Optimal Strain Gauge Placement on Testing Samples for Assessing the Effect of Residual Stress in Weld Fatigue

Strain gauges are frequently used for monitoring and for measure of the deformation or strain of a material under stress. They are widely used in fatigue degradation testing, which are methods to evaluate the performance and durability of structures and components under varying loads and cycles. They are also applied on small-scale test samples used for fatigue testing of welds where they are used in determination of hot spot stress that is found to give good reference stress approximations for the fatigue-loaded welded joints. The meticulous selection of optimal strain gauge placement on welded test samples is crucial for capturing the complicated impact of residual stresses. The careful consideration of sample preparation and extraction processes holds paramount significance, as it directly dictates the precision and reliability of the ensuing fatigue test results. This article highlights the significance of placement of strain gauges on test samples for fatigue testing of welds and for the determining residual stress release utilizing the sectioning method. The location of strain gauges should consider factors such as size of the test sample, thickness, weld bead profile, and potential stress concentrations. There have not been given any standard placement and guidelines for location of strain gauges on small-scale test samples or for measuring relies of residual stress applying the section method. Drawing upon a comprehensive literature survey of established principles and guidelines regarding strain gauge placement, this article focuses to offer instructive guidance on the judicious application of strain gauges in the examination of small-scale welded test samples. Furthermore, the paper aims to reveal best practices for employing strain gauges during the extraction process to ascertain the extent of residual stress relief.