LAUSR

The optimisation methodology was applied to design a specific geometry for a ring-shaped clip gauge as a quasi-static displacement measurement. The gauge was designed to maximise sensitivity under various types of constraints, including working range, strength, and installation. The analytical expressions of the ring gauge’s responses and constraints were derived to formulate an optimisation problem. The optimal solution was determined by an optimisation solver in the MathCAD Prime 4 program. The sensitivity of the objective function with respect to the parameters in the optimisation problem evaluated at the optimal solution was also determined. The sensitivity and linearity of the designed ring gauge is in the range of commercial gauges. The accuracy of the ring gauge was better than 0.1%, complying with ASTM standard E1820. Performance of the ring gauge, i.e. its linearity, hysteresis, and repeatability, was better than the DCB gauge reproduced from the standard. Applying the ring gauge to a tensile test with a cracked specimen yielded an accurate displacement measurement. Limitations of the analytical formulation are highlighted and recommendations for improving the formulation are discussed.