a)With a rope that is rolled over the corners, the worker raises the loadto a height of 10 m. Weight of load is 30 kg.It is necessary to carry out an ergonomic and biomechanical analysis ofthe given case for the different angles of the rope in relation to thehorizontal plane on which the worker is located. Calculate the optimum position of the worker, the optimum angle and ifit is necessary to redesign the working space or dimension the load that islifted to avoid long-term damage to the health of the worker.- Load L4 / L5- NIOSH / RULA analysis- Conduct Lift / Lover analysis The activity takes place every 10 minutes, 8 hours a day (pause 30 min).Height of worker is 1,8 m.b) CATIA has a well-developed ergonomic platform that allows the user tocustomize and design equipment to maximize productivity by reducing workloadson the worker. For the modeling and calculation of the forces and loads thataffect man in the work environment, we use the toolbar from the”Ergonomics Design and Analysis”, which consists of 4 parts:- Human builder (building a man)- Human measure editor (editing dimensions / measures of man)- Human posture analysis (analysis of man’s posture)- Human activity analysis (analysis of human activity)These four functions allow us to analyze from the comfort of our home,the influence of various forces and loads on man in the working position.
Themodel of the man under analysis in Catia is called “Manikin”.Before we begin to do anything, it is necessary to create a man in hisnatural position and dimensions. To define the dimensions of a person (hisheight and weight) in the CATIA V5 software, we open the Human MeasurementsEditor, where we see a window as in Figure 1. Figure 1. Dimensions of workerAfter setting the height and weight of the workers, in order to carryout the biomechanical analysis, it is necessary to enter the Human activityanalysis module. In this module, we insert the work environment and set theworker positions for each of the analysis cases. Positioning is done using theForward kinematics tool, as shown in Figure.2 a) for one of the positions.
Thena load of 30 kg is added at the required angle as shown in Figure.2 b). a) b)Figure 2. a) Positioning a worker b) Setting a load -Pulling the rope at an angle of 0º Figure 3.
Position of the worker at an angle of 0º and loadresults-Pulling the rope at an angle of 30º Figure 4. Position of the worker at an angle of 30º and loadresults-Pulling the rope at an angle of 45º Figure 5. Position of the worker at an angle of 45º and loadresults-Pulling the rope at an angle of 60º Figure 6. Position of the worker at an angle of 60º and loadresults-Pulling the rope at an angle of 90º Figure 7. Position of the worker at an angle of 90º and loadresultsBiomechanicalanalysisThis analysis implies certain sizes such asabdominal force, abdominal pressure, body movements, forces and moments in thejoints. However, what is most important for this analysis is the force, theload that affects the man’s 4 and 5 lumbar vertebra, which shouldn’t have avalue greater than 3,4 kN. The following figures give a tabular anddiagrammatic representation of the force and moment values of L4 and L5 spacedrelative to the angle between the rope and the vertical.
Figure 8. Spreadsheet of torque and force values on L4 andL5 depending on the pullback angle Figure 9. Graphic of torquevalues on L4 and L5 depending on the angle of pulling the rope Figure 10. Graphic of the pressure value of the pressure onL4 and L5 depending on the angle of pulling the ropeFrom the attached analyse it is clearly seen thatthe optimal angle between the rope and the vertical plane is 90º, and it isachieved by mounting another roller that reduces the pressure force by half itsvalue, and the moment on the L4-L5 by 80-90%.NIOSH/RULA analyseThe RULA assessment tool was developed to evaluatethe exposure of workers to the ergonomic risk factors associated with the upperextremities. The RULA tool looks at the biomechanical and requirements ofholding the neck, upper extremities, and torso when performing a certainactivity.
RULA is designed so that it is easy to use those who do not have advancedknowledge from ergonomics. Using RULA workspace, results for each region of thebody will be shown: shoulders, forearms, wrist, neck, hull, legs. The resultswe get represent the level of risk that the given activity carries with it. Results Level of risk 1-2 There is no risk, no changes are needed 3-4 Small risk, you might need to consider the changes 5-6 Medium risk, carry out further testing, as soon as possible to implement the changes 6+ Very high risk, make changes immediately This analysis will be carried out only for an optimal working position,i.e. for an angle of 90º. Figure 11. RULA analysis for angle 90ºPush-Pull analysis Figure 12.
Push-Pull analysis for angle 90ºThe results of the Push-Pull analysis for a lifting height of 10 m,taking into account the characteristics of a man, give a maximum starting forceof 321 N and a load force of 219N.The load generated by the load of 30kg is 295N.This leads to the conclusion that it is necessary to dimension the loadto a new value, and we adopt a weight of 20 kg. Now it’s a force to overcome aworker around 200N and it meets Push-Pull analysis.