DEVELOPMENT OF AN AXIAL - TORSION BIAXIAL FATIGUE TESTING MACHINE

Eleazar Cristian Mejia Sanchez¹; Marco Antonio Meggiolaro¹; Jaime Tupiassú Pinho de Castro¹

¹ DEPARTAMENTO DE ENGENHARIA MECÂNICA, PUC-Rio

doi:10.20906/CPS/COB-2015-0450

Resumo

The experimental evaluation of incremental plasticity models and multiaxial fatigue life prediction require the use of multiaxial testing machines. In this paper, an axial-torsion biaxial machine is developed and applied to perform multiaxial fatigue tests. This innovative electromechanical system uses two DC motors connected to gearboxes to generate axial and/or torsion loads. The design of the axial-torsion machine comprises the analysis of its structural integrity, component dimensioning and fatigue life prediction, complete modeling of the resulting dynamic system, development of a control technique, and finally its construction and testing. The control technique applied is a PID sliding control, which combines the advantages of a PID and sliding control. The optimal values of control parameters (proportional, integral, derivative) allow reaching the desired control response and avoid overshoot. The proposed sliding mode controller is chosen to ensure the stability of this electromechanical system. The controller is able to independently specify the axial force and torque load to be applied, being implemented in LabVIEW software running in a cRIO-NI control system. The inputs for both control systems are the error values of each load to be applied to the test specimen. The tension-torsion machine is designed to meet the requirements of a wide range of multiaxial fatigue tests, with a maximum axial force capacity of ±200kN and ±1300N.m torque capacity. The performance of the electromechanical system is experimentally evaluated from stress-strain multiaxial test results.

Palavras-chave: PID Sliding Control; Electromechanical Test Machine; Axial-Torsion Test Machine; Multiaxial Fatigue