拟和浅壳理论，我们量化了与这种局部变形相关的特征长度，包括线性和非线性区域。我们的结果证明了使用探测作为一种非破坏性技术来评估球壳稳定性的适用性的限制条件。