Research On Strain Transfer Mechanism And Temperature Compensated Strain In Structural Strain Measurement

Although the Finite Element Method has been generally applied in aerospace engineering,mechanical engineering,civil engineering and marine engineering,structural strain measurement is still the most objective and reliable method to obtain the stress of structures.In structural strain measurement,the actual stress state of structure is acquired by experimental method and this provides a basis for the analysis of structure strength.The reliability of data of structural strain response is largely dependent on the strain gage,strain transfer mechanism and testing system.Testing principles of all types of strain gages have been studied to ensure the objectivity and accuracy of responsing data.In this paper,theoretical analysis and numerical simulation are used to study the strain transfer mechanism and temperature compensated strain of strain gauges which are commonly used in engineering field.The research contents are summarized as follows:On the basis of the review of various strain testing technologies,the working principles of conventional strain gauge and the relevant test technologies are emphatically introduced;various mechanical models for gauge strain transfer have been conducted respectively considering the different packages,measured substrate,grouting agent,package substrate and clamping way.Computational formula of strain transfer rate has been deduced and strain transfer mechanism of gauge was also been studied thoroughly.An structural analysis software abaqus has been used to build finite elementmodels including surface resistance strain gauge,surface vibrating wire strain gages,surface chip package FBG strain gauge and embedded vibrating wire strain gauges,embedded FBG strain gauge steel package.Sensitivity analysis of related parameters of strain transfer rate has been conducted;besides the results of strain transfer rate obtained respectively from theoretical and numerical analysis have been compared to assess the working performance.With regard to temperature compensated strain in test,the temperature strains of structure being tested,gauge and compensation block have been studied and analysisof the relevance and differences between the three units also has been conducted based on the producing of temperature strain and temperature compensation principle.On the basis,the misunderstanding of current temperature compensation has been pointed out and the environment in which a correct structural strain test can be achieved is given and compensation scheme has also been proposed.Strain transfer and temperature compensated strain of strain gauge are important guarantees for the objectivity and reliability of data from structural strain test.In consequence,the research results have a significant role in guiding the strain sensor development and strain test in scientific and engineering research.