Experimental Modal Analysis of a Linear Reciprocating Tribometer for Maximum Reciprocating Frequency

Abstract

This work demonstrates estimation of critical reciprocating frequency of a fabricated linear pin-on-reciprocating plate tribometer by modal analysis. Experimental investigation by impact testing and numerical analysis using ANSYS Work bench 14 were performed to extract the modal parameters of individual subsystems. The authors could not find reported literature on of estimation of critical reciprocating frequency of pin-on-reciprocating plate tribometer. Authors developed a pin-onreciprocating plate tribometer that can simulate friction and wear under reciprocating sliding conditions for stroke lengths up to 150 mm. The developed pinon- reciprocating plate tribometer had a loading sub system, transmission subsystem and measurement subsystem. From experimental and numerical estimation of modal parameters, transmission subsystem found to had the lowest modal frequency of 18 Hz. Maximum frequency of reciprocation then fixed at 30% of the lowest modal frequency of 18 Hz that is 5 Hz. Confirmatory friction tests were then conducted on the tribometer and found that identification of maximum frictional force was difficult when the reciprocating frequency of plate of tribometer exceeded 4 Hz due to vibrations in measuring system and agreed with the reported literature. This work addresses the need of methodology for establishing critical reciprocating frequency of tribometer. This paper elaborates the modal analysis of a fabricated linear reciprocating tribometer. Resonance of subsystems in reciprocating tribometer affects experimental estimate of coefficient of friction (CoF). Subsystems have their own individual modal frequencies. Hence, modal analysis of all subsystems becomes obligatory. Tribometer developed for this study can simulate reciprocating friction and wear for stroke lengths up to 150 mm. Experimental and numerical analysis utilized to identify modal frequency of individual subsystems. Tests identified that transmission subsystem had the lowest modal frequency of 18 Hz. Maximum frequency of reciprocation then fixed at 4Hz. This is 25% of the lowest modal frequency of 18 Hz as delineated in literature. Confirmatory friction tests then conducted on the tribometer. Resolving maximum frictional force along the stroke length was impossible over 4 Hz of reciprocating frequency. This is 25% of the lowest modal frequency of structure and agreed with the reported literature. Authors sincerely hope the methodology used in this paper will guide fellow researchers for modal analysis of reciprocating tribometer.