The main goal of this research is the experimental and numerical study on the Fatigue function and failure of the crankshaft of diesel engine of a heavy truck. To do this, a crankshaft of the diesel engine of a heavy truck that has gone under failure after traveling 955000 km, has been used. To examine the sources of this failure, several experimental studies have been carried out including chemical composition, the strength of the material, determining the hardness and the microstructure of the material. Besides, using an elastic– plastic three dimensional finite element method (FEM) model, the location of the maximum stress in the crankshaft was determined using the ‘ ‘ complete crankshaft model’ ’ and ‘ ‘ one crank model’ ’ . Using the results of stress analysis, was a basis for the three-dimensional crack growth model and Fatigue life estimation to determine the stress intensity factor and Fatigue life considering the related parameters and boundary conditions method. At the final stage, using the results gotten from the given model for the Fatigue crack growth, comparing it with experimental results, and examining the whole process, it was concluded that the scratches in crankpin region, was the main reason for the Fatigue failure got from bending-torsional load-combination.

This paper provides a review of the research that has led to our current understanding of the process of Fatigue striation formation. An important question addressed is whether or not at low stress intensity values, Fatigue cracks can propagate intermittently in steels and aluminum alloys. It is concluded that there is no valid evidence for propagation on other than a cycle-by-cycle basis.

Background :With the widespread use of electronic devices, visual Fatigue has become a prevalent issue in modern society. Non-pharmacological interventions, such as facial massage and exercise, have been proposed as effective methods for alleviating visual Fatigue. However, the specific effects and mechanisms behind these interventions require further exploration.Objectives :This systematic review aims to evaluate the effectiveness of facial massage and exercise in reducing visual Fatigue and to explore the underlying mechanisms of these interventions.Methods :A comprehensive search was conducted across multiple databases, including PubMed, Web of Science, Scopus, and the Cochrane Library. Randomized controlled trials and crossover experiments were included for both quantitative and qualitative analyses of relevant studies.Results :The findings suggest that both facial massage and exercise can reduce visual Fatigue. Facial massage alleviates eye strain by stimulating the parasympathetic nervous system, reducing stress and anxiety, relaxing muscles, and improving blood circulation. Exercise alleviates visual Fatigue through two mechanisms: (1) enhancing overall blood circulation, reducing stress, improving sleep quality, and overall health; (2) directly exercising eye muscles through eye yoga, which helps relieve visual Fatigue.Conclusions :Preliminary research indicates that facial massage, full-body exercise, and eye yoga hold potential as non-pharmacological interventions for visual Fatigue. Eye yoga has experimental support for its ability to strengthen eye muscles and improve focus. Massage stimulates parasympathetic activity and boosts blood circulation, while full-body exercise enhances systemic circulation to relieve eye Fatigue. Future research should focus on investigating the mechanisms of these interventions in more detail and comparing the effects of various types, intensities, and durations to provide more precise clinical recommendations.