Strain measurements of cylinder magnetostrictive samples by interferometer readings

Magnetoelastic materials are utilized in applications under variable stress in presence of a magnetic field excitation. An accurate characterization of the material behaviour needs of magnetic and strain measurements on the material specimen, usually performed on a dynamic test machine equipped with a magnetic excitation core. Strain measurements are usually made by means of a strain gauge glued on the specimen. This method has some limitations: it requires a bonding of strain gauge for each specimen. Moreover, the strain gauge performs a local strain measurement, which is significant if the magnetization of the sample is uniform. To overcome the above-mentioned limitations of strain gauges in this application, an interferometer with a differential optical setup has been designed and tested onto a measuring machine. The design makes use of symmetric and differential paths by the reference and moving arms of the interferometer, thus compensating for drifts and dead-path of linear set-ups. The interferometer reading is zeroed or corrected afterwards by pre-registering strain of the loading cylinders at the same loading curve to be used for testing the sample. Preliminary results highlight a good repeatability of measured strain. Some further steps are envisaged by suitable control of the strain test runs

Generation of CO2 gas mixtures by dynamic dilution for the development of gaseous certified reference materials

The use of Certified Reference Materials (CRMs) is of utmost importance to achieve the comparability and traceability of data, which are essential features of measurement results in environmental and climate fields. The present paper focuses on the generation of gas mixtures at known composition of carbon dioxide at atmospheric amount-of-substance fraction in synthetic air by means of a dynamic dilution system, designed and implemented at the Istituto Nazionale di Ricerca Metrologica (INRiM). The validation of the dynamic system in terms of amount-of-substance fraction is presented. The system was also used to verify the carbon dioxide amount-ofsubstance fraction of a suite of gas mixtures gravimetrically prepared at INRiM in the framework of the EMPIR Joint Research Project 19ENV05 – STELLAR. Dynamic dilution proved to be an effective tool for the preparation and certification of CRMs for gaseous pollutants (i.e. carbon dioxide, nitrogen oxides) relevant for monitoring environmental pollution and climate changes