Development of "omega" deformeter

Abstract

Since the late thirties of the former century, Strain gauge is a renowned device for the stress-strain measurements on a different kinds of structures. There is a great variety of Strain gauges on the market and despite that fact, usually some specific application requires a unique solution. Far the most frequently, such cases are related to Strain gauge mounting on coarse, hardly accessible or inaccessible surfaces. Methodology proposed by this paper involves a deformeter, actually a pre-formed resilient piece of metal with attached Strain gauge. Commercially, various types of deformeters are available on the market. They are described in the available literature. Usually a minimal span of such deformeter is 50mm or greater. Therefore for a shorter span a dedicated deformeter must be developed. In order to design a multipurpose, widely applicable linear deformeter, with adaptable span, a new concept of Ω form is explored. This paper describes a research and development effort, invested into creation of a new type of deformeter. The design process started with 3D modelling of different Ω forms. Among several drafted shapes an optimal form is selected. Based on a 3D modelling outcome, a prototype of a spring strip is shaped and thermally treated. After that, Strain gauges are bonded to Ω deformeter and the model is justified in the Lab conditions. A very high degree of compliance is achieved with the invented solution, providing operation in a wide stretching range (0-5 mm) including prominent stability under different ambient conditions.