RELIABILITY STUDY OF A CONCEIVED WORKBENCH TO PERFORM FRICTION TESTS UNDER CONTROLLED CONDICTIONS
Antonio Luiz Marques Júnior1; José Ricardo Corrêa de Souza Sobrinho1; Sergio Yoshinobu Araki1; Aron José Pazin de Andrade2; Eduardo Guy Perpétuo Bock1
1 Instituto Federal de Educação, Ciência e Tecnologia de São Paulo; 2 Instituto Dante Pazzanese de Cardiologia, São Paulo, Brasil.
doi:10.20906/CPS/COB-2015-1904
Resumo
A Test Workbench (TW) was designed and built at the Bioengineering Laboratory of the Federal Institute of Technology in Sao Paulo (IFSP) to make the selection of materials used in a Implantable Centrifugal Blood Pump (ICBP). The ICPB is a blood pump for long term ventricular assist in patients with advanced stages of cardiac insufficiency, maintaining blood flow and supporting life. The ICPB can be classified as a Ventricular Assist Device (VAD) of third generation with ceramic-polymeric pivot bearings. The tests are performed in TW evaluating ICBP bearings and the rotor shaft, which are subject to friction. ICBP actuator is composed by Brushless Direct Current Motor BLCDM that is magnetically coupled to the pump impeller. The impeller is supported by the pivot bearings. Various bearings and rotor shafts with predefined dimensions were developed and tested. The methodology used to assess the efficiency of TW was based on functionality and capability to simulate ICPB wear "in loco". The calibration was performed by standard weights on a precision balance. During the tests, the TW provided precise control of the contact pressure between the bearings and the rotor shaft for applying a constant force. A load cell sends an analog signal to an electronic circuit that converts this signal strength and shows it in a liquid crystal display. The speed control is made by an electronic converter, called a frequency inverter. The results of tribological testing of pivot bearing pairs serve for the selection of materials seeking greater mechanical durability of the ICPB. In this study, vibration in ceramic-polymeric pivot bearings was not evaluated although there is a study in parallel for this purpose. The TW was considered a reliable tool to perform the friction test (under controlled conditions). TW is been used to evaluate the wear materials of ICPB pivot bearings. In future, tests conjugating vibration and wear will be performed for a more accurate assessment of the friction inside the pump and its relation with possible
Palavras-chave: Test Workbench; Blood Pumps; Biomaterials; Tribology