Hill Engineering has been recently issued its second US patent for the DART™ measurement system. This updated device offers improved residual stress measurements within small-diameter pipe applications, allowing for more accurate analysis in both in-laboratory and non-laboratory settings.
TrueSlot® is an innovative technique for measuring near-surface residual stress that is more reliable than conventional techniques.
TrueSlot® is a residual stress measurement technique for generating a profile of residual stress versus depth from the material surface. The stress computation is similar to slitting but offers more sensitivity near the surface due to the proximity of the strain gage.
Additionally, TrueSlot® is globally less invasive than slitting because the volume of removed material is localized to the surface and does not typically extend through most of the specimen thickness.
A model of a completed TrueSlot® method measurement.
The physical application of TrueSlot® is like hole drilling, however instead of a shallow hole being milled into the body of a specimen containing residual stress, the material removed is a shallow slot. The strain released with each incremental slot depth is measured near the slot using a strain gage.
TrueSlot® is useful for
Production quality control applications
Applications requiring in-field measurements with portable equipment
Near-surface residual stress determination
Parts with large or complex geometry
Applications with challenging measurement access
Applications requiring rapid turn time
TrueSlot® was found to have better repeatability when compared with conventional x-ray diffraction.
Results from the method repeatability study which found TrueSlot® to be a more repeatable measurement method than XRD
We are very excited today because in this blog we cross an incredible milestone: our 200th post! That’s right. Since the inception of the Hill Engineering blog back in March 2016, we have published 200 times.
Let’s take a look back over the past 7 years of blogging bliss!
Strain gages are devices used to measure strain on the surface of an object. These strain measurements can be used to infer the amount of stress induced on the object, as is done with many types of residual stress measurements.
Additionally, strain gages can be used to measure things such as aircraft wing deflection, bridge cable creep, and tensile testing for material properties, making them an ideal tool for in-field measurements.
Strain gages come in many shapes and sizes and can measure strain in a single direction or in multiple directions, depending on the goal of the experiment. Strain gages can be used on a wide variety of materials under many conditions, such as in extreme temperatures or underwater.
Hill Engineering has extensive experience with strain gage application and can help design the experiment needed to reach your project’s goals. Strain gage application can be performed in our laboratory or at your site, to your specifications.
Strain gage application is useful for:
Applications requiring in-field measurements with portable equipment
Measuring strain in multiple directions
Parts in every shape and size – nothing is too big or too small
Measuring residual stress
If you’re interested in how we apply a strain gage to a simple specimen, watch our video:
Strain gages are a key component of many of the residual stress measurements that we perform at Hill Engineering. These small but mighty sensors can also be used for other experiments, and this is something that we highlight in our recent case study.
The heart of work at Hill Engineering has everything to do with residual stress. That’s why we thought it was about time we published a case study giving a general overview of what residual stress is, and why it is so important for designers and manufacturers to consider.
by Adrian DeWald
