Evaluation of mental fatigue in pipe cutting and pipe machining workby fuzzy set

Abstract

Mental fatigue refers to feelings of weariness, somnolence, faintness and distaste for work. It is a state that involves the activating and inhibiting systems of reticular formation in the central nervous system. The effects of mental fatigue may lead to various problems in manufacturing industries such as high risk of accidents, decreased productivity and absenteeism. The objectives of this study were to: 1) compare work strain, i.e., mental fatigue accumulated throughout a day shift, of two kinds of repetitive work 2) study the relationship between fuzzy critical flicker fusion freguency (FCFF) and the assessment using the self-scaling questionnaire 3) attempt to employ results of the study as an indicator of mental fatigue. Both objective and subjective methods were used to carry out this experiment using eight male workers as subjects: four pipe cutting workers and four pipe machining workers. The critical flicker fusion frequency, reaction time and hand grip strength were used to assess the objective measurement. The subjective assessment was obtained by using a self-scaling questionnaire. The results were analyzed by statistical inference. It was concluded that the pipe machining operation was likely to cause a higher level of mental fatigue than the pipe cutting operation. The size of the product also affected the fatigue level.