A New Loading-Constraining Device for Mechanical Testing With Misalignment Auto-Compensation

Abstract

ABSTRACT. Experimental testing represents the basic approach for mechanical characterization. Due to the high costs for test execution, the research is often developed with the collaboration of several laboratories, finally collating al the results. At this stage problems may arise due to data scattering, often due to (lateral or angular) misalignments between the fixed and the moving machine crossheads. The object of this work is to manufacture and experimentally validate a novel loading-constraining device for misalignment compensation. Conceptual design is applied to investigate on the optimal technical solution. The developed device achieves misalignment reduction with the use of a thrust bearing with sphered housing washers. The bearing is mounted under one of the specimen heads: the inverted orientation of the upper ring, allowing relative lateral displacement between the two rings, and the spherical shape of the washer compensate for offset and angular misalignments. Experimental results showed that such misalignments are respectively reduced to less than 0.02 mm and 0.05°, while the bending strain is lowered to just 6% of the nominal one, so that requirements in different standards for mechanical testing can be fulfilled.

Failure of the chassis of roller skates for agonistic figure skating

“…Strain gauges were connected to form two quarter Wheatstone bridges by three-wire connection. The decision of making use of strain gauges is supported by many papers in literature [5][6][7][8][9][10][11][12][13][14][15][16], dealing with on fields tests by instrumented components or specifically developed load cells. Especially in the case of dynamic loads, the execution of tests in the field is often the only option to get a reliable estimation [6-7, 9, 11, 13, 16].…”

Load Cell Training for the Students of Experimental Stress Analysis

“…This matrix was then inverted to determine the calibration matrix C (Eq. (11)) that yields the unknown loads as a function of the output voltages. In this case too, for the sake of generality, the ratios between output voltages ( e C , e D , e E in mV) and the supply voltage (e 0 , in V) were considered.…”

“…5 -7 Other contributions are regarding sailing 8 or, beyond specific sport applications, the dynamic response of structures under wind 9,10 and the development and checking of testing devices for the mechanics of materials lab experimentation. 11,12 Further interesting applications are in the field of vehicle engineering. Strain gage load cells were used in Refs.…”

Load Cell Training for the Students of Experimental Stress Analysis

“…This matrix was then inverted to determine the calibration matrix C (Eq. (11)) that yields the unknown loads as a function of the output voltages. 23 In this case too, for the sake of generality, the ratios between output voltages ( e C , e D , e E in mV) and the supply voltage (e 0 , in V) were considered.…”