Study On Biomechanics Of Operating Forest Fire Suppression Hand Pump Based On Ergonomics

Forest fire suppression hand pump is personal fire service equipment widely used in forest fire. In china, the work condition is very terrible. Unreasonable operating force and parameters of operation interface of hand pump will cause the increasing of workload and fatigue, even occupational musculoskeletal disease. Therefore, it is necessary to study on the posture and operating force in the operating of forest fire suppression hand pump based on occupational biomechanics.In this thesis, the factors affecting the operator's physical strength and work ability are analyzed and discussed based on the study of the static operating force of forest fire suppression hand pump. And the effect of postures, size of hand pump, human characteristics on static operating force are studied, so is the effect of hand pump's operation interface parameters on the human physiological stress. Additionally, a model of upper limb operating the hand pump is established to analyze the stress, and the operating postures are analyzed by computer evaluation. Experimental methods involving static mechanics and human balance function are used to research the influence of water bag on the stress of spine and balance function when operating forest fire suppression hand pump. Based on the results above, a multi-level fuzzy evaluation system of forest fire suppression hand pump is established. Studies have shown as following:In different operating posture, there are some differences in the maximum static operating force, while the postures are affected by the hand pump length and human characteristics. Among hand pump operation interface parameters, grip length, grip diameter, operating postures are of significant influence (p<0.05); grip length of 450 800mm is more suitable for Chinese; grip diameter of 35mm is propitious to exert the work ability; when holding hand pump, static operating force with the axis upwards is greater than that with axis downwards.When analyzing the operation interface parameters of forest fire suppression hand pump and physiological load, effect of interface parameters is found both on systemic physiological load and partial muscle load; hand pump's grip length influences the increase ratio of heart rate significantly (p <0.05), and 800mm makes the systemic physiological load relatively larger; hand pump's grip diameter is of significant influence on iEMG of the biceps muscles (p<0.05), and when 35mm in diameter, the physiological load of the muscles is smaller.Mechanical model of forest fire suppression hand pump-operated is established, then the angle between the arms with a maximum operating force and the hand pump is figured out; visualized emulation of the hand pump-operated postures is accomplished by simplifying the arms to a motion system and using the principles of geometry of motion. On these basis, a man-machine analysis interface for forest fire suppression hand pump operation parameters are developed, through which the most reasonable grip length, grip diameter, working pressure of the hand pump can be easily calculated for different body dimension.When working with forest fire suppression hand pump, carrying water increases the work load and the possibility of tumble. Using the principle of static mechanics, based on the analysis of the thoraco-abdominal cavity pressure and muscle strength, a biomechanical model of spine when carrying water bag is established. The effects of weight, position of gravity center and carrying posture of the water bag on the force at lumbar L₅/S₁ joint (inter-vertebral discs between the five lumbar and sacral vertebras) were analyzed, and then the maximum of the weight and posture which are safer were preliminarily fixed. The results indicated that weight, position of gravity center and carrying posture of the water bag had great influence on the force at L₅/S₁. Based on the experimental study on the effect, which the water bag have on body sway and fatigue, it is obtained that the style of water bag has obviously effects on the total length of body sway, the fore-and-aft length of body sway, the displacement velocity(p<0.05).Based on the research findings above, an ergonomic evaluation system for forest fire suppression hand pump is established, and the fuzzy membership function is defined. The weight vector for evaluating is obtained through experimental methods. On these bases, a multi-level fuzzy evaluation model of forest fire suppression hand pump is established. Taking three kinds of hand pump for example, fuzzy comprehensive evaluation on its ergonomic features is carried out.The study offers some reference to fix the operating force of forest fire suppression hand pump, and is of important theoretical value and practical significance for the research on the effect of operation postures on physical strength, work ability and physiological stress. In addition, it is also important for the design and improvement of the tool, the rectification of harmful work posture, the reduction of work fatigue, the preventment and decreasement of occupational musculoskeletal injury and improvement of work efficiency.