Development of a Multiaxial Loading Device for Mechanical Property Testing

Mechanical mechanisms or components typically subjected to multiaxial loads in engineering practice, and materials in such working conditions usually exhibited new mechanical properties or behaviors that were different from those under uniaxial loads. However, maximum errors of the widely used strength criteria, such as Von Mises and Tresca criteria, could reach up to 15.00% since they were derived equivalently from the results of uniaxial mechanical experiments due to the lack of multiaxial loading devices (MLDs). To utilize materials more safely and effectively, a new MLD based on the hybrid mechanism was designed and fabricated in this article. Meanwhile, its workspace was optimized based on the kinematic analysis, while values of the driving force decreased 66.67% compared to that before. Following mechanical calibration and compensation, the expanded relative uncertainty of the MLD was only 0.42% (k =2). Notably, the maximum error in uniaxial and multiaxial loading experiments on the MLD was merely 2.40%, which demonstrated that it was feasible to perform multiaxial force loading experiments on the MLD. Finally, the coupling and strengthening effects, under different types of loads on a carbon fiber reinforced polymer (CFRP) composite material, were investigated based on the multiaxial force loading experiments.